1 //===- CFG.cpp - Classes for representing and building CFGs ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines the CFG and CFGBuilder classes for representing and
10 // building Control-Flow Graphs (CFGs) from ASTs.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/Analysis/CFG.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Attr.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclBase.h"
19 #include "clang/AST/DeclCXX.h"
20 #include "clang/AST/DeclGroup.h"
21 #include "clang/AST/Expr.h"
22 #include "clang/AST/ExprCXX.h"
23 #include "clang/AST/OperationKinds.h"
24 #include "clang/AST/PrettyPrinter.h"
25 #include "clang/AST/Stmt.h"
26 #include "clang/AST/StmtCXX.h"
27 #include "clang/AST/StmtObjC.h"
28 #include "clang/AST/StmtVisitor.h"
29 #include "clang/AST/Type.h"
30 #include "clang/Analysis/ConstructionContext.h"
31 #include "clang/Analysis/Support/BumpVector.h"
32 #include "clang/Basic/Builtins.h"
33 #include "clang/Basic/ExceptionSpecificationType.h"
34 #include "clang/Basic/JsonSupport.h"
35 #include "clang/Basic/LLVM.h"
36 #include "clang/Basic/LangOptions.h"
37 #include "clang/Basic/SourceLocation.h"
38 #include "clang/Basic/Specifiers.h"
39 #include "llvm/ADT/APInt.h"
40 #include "llvm/ADT/APSInt.h"
41 #include "llvm/ADT/ArrayRef.h"
42 #include "llvm/ADT/DenseMap.h"
43 #include "llvm/ADT/Optional.h"
44 #include "llvm/ADT/STLExtras.h"
45 #include "llvm/ADT/SetVector.h"
46 #include "llvm/ADT/SmallPtrSet.h"
47 #include "llvm/ADT/SmallVector.h"
48 #include "llvm/Support/Allocator.h"
49 #include "llvm/Support/Casting.h"
50 #include "llvm/Support/Compiler.h"
51 #include "llvm/Support/DOTGraphTraits.h"
52 #include "llvm/Support/ErrorHandling.h"
53 #include "llvm/Support/Format.h"
54 #include "llvm/Support/GraphWriter.h"
55 #include "llvm/Support/SaveAndRestore.h"
56 #include "llvm/Support/raw_ostream.h"
57 #include <cassert>
58 #include <memory>
59 #include <string>
60 #include <tuple>
61 #include <utility>
62 #include <vector>
63
64 using namespace clang;
65
GetEndLoc(Decl * D)66 static SourceLocation GetEndLoc(Decl *D) {
67 if (VarDecl *VD = dyn_cast<VarDecl>(D))
68 if (Expr *Ex = VD->getInit())
69 return Ex->getSourceRange().getEnd();
70 return D->getLocation();
71 }
72
73 /// Returns true on constant values based around a single IntegerLiteral.
74 /// Allow for use of parentheses, integer casts, and negative signs.
IsIntegerLiteralConstantExpr(const Expr * E)75 static bool IsIntegerLiteralConstantExpr(const Expr *E) {
76 // Allow parentheses
77 E = E->IgnoreParens();
78
79 // Allow conversions to different integer kind.
80 if (const auto *CE = dyn_cast<CastExpr>(E)) {
81 if (CE->getCastKind() != CK_IntegralCast)
82 return false;
83 E = CE->getSubExpr();
84 }
85
86 // Allow negative numbers.
87 if (const auto *UO = dyn_cast<UnaryOperator>(E)) {
88 if (UO->getOpcode() != UO_Minus)
89 return false;
90 E = UO->getSubExpr();
91 }
92
93 return isa<IntegerLiteral>(E);
94 }
95
96 /// Helper for tryNormalizeBinaryOperator. Attempts to extract an IntegerLiteral
97 /// constant expression or EnumConstantDecl from the given Expr. If it fails,
98 /// returns nullptr.
tryTransformToIntOrEnumConstant(const Expr * E)99 static const Expr *tryTransformToIntOrEnumConstant(const Expr *E) {
100 E = E->IgnoreParens();
101 if (IsIntegerLiteralConstantExpr(E))
102 return E;
103 if (auto *DR = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
104 return isa<EnumConstantDecl>(DR->getDecl()) ? DR : nullptr;
105 return nullptr;
106 }
107
108 /// Tries to interpret a binary operator into `Expr Op NumExpr` form, if
109 /// NumExpr is an integer literal or an enum constant.
110 ///
111 /// If this fails, at least one of the returned DeclRefExpr or Expr will be
112 /// null.
113 static std::tuple<const Expr *, BinaryOperatorKind, const Expr *>
tryNormalizeBinaryOperator(const BinaryOperator * B)114 tryNormalizeBinaryOperator(const BinaryOperator *B) {
115 BinaryOperatorKind Op = B->getOpcode();
116
117 const Expr *MaybeDecl = B->getLHS();
118 const Expr *Constant = tryTransformToIntOrEnumConstant(B->getRHS());
119 // Expr looked like `0 == Foo` instead of `Foo == 0`
120 if (Constant == nullptr) {
121 // Flip the operator
122 if (Op == BO_GT)
123 Op = BO_LT;
124 else if (Op == BO_GE)
125 Op = BO_LE;
126 else if (Op == BO_LT)
127 Op = BO_GT;
128 else if (Op == BO_LE)
129 Op = BO_GE;
130
131 MaybeDecl = B->getRHS();
132 Constant = tryTransformToIntOrEnumConstant(B->getLHS());
133 }
134
135 return std::make_tuple(MaybeDecl, Op, Constant);
136 }
137
138 /// For an expression `x == Foo && x == Bar`, this determines whether the
139 /// `Foo` and `Bar` are either of the same enumeration type, or both integer
140 /// literals.
141 ///
142 /// It's an error to pass this arguments that are not either IntegerLiterals
143 /// or DeclRefExprs (that have decls of type EnumConstantDecl)
areExprTypesCompatible(const Expr * E1,const Expr * E2)144 static bool areExprTypesCompatible(const Expr *E1, const Expr *E2) {
145 // User intent isn't clear if they're mixing int literals with enum
146 // constants.
147 if (isa<DeclRefExpr>(E1) != isa<DeclRefExpr>(E2))
148 return false;
149
150 // Integer literal comparisons, regardless of literal type, are acceptable.
151 if (!isa<DeclRefExpr>(E1))
152 return true;
153
154 // IntegerLiterals are handled above and only EnumConstantDecls are expected
155 // beyond this point
156 assert(isa<DeclRefExpr>(E1) && isa<DeclRefExpr>(E2));
157 auto *Decl1 = cast<DeclRefExpr>(E1)->getDecl();
158 auto *Decl2 = cast<DeclRefExpr>(E2)->getDecl();
159
160 assert(isa<EnumConstantDecl>(Decl1) && isa<EnumConstantDecl>(Decl2));
161 const DeclContext *DC1 = Decl1->getDeclContext();
162 const DeclContext *DC2 = Decl2->getDeclContext();
163
164 assert(isa<EnumDecl>(DC1) && isa<EnumDecl>(DC2));
165 return DC1 == DC2;
166 }
167
168 namespace {
169
170 class CFGBuilder;
171
172 /// The CFG builder uses a recursive algorithm to build the CFG. When
173 /// we process an expression, sometimes we know that we must add the
174 /// subexpressions as block-level expressions. For example:
175 ///
176 /// exp1 || exp2
177 ///
178 /// When processing the '||' expression, we know that exp1 and exp2
179 /// need to be added as block-level expressions, even though they
180 /// might not normally need to be. AddStmtChoice records this
181 /// contextual information. If AddStmtChoice is 'NotAlwaysAdd', then
182 /// the builder has an option not to add a subexpression as a
183 /// block-level expression.
184 class AddStmtChoice {
185 public:
186 enum Kind { NotAlwaysAdd = 0, AlwaysAdd = 1 };
187
AddStmtChoice(Kind a_kind=NotAlwaysAdd)188 AddStmtChoice(Kind a_kind = NotAlwaysAdd) : kind(a_kind) {}
189
190 bool alwaysAdd(CFGBuilder &builder,
191 const Stmt *stmt) const;
192
193 /// Return a copy of this object, except with the 'always-add' bit
194 /// set as specified.
withAlwaysAdd(bool alwaysAdd) const195 AddStmtChoice withAlwaysAdd(bool alwaysAdd) const {
196 return AddStmtChoice(alwaysAdd ? AlwaysAdd : NotAlwaysAdd);
197 }
198
199 private:
200 Kind kind;
201 };
202
203 /// LocalScope - Node in tree of local scopes created for C++ implicit
204 /// destructor calls generation. It contains list of automatic variables
205 /// declared in the scope and link to position in previous scope this scope
206 /// began in.
207 ///
208 /// The process of creating local scopes is as follows:
209 /// - Init CFGBuilder::ScopePos with invalid position (equivalent for null),
210 /// - Before processing statements in scope (e.g. CompoundStmt) create
211 /// LocalScope object using CFGBuilder::ScopePos as link to previous scope
212 /// and set CFGBuilder::ScopePos to the end of new scope,
213 /// - On every occurrence of VarDecl increase CFGBuilder::ScopePos if it points
214 /// at this VarDecl,
215 /// - For every normal (without jump) end of scope add to CFGBlock destructors
216 /// for objects in the current scope,
217 /// - For every jump add to CFGBlock destructors for objects
218 /// between CFGBuilder::ScopePos and local scope position saved for jump
219 /// target. Thanks to C++ restrictions on goto jumps we can be sure that
220 /// jump target position will be on the path to root from CFGBuilder::ScopePos
221 /// (adding any variable that doesn't need constructor to be called to
222 /// LocalScope can break this assumption),
223 ///
224 class LocalScope {
225 public:
226 using AutomaticVarsTy = BumpVector<VarDecl *>;
227
228 /// const_iterator - Iterates local scope backwards and jumps to previous
229 /// scope on reaching the beginning of currently iterated scope.
230 class const_iterator {
231 const LocalScope* Scope = nullptr;
232
233 /// VarIter is guaranteed to be greater then 0 for every valid iterator.
234 /// Invalid iterator (with null Scope) has VarIter equal to 0.
235 unsigned VarIter = 0;
236
237 public:
238 /// Create invalid iterator. Dereferencing invalid iterator is not allowed.
239 /// Incrementing invalid iterator is allowed and will result in invalid
240 /// iterator.
241 const_iterator() = default;
242
243 /// Create valid iterator. In case when S.Prev is an invalid iterator and
244 /// I is equal to 0, this will create invalid iterator.
const_iterator(const LocalScope & S,unsigned I)245 const_iterator(const LocalScope& S, unsigned I)
246 : Scope(&S), VarIter(I) {
247 // Iterator to "end" of scope is not allowed. Handle it by going up
248 // in scopes tree possibly up to invalid iterator in the root.
249 if (VarIter == 0 && Scope)
250 *this = Scope->Prev;
251 }
252
operator ->() const253 VarDecl *const* operator->() const {
254 assert(Scope && "Dereferencing invalid iterator is not allowed");
255 assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
256 return &Scope->Vars[VarIter - 1];
257 }
258
getFirstVarInScope() const259 const VarDecl *getFirstVarInScope() const {
260 assert(Scope && "Dereferencing invalid iterator is not allowed");
261 assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
262 return Scope->Vars[0];
263 }
264
operator *() const265 VarDecl *operator*() const {
266 return *this->operator->();
267 }
268
operator ++()269 const_iterator &operator++() {
270 if (!Scope)
271 return *this;
272
273 assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
274 --VarIter;
275 if (VarIter == 0)
276 *this = Scope->Prev;
277 return *this;
278 }
operator ++(int)279 const_iterator operator++(int) {
280 const_iterator P = *this;
281 ++*this;
282 return P;
283 }
284
operator ==(const const_iterator & rhs) const285 bool operator==(const const_iterator &rhs) const {
286 return Scope == rhs.Scope && VarIter == rhs.VarIter;
287 }
operator !=(const const_iterator & rhs) const288 bool operator!=(const const_iterator &rhs) const {
289 return !(*this == rhs);
290 }
291
operator bool() const292 explicit operator bool() const {
293 return *this != const_iterator();
294 }
295
296 int distance(const_iterator L);
297 const_iterator shared_parent(const_iterator L);
pointsToFirstDeclaredVar()298 bool pointsToFirstDeclaredVar() { return VarIter == 1; }
299 };
300
301 private:
302 BumpVectorContext ctx;
303
304 /// Automatic variables in order of declaration.
305 AutomaticVarsTy Vars;
306
307 /// Iterator to variable in previous scope that was declared just before
308 /// begin of this scope.
309 const_iterator Prev;
310
311 public:
312 /// Constructs empty scope linked to previous scope in specified place.
LocalScope(BumpVectorContext ctx,const_iterator P)313 LocalScope(BumpVectorContext ctx, const_iterator P)
314 : ctx(std::move(ctx)), Vars(this->ctx, 4), Prev(P) {}
315
316 /// Begin of scope in direction of CFG building (backwards).
begin() const317 const_iterator begin() const { return const_iterator(*this, Vars.size()); }
318
addVar(VarDecl * VD)319 void addVar(VarDecl *VD) {
320 Vars.push_back(VD, ctx);
321 }
322 };
323
324 } // namespace
325
326 /// distance - Calculates distance from this to L. L must be reachable from this
327 /// (with use of ++ operator). Cost of calculating the distance is linear w.r.t.
328 /// number of scopes between this and L.
distance(LocalScope::const_iterator L)329 int LocalScope::const_iterator::distance(LocalScope::const_iterator L) {
330 int D = 0;
331 const_iterator F = *this;
332 while (F.Scope != L.Scope) {
333 assert(F != const_iterator() &&
334 "L iterator is not reachable from F iterator.");
335 D += F.VarIter;
336 F = F.Scope->Prev;
337 }
338 D += F.VarIter - L.VarIter;
339 return D;
340 }
341
342 /// Calculates the closest parent of this iterator
343 /// that is in a scope reachable through the parents of L.
344 /// I.e. when using 'goto' from this to L, the lifetime of all variables
345 /// between this and shared_parent(L) end.
346 LocalScope::const_iterator
shared_parent(LocalScope::const_iterator L)347 LocalScope::const_iterator::shared_parent(LocalScope::const_iterator L) {
348 llvm::SmallPtrSet<const LocalScope *, 4> ScopesOfL;
349 while (true) {
350 ScopesOfL.insert(L.Scope);
351 if (L == const_iterator())
352 break;
353 L = L.Scope->Prev;
354 }
355
356 const_iterator F = *this;
357 while (true) {
358 if (ScopesOfL.count(F.Scope))
359 return F;
360 assert(F != const_iterator() &&
361 "L iterator is not reachable from F iterator.");
362 F = F.Scope->Prev;
363 }
364 }
365
366 namespace {
367
368 /// Structure for specifying position in CFG during its build process. It
369 /// consists of CFGBlock that specifies position in CFG and
370 /// LocalScope::const_iterator that specifies position in LocalScope graph.
371 struct BlockScopePosPair {
372 CFGBlock *block = nullptr;
373 LocalScope::const_iterator scopePosition;
374
375 BlockScopePosPair() = default;
BlockScopePosPair__anon372dbe770211::BlockScopePosPair376 BlockScopePosPair(CFGBlock *b, LocalScope::const_iterator scopePos)
377 : block(b), scopePosition(scopePos) {}
378 };
379
380 /// TryResult - a class representing a variant over the values
381 /// 'true', 'false', or 'unknown'. This is returned by tryEvaluateBool,
382 /// and is used by the CFGBuilder to decide if a branch condition
383 /// can be decided up front during CFG construction.
384 class TryResult {
385 int X = -1;
386
387 public:
388 TryResult() = default;
TryResult(bool b)389 TryResult(bool b) : X(b ? 1 : 0) {}
390
isTrue() const391 bool isTrue() const { return X == 1; }
isFalse() const392 bool isFalse() const { return X == 0; }
isKnown() const393 bool isKnown() const { return X >= 0; }
394
negate()395 void negate() {
396 assert(isKnown());
397 X ^= 0x1;
398 }
399 };
400
401 } // namespace
402
bothKnownTrue(TryResult R1,TryResult R2)403 static TryResult bothKnownTrue(TryResult R1, TryResult R2) {
404 if (!R1.isKnown() || !R2.isKnown())
405 return TryResult();
406 return TryResult(R1.isTrue() && R2.isTrue());
407 }
408
409 namespace {
410
411 class reverse_children {
412 llvm::SmallVector<Stmt *, 12> childrenBuf;
413 ArrayRef<Stmt *> children;
414
415 public:
416 reverse_children(Stmt *S);
417
418 using iterator = ArrayRef<Stmt *>::reverse_iterator;
419
begin() const420 iterator begin() const { return children.rbegin(); }
end() const421 iterator end() const { return children.rend(); }
422 };
423
424 } // namespace
425
reverse_children(Stmt * S)426 reverse_children::reverse_children(Stmt *S) {
427 if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
428 children = CE->getRawSubExprs();
429 return;
430 }
431 switch (S->getStmtClass()) {
432 // Note: Fill in this switch with more cases we want to optimize.
433 case Stmt::InitListExprClass: {
434 InitListExpr *IE = cast<InitListExpr>(S);
435 children = llvm::makeArrayRef(reinterpret_cast<Stmt**>(IE->getInits()),
436 IE->getNumInits());
437 return;
438 }
439 default:
440 break;
441 }
442
443 // Default case for all other statements.
444 for (Stmt *SubStmt : S->children())
445 childrenBuf.push_back(SubStmt);
446
447 // This needs to be done *after* childrenBuf has been populated.
448 children = childrenBuf;
449 }
450
451 namespace {
452
453 /// CFGBuilder - This class implements CFG construction from an AST.
454 /// The builder is stateful: an instance of the builder should be used to only
455 /// construct a single CFG.
456 ///
457 /// Example usage:
458 ///
459 /// CFGBuilder builder;
460 /// std::unique_ptr<CFG> cfg = builder.buildCFG(decl, stmt1);
461 ///
462 /// CFG construction is done via a recursive walk of an AST. We actually parse
463 /// the AST in reverse order so that the successor of a basic block is
464 /// constructed prior to its predecessor. This allows us to nicely capture
465 /// implicit fall-throughs without extra basic blocks.
466 class CFGBuilder {
467 using JumpTarget = BlockScopePosPair;
468 using JumpSource = BlockScopePosPair;
469
470 ASTContext *Context;
471 std::unique_ptr<CFG> cfg;
472
473 // Current block.
474 CFGBlock *Block = nullptr;
475
476 // Block after the current block.
477 CFGBlock *Succ = nullptr;
478
479 JumpTarget ContinueJumpTarget;
480 JumpTarget BreakJumpTarget;
481 JumpTarget SEHLeaveJumpTarget;
482 CFGBlock *SwitchTerminatedBlock = nullptr;
483 CFGBlock *DefaultCaseBlock = nullptr;
484
485 // This can point either to a try or a __try block. The frontend forbids
486 // mixing both kinds in one function, so having one for both is enough.
487 CFGBlock *TryTerminatedBlock = nullptr;
488
489 // Current position in local scope.
490 LocalScope::const_iterator ScopePos;
491
492 // LabelMap records the mapping from Label expressions to their jump targets.
493 using LabelMapTy = llvm::DenseMap<LabelDecl *, JumpTarget>;
494 LabelMapTy LabelMap;
495
496 // A list of blocks that end with a "goto" that must be backpatched to their
497 // resolved targets upon completion of CFG construction.
498 using BackpatchBlocksTy = std::vector<JumpSource>;
499 BackpatchBlocksTy BackpatchBlocks;
500
501 // A list of labels whose address has been taken (for indirect gotos).
502 using LabelSetTy = llvm::SmallSetVector<LabelDecl *, 8>;
503 LabelSetTy AddressTakenLabels;
504
505 // Information about the currently visited C++ object construction site.
506 // This is set in the construction trigger and read when the constructor
507 // or a function that returns an object by value is being visited.
508 llvm::DenseMap<Expr *, const ConstructionContextLayer *>
509 ConstructionContextMap;
510
511 using DeclsWithEndedScopeSetTy = llvm::SmallSetVector<VarDecl *, 16>;
512 DeclsWithEndedScopeSetTy DeclsWithEndedScope;
513
514 bool badCFG = false;
515 const CFG::BuildOptions &BuildOpts;
516
517 // State to track for building switch statements.
518 bool switchExclusivelyCovered = false;
519 Expr::EvalResult *switchCond = nullptr;
520
521 CFG::BuildOptions::ForcedBlkExprs::value_type *cachedEntry = nullptr;
522 const Stmt *lastLookup = nullptr;
523
524 // Caches boolean evaluations of expressions to avoid multiple re-evaluations
525 // during construction of branches for chained logical operators.
526 using CachedBoolEvalsTy = llvm::DenseMap<Expr *, TryResult>;
527 CachedBoolEvalsTy CachedBoolEvals;
528
529 public:
CFGBuilder(ASTContext * astContext,const CFG::BuildOptions & buildOpts)530 explicit CFGBuilder(ASTContext *astContext,
531 const CFG::BuildOptions &buildOpts)
532 : Context(astContext), cfg(new CFG()), // crew a new CFG
533 ConstructionContextMap(), BuildOpts(buildOpts) {}
534
535
536 // buildCFG - Used by external clients to construct the CFG.
537 std::unique_ptr<CFG> buildCFG(const Decl *D, Stmt *Statement);
538
539 bool alwaysAdd(const Stmt *stmt);
540
541 private:
542 // Visitors to walk an AST and construct the CFG.
543 CFGBlock *VisitInitListExpr(InitListExpr *ILE, AddStmtChoice asc);
544 CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc);
545 CFGBlock *VisitAttributedStmt(AttributedStmt *A, AddStmtChoice asc);
546 CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc);
547 CFGBlock *VisitBreakStmt(BreakStmt *B);
548 CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc);
549 CFGBlock *VisitCaseStmt(CaseStmt *C);
550 CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc);
551 CFGBlock *VisitCompoundStmt(CompoundStmt *C, bool ExternallyDestructed);
552 CFGBlock *VisitConditionalOperator(AbstractConditionalOperator *C,
553 AddStmtChoice asc);
554 CFGBlock *VisitContinueStmt(ContinueStmt *C);
555 CFGBlock *VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E,
556 AddStmtChoice asc);
557 CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S);
558 CFGBlock *VisitCXXConstructExpr(CXXConstructExpr *C, AddStmtChoice asc);
559 CFGBlock *VisitCXXNewExpr(CXXNewExpr *DE, AddStmtChoice asc);
560 CFGBlock *VisitCXXDeleteExpr(CXXDeleteExpr *DE, AddStmtChoice asc);
561 CFGBlock *VisitCXXForRangeStmt(CXXForRangeStmt *S);
562 CFGBlock *VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
563 AddStmtChoice asc);
564 CFGBlock *VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C,
565 AddStmtChoice asc);
566 CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T);
567 CFGBlock *VisitCXXTryStmt(CXXTryStmt *S);
568 CFGBlock *VisitDeclStmt(DeclStmt *DS);
569 CFGBlock *VisitDeclSubExpr(DeclStmt *DS);
570 CFGBlock *VisitDefaultStmt(DefaultStmt *D);
571 CFGBlock *VisitDoStmt(DoStmt *D);
572 CFGBlock *VisitExprWithCleanups(ExprWithCleanups *E,
573 AddStmtChoice asc, bool ExternallyDestructed);
574 CFGBlock *VisitForStmt(ForStmt *F);
575 CFGBlock *VisitGotoStmt(GotoStmt *G);
576 CFGBlock *VisitGCCAsmStmt(GCCAsmStmt *G, AddStmtChoice asc);
577 CFGBlock *VisitIfStmt(IfStmt *I);
578 CFGBlock *VisitImplicitCastExpr(ImplicitCastExpr *E, AddStmtChoice asc);
579 CFGBlock *VisitConstantExpr(ConstantExpr *E, AddStmtChoice asc);
580 CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I);
581 CFGBlock *VisitLabelStmt(LabelStmt *L);
582 CFGBlock *VisitBlockExpr(BlockExpr *E, AddStmtChoice asc);
583 CFGBlock *VisitLambdaExpr(LambdaExpr *E, AddStmtChoice asc);
584 CFGBlock *VisitLogicalOperator(BinaryOperator *B);
585 std::pair<CFGBlock *, CFGBlock *> VisitLogicalOperator(BinaryOperator *B,
586 Stmt *Term,
587 CFGBlock *TrueBlock,
588 CFGBlock *FalseBlock);
589 CFGBlock *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE,
590 AddStmtChoice asc);
591 CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc);
592 CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S);
593 CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S);
594 CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S);
595 CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S);
596 CFGBlock *VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S);
597 CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S);
598 CFGBlock *VisitObjCMessageExpr(ObjCMessageExpr *E, AddStmtChoice asc);
599 CFGBlock *VisitPseudoObjectExpr(PseudoObjectExpr *E);
600 CFGBlock *VisitReturnStmt(Stmt *S);
601 CFGBlock *VisitSEHExceptStmt(SEHExceptStmt *S);
602 CFGBlock *VisitSEHFinallyStmt(SEHFinallyStmt *S);
603 CFGBlock *VisitSEHLeaveStmt(SEHLeaveStmt *S);
604 CFGBlock *VisitSEHTryStmt(SEHTryStmt *S);
605 CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc);
606 CFGBlock *VisitSwitchStmt(SwitchStmt *S);
607 CFGBlock *VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E,
608 AddStmtChoice asc);
609 CFGBlock *VisitUnaryOperator(UnaryOperator *U, AddStmtChoice asc);
610 CFGBlock *VisitWhileStmt(WhileStmt *W);
611
612 CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd,
613 bool ExternallyDestructed = false);
614 CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc);
615 CFGBlock *VisitChildren(Stmt *S);
616 CFGBlock *VisitNoRecurse(Expr *E, AddStmtChoice asc);
617 CFGBlock *VisitOMPExecutableDirective(OMPExecutableDirective *D,
618 AddStmtChoice asc);
619
maybeAddScopeBeginForVarDecl(CFGBlock * B,const VarDecl * VD,const Stmt * S)620 void maybeAddScopeBeginForVarDecl(CFGBlock *B, const VarDecl *VD,
621 const Stmt *S) {
622 if (ScopePos && (VD == ScopePos.getFirstVarInScope()))
623 appendScopeBegin(B, VD, S);
624 }
625
626 /// When creating the CFG for temporary destructors, we want to mirror the
627 /// branch structure of the corresponding constructor calls.
628 /// Thus, while visiting a statement for temporary destructors, we keep a
629 /// context to keep track of the following information:
630 /// - whether a subexpression is executed unconditionally
631 /// - if a subexpression is executed conditionally, the first
632 /// CXXBindTemporaryExpr we encounter in that subexpression (which
633 /// corresponds to the last temporary destructor we have to call for this
634 /// subexpression) and the CFG block at that point (which will become the
635 /// successor block when inserting the decision point).
636 ///
637 /// That way, we can build the branch structure for temporary destructors as
638 /// follows:
639 /// 1. If a subexpression is executed unconditionally, we add the temporary
640 /// destructor calls to the current block.
641 /// 2. If a subexpression is executed conditionally, when we encounter a
642 /// CXXBindTemporaryExpr:
643 /// a) If it is the first temporary destructor call in the subexpression,
644 /// we remember the CXXBindTemporaryExpr and the current block in the
645 /// TempDtorContext; we start a new block, and insert the temporary
646 /// destructor call.
647 /// b) Otherwise, add the temporary destructor call to the current block.
648 /// 3. When we finished visiting a conditionally executed subexpression,
649 /// and we found at least one temporary constructor during the visitation
650 /// (2.a has executed), we insert a decision block that uses the
651 /// CXXBindTemporaryExpr as terminator, and branches to the current block
652 /// if the CXXBindTemporaryExpr was marked executed, and otherwise
653 /// branches to the stored successor.
654 struct TempDtorContext {
655 TempDtorContext() = default;
TempDtorContext__anon372dbe770411::CFGBuilder::TempDtorContext656 TempDtorContext(TryResult KnownExecuted)
657 : IsConditional(true), KnownExecuted(KnownExecuted) {}
658
659 /// Returns whether we need to start a new branch for a temporary destructor
660 /// call. This is the case when the temporary destructor is
661 /// conditionally executed, and it is the first one we encounter while
662 /// visiting a subexpression - other temporary destructors at the same level
663 /// will be added to the same block and are executed under the same
664 /// condition.
needsTempDtorBranch__anon372dbe770411::CFGBuilder::TempDtorContext665 bool needsTempDtorBranch() const {
666 return IsConditional && !TerminatorExpr;
667 }
668
669 /// Remember the successor S of a temporary destructor decision branch for
670 /// the corresponding CXXBindTemporaryExpr E.
setDecisionPoint__anon372dbe770411::CFGBuilder::TempDtorContext671 void setDecisionPoint(CFGBlock *S, CXXBindTemporaryExpr *E) {
672 Succ = S;
673 TerminatorExpr = E;
674 }
675
676 const bool IsConditional = false;
677 const TryResult KnownExecuted = true;
678 CFGBlock *Succ = nullptr;
679 CXXBindTemporaryExpr *TerminatorExpr = nullptr;
680 };
681
682 // Visitors to walk an AST and generate destructors of temporaries in
683 // full expression.
684 CFGBlock *VisitForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
685 TempDtorContext &Context);
686 CFGBlock *VisitChildrenForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
687 TempDtorContext &Context);
688 CFGBlock *VisitBinaryOperatorForTemporaryDtors(BinaryOperator *E,
689 bool ExternallyDestructed,
690 TempDtorContext &Context);
691 CFGBlock *VisitCXXBindTemporaryExprForTemporaryDtors(
692 CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context);
693 CFGBlock *VisitConditionalOperatorForTemporaryDtors(
694 AbstractConditionalOperator *E, bool ExternallyDestructed,
695 TempDtorContext &Context);
696 void InsertTempDtorDecisionBlock(const TempDtorContext &Context,
697 CFGBlock *FalseSucc = nullptr);
698
699 // NYS == Not Yet Supported
NYS()700 CFGBlock *NYS() {
701 badCFG = true;
702 return Block;
703 }
704
705 // Remember to apply the construction context based on the current \p Layer
706 // when constructing the CFG element for \p CE.
707 void consumeConstructionContext(const ConstructionContextLayer *Layer,
708 Expr *E);
709
710 // Scan \p Child statement to find constructors in it, while keeping in mind
711 // that its parent statement is providing a partial construction context
712 // described by \p Layer. If a constructor is found, it would be assigned
713 // the context based on the layer. If an additional construction context layer
714 // is found, the function recurses into that.
715 void findConstructionContexts(const ConstructionContextLayer *Layer,
716 Stmt *Child);
717
718 // Scan all arguments of a call expression for a construction context.
719 // These sorts of call expressions don't have a common superclass,
720 // hence strict duck-typing.
721 template <typename CallLikeExpr,
722 typename = std::enable_if_t<
723 std::is_base_of<CallExpr, CallLikeExpr>::value ||
724 std::is_base_of<CXXConstructExpr, CallLikeExpr>::value ||
725 std::is_base_of<ObjCMessageExpr, CallLikeExpr>::value>>
findConstructionContextsForArguments(CallLikeExpr * E)726 void findConstructionContextsForArguments(CallLikeExpr *E) {
727 for (unsigned i = 0, e = E->getNumArgs(); i != e; ++i) {
728 Expr *Arg = E->getArg(i);
729 if (Arg->getType()->getAsCXXRecordDecl() && !Arg->isGLValue())
730 findConstructionContexts(
731 ConstructionContextLayer::create(cfg->getBumpVectorContext(),
732 ConstructionContextItem(E, i)),
733 Arg);
734 }
735 }
736
737 // Unset the construction context after consuming it. This is done immediately
738 // after adding the CFGConstructor or CFGCXXRecordTypedCall element, so
739 // there's no need to do this manually in every Visit... function.
740 void cleanupConstructionContext(Expr *E);
741
autoCreateBlock()742 void autoCreateBlock() { if (!Block) Block = createBlock(); }
743 CFGBlock *createBlock(bool add_successor = true);
744 CFGBlock *createNoReturnBlock();
745
addStmt(Stmt * S)746 CFGBlock *addStmt(Stmt *S) {
747 return Visit(S, AddStmtChoice::AlwaysAdd);
748 }
749
750 CFGBlock *addInitializer(CXXCtorInitializer *I);
751 void addLoopExit(const Stmt *LoopStmt);
752 void addAutomaticObjDtors(LocalScope::const_iterator B,
753 LocalScope::const_iterator E, Stmt *S);
754 void addLifetimeEnds(LocalScope::const_iterator B,
755 LocalScope::const_iterator E, Stmt *S);
756 void addAutomaticObjHandling(LocalScope::const_iterator B,
757 LocalScope::const_iterator E, Stmt *S);
758 void addImplicitDtorsForDestructor(const CXXDestructorDecl *DD);
759 void addScopesEnd(LocalScope::const_iterator B, LocalScope::const_iterator E,
760 Stmt *S);
761
762 void getDeclsWithEndedScope(LocalScope::const_iterator B,
763 LocalScope::const_iterator E, Stmt *S);
764
765 // Local scopes creation.
766 LocalScope* createOrReuseLocalScope(LocalScope* Scope);
767
768 void addLocalScopeForStmt(Stmt *S);
769 LocalScope* addLocalScopeForDeclStmt(DeclStmt *DS,
770 LocalScope* Scope = nullptr);
771 LocalScope* addLocalScopeForVarDecl(VarDecl *VD, LocalScope* Scope = nullptr);
772
773 void addLocalScopeAndDtors(Stmt *S);
774
retrieveAndCleanupConstructionContext(Expr * E)775 const ConstructionContext *retrieveAndCleanupConstructionContext(Expr *E) {
776 if (!BuildOpts.AddRichCXXConstructors)
777 return nullptr;
778
779 const ConstructionContextLayer *Layer = ConstructionContextMap.lookup(E);
780 if (!Layer)
781 return nullptr;
782
783 cleanupConstructionContext(E);
784 return ConstructionContext::createFromLayers(cfg->getBumpVectorContext(),
785 Layer);
786 }
787
788 // Interface to CFGBlock - adding CFGElements.
789
appendStmt(CFGBlock * B,const Stmt * S)790 void appendStmt(CFGBlock *B, const Stmt *S) {
791 if (alwaysAdd(S) && cachedEntry)
792 cachedEntry->second = B;
793
794 // All block-level expressions should have already been IgnoreParens()ed.
795 assert(!isa<Expr>(S) || cast<Expr>(S)->IgnoreParens() == S);
796 B->appendStmt(const_cast<Stmt*>(S), cfg->getBumpVectorContext());
797 }
798
appendConstructor(CFGBlock * B,CXXConstructExpr * CE)799 void appendConstructor(CFGBlock *B, CXXConstructExpr *CE) {
800 if (const ConstructionContext *CC =
801 retrieveAndCleanupConstructionContext(CE)) {
802 B->appendConstructor(CE, CC, cfg->getBumpVectorContext());
803 return;
804 }
805
806 // No valid construction context found. Fall back to statement.
807 B->appendStmt(CE, cfg->getBumpVectorContext());
808 }
809
appendCall(CFGBlock * B,CallExpr * CE)810 void appendCall(CFGBlock *B, CallExpr *CE) {
811 if (alwaysAdd(CE) && cachedEntry)
812 cachedEntry->second = B;
813
814 if (const ConstructionContext *CC =
815 retrieveAndCleanupConstructionContext(CE)) {
816 B->appendCXXRecordTypedCall(CE, CC, cfg->getBumpVectorContext());
817 return;
818 }
819
820 // No valid construction context found. Fall back to statement.
821 B->appendStmt(CE, cfg->getBumpVectorContext());
822 }
823
appendInitializer(CFGBlock * B,CXXCtorInitializer * I)824 void appendInitializer(CFGBlock *B, CXXCtorInitializer *I) {
825 B->appendInitializer(I, cfg->getBumpVectorContext());
826 }
827
appendNewAllocator(CFGBlock * B,CXXNewExpr * NE)828 void appendNewAllocator(CFGBlock *B, CXXNewExpr *NE) {
829 B->appendNewAllocator(NE, cfg->getBumpVectorContext());
830 }
831
appendBaseDtor(CFGBlock * B,const CXXBaseSpecifier * BS)832 void appendBaseDtor(CFGBlock *B, const CXXBaseSpecifier *BS) {
833 B->appendBaseDtor(BS, cfg->getBumpVectorContext());
834 }
835
appendMemberDtor(CFGBlock * B,FieldDecl * FD)836 void appendMemberDtor(CFGBlock *B, FieldDecl *FD) {
837 B->appendMemberDtor(FD, cfg->getBumpVectorContext());
838 }
839
appendObjCMessage(CFGBlock * B,ObjCMessageExpr * ME)840 void appendObjCMessage(CFGBlock *B, ObjCMessageExpr *ME) {
841 if (alwaysAdd(ME) && cachedEntry)
842 cachedEntry->second = B;
843
844 if (const ConstructionContext *CC =
845 retrieveAndCleanupConstructionContext(ME)) {
846 B->appendCXXRecordTypedCall(ME, CC, cfg->getBumpVectorContext());
847 return;
848 }
849
850 B->appendStmt(const_cast<ObjCMessageExpr *>(ME),
851 cfg->getBumpVectorContext());
852 }
853
appendTemporaryDtor(CFGBlock * B,CXXBindTemporaryExpr * E)854 void appendTemporaryDtor(CFGBlock *B, CXXBindTemporaryExpr *E) {
855 B->appendTemporaryDtor(E, cfg->getBumpVectorContext());
856 }
857
appendAutomaticObjDtor(CFGBlock * B,VarDecl * VD,Stmt * S)858 void appendAutomaticObjDtor(CFGBlock *B, VarDecl *VD, Stmt *S) {
859 B->appendAutomaticObjDtor(VD, S, cfg->getBumpVectorContext());
860 }
861
appendLifetimeEnds(CFGBlock * B,VarDecl * VD,Stmt * S)862 void appendLifetimeEnds(CFGBlock *B, VarDecl *VD, Stmt *S) {
863 B->appendLifetimeEnds(VD, S, cfg->getBumpVectorContext());
864 }
865
appendLoopExit(CFGBlock * B,const Stmt * LoopStmt)866 void appendLoopExit(CFGBlock *B, const Stmt *LoopStmt) {
867 B->appendLoopExit(LoopStmt, cfg->getBumpVectorContext());
868 }
869
appendDeleteDtor(CFGBlock * B,CXXRecordDecl * RD,CXXDeleteExpr * DE)870 void appendDeleteDtor(CFGBlock *B, CXXRecordDecl *RD, CXXDeleteExpr *DE) {
871 B->appendDeleteDtor(RD, DE, cfg->getBumpVectorContext());
872 }
873
874 void prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk,
875 LocalScope::const_iterator B, LocalScope::const_iterator E);
876
877 void prependAutomaticObjLifetimeWithTerminator(CFGBlock *Blk,
878 LocalScope::const_iterator B,
879 LocalScope::const_iterator E);
880
881 const VarDecl *
882 prependAutomaticObjScopeEndWithTerminator(CFGBlock *Blk,
883 LocalScope::const_iterator B,
884 LocalScope::const_iterator E);
885
addSuccessor(CFGBlock * B,CFGBlock * S,bool IsReachable=true)886 void addSuccessor(CFGBlock *B, CFGBlock *S, bool IsReachable = true) {
887 B->addSuccessor(CFGBlock::AdjacentBlock(S, IsReachable),
888 cfg->getBumpVectorContext());
889 }
890
891 /// Add a reachable successor to a block, with the alternate variant that is
892 /// unreachable.
addSuccessor(CFGBlock * B,CFGBlock * ReachableBlock,CFGBlock * AltBlock)893 void addSuccessor(CFGBlock *B, CFGBlock *ReachableBlock, CFGBlock *AltBlock) {
894 B->addSuccessor(CFGBlock::AdjacentBlock(ReachableBlock, AltBlock),
895 cfg->getBumpVectorContext());
896 }
897
appendScopeBegin(CFGBlock * B,const VarDecl * VD,const Stmt * S)898 void appendScopeBegin(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
899 if (BuildOpts.AddScopes)
900 B->appendScopeBegin(VD, S, cfg->getBumpVectorContext());
901 }
902
prependScopeBegin(CFGBlock * B,const VarDecl * VD,const Stmt * S)903 void prependScopeBegin(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
904 if (BuildOpts.AddScopes)
905 B->prependScopeBegin(VD, S, cfg->getBumpVectorContext());
906 }
907
appendScopeEnd(CFGBlock * B,const VarDecl * VD,const Stmt * S)908 void appendScopeEnd(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
909 if (BuildOpts.AddScopes)
910 B->appendScopeEnd(VD, S, cfg->getBumpVectorContext());
911 }
912
prependScopeEnd(CFGBlock * B,const VarDecl * VD,const Stmt * S)913 void prependScopeEnd(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
914 if (BuildOpts.AddScopes)
915 B->prependScopeEnd(VD, S, cfg->getBumpVectorContext());
916 }
917
918 /// Find a relational comparison with an expression evaluating to a
919 /// boolean and a constant other than 0 and 1.
920 /// e.g. if ((x < y) == 10)
checkIncorrectRelationalOperator(const BinaryOperator * B)921 TryResult checkIncorrectRelationalOperator(const BinaryOperator *B) {
922 const Expr *LHSExpr = B->getLHS()->IgnoreParens();
923 const Expr *RHSExpr = B->getRHS()->IgnoreParens();
924
925 const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
926 const Expr *BoolExpr = RHSExpr;
927 bool IntFirst = true;
928 if (!IntLiteral) {
929 IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
930 BoolExpr = LHSExpr;
931 IntFirst = false;
932 }
933
934 if (!IntLiteral || !BoolExpr->isKnownToHaveBooleanValue())
935 return TryResult();
936
937 llvm::APInt IntValue = IntLiteral->getValue();
938 if ((IntValue == 1) || (IntValue == 0))
939 return TryResult();
940
941 bool IntLarger = IntLiteral->getType()->isUnsignedIntegerType() ||
942 !IntValue.isNegative();
943
944 BinaryOperatorKind Bok = B->getOpcode();
945 if (Bok == BO_GT || Bok == BO_GE) {
946 // Always true for 10 > bool and bool > -1
947 // Always false for -1 > bool and bool > 10
948 return TryResult(IntFirst == IntLarger);
949 } else {
950 // Always true for -1 < bool and bool < 10
951 // Always false for 10 < bool and bool < -1
952 return TryResult(IntFirst != IntLarger);
953 }
954 }
955
956 /// Find an incorrect equality comparison. Either with an expression
957 /// evaluating to a boolean and a constant other than 0 and 1.
958 /// e.g. if (!x == 10) or a bitwise and/or operation that always evaluates to
959 /// true/false e.q. (x & 8) == 4.
checkIncorrectEqualityOperator(const BinaryOperator * B)960 TryResult checkIncorrectEqualityOperator(const BinaryOperator *B) {
961 const Expr *LHSExpr = B->getLHS()->IgnoreParens();
962 const Expr *RHSExpr = B->getRHS()->IgnoreParens();
963
964 const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
965 const Expr *BoolExpr = RHSExpr;
966
967 if (!IntLiteral) {
968 IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
969 BoolExpr = LHSExpr;
970 }
971
972 if (!IntLiteral)
973 return TryResult();
974
975 const BinaryOperator *BitOp = dyn_cast<BinaryOperator>(BoolExpr);
976 if (BitOp && (BitOp->getOpcode() == BO_And ||
977 BitOp->getOpcode() == BO_Or)) {
978 const Expr *LHSExpr2 = BitOp->getLHS()->IgnoreParens();
979 const Expr *RHSExpr2 = BitOp->getRHS()->IgnoreParens();
980
981 const IntegerLiteral *IntLiteral2 = dyn_cast<IntegerLiteral>(LHSExpr2);
982
983 if (!IntLiteral2)
984 IntLiteral2 = dyn_cast<IntegerLiteral>(RHSExpr2);
985
986 if (!IntLiteral2)
987 return TryResult();
988
989 llvm::APInt L1 = IntLiteral->getValue();
990 llvm::APInt L2 = IntLiteral2->getValue();
991 if ((BitOp->getOpcode() == BO_And && (L2 & L1) != L1) ||
992 (BitOp->getOpcode() == BO_Or && (L2 | L1) != L1)) {
993 if (BuildOpts.Observer)
994 BuildOpts.Observer->compareBitwiseEquality(B,
995 B->getOpcode() != BO_EQ);
996 TryResult(B->getOpcode() != BO_EQ);
997 }
998 } else if (BoolExpr->isKnownToHaveBooleanValue()) {
999 llvm::APInt IntValue = IntLiteral->getValue();
1000 if ((IntValue == 1) || (IntValue == 0)) {
1001 return TryResult();
1002 }
1003 return TryResult(B->getOpcode() != BO_EQ);
1004 }
1005
1006 return TryResult();
1007 }
1008
analyzeLogicOperatorCondition(BinaryOperatorKind Relation,const llvm::APSInt & Value1,const llvm::APSInt & Value2)1009 TryResult analyzeLogicOperatorCondition(BinaryOperatorKind Relation,
1010 const llvm::APSInt &Value1,
1011 const llvm::APSInt &Value2) {
1012 assert(Value1.isSigned() == Value2.isSigned());
1013 switch (Relation) {
1014 default:
1015 return TryResult();
1016 case BO_EQ:
1017 return TryResult(Value1 == Value2);
1018 case BO_NE:
1019 return TryResult(Value1 != Value2);
1020 case BO_LT:
1021 return TryResult(Value1 < Value2);
1022 case BO_LE:
1023 return TryResult(Value1 <= Value2);
1024 case BO_GT:
1025 return TryResult(Value1 > Value2);
1026 case BO_GE:
1027 return TryResult(Value1 >= Value2);
1028 }
1029 }
1030
1031 /// Find a pair of comparison expressions with or without parentheses
1032 /// with a shared variable and constants and a logical operator between them
1033 /// that always evaluates to either true or false.
1034 /// e.g. if (x != 3 || x != 4)
checkIncorrectLogicOperator(const BinaryOperator * B)1035 TryResult checkIncorrectLogicOperator(const BinaryOperator *B) {
1036 assert(B->isLogicalOp());
1037 const BinaryOperator *LHS =
1038 dyn_cast<BinaryOperator>(B->getLHS()->IgnoreParens());
1039 const BinaryOperator *RHS =
1040 dyn_cast<BinaryOperator>(B->getRHS()->IgnoreParens());
1041 if (!LHS || !RHS)
1042 return {};
1043
1044 if (!LHS->isComparisonOp() || !RHS->isComparisonOp())
1045 return {};
1046
1047 const Expr *DeclExpr1;
1048 const Expr *NumExpr1;
1049 BinaryOperatorKind BO1;
1050 std::tie(DeclExpr1, BO1, NumExpr1) = tryNormalizeBinaryOperator(LHS);
1051
1052 if (!DeclExpr1 || !NumExpr1)
1053 return {};
1054
1055 const Expr *DeclExpr2;
1056 const Expr *NumExpr2;
1057 BinaryOperatorKind BO2;
1058 std::tie(DeclExpr2, BO2, NumExpr2) = tryNormalizeBinaryOperator(RHS);
1059
1060 if (!DeclExpr2 || !NumExpr2)
1061 return {};
1062
1063 // Check that it is the same variable on both sides.
1064 if (!Expr::isSameComparisonOperand(DeclExpr1, DeclExpr2))
1065 return {};
1066
1067 // Make sure the user's intent is clear (e.g. they're comparing against two
1068 // int literals, or two things from the same enum)
1069 if (!areExprTypesCompatible(NumExpr1, NumExpr2))
1070 return {};
1071
1072 Expr::EvalResult L1Result, L2Result;
1073 if (!NumExpr1->EvaluateAsInt(L1Result, *Context) ||
1074 !NumExpr2->EvaluateAsInt(L2Result, *Context))
1075 return {};
1076
1077 llvm::APSInt L1 = L1Result.Val.getInt();
1078 llvm::APSInt L2 = L2Result.Val.getInt();
1079
1080 // Can't compare signed with unsigned or with different bit width.
1081 if (L1.isSigned() != L2.isSigned() || L1.getBitWidth() != L2.getBitWidth())
1082 return {};
1083
1084 // Values that will be used to determine if result of logical
1085 // operator is always true/false
1086 const llvm::APSInt Values[] = {
1087 // Value less than both Value1 and Value2
1088 llvm::APSInt::getMinValue(L1.getBitWidth(), L1.isUnsigned()),
1089 // L1
1090 L1,
1091 // Value between Value1 and Value2
1092 ((L1 < L2) ? L1 : L2) + llvm::APSInt(llvm::APInt(L1.getBitWidth(), 1),
1093 L1.isUnsigned()),
1094 // L2
1095 L2,
1096 // Value greater than both Value1 and Value2
1097 llvm::APSInt::getMaxValue(L1.getBitWidth(), L1.isUnsigned()),
1098 };
1099
1100 // Check whether expression is always true/false by evaluating the following
1101 // * variable x is less than the smallest literal.
1102 // * variable x is equal to the smallest literal.
1103 // * Variable x is between smallest and largest literal.
1104 // * Variable x is equal to the largest literal.
1105 // * Variable x is greater than largest literal.
1106 bool AlwaysTrue = true, AlwaysFalse = true;
1107 // Track value of both subexpressions. If either side is always
1108 // true/false, another warning should have already been emitted.
1109 bool LHSAlwaysTrue = true, LHSAlwaysFalse = true;
1110 bool RHSAlwaysTrue = true, RHSAlwaysFalse = true;
1111 for (const llvm::APSInt &Value : Values) {
1112 TryResult Res1, Res2;
1113 Res1 = analyzeLogicOperatorCondition(BO1, Value, L1);
1114 Res2 = analyzeLogicOperatorCondition(BO2, Value, L2);
1115
1116 if (!Res1.isKnown() || !Res2.isKnown())
1117 return {};
1118
1119 if (B->getOpcode() == BO_LAnd) {
1120 AlwaysTrue &= (Res1.isTrue() && Res2.isTrue());
1121 AlwaysFalse &= !(Res1.isTrue() && Res2.isTrue());
1122 } else {
1123 AlwaysTrue &= (Res1.isTrue() || Res2.isTrue());
1124 AlwaysFalse &= !(Res1.isTrue() || Res2.isTrue());
1125 }
1126
1127 LHSAlwaysTrue &= Res1.isTrue();
1128 LHSAlwaysFalse &= Res1.isFalse();
1129 RHSAlwaysTrue &= Res2.isTrue();
1130 RHSAlwaysFalse &= Res2.isFalse();
1131 }
1132
1133 if (AlwaysTrue || AlwaysFalse) {
1134 if (!LHSAlwaysTrue && !LHSAlwaysFalse && !RHSAlwaysTrue &&
1135 !RHSAlwaysFalse && BuildOpts.Observer)
1136 BuildOpts.Observer->compareAlwaysTrue(B, AlwaysTrue);
1137 return TryResult(AlwaysTrue);
1138 }
1139 return {};
1140 }
1141
1142 /// A bitwise-or with a non-zero constant always evaluates to true.
checkIncorrectBitwiseOrOperator(const BinaryOperator * B)1143 TryResult checkIncorrectBitwiseOrOperator(const BinaryOperator *B) {
1144 const Expr *LHSConstant =
1145 tryTransformToIntOrEnumConstant(B->getLHS()->IgnoreParenImpCasts());
1146 const Expr *RHSConstant =
1147 tryTransformToIntOrEnumConstant(B->getRHS()->IgnoreParenImpCasts());
1148
1149 if ((LHSConstant && RHSConstant) || (!LHSConstant && !RHSConstant))
1150 return {};
1151
1152 const Expr *Constant = LHSConstant ? LHSConstant : RHSConstant;
1153
1154 Expr::EvalResult Result;
1155 if (!Constant->EvaluateAsInt(Result, *Context))
1156 return {};
1157
1158 if (Result.Val.getInt() == 0)
1159 return {};
1160
1161 if (BuildOpts.Observer)
1162 BuildOpts.Observer->compareBitwiseOr(B);
1163
1164 return TryResult(true);
1165 }
1166
1167 /// Try and evaluate an expression to an integer constant.
tryEvaluate(Expr * S,Expr::EvalResult & outResult)1168 bool tryEvaluate(Expr *S, Expr::EvalResult &outResult) {
1169 if (!BuildOpts.PruneTriviallyFalseEdges)
1170 return false;
1171 return !S->isTypeDependent() &&
1172 !S->isValueDependent() &&
1173 S->EvaluateAsRValue(outResult, *Context);
1174 }
1175
1176 /// tryEvaluateBool - Try and evaluate the Stmt and return 0 or 1
1177 /// if we can evaluate to a known value, otherwise return -1.
tryEvaluateBool(Expr * S)1178 TryResult tryEvaluateBool(Expr *S) {
1179 if (!BuildOpts.PruneTriviallyFalseEdges ||
1180 S->isTypeDependent() || S->isValueDependent())
1181 return {};
1182
1183 if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(S)) {
1184 if (Bop->isLogicalOp() || Bop->isEqualityOp()) {
1185 // Check the cache first.
1186 CachedBoolEvalsTy::iterator I = CachedBoolEvals.find(S);
1187 if (I != CachedBoolEvals.end())
1188 return I->second; // already in map;
1189
1190 // Retrieve result at first, or the map might be updated.
1191 TryResult Result = evaluateAsBooleanConditionNoCache(S);
1192 CachedBoolEvals[S] = Result; // update or insert
1193 return Result;
1194 }
1195 else {
1196 switch (Bop->getOpcode()) {
1197 default: break;
1198 // For 'x & 0' and 'x * 0', we can determine that
1199 // the value is always false.
1200 case BO_Mul:
1201 case BO_And: {
1202 // If either operand is zero, we know the value
1203 // must be false.
1204 Expr::EvalResult LHSResult;
1205 if (Bop->getLHS()->EvaluateAsInt(LHSResult, *Context)) {
1206 llvm::APSInt IntVal = LHSResult.Val.getInt();
1207 if (!IntVal.getBoolValue()) {
1208 return TryResult(false);
1209 }
1210 }
1211 Expr::EvalResult RHSResult;
1212 if (Bop->getRHS()->EvaluateAsInt(RHSResult, *Context)) {
1213 llvm::APSInt IntVal = RHSResult.Val.getInt();
1214 if (!IntVal.getBoolValue()) {
1215 return TryResult(false);
1216 }
1217 }
1218 }
1219 break;
1220 }
1221 }
1222 }
1223
1224 return evaluateAsBooleanConditionNoCache(S);
1225 }
1226
1227 /// Evaluate as boolean \param E without using the cache.
evaluateAsBooleanConditionNoCache(Expr * E)1228 TryResult evaluateAsBooleanConditionNoCache(Expr *E) {
1229 if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(E)) {
1230 if (Bop->isLogicalOp()) {
1231 TryResult LHS = tryEvaluateBool(Bop->getLHS());
1232 if (LHS.isKnown()) {
1233 // We were able to evaluate the LHS, see if we can get away with not
1234 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1
1235 if (LHS.isTrue() == (Bop->getOpcode() == BO_LOr))
1236 return LHS.isTrue();
1237
1238 TryResult RHS = tryEvaluateBool(Bop->getRHS());
1239 if (RHS.isKnown()) {
1240 if (Bop->getOpcode() == BO_LOr)
1241 return LHS.isTrue() || RHS.isTrue();
1242 else
1243 return LHS.isTrue() && RHS.isTrue();
1244 }
1245 } else {
1246 TryResult RHS = tryEvaluateBool(Bop->getRHS());
1247 if (RHS.isKnown()) {
1248 // We can't evaluate the LHS; however, sometimes the result
1249 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
1250 if (RHS.isTrue() == (Bop->getOpcode() == BO_LOr))
1251 return RHS.isTrue();
1252 } else {
1253 TryResult BopRes = checkIncorrectLogicOperator(Bop);
1254 if (BopRes.isKnown())
1255 return BopRes.isTrue();
1256 }
1257 }
1258
1259 return {};
1260 } else if (Bop->isEqualityOp()) {
1261 TryResult BopRes = checkIncorrectEqualityOperator(Bop);
1262 if (BopRes.isKnown())
1263 return BopRes.isTrue();
1264 } else if (Bop->isRelationalOp()) {
1265 TryResult BopRes = checkIncorrectRelationalOperator(Bop);
1266 if (BopRes.isKnown())
1267 return BopRes.isTrue();
1268 } else if (Bop->getOpcode() == BO_Or) {
1269 TryResult BopRes = checkIncorrectBitwiseOrOperator(Bop);
1270 if (BopRes.isKnown())
1271 return BopRes.isTrue();
1272 }
1273 }
1274
1275 bool Result;
1276 if (E->EvaluateAsBooleanCondition(Result, *Context))
1277 return Result;
1278
1279 return {};
1280 }
1281
1282 bool hasTrivialDestructor(VarDecl *VD);
1283 };
1284
1285 } // namespace
1286
alwaysAdd(CFGBuilder & builder,const Stmt * stmt) const1287 inline bool AddStmtChoice::alwaysAdd(CFGBuilder &builder,
1288 const Stmt *stmt) const {
1289 return builder.alwaysAdd(stmt) || kind == AlwaysAdd;
1290 }
1291
alwaysAdd(const Stmt * stmt)1292 bool CFGBuilder::alwaysAdd(const Stmt *stmt) {
1293 bool shouldAdd = BuildOpts.alwaysAdd(stmt);
1294
1295 if (!BuildOpts.forcedBlkExprs)
1296 return shouldAdd;
1297
1298 if (lastLookup == stmt) {
1299 if (cachedEntry) {
1300 assert(cachedEntry->first == stmt);
1301 return true;
1302 }
1303 return shouldAdd;
1304 }
1305
1306 lastLookup = stmt;
1307
1308 // Perform the lookup!
1309 CFG::BuildOptions::ForcedBlkExprs *fb = *BuildOpts.forcedBlkExprs;
1310
1311 if (!fb) {
1312 // No need to update 'cachedEntry', since it will always be null.
1313 assert(!cachedEntry);
1314 return shouldAdd;
1315 }
1316
1317 CFG::BuildOptions::ForcedBlkExprs::iterator itr = fb->find(stmt);
1318 if (itr == fb->end()) {
1319 cachedEntry = nullptr;
1320 return shouldAdd;
1321 }
1322
1323 cachedEntry = &*itr;
1324 return true;
1325 }
1326
1327 // FIXME: Add support for dependent-sized array types in C++?
1328 // Does it even make sense to build a CFG for an uninstantiated template?
FindVA(const Type * t)1329 static const VariableArrayType *FindVA(const Type *t) {
1330 while (const ArrayType *vt = dyn_cast<ArrayType>(t)) {
1331 if (const VariableArrayType *vat = dyn_cast<VariableArrayType>(vt))
1332 if (vat->getSizeExpr())
1333 return vat;
1334
1335 t = vt->getElementType().getTypePtr();
1336 }
1337
1338 return nullptr;
1339 }
1340
consumeConstructionContext(const ConstructionContextLayer * Layer,Expr * E)1341 void CFGBuilder::consumeConstructionContext(
1342 const ConstructionContextLayer *Layer, Expr *E) {
1343 assert((isa<CXXConstructExpr>(E) || isa<CallExpr>(E) ||
1344 isa<ObjCMessageExpr>(E)) && "Expression cannot construct an object!");
1345 if (const ConstructionContextLayer *PreviouslyStoredLayer =
1346 ConstructionContextMap.lookup(E)) {
1347 (void)PreviouslyStoredLayer;
1348 // We might have visited this child when we were finding construction
1349 // contexts within its parents.
1350 assert(PreviouslyStoredLayer->isStrictlyMoreSpecificThan(Layer) &&
1351 "Already within a different construction context!");
1352 } else {
1353 ConstructionContextMap[E] = Layer;
1354 }
1355 }
1356
findConstructionContexts(const ConstructionContextLayer * Layer,Stmt * Child)1357 void CFGBuilder::findConstructionContexts(
1358 const ConstructionContextLayer *Layer, Stmt *Child) {
1359 if (!BuildOpts.AddRichCXXConstructors)
1360 return;
1361
1362 if (!Child)
1363 return;
1364
1365 auto withExtraLayer = [this, Layer](const ConstructionContextItem &Item) {
1366 return ConstructionContextLayer::create(cfg->getBumpVectorContext(), Item,
1367 Layer);
1368 };
1369
1370 switch(Child->getStmtClass()) {
1371 case Stmt::CXXConstructExprClass:
1372 case Stmt::CXXTemporaryObjectExprClass: {
1373 // Support pre-C++17 copy elision AST.
1374 auto *CE = cast<CXXConstructExpr>(Child);
1375 if (BuildOpts.MarkElidedCXXConstructors && CE->isElidable()) {
1376 findConstructionContexts(withExtraLayer(CE), CE->getArg(0));
1377 }
1378
1379 consumeConstructionContext(Layer, CE);
1380 break;
1381 }
1382 // FIXME: This, like the main visit, doesn't support CUDAKernelCallExpr.
1383 // FIXME: An isa<> would look much better but this whole switch is a
1384 // workaround for an internal compiler error in MSVC 2015 (see r326021).
1385 case Stmt::CallExprClass:
1386 case Stmt::CXXMemberCallExprClass:
1387 case Stmt::CXXOperatorCallExprClass:
1388 case Stmt::UserDefinedLiteralClass:
1389 case Stmt::ObjCMessageExprClass: {
1390 auto *E = cast<Expr>(Child);
1391 if (CFGCXXRecordTypedCall::isCXXRecordTypedCall(E))
1392 consumeConstructionContext(Layer, E);
1393 break;
1394 }
1395 case Stmt::ExprWithCleanupsClass: {
1396 auto *Cleanups = cast<ExprWithCleanups>(Child);
1397 findConstructionContexts(Layer, Cleanups->getSubExpr());
1398 break;
1399 }
1400 case Stmt::CXXFunctionalCastExprClass: {
1401 auto *Cast = cast<CXXFunctionalCastExpr>(Child);
1402 findConstructionContexts(Layer, Cast->getSubExpr());
1403 break;
1404 }
1405 case Stmt::ImplicitCastExprClass: {
1406 auto *Cast = cast<ImplicitCastExpr>(Child);
1407 // Should we support other implicit cast kinds?
1408 switch (Cast->getCastKind()) {
1409 case CK_NoOp:
1410 case CK_ConstructorConversion:
1411 findConstructionContexts(Layer, Cast->getSubExpr());
1412 break;
1413 default:
1414 break;
1415 }
1416 break;
1417 }
1418 case Stmt::CXXBindTemporaryExprClass: {
1419 auto *BTE = cast<CXXBindTemporaryExpr>(Child);
1420 findConstructionContexts(withExtraLayer(BTE), BTE->getSubExpr());
1421 break;
1422 }
1423 case Stmt::MaterializeTemporaryExprClass: {
1424 // Normally we don't want to search in MaterializeTemporaryExpr because
1425 // it indicates the beginning of a temporary object construction context,
1426 // so it shouldn't be found in the middle. However, if it is the beginning
1427 // of an elidable copy or move construction context, we need to include it.
1428 if (Layer->getItem().getKind() ==
1429 ConstructionContextItem::ElidableConstructorKind) {
1430 auto *MTE = cast<MaterializeTemporaryExpr>(Child);
1431 findConstructionContexts(withExtraLayer(MTE), MTE->getSubExpr());
1432 }
1433 break;
1434 }
1435 case Stmt::ConditionalOperatorClass: {
1436 auto *CO = cast<ConditionalOperator>(Child);
1437 if (Layer->getItem().getKind() !=
1438 ConstructionContextItem::MaterializationKind) {
1439 // If the object returned by the conditional operator is not going to be a
1440 // temporary object that needs to be immediately materialized, then
1441 // it must be C++17 with its mandatory copy elision. Do not yet promise
1442 // to support this case.
1443 assert(!CO->getType()->getAsCXXRecordDecl() || CO->isGLValue() ||
1444 Context->getLangOpts().CPlusPlus17);
1445 break;
1446 }
1447 findConstructionContexts(Layer, CO->getLHS());
1448 findConstructionContexts(Layer, CO->getRHS());
1449 break;
1450 }
1451 case Stmt::InitListExprClass: {
1452 auto *ILE = cast<InitListExpr>(Child);
1453 if (ILE->isTransparent()) {
1454 findConstructionContexts(Layer, ILE->getInit(0));
1455 break;
1456 }
1457 // TODO: Handle other cases. For now, fail to find construction contexts.
1458 break;
1459 }
1460 case Stmt::ParenExprClass: {
1461 // If expression is placed into parenthesis we should propagate the parent
1462 // construction context to subexpressions.
1463 auto *PE = cast<ParenExpr>(Child);
1464 findConstructionContexts(Layer, PE->getSubExpr());
1465 break;
1466 }
1467 default:
1468 break;
1469 }
1470 }
1471
cleanupConstructionContext(Expr * E)1472 void CFGBuilder::cleanupConstructionContext(Expr *E) {
1473 assert(BuildOpts.AddRichCXXConstructors &&
1474 "We should not be managing construction contexts!");
1475 assert(ConstructionContextMap.count(E) &&
1476 "Cannot exit construction context without the context!");
1477 ConstructionContextMap.erase(E);
1478 }
1479
1480
1481 /// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an
1482 /// arbitrary statement. Examples include a single expression or a function
1483 /// body (compound statement). The ownership of the returned CFG is
1484 /// transferred to the caller. If CFG construction fails, this method returns
1485 /// NULL.
buildCFG(const Decl * D,Stmt * Statement)1486 std::unique_ptr<CFG> CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) {
1487 assert(cfg.get());
1488 if (!Statement)
1489 return nullptr;
1490
1491 // Create an empty block that will serve as the exit block for the CFG. Since
1492 // this is the first block added to the CFG, it will be implicitly registered
1493 // as the exit block.
1494 Succ = createBlock();
1495 assert(Succ == &cfg->getExit());
1496 Block = nullptr; // the EXIT block is empty. Create all other blocks lazily.
1497
1498 assert(!(BuildOpts.AddImplicitDtors && BuildOpts.AddLifetime) &&
1499 "AddImplicitDtors and AddLifetime cannot be used at the same time");
1500
1501 if (BuildOpts.AddImplicitDtors)
1502 if (const CXXDestructorDecl *DD = dyn_cast_or_null<CXXDestructorDecl>(D))
1503 addImplicitDtorsForDestructor(DD);
1504
1505 // Visit the statements and create the CFG.
1506 CFGBlock *B = addStmt(Statement);
1507
1508 if (badCFG)
1509 return nullptr;
1510
1511 // For C++ constructor add initializers to CFG. Constructors of virtual bases
1512 // are ignored unless the object is of the most derived class.
1513 // class VBase { VBase() = default; VBase(int) {} };
1514 // class A : virtual public VBase { A() : VBase(0) {} };
1515 // class B : public A {};
1516 // B b; // Constructor calls in order: VBase(), A(), B().
1517 // // VBase(0) is ignored because A isn't the most derived class.
1518 // This may result in the virtual base(s) being already initialized at this
1519 // point, in which case we should jump right onto non-virtual bases and
1520 // fields. To handle this, make a CFG branch. We only need to add one such
1521 // branch per constructor, since the Standard states that all virtual bases
1522 // shall be initialized before non-virtual bases and direct data members.
1523 if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) {
1524 CFGBlock *VBaseSucc = nullptr;
1525 for (auto *I : llvm::reverse(CD->inits())) {
1526 if (BuildOpts.AddVirtualBaseBranches && !VBaseSucc &&
1527 I->isBaseInitializer() && I->isBaseVirtual()) {
1528 // We've reached the first virtual base init while iterating in reverse
1529 // order. Make a new block for virtual base initializers so that we
1530 // could skip them.
1531 VBaseSucc = Succ = B ? B : &cfg->getExit();
1532 Block = createBlock();
1533 }
1534 B = addInitializer(I);
1535 if (badCFG)
1536 return nullptr;
1537 }
1538 if (VBaseSucc) {
1539 // Make a branch block for potentially skipping virtual base initializers.
1540 Succ = VBaseSucc;
1541 B = createBlock();
1542 B->setTerminator(
1543 CFGTerminator(nullptr, CFGTerminator::VirtualBaseBranch));
1544 addSuccessor(B, Block, true);
1545 }
1546 }
1547
1548 if (B)
1549 Succ = B;
1550
1551 // Backpatch the gotos whose label -> block mappings we didn't know when we
1552 // encountered them.
1553 for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(),
1554 E = BackpatchBlocks.end(); I != E; ++I ) {
1555
1556 CFGBlock *B = I->block;
1557 if (auto *G = dyn_cast<GotoStmt>(B->getTerminator())) {
1558 LabelMapTy::iterator LI = LabelMap.find(G->getLabel());
1559 // If there is no target for the goto, then we are looking at an
1560 // incomplete AST. Handle this by not registering a successor.
1561 if (LI == LabelMap.end())
1562 continue;
1563 JumpTarget JT = LI->second;
1564 prependAutomaticObjLifetimeWithTerminator(B, I->scopePosition,
1565 JT.scopePosition);
1566 prependAutomaticObjDtorsWithTerminator(B, I->scopePosition,
1567 JT.scopePosition);
1568 const VarDecl *VD = prependAutomaticObjScopeEndWithTerminator(
1569 B, I->scopePosition, JT.scopePosition);
1570 appendScopeBegin(JT.block, VD, G);
1571 addSuccessor(B, JT.block);
1572 };
1573 if (auto *G = dyn_cast<GCCAsmStmt>(B->getTerminator())) {
1574 CFGBlock *Successor = (I+1)->block;
1575 for (auto *L : G->labels()) {
1576 LabelMapTy::iterator LI = LabelMap.find(L->getLabel());
1577 // If there is no target for the goto, then we are looking at an
1578 // incomplete AST. Handle this by not registering a successor.
1579 if (LI == LabelMap.end())
1580 continue;
1581 JumpTarget JT = LI->second;
1582 // Successor has been added, so skip it.
1583 if (JT.block == Successor)
1584 continue;
1585 addSuccessor(B, JT.block);
1586 }
1587 I++;
1588 }
1589 }
1590
1591 // Add successors to the Indirect Goto Dispatch block (if we have one).
1592 if (CFGBlock *B = cfg->getIndirectGotoBlock())
1593 for (LabelSetTy::iterator I = AddressTakenLabels.begin(),
1594 E = AddressTakenLabels.end(); I != E; ++I ) {
1595 // Lookup the target block.
1596 LabelMapTy::iterator LI = LabelMap.find(*I);
1597
1598 // If there is no target block that contains label, then we are looking
1599 // at an incomplete AST. Handle this by not registering a successor.
1600 if (LI == LabelMap.end()) continue;
1601
1602 addSuccessor(B, LI->second.block);
1603 }
1604
1605 // Create an empty entry block that has no predecessors.
1606 cfg->setEntry(createBlock());
1607
1608 if (BuildOpts.AddRichCXXConstructors)
1609 assert(ConstructionContextMap.empty() &&
1610 "Not all construction contexts were cleaned up!");
1611
1612 return std::move(cfg);
1613 }
1614
1615 /// createBlock - Used to lazily create blocks that are connected
1616 /// to the current (global) succcessor.
createBlock(bool add_successor)1617 CFGBlock *CFGBuilder::createBlock(bool add_successor) {
1618 CFGBlock *B = cfg->createBlock();
1619 if (add_successor && Succ)
1620 addSuccessor(B, Succ);
1621 return B;
1622 }
1623
1624 /// createNoReturnBlock - Used to create a block is a 'noreturn' point in the
1625 /// CFG. It is *not* connected to the current (global) successor, and instead
1626 /// directly tied to the exit block in order to be reachable.
createNoReturnBlock()1627 CFGBlock *CFGBuilder::createNoReturnBlock() {
1628 CFGBlock *B = createBlock(false);
1629 B->setHasNoReturnElement();
1630 addSuccessor(B, &cfg->getExit(), Succ);
1631 return B;
1632 }
1633
1634 /// addInitializer - Add C++ base or member initializer element to CFG.
addInitializer(CXXCtorInitializer * I)1635 CFGBlock *CFGBuilder::addInitializer(CXXCtorInitializer *I) {
1636 if (!BuildOpts.AddInitializers)
1637 return Block;
1638
1639 bool HasTemporaries = false;
1640
1641 // Destructors of temporaries in initialization expression should be called
1642 // after initialization finishes.
1643 Expr *Init = I->getInit();
1644 if (Init) {
1645 HasTemporaries = isa<ExprWithCleanups>(Init);
1646
1647 if (BuildOpts.AddTemporaryDtors && HasTemporaries) {
1648 // Generate destructors for temporaries in initialization expression.
1649 TempDtorContext Context;
1650 VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(),
1651 /*ExternallyDestructed=*/false, Context);
1652 }
1653 }
1654
1655 autoCreateBlock();
1656 appendInitializer(Block, I);
1657
1658 if (Init) {
1659 findConstructionContexts(
1660 ConstructionContextLayer::create(cfg->getBumpVectorContext(), I),
1661 Init);
1662
1663 if (HasTemporaries) {
1664 // For expression with temporaries go directly to subexpression to omit
1665 // generating destructors for the second time.
1666 return Visit(cast<ExprWithCleanups>(Init)->getSubExpr());
1667 }
1668 if (BuildOpts.AddCXXDefaultInitExprInCtors) {
1669 if (CXXDefaultInitExpr *Default = dyn_cast<CXXDefaultInitExpr>(Init)) {
1670 // In general, appending the expression wrapped by a CXXDefaultInitExpr
1671 // may cause the same Expr to appear more than once in the CFG. Doing it
1672 // here is safe because there's only one initializer per field.
1673 autoCreateBlock();
1674 appendStmt(Block, Default);
1675 if (Stmt *Child = Default->getExpr())
1676 if (CFGBlock *R = Visit(Child))
1677 Block = R;
1678 return Block;
1679 }
1680 }
1681 return Visit(Init);
1682 }
1683
1684 return Block;
1685 }
1686
1687 /// Retrieve the type of the temporary object whose lifetime was
1688 /// extended by a local reference with the given initializer.
getReferenceInitTemporaryType(const Expr * Init,bool * FoundMTE=nullptr)1689 static QualType getReferenceInitTemporaryType(const Expr *Init,
1690 bool *FoundMTE = nullptr) {
1691 while (true) {
1692 // Skip parentheses.
1693 Init = Init->IgnoreParens();
1694
1695 // Skip through cleanups.
1696 if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Init)) {
1697 Init = EWC->getSubExpr();
1698 continue;
1699 }
1700
1701 // Skip through the temporary-materialization expression.
1702 if (const MaterializeTemporaryExpr *MTE
1703 = dyn_cast<MaterializeTemporaryExpr>(Init)) {
1704 Init = MTE->getSubExpr();
1705 if (FoundMTE)
1706 *FoundMTE = true;
1707 continue;
1708 }
1709
1710 // Skip sub-object accesses into rvalues.
1711 SmallVector<const Expr *, 2> CommaLHSs;
1712 SmallVector<SubobjectAdjustment, 2> Adjustments;
1713 const Expr *SkippedInit =
1714 Init->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
1715 if (SkippedInit != Init) {
1716 Init = SkippedInit;
1717 continue;
1718 }
1719
1720 break;
1721 }
1722
1723 return Init->getType();
1724 }
1725
1726 // TODO: Support adding LoopExit element to the CFG in case where the loop is
1727 // ended by ReturnStmt, GotoStmt or ThrowExpr.
addLoopExit(const Stmt * LoopStmt)1728 void CFGBuilder::addLoopExit(const Stmt *LoopStmt){
1729 if(!BuildOpts.AddLoopExit)
1730 return;
1731 autoCreateBlock();
1732 appendLoopExit(Block, LoopStmt);
1733 }
1734
getDeclsWithEndedScope(LocalScope::const_iterator B,LocalScope::const_iterator E,Stmt * S)1735 void CFGBuilder::getDeclsWithEndedScope(LocalScope::const_iterator B,
1736 LocalScope::const_iterator E, Stmt *S) {
1737 if (!BuildOpts.AddScopes)
1738 return;
1739
1740 if (B == E)
1741 return;
1742
1743 // To go from B to E, one first goes up the scopes from B to P
1744 // then sideways in one scope from P to P' and then down
1745 // the scopes from P' to E.
1746 // The lifetime of all objects between B and P end.
1747 LocalScope::const_iterator P = B.shared_parent(E);
1748 int Dist = B.distance(P);
1749 if (Dist <= 0)
1750 return;
1751
1752 for (LocalScope::const_iterator I = B; I != P; ++I)
1753 if (I.pointsToFirstDeclaredVar())
1754 DeclsWithEndedScope.insert(*I);
1755 }
1756
addAutomaticObjHandling(LocalScope::const_iterator B,LocalScope::const_iterator E,Stmt * S)1757 void CFGBuilder::addAutomaticObjHandling(LocalScope::const_iterator B,
1758 LocalScope::const_iterator E,
1759 Stmt *S) {
1760 getDeclsWithEndedScope(B, E, S);
1761 if (BuildOpts.AddScopes)
1762 addScopesEnd(B, E, S);
1763 if (BuildOpts.AddImplicitDtors)
1764 addAutomaticObjDtors(B, E, S);
1765 if (BuildOpts.AddLifetime)
1766 addLifetimeEnds(B, E, S);
1767 }
1768
1769 /// Add to current block automatic objects that leave the scope.
addLifetimeEnds(LocalScope::const_iterator B,LocalScope::const_iterator E,Stmt * S)1770 void CFGBuilder::addLifetimeEnds(LocalScope::const_iterator B,
1771 LocalScope::const_iterator E, Stmt *S) {
1772 if (!BuildOpts.AddLifetime)
1773 return;
1774
1775 if (B == E)
1776 return;
1777
1778 // To go from B to E, one first goes up the scopes from B to P
1779 // then sideways in one scope from P to P' and then down
1780 // the scopes from P' to E.
1781 // The lifetime of all objects between B and P end.
1782 LocalScope::const_iterator P = B.shared_parent(E);
1783 int dist = B.distance(P);
1784 if (dist <= 0)
1785 return;
1786
1787 // We need to perform the scope leaving in reverse order
1788 SmallVector<VarDecl *, 10> DeclsTrivial;
1789 SmallVector<VarDecl *, 10> DeclsNonTrivial;
1790 DeclsTrivial.reserve(dist);
1791 DeclsNonTrivial.reserve(dist);
1792
1793 for (LocalScope::const_iterator I = B; I != P; ++I)
1794 if (hasTrivialDestructor(*I))
1795 DeclsTrivial.push_back(*I);
1796 else
1797 DeclsNonTrivial.push_back(*I);
1798
1799 autoCreateBlock();
1800 // object with trivial destructor end their lifetime last (when storage
1801 // duration ends)
1802 for (SmallVectorImpl<VarDecl *>::reverse_iterator I = DeclsTrivial.rbegin(),
1803 E = DeclsTrivial.rend();
1804 I != E; ++I)
1805 appendLifetimeEnds(Block, *I, S);
1806
1807 for (SmallVectorImpl<VarDecl *>::reverse_iterator
1808 I = DeclsNonTrivial.rbegin(),
1809 E = DeclsNonTrivial.rend();
1810 I != E; ++I)
1811 appendLifetimeEnds(Block, *I, S);
1812 }
1813
1814 /// Add to current block markers for ending scopes.
addScopesEnd(LocalScope::const_iterator B,LocalScope::const_iterator E,Stmt * S)1815 void CFGBuilder::addScopesEnd(LocalScope::const_iterator B,
1816 LocalScope::const_iterator E, Stmt *S) {
1817 // If implicit destructors are enabled, we'll add scope ends in
1818 // addAutomaticObjDtors.
1819 if (BuildOpts.AddImplicitDtors)
1820 return;
1821
1822 autoCreateBlock();
1823
1824 for (auto I = DeclsWithEndedScope.rbegin(), E = DeclsWithEndedScope.rend();
1825 I != E; ++I)
1826 appendScopeEnd(Block, *I, S);
1827
1828 return;
1829 }
1830
1831 /// addAutomaticObjDtors - Add to current block automatic objects destructors
1832 /// for objects in range of local scope positions. Use S as trigger statement
1833 /// for destructors.
addAutomaticObjDtors(LocalScope::const_iterator B,LocalScope::const_iterator E,Stmt * S)1834 void CFGBuilder::addAutomaticObjDtors(LocalScope::const_iterator B,
1835 LocalScope::const_iterator E, Stmt *S) {
1836 if (!BuildOpts.AddImplicitDtors)
1837 return;
1838
1839 if (B == E)
1840 return;
1841
1842 // We need to append the destructors in reverse order, but any one of them
1843 // may be a no-return destructor which changes the CFG. As a result, buffer
1844 // this sequence up and replay them in reverse order when appending onto the
1845 // CFGBlock(s).
1846 SmallVector<VarDecl*, 10> Decls;
1847 Decls.reserve(B.distance(E));
1848 for (LocalScope::const_iterator I = B; I != E; ++I)
1849 Decls.push_back(*I);
1850
1851 for (SmallVectorImpl<VarDecl*>::reverse_iterator I = Decls.rbegin(),
1852 E = Decls.rend();
1853 I != E; ++I) {
1854 if (hasTrivialDestructor(*I)) {
1855 // If AddScopes is enabled and *I is a first variable in a scope, add a
1856 // ScopeEnd marker in a Block.
1857 if (BuildOpts.AddScopes && DeclsWithEndedScope.count(*I)) {
1858 autoCreateBlock();
1859 appendScopeEnd(Block, *I, S);
1860 }
1861 continue;
1862 }
1863 // If this destructor is marked as a no-return destructor, we need to
1864 // create a new block for the destructor which does not have as a successor
1865 // anything built thus far: control won't flow out of this block.
1866 QualType Ty = (*I)->getType();
1867 if (Ty->isReferenceType()) {
1868 Ty = getReferenceInitTemporaryType((*I)->getInit());
1869 }
1870 Ty = Context->getBaseElementType(Ty);
1871
1872 if (Ty->getAsCXXRecordDecl()->isAnyDestructorNoReturn())
1873 Block = createNoReturnBlock();
1874 else
1875 autoCreateBlock();
1876
1877 // Add ScopeEnd just after automatic obj destructor.
1878 if (BuildOpts.AddScopes && DeclsWithEndedScope.count(*I))
1879 appendScopeEnd(Block, *I, S);
1880 appendAutomaticObjDtor(Block, *I, S);
1881 }
1882 }
1883
1884 /// addImplicitDtorsForDestructor - Add implicit destructors generated for
1885 /// base and member objects in destructor.
addImplicitDtorsForDestructor(const CXXDestructorDecl * DD)1886 void CFGBuilder::addImplicitDtorsForDestructor(const CXXDestructorDecl *DD) {
1887 assert(BuildOpts.AddImplicitDtors &&
1888 "Can be called only when dtors should be added");
1889 const CXXRecordDecl *RD = DD->getParent();
1890
1891 // At the end destroy virtual base objects.
1892 for (const auto &VI : RD->vbases()) {
1893 // TODO: Add a VirtualBaseBranch to see if the most derived class
1894 // (which is different from the current class) is responsible for
1895 // destroying them.
1896 const CXXRecordDecl *CD = VI.getType()->getAsCXXRecordDecl();
1897 if (!CD->hasTrivialDestructor()) {
1898 autoCreateBlock();
1899 appendBaseDtor(Block, &VI);
1900 }
1901 }
1902
1903 // Before virtual bases destroy direct base objects.
1904 for (const auto &BI : RD->bases()) {
1905 if (!BI.isVirtual()) {
1906 const CXXRecordDecl *CD = BI.getType()->getAsCXXRecordDecl();
1907 if (!CD->hasTrivialDestructor()) {
1908 autoCreateBlock();
1909 appendBaseDtor(Block, &BI);
1910 }
1911 }
1912 }
1913
1914 // First destroy member objects.
1915 for (auto *FI : RD->fields()) {
1916 // Check for constant size array. Set type to array element type.
1917 QualType QT = FI->getType();
1918 if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
1919 if (AT->getSize() == 0)
1920 continue;
1921 QT = AT->getElementType();
1922 }
1923
1924 if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl())
1925 if (!CD->hasTrivialDestructor()) {
1926 autoCreateBlock();
1927 appendMemberDtor(Block, FI);
1928 }
1929 }
1930 }
1931
1932 /// createOrReuseLocalScope - If Scope is NULL create new LocalScope. Either
1933 /// way return valid LocalScope object.
createOrReuseLocalScope(LocalScope * Scope)1934 LocalScope* CFGBuilder::createOrReuseLocalScope(LocalScope* Scope) {
1935 if (Scope)
1936 return Scope;
1937 llvm::BumpPtrAllocator &alloc = cfg->getAllocator();
1938 return new (alloc.Allocate<LocalScope>())
1939 LocalScope(BumpVectorContext(alloc), ScopePos);
1940 }
1941
1942 /// addLocalScopeForStmt - Add LocalScope to local scopes tree for statement
1943 /// that should create implicit scope (e.g. if/else substatements).
addLocalScopeForStmt(Stmt * S)1944 void CFGBuilder::addLocalScopeForStmt(Stmt *S) {
1945 if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
1946 !BuildOpts.AddScopes)
1947 return;
1948
1949 LocalScope *Scope = nullptr;
1950
1951 // For compound statement we will be creating explicit scope.
1952 if (CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
1953 for (auto *BI : CS->body()) {
1954 Stmt *SI = BI->stripLabelLikeStatements();
1955 if (DeclStmt *DS = dyn_cast<DeclStmt>(SI))
1956 Scope = addLocalScopeForDeclStmt(DS, Scope);
1957 }
1958 return;
1959 }
1960
1961 // For any other statement scope will be implicit and as such will be
1962 // interesting only for DeclStmt.
1963 if (DeclStmt *DS = dyn_cast<DeclStmt>(S->stripLabelLikeStatements()))
1964 addLocalScopeForDeclStmt(DS);
1965 }
1966
1967 /// addLocalScopeForDeclStmt - Add LocalScope for declaration statement. Will
1968 /// reuse Scope if not NULL.
addLocalScopeForDeclStmt(DeclStmt * DS,LocalScope * Scope)1969 LocalScope* CFGBuilder::addLocalScopeForDeclStmt(DeclStmt *DS,
1970 LocalScope* Scope) {
1971 if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
1972 !BuildOpts.AddScopes)
1973 return Scope;
1974
1975 for (auto *DI : DS->decls())
1976 if (VarDecl *VD = dyn_cast<VarDecl>(DI))
1977 Scope = addLocalScopeForVarDecl(VD, Scope);
1978 return Scope;
1979 }
1980
hasTrivialDestructor(VarDecl * VD)1981 bool CFGBuilder::hasTrivialDestructor(VarDecl *VD) {
1982 // Check for const references bound to temporary. Set type to pointee.
1983 QualType QT = VD->getType();
1984 if (QT->isReferenceType()) {
1985 // Attempt to determine whether this declaration lifetime-extends a
1986 // temporary.
1987 //
1988 // FIXME: This is incorrect. Non-reference declarations can lifetime-extend
1989 // temporaries, and a single declaration can extend multiple temporaries.
1990 // We should look at the storage duration on each nested
1991 // MaterializeTemporaryExpr instead.
1992
1993 const Expr *Init = VD->getInit();
1994 if (!Init) {
1995 // Probably an exception catch-by-reference variable.
1996 // FIXME: It doesn't really mean that the object has a trivial destructor.
1997 // Also are there other cases?
1998 return true;
1999 }
2000
2001 // Lifetime-extending a temporary?
2002 bool FoundMTE = false;
2003 QT = getReferenceInitTemporaryType(Init, &FoundMTE);
2004 if (!FoundMTE)
2005 return true;
2006 }
2007
2008 // Check for constant size array. Set type to array element type.
2009 while (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
2010 if (AT->getSize() == 0)
2011 return true;
2012 QT = AT->getElementType();
2013 }
2014
2015 // Check if type is a C++ class with non-trivial destructor.
2016 if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl())
2017 return !CD->hasDefinition() || CD->hasTrivialDestructor();
2018 return true;
2019 }
2020
2021 /// addLocalScopeForVarDecl - Add LocalScope for variable declaration. It will
2022 /// create add scope for automatic objects and temporary objects bound to
2023 /// const reference. Will reuse Scope if not NULL.
addLocalScopeForVarDecl(VarDecl * VD,LocalScope * Scope)2024 LocalScope* CFGBuilder::addLocalScopeForVarDecl(VarDecl *VD,
2025 LocalScope* Scope) {
2026 assert(!(BuildOpts.AddImplicitDtors && BuildOpts.AddLifetime) &&
2027 "AddImplicitDtors and AddLifetime cannot be used at the same time");
2028 if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
2029 !BuildOpts.AddScopes)
2030 return Scope;
2031
2032 // Check if variable is local.
2033 switch (VD->getStorageClass()) {
2034 case SC_None:
2035 case SC_Auto:
2036 case SC_Register:
2037 break;
2038 default: return Scope;
2039 }
2040
2041 if (BuildOpts.AddImplicitDtors) {
2042 if (!hasTrivialDestructor(VD) || BuildOpts.AddScopes) {
2043 // Add the variable to scope
2044 Scope = createOrReuseLocalScope(Scope);
2045 Scope->addVar(VD);
2046 ScopePos = Scope->begin();
2047 }
2048 return Scope;
2049 }
2050
2051 assert(BuildOpts.AddLifetime);
2052 // Add the variable to scope
2053 Scope = createOrReuseLocalScope(Scope);
2054 Scope->addVar(VD);
2055 ScopePos = Scope->begin();
2056 return Scope;
2057 }
2058
2059 /// addLocalScopeAndDtors - For given statement add local scope for it and
2060 /// add destructors that will cleanup the scope. Will reuse Scope if not NULL.
addLocalScopeAndDtors(Stmt * S)2061 void CFGBuilder::addLocalScopeAndDtors(Stmt *S) {
2062 LocalScope::const_iterator scopeBeginPos = ScopePos;
2063 addLocalScopeForStmt(S);
2064 addAutomaticObjHandling(ScopePos, scopeBeginPos, S);
2065 }
2066
2067 /// prependAutomaticObjDtorsWithTerminator - Prepend destructor CFGElements for
2068 /// variables with automatic storage duration to CFGBlock's elements vector.
2069 /// Elements will be prepended to physical beginning of the vector which
2070 /// happens to be logical end. Use blocks terminator as statement that specifies
2071 /// destructors call site.
2072 /// FIXME: This mechanism for adding automatic destructors doesn't handle
2073 /// no-return destructors properly.
prependAutomaticObjDtorsWithTerminator(CFGBlock * Blk,LocalScope::const_iterator B,LocalScope::const_iterator E)2074 void CFGBuilder::prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk,
2075 LocalScope::const_iterator B, LocalScope::const_iterator E) {
2076 if (!BuildOpts.AddImplicitDtors)
2077 return;
2078 BumpVectorContext &C = cfg->getBumpVectorContext();
2079 CFGBlock::iterator InsertPos
2080 = Blk->beginAutomaticObjDtorsInsert(Blk->end(), B.distance(E), C);
2081 for (LocalScope::const_iterator I = B; I != E; ++I)
2082 InsertPos = Blk->insertAutomaticObjDtor(InsertPos, *I,
2083 Blk->getTerminatorStmt());
2084 }
2085
2086 /// prependAutomaticObjLifetimeWithTerminator - Prepend lifetime CFGElements for
2087 /// variables with automatic storage duration to CFGBlock's elements vector.
2088 /// Elements will be prepended to physical beginning of the vector which
2089 /// happens to be logical end. Use blocks terminator as statement that specifies
2090 /// where lifetime ends.
prependAutomaticObjLifetimeWithTerminator(CFGBlock * Blk,LocalScope::const_iterator B,LocalScope::const_iterator E)2091 void CFGBuilder::prependAutomaticObjLifetimeWithTerminator(
2092 CFGBlock *Blk, LocalScope::const_iterator B, LocalScope::const_iterator E) {
2093 if (!BuildOpts.AddLifetime)
2094 return;
2095 BumpVectorContext &C = cfg->getBumpVectorContext();
2096 CFGBlock::iterator InsertPos =
2097 Blk->beginLifetimeEndsInsert(Blk->end(), B.distance(E), C);
2098 for (LocalScope::const_iterator I = B; I != E; ++I) {
2099 InsertPos =
2100 Blk->insertLifetimeEnds(InsertPos, *I, Blk->getTerminatorStmt());
2101 }
2102 }
2103
2104 /// prependAutomaticObjScopeEndWithTerminator - Prepend scope end CFGElements for
2105 /// variables with automatic storage duration to CFGBlock's elements vector.
2106 /// Elements will be prepended to physical beginning of the vector which
2107 /// happens to be logical end. Use blocks terminator as statement that specifies
2108 /// where scope ends.
2109 const VarDecl *
prependAutomaticObjScopeEndWithTerminator(CFGBlock * Blk,LocalScope::const_iterator B,LocalScope::const_iterator E)2110 CFGBuilder::prependAutomaticObjScopeEndWithTerminator(
2111 CFGBlock *Blk, LocalScope::const_iterator B, LocalScope::const_iterator E) {
2112 if (!BuildOpts.AddScopes)
2113 return nullptr;
2114 BumpVectorContext &C = cfg->getBumpVectorContext();
2115 CFGBlock::iterator InsertPos =
2116 Blk->beginScopeEndInsert(Blk->end(), 1, C);
2117 LocalScope::const_iterator PlaceToInsert = B;
2118 for (LocalScope::const_iterator I = B; I != E; ++I)
2119 PlaceToInsert = I;
2120 Blk->insertScopeEnd(InsertPos, *PlaceToInsert, Blk->getTerminatorStmt());
2121 return *PlaceToInsert;
2122 }
2123
2124 /// Visit - Walk the subtree of a statement and add extra
2125 /// blocks for ternary operators, &&, and ||. We also process "," and
2126 /// DeclStmts (which may contain nested control-flow).
Visit(Stmt * S,AddStmtChoice asc,bool ExternallyDestructed)2127 CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc,
2128 bool ExternallyDestructed) {
2129 if (!S) {
2130 badCFG = true;
2131 return nullptr;
2132 }
2133
2134 if (Expr *E = dyn_cast<Expr>(S))
2135 S = E->IgnoreParens();
2136
2137 if (Context->getLangOpts().OpenMP)
2138 if (auto *D = dyn_cast<OMPExecutableDirective>(S))
2139 return VisitOMPExecutableDirective(D, asc);
2140
2141 switch (S->getStmtClass()) {
2142 default:
2143 return VisitStmt(S, asc);
2144
2145 case Stmt::ImplicitValueInitExprClass:
2146 if (BuildOpts.OmitImplicitValueInitializers)
2147 return Block;
2148 return VisitStmt(S, asc);
2149
2150 case Stmt::InitListExprClass:
2151 return VisitInitListExpr(cast<InitListExpr>(S), asc);
2152
2153 case Stmt::AttributedStmtClass:
2154 return VisitAttributedStmt(cast<AttributedStmt>(S), asc);
2155
2156 case Stmt::AddrLabelExprClass:
2157 return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc);
2158
2159 case Stmt::BinaryConditionalOperatorClass:
2160 return VisitConditionalOperator(cast<BinaryConditionalOperator>(S), asc);
2161
2162 case Stmt::BinaryOperatorClass:
2163 return VisitBinaryOperator(cast<BinaryOperator>(S), asc);
2164
2165 case Stmt::BlockExprClass:
2166 return VisitBlockExpr(cast<BlockExpr>(S), asc);
2167
2168 case Stmt::BreakStmtClass:
2169 return VisitBreakStmt(cast<BreakStmt>(S));
2170
2171 case Stmt::CallExprClass:
2172 case Stmt::CXXOperatorCallExprClass:
2173 case Stmt::CXXMemberCallExprClass:
2174 case Stmt::UserDefinedLiteralClass:
2175 return VisitCallExpr(cast<CallExpr>(S), asc);
2176
2177 case Stmt::CaseStmtClass:
2178 return VisitCaseStmt(cast<CaseStmt>(S));
2179
2180 case Stmt::ChooseExprClass:
2181 return VisitChooseExpr(cast<ChooseExpr>(S), asc);
2182
2183 case Stmt::CompoundStmtClass:
2184 return VisitCompoundStmt(cast<CompoundStmt>(S), ExternallyDestructed);
2185
2186 case Stmt::ConditionalOperatorClass:
2187 return VisitConditionalOperator(cast<ConditionalOperator>(S), asc);
2188
2189 case Stmt::ContinueStmtClass:
2190 return VisitContinueStmt(cast<ContinueStmt>(S));
2191
2192 case Stmt::CXXCatchStmtClass:
2193 return VisitCXXCatchStmt(cast<CXXCatchStmt>(S));
2194
2195 case Stmt::ExprWithCleanupsClass:
2196 return VisitExprWithCleanups(cast<ExprWithCleanups>(S),
2197 asc, ExternallyDestructed);
2198
2199 case Stmt::CXXDefaultArgExprClass:
2200 case Stmt::CXXDefaultInitExprClass:
2201 // FIXME: The expression inside a CXXDefaultArgExpr is owned by the
2202 // called function's declaration, not by the caller. If we simply add
2203 // this expression to the CFG, we could end up with the same Expr
2204 // appearing multiple times.
2205 // PR13385 / <rdar://problem/12156507>
2206 //
2207 // It's likewise possible for multiple CXXDefaultInitExprs for the same
2208 // expression to be used in the same function (through aggregate
2209 // initialization).
2210 return VisitStmt(S, asc);
2211
2212 case Stmt::CXXBindTemporaryExprClass:
2213 return VisitCXXBindTemporaryExpr(cast<CXXBindTemporaryExpr>(S), asc);
2214
2215 case Stmt::CXXConstructExprClass:
2216 return VisitCXXConstructExpr(cast<CXXConstructExpr>(S), asc);
2217
2218 case Stmt::CXXNewExprClass:
2219 return VisitCXXNewExpr(cast<CXXNewExpr>(S), asc);
2220
2221 case Stmt::CXXDeleteExprClass:
2222 return VisitCXXDeleteExpr(cast<CXXDeleteExpr>(S), asc);
2223
2224 case Stmt::CXXFunctionalCastExprClass:
2225 return VisitCXXFunctionalCastExpr(cast<CXXFunctionalCastExpr>(S), asc);
2226
2227 case Stmt::CXXTemporaryObjectExprClass:
2228 return VisitCXXTemporaryObjectExpr(cast<CXXTemporaryObjectExpr>(S), asc);
2229
2230 case Stmt::CXXThrowExprClass:
2231 return VisitCXXThrowExpr(cast<CXXThrowExpr>(S));
2232
2233 case Stmt::CXXTryStmtClass:
2234 return VisitCXXTryStmt(cast<CXXTryStmt>(S));
2235
2236 case Stmt::CXXForRangeStmtClass:
2237 return VisitCXXForRangeStmt(cast<CXXForRangeStmt>(S));
2238
2239 case Stmt::DeclStmtClass:
2240 return VisitDeclStmt(cast<DeclStmt>(S));
2241
2242 case Stmt::DefaultStmtClass:
2243 return VisitDefaultStmt(cast<DefaultStmt>(S));
2244
2245 case Stmt::DoStmtClass:
2246 return VisitDoStmt(cast<DoStmt>(S));
2247
2248 case Stmt::ForStmtClass:
2249 return VisitForStmt(cast<ForStmt>(S));
2250
2251 case Stmt::GotoStmtClass:
2252 return VisitGotoStmt(cast<GotoStmt>(S));
2253
2254 case Stmt::GCCAsmStmtClass:
2255 return VisitGCCAsmStmt(cast<GCCAsmStmt>(S), asc);
2256
2257 case Stmt::IfStmtClass:
2258 return VisitIfStmt(cast<IfStmt>(S));
2259
2260 case Stmt::ImplicitCastExprClass:
2261 return VisitImplicitCastExpr(cast<ImplicitCastExpr>(S), asc);
2262
2263 case Stmt::ConstantExprClass:
2264 return VisitConstantExpr(cast<ConstantExpr>(S), asc);
2265
2266 case Stmt::IndirectGotoStmtClass:
2267 return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S));
2268
2269 case Stmt::LabelStmtClass:
2270 return VisitLabelStmt(cast<LabelStmt>(S));
2271
2272 case Stmt::LambdaExprClass:
2273 return VisitLambdaExpr(cast<LambdaExpr>(S), asc);
2274
2275 case Stmt::MaterializeTemporaryExprClass:
2276 return VisitMaterializeTemporaryExpr(cast<MaterializeTemporaryExpr>(S),
2277 asc);
2278
2279 case Stmt::MemberExprClass:
2280 return VisitMemberExpr(cast<MemberExpr>(S), asc);
2281
2282 case Stmt::NullStmtClass:
2283 return Block;
2284
2285 case Stmt::ObjCAtCatchStmtClass:
2286 return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S));
2287
2288 case Stmt::ObjCAutoreleasePoolStmtClass:
2289 return VisitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(S));
2290
2291 case Stmt::ObjCAtSynchronizedStmtClass:
2292 return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S));
2293
2294 case Stmt::ObjCAtThrowStmtClass:
2295 return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S));
2296
2297 case Stmt::ObjCAtTryStmtClass:
2298 return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S));
2299
2300 case Stmt::ObjCForCollectionStmtClass:
2301 return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S));
2302
2303 case Stmt::ObjCMessageExprClass:
2304 return VisitObjCMessageExpr(cast<ObjCMessageExpr>(S), asc);
2305
2306 case Stmt::OpaqueValueExprClass:
2307 return Block;
2308
2309 case Stmt::PseudoObjectExprClass:
2310 return VisitPseudoObjectExpr(cast<PseudoObjectExpr>(S));
2311
2312 case Stmt::ReturnStmtClass:
2313 case Stmt::CoreturnStmtClass:
2314 return VisitReturnStmt(S);
2315
2316 case Stmt::SEHExceptStmtClass:
2317 return VisitSEHExceptStmt(cast<SEHExceptStmt>(S));
2318
2319 case Stmt::SEHFinallyStmtClass:
2320 return VisitSEHFinallyStmt(cast<SEHFinallyStmt>(S));
2321
2322 case Stmt::SEHLeaveStmtClass:
2323 return VisitSEHLeaveStmt(cast<SEHLeaveStmt>(S));
2324
2325 case Stmt::SEHTryStmtClass:
2326 return VisitSEHTryStmt(cast<SEHTryStmt>(S));
2327
2328 case Stmt::UnaryExprOrTypeTraitExprClass:
2329 return VisitUnaryExprOrTypeTraitExpr(cast<UnaryExprOrTypeTraitExpr>(S),
2330 asc);
2331
2332 case Stmt::StmtExprClass:
2333 return VisitStmtExpr(cast<StmtExpr>(S), asc);
2334
2335 case Stmt::SwitchStmtClass:
2336 return VisitSwitchStmt(cast<SwitchStmt>(S));
2337
2338 case Stmt::UnaryOperatorClass:
2339 return VisitUnaryOperator(cast<UnaryOperator>(S), asc);
2340
2341 case Stmt::WhileStmtClass:
2342 return VisitWhileStmt(cast<WhileStmt>(S));
2343 }
2344 }
2345
VisitStmt(Stmt * S,AddStmtChoice asc)2346 CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) {
2347 if (asc.alwaysAdd(*this, S)) {
2348 autoCreateBlock();
2349 appendStmt(Block, S);
2350 }
2351
2352 return VisitChildren(S);
2353 }
2354
2355 /// VisitChildren - Visit the children of a Stmt.
VisitChildren(Stmt * S)2356 CFGBlock *CFGBuilder::VisitChildren(Stmt *S) {
2357 CFGBlock *B = Block;
2358
2359 // Visit the children in their reverse order so that they appear in
2360 // left-to-right (natural) order in the CFG.
2361 reverse_children RChildren(S);
2362 for (Stmt *Child : RChildren) {
2363 if (Child)
2364 if (CFGBlock *R = Visit(Child))
2365 B = R;
2366 }
2367 return B;
2368 }
2369
VisitInitListExpr(InitListExpr * ILE,AddStmtChoice asc)2370 CFGBlock *CFGBuilder::VisitInitListExpr(InitListExpr *ILE, AddStmtChoice asc) {
2371 if (asc.alwaysAdd(*this, ILE)) {
2372 autoCreateBlock();
2373 appendStmt(Block, ILE);
2374 }
2375 CFGBlock *B = Block;
2376
2377 reverse_children RChildren(ILE);
2378 for (Stmt *Child : RChildren) {
2379 if (!Child)
2380 continue;
2381 if (CFGBlock *R = Visit(Child))
2382 B = R;
2383 if (BuildOpts.AddCXXDefaultInitExprInAggregates) {
2384 if (auto *DIE = dyn_cast<CXXDefaultInitExpr>(Child))
2385 if (Stmt *Child = DIE->getExpr())
2386 if (CFGBlock *R = Visit(Child))
2387 B = R;
2388 }
2389 }
2390 return B;
2391 }
2392
VisitAddrLabelExpr(AddrLabelExpr * A,AddStmtChoice asc)2393 CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A,
2394 AddStmtChoice asc) {
2395 AddressTakenLabels.insert(A->getLabel());
2396
2397 if (asc.alwaysAdd(*this, A)) {
2398 autoCreateBlock();
2399 appendStmt(Block, A);
2400 }
2401
2402 return Block;
2403 }
2404
isFallthroughStatement(const AttributedStmt * A)2405 static bool isFallthroughStatement(const AttributedStmt *A) {
2406 bool isFallthrough = hasSpecificAttr<FallThroughAttr>(A->getAttrs());
2407 assert((!isFallthrough || isa<NullStmt>(A->getSubStmt())) &&
2408 "expected fallthrough not to have children");
2409 return isFallthrough;
2410 }
2411
VisitAttributedStmt(AttributedStmt * A,AddStmtChoice asc)2412 CFGBlock *CFGBuilder::VisitAttributedStmt(AttributedStmt *A,
2413 AddStmtChoice asc) {
2414 // AttributedStmts for [[likely]] can have arbitrary statements as children,
2415 // and the current visitation order here would add the AttributedStmts
2416 // for [[likely]] after the child nodes, which is undesirable: For example,
2417 // if the child contains an unconditional return, the [[likely]] would be
2418 // considered unreachable.
2419 // So only add the AttributedStmt for FallThrough, which has CFG effects and
2420 // also no children, and omit the others. None of the other current StmtAttrs
2421 // have semantic meaning for the CFG.
2422 if (isFallthroughStatement(A) && asc.alwaysAdd(*this, A)) {
2423 autoCreateBlock();
2424 appendStmt(Block, A);
2425 }
2426
2427 return VisitChildren(A);
2428 }
2429
VisitUnaryOperator(UnaryOperator * U,AddStmtChoice asc)2430 CFGBlock *CFGBuilder::VisitUnaryOperator(UnaryOperator *U, AddStmtChoice asc) {
2431 if (asc.alwaysAdd(*this, U)) {
2432 autoCreateBlock();
2433 appendStmt(Block, U);
2434 }
2435
2436 if (U->getOpcode() == UO_LNot)
2437 tryEvaluateBool(U->getSubExpr()->IgnoreParens());
2438
2439 return Visit(U->getSubExpr(), AddStmtChoice());
2440 }
2441
VisitLogicalOperator(BinaryOperator * B)2442 CFGBlock *CFGBuilder::VisitLogicalOperator(BinaryOperator *B) {
2443 CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
2444 appendStmt(ConfluenceBlock, B);
2445
2446 if (badCFG)
2447 return nullptr;
2448
2449 return VisitLogicalOperator(B, nullptr, ConfluenceBlock,
2450 ConfluenceBlock).first;
2451 }
2452
2453 std::pair<CFGBlock*, CFGBlock*>
VisitLogicalOperator(BinaryOperator * B,Stmt * Term,CFGBlock * TrueBlock,CFGBlock * FalseBlock)2454 CFGBuilder::VisitLogicalOperator(BinaryOperator *B,
2455 Stmt *Term,
2456 CFGBlock *TrueBlock,
2457 CFGBlock *FalseBlock) {
2458 // Introspect the RHS. If it is a nested logical operation, we recursively
2459 // build the CFG using this function. Otherwise, resort to default
2460 // CFG construction behavior.
2461 Expr *RHS = B->getRHS()->IgnoreParens();
2462 CFGBlock *RHSBlock, *ExitBlock;
2463
2464 do {
2465 if (BinaryOperator *B_RHS = dyn_cast<BinaryOperator>(RHS))
2466 if (B_RHS->isLogicalOp()) {
2467 std::tie(RHSBlock, ExitBlock) =
2468 VisitLogicalOperator(B_RHS, Term, TrueBlock, FalseBlock);
2469 break;
2470 }
2471
2472 // The RHS is not a nested logical operation. Don't push the terminator
2473 // down further, but instead visit RHS and construct the respective
2474 // pieces of the CFG, and link up the RHSBlock with the terminator
2475 // we have been provided.
2476 ExitBlock = RHSBlock = createBlock(false);
2477
2478 // Even though KnownVal is only used in the else branch of the next
2479 // conditional, tryEvaluateBool performs additional checking on the
2480 // Expr, so it should be called unconditionally.
2481 TryResult KnownVal = tryEvaluateBool(RHS);
2482 if (!KnownVal.isKnown())
2483 KnownVal = tryEvaluateBool(B);
2484
2485 if (!Term) {
2486 assert(TrueBlock == FalseBlock);
2487 addSuccessor(RHSBlock, TrueBlock);
2488 }
2489 else {
2490 RHSBlock->setTerminator(Term);
2491 addSuccessor(RHSBlock, TrueBlock, !KnownVal.isFalse());
2492 addSuccessor(RHSBlock, FalseBlock, !KnownVal.isTrue());
2493 }
2494
2495 Block = RHSBlock;
2496 RHSBlock = addStmt(RHS);
2497 }
2498 while (false);
2499
2500 if (badCFG)
2501 return std::make_pair(nullptr, nullptr);
2502
2503 // Generate the blocks for evaluating the LHS.
2504 Expr *LHS = B->getLHS()->IgnoreParens();
2505
2506 if (BinaryOperator *B_LHS = dyn_cast<BinaryOperator>(LHS))
2507 if (B_LHS->isLogicalOp()) {
2508 if (B->getOpcode() == BO_LOr)
2509 FalseBlock = RHSBlock;
2510 else
2511 TrueBlock = RHSBlock;
2512
2513 // For the LHS, treat 'B' as the terminator that we want to sink
2514 // into the nested branch. The RHS always gets the top-most
2515 // terminator.
2516 return VisitLogicalOperator(B_LHS, B, TrueBlock, FalseBlock);
2517 }
2518
2519 // Create the block evaluating the LHS.
2520 // This contains the '&&' or '||' as the terminator.
2521 CFGBlock *LHSBlock = createBlock(false);
2522 LHSBlock->setTerminator(B);
2523
2524 Block = LHSBlock;
2525 CFGBlock *EntryLHSBlock = addStmt(LHS);
2526
2527 if (badCFG)
2528 return std::make_pair(nullptr, nullptr);
2529
2530 // See if this is a known constant.
2531 TryResult KnownVal = tryEvaluateBool(LHS);
2532
2533 // Now link the LHSBlock with RHSBlock.
2534 if (B->getOpcode() == BO_LOr) {
2535 addSuccessor(LHSBlock, TrueBlock, !KnownVal.isFalse());
2536 addSuccessor(LHSBlock, RHSBlock, !KnownVal.isTrue());
2537 } else {
2538 assert(B->getOpcode() == BO_LAnd);
2539 addSuccessor(LHSBlock, RHSBlock, !KnownVal.isFalse());
2540 addSuccessor(LHSBlock, FalseBlock, !KnownVal.isTrue());
2541 }
2542
2543 return std::make_pair(EntryLHSBlock, ExitBlock);
2544 }
2545
VisitBinaryOperator(BinaryOperator * B,AddStmtChoice asc)2546 CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B,
2547 AddStmtChoice asc) {
2548 // && or ||
2549 if (B->isLogicalOp())
2550 return VisitLogicalOperator(B);
2551
2552 if (B->getOpcode() == BO_Comma) { // ,
2553 autoCreateBlock();
2554 appendStmt(Block, B);
2555 addStmt(B->getRHS());
2556 return addStmt(B->getLHS());
2557 }
2558
2559 if (B->isAssignmentOp()) {
2560 if (asc.alwaysAdd(*this, B)) {
2561 autoCreateBlock();
2562 appendStmt(Block, B);
2563 }
2564 Visit(B->getLHS());
2565 return Visit(B->getRHS());
2566 }
2567
2568 if (asc.alwaysAdd(*this, B)) {
2569 autoCreateBlock();
2570 appendStmt(Block, B);
2571 }
2572
2573 if (B->isEqualityOp() || B->isRelationalOp())
2574 tryEvaluateBool(B);
2575
2576 CFGBlock *RBlock = Visit(B->getRHS());
2577 CFGBlock *LBlock = Visit(B->getLHS());
2578 // If visiting RHS causes us to finish 'Block', e.g. the RHS is a StmtExpr
2579 // containing a DoStmt, and the LHS doesn't create a new block, then we should
2580 // return RBlock. Otherwise we'll incorrectly return NULL.
2581 return (LBlock ? LBlock : RBlock);
2582 }
2583
VisitNoRecurse(Expr * E,AddStmtChoice asc)2584 CFGBlock *CFGBuilder::VisitNoRecurse(Expr *E, AddStmtChoice asc) {
2585 if (asc.alwaysAdd(*this, E)) {
2586 autoCreateBlock();
2587 appendStmt(Block, E);
2588 }
2589 return Block;
2590 }
2591
VisitBreakStmt(BreakStmt * B)2592 CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) {
2593 // "break" is a control-flow statement. Thus we stop processing the current
2594 // block.
2595 if (badCFG)
2596 return nullptr;
2597
2598 // Now create a new block that ends with the break statement.
2599 Block = createBlock(false);
2600 Block->setTerminator(B);
2601
2602 // If there is no target for the break, then we are looking at an incomplete
2603 // AST. This means that the CFG cannot be constructed.
2604 if (BreakJumpTarget.block) {
2605 addAutomaticObjHandling(ScopePos, BreakJumpTarget.scopePosition, B);
2606 addSuccessor(Block, BreakJumpTarget.block);
2607 } else
2608 badCFG = true;
2609
2610 return Block;
2611 }
2612
CanThrow(Expr * E,ASTContext & Ctx)2613 static bool CanThrow(Expr *E, ASTContext &Ctx) {
2614 QualType Ty = E->getType();
2615 if (Ty->isFunctionPointerType() || Ty->isBlockPointerType())
2616 Ty = Ty->getPointeeType();
2617
2618 const FunctionType *FT = Ty->getAs<FunctionType>();
2619 if (FT) {
2620 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
2621 if (!isUnresolvedExceptionSpec(Proto->getExceptionSpecType()) &&
2622 Proto->isNothrow())
2623 return false;
2624 }
2625 return true;
2626 }
2627
VisitCallExpr(CallExpr * C,AddStmtChoice asc)2628 CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) {
2629 // Compute the callee type.
2630 QualType calleeType = C->getCallee()->getType();
2631 if (calleeType == Context->BoundMemberTy) {
2632 QualType boundType = Expr::findBoundMemberType(C->getCallee());
2633
2634 // We should only get a null bound type if processing a dependent
2635 // CFG. Recover by assuming nothing.
2636 if (!boundType.isNull()) calleeType = boundType;
2637 }
2638
2639 // If this is a call to a no-return function, this stops the block here.
2640 bool NoReturn = getFunctionExtInfo(*calleeType).getNoReturn();
2641
2642 bool AddEHEdge = false;
2643
2644 // Languages without exceptions are assumed to not throw.
2645 if (Context->getLangOpts().Exceptions) {
2646 if (BuildOpts.AddEHEdges)
2647 AddEHEdge = true;
2648 }
2649
2650 // If this is a call to a builtin function, it might not actually evaluate
2651 // its arguments. Don't add them to the CFG if this is the case.
2652 bool OmitArguments = false;
2653
2654 if (FunctionDecl *FD = C->getDirectCallee()) {
2655 // TODO: Support construction contexts for variadic function arguments.
2656 // These are a bit problematic and not very useful because passing
2657 // C++ objects as C-style variadic arguments doesn't work in general
2658 // (see [expr.call]).
2659 if (!FD->isVariadic())
2660 findConstructionContextsForArguments(C);
2661
2662 if (FD->isNoReturn() || C->isBuiltinAssumeFalse(*Context))
2663 NoReturn = true;
2664 if (FD->hasAttr<NoThrowAttr>())
2665 AddEHEdge = false;
2666 if (FD->getBuiltinID() == Builtin::BI__builtin_object_size ||
2667 FD->getBuiltinID() == Builtin::BI__builtin_dynamic_object_size)
2668 OmitArguments = true;
2669 }
2670
2671 if (!CanThrow(C->getCallee(), *Context))
2672 AddEHEdge = false;
2673
2674 if (OmitArguments) {
2675 assert(!NoReturn && "noreturn calls with unevaluated args not implemented");
2676 assert(!AddEHEdge && "EH calls with unevaluated args not implemented");
2677 autoCreateBlock();
2678 appendStmt(Block, C);
2679 return Visit(C->getCallee());
2680 }
2681
2682 if (!NoReturn && !AddEHEdge) {
2683 autoCreateBlock();
2684 appendCall(Block, C);
2685
2686 return VisitChildren(C);
2687 }
2688
2689 if (Block) {
2690 Succ = Block;
2691 if (badCFG)
2692 return nullptr;
2693 }
2694
2695 if (NoReturn)
2696 Block = createNoReturnBlock();
2697 else
2698 Block = createBlock();
2699
2700 appendCall(Block, C);
2701
2702 if (AddEHEdge) {
2703 // Add exceptional edges.
2704 if (TryTerminatedBlock)
2705 addSuccessor(Block, TryTerminatedBlock);
2706 else
2707 addSuccessor(Block, &cfg->getExit());
2708 }
2709
2710 return VisitChildren(C);
2711 }
2712
VisitChooseExpr(ChooseExpr * C,AddStmtChoice asc)2713 CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C,
2714 AddStmtChoice asc) {
2715 CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
2716 appendStmt(ConfluenceBlock, C);
2717 if (badCFG)
2718 return nullptr;
2719
2720 AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true);
2721 Succ = ConfluenceBlock;
2722 Block = nullptr;
2723 CFGBlock *LHSBlock = Visit(C->getLHS(), alwaysAdd);
2724 if (badCFG)
2725 return nullptr;
2726
2727 Succ = ConfluenceBlock;
2728 Block = nullptr;
2729 CFGBlock *RHSBlock = Visit(C->getRHS(), alwaysAdd);
2730 if (badCFG)
2731 return nullptr;
2732
2733 Block = createBlock(false);
2734 // See if this is a known constant.
2735 const TryResult& KnownVal = tryEvaluateBool(C->getCond());
2736 addSuccessor(Block, KnownVal.isFalse() ? nullptr : LHSBlock);
2737 addSuccessor(Block, KnownVal.isTrue() ? nullptr : RHSBlock);
2738 Block->setTerminator(C);
2739 return addStmt(C->getCond());
2740 }
2741
VisitCompoundStmt(CompoundStmt * C,bool ExternallyDestructed)2742 CFGBlock *CFGBuilder::VisitCompoundStmt(CompoundStmt *C, bool ExternallyDestructed) {
2743 LocalScope::const_iterator scopeBeginPos = ScopePos;
2744 addLocalScopeForStmt(C);
2745
2746 if (!C->body_empty() && !isa<ReturnStmt>(*C->body_rbegin())) {
2747 // If the body ends with a ReturnStmt, the dtors will be added in
2748 // VisitReturnStmt.
2749 addAutomaticObjHandling(ScopePos, scopeBeginPos, C);
2750 }
2751
2752 CFGBlock *LastBlock = Block;
2753
2754 for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend();
2755 I != E; ++I ) {
2756 // If we hit a segment of code just containing ';' (NullStmts), we can
2757 // get a null block back. In such cases, just use the LastBlock
2758 CFGBlock *newBlock = Visit(*I, AddStmtChoice::AlwaysAdd,
2759 ExternallyDestructed);
2760
2761 if (newBlock)
2762 LastBlock = newBlock;
2763
2764 if (badCFG)
2765 return nullptr;
2766
2767 ExternallyDestructed = false;
2768 }
2769
2770 return LastBlock;
2771 }
2772
VisitConditionalOperator(AbstractConditionalOperator * C,AddStmtChoice asc)2773 CFGBlock *CFGBuilder::VisitConditionalOperator(AbstractConditionalOperator *C,
2774 AddStmtChoice asc) {
2775 const BinaryConditionalOperator *BCO = dyn_cast<BinaryConditionalOperator>(C);
2776 const OpaqueValueExpr *opaqueValue = (BCO ? BCO->getOpaqueValue() : nullptr);
2777
2778 // Create the confluence block that will "merge" the results of the ternary
2779 // expression.
2780 CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
2781 appendStmt(ConfluenceBlock, C);
2782 if (badCFG)
2783 return nullptr;
2784
2785 AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true);
2786
2787 // Create a block for the LHS expression if there is an LHS expression. A
2788 // GCC extension allows LHS to be NULL, causing the condition to be the
2789 // value that is returned instead.
2790 // e.g: x ?: y is shorthand for: x ? x : y;
2791 Succ = ConfluenceBlock;
2792 Block = nullptr;
2793 CFGBlock *LHSBlock = nullptr;
2794 const Expr *trueExpr = C->getTrueExpr();
2795 if (trueExpr != opaqueValue) {
2796 LHSBlock = Visit(C->getTrueExpr(), alwaysAdd);
2797 if (badCFG)
2798 return nullptr;
2799 Block = nullptr;
2800 }
2801 else
2802 LHSBlock = ConfluenceBlock;
2803
2804 // Create the block for the RHS expression.
2805 Succ = ConfluenceBlock;
2806 CFGBlock *RHSBlock = Visit(C->getFalseExpr(), alwaysAdd);
2807 if (badCFG)
2808 return nullptr;
2809
2810 // If the condition is a logical '&&' or '||', build a more accurate CFG.
2811 if (BinaryOperator *Cond =
2812 dyn_cast<BinaryOperator>(C->getCond()->IgnoreParens()))
2813 if (Cond->isLogicalOp())
2814 return VisitLogicalOperator(Cond, C, LHSBlock, RHSBlock).first;
2815
2816 // Create the block that will contain the condition.
2817 Block = createBlock(false);
2818
2819 // See if this is a known constant.
2820 const TryResult& KnownVal = tryEvaluateBool(C->getCond());
2821 addSuccessor(Block, LHSBlock, !KnownVal.isFalse());
2822 addSuccessor(Block, RHSBlock, !KnownVal.isTrue());
2823 Block->setTerminator(C);
2824 Expr *condExpr = C->getCond();
2825
2826 if (opaqueValue) {
2827 // Run the condition expression if it's not trivially expressed in
2828 // terms of the opaque value (or if there is no opaque value).
2829 if (condExpr != opaqueValue)
2830 addStmt(condExpr);
2831
2832 // Before that, run the common subexpression if there was one.
2833 // At least one of this or the above will be run.
2834 return addStmt(BCO->getCommon());
2835 }
2836
2837 return addStmt(condExpr);
2838 }
2839
VisitDeclStmt(DeclStmt * DS)2840 CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) {
2841 // Check if the Decl is for an __label__. If so, elide it from the
2842 // CFG entirely.
2843 if (isa<LabelDecl>(*DS->decl_begin()))
2844 return Block;
2845
2846 // This case also handles static_asserts.
2847 if (DS->isSingleDecl())
2848 return VisitDeclSubExpr(DS);
2849
2850 CFGBlock *B = nullptr;
2851
2852 // Build an individual DeclStmt for each decl.
2853 for (DeclStmt::reverse_decl_iterator I = DS->decl_rbegin(),
2854 E = DS->decl_rend();
2855 I != E; ++I) {
2856
2857 // Allocate the DeclStmt using the BumpPtrAllocator. It will get
2858 // automatically freed with the CFG.
2859 DeclGroupRef DG(*I);
2860 Decl *D = *I;
2861 DeclStmt *DSNew = new (Context) DeclStmt(DG, D->getLocation(), GetEndLoc(D));
2862 cfg->addSyntheticDeclStmt(DSNew, DS);
2863
2864 // Append the fake DeclStmt to block.
2865 B = VisitDeclSubExpr(DSNew);
2866 }
2867
2868 return B;
2869 }
2870
2871 /// VisitDeclSubExpr - Utility method to add block-level expressions for
2872 /// DeclStmts and initializers in them.
VisitDeclSubExpr(DeclStmt * DS)2873 CFGBlock *CFGBuilder::VisitDeclSubExpr(DeclStmt *DS) {
2874 assert(DS->isSingleDecl() && "Can handle single declarations only.");
2875
2876 if (const auto *TND = dyn_cast<TypedefNameDecl>(DS->getSingleDecl())) {
2877 // If we encounter a VLA, process its size expressions.
2878 const Type *T = TND->getUnderlyingType().getTypePtr();
2879 if (!T->isVariablyModifiedType())
2880 return Block;
2881
2882 autoCreateBlock();
2883 appendStmt(Block, DS);
2884
2885 CFGBlock *LastBlock = Block;
2886 for (const VariableArrayType *VA = FindVA(T); VA != nullptr;
2887 VA = FindVA(VA->getElementType().getTypePtr())) {
2888 if (CFGBlock *NewBlock = addStmt(VA->getSizeExpr()))
2889 LastBlock = NewBlock;
2890 }
2891 return LastBlock;
2892 }
2893
2894 VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
2895
2896 if (!VD) {
2897 // Of everything that can be declared in a DeclStmt, only VarDecls and the
2898 // exceptions above impact runtime semantics.
2899 return Block;
2900 }
2901
2902 bool HasTemporaries = false;
2903
2904 // Guard static initializers under a branch.
2905 CFGBlock *blockAfterStaticInit = nullptr;
2906
2907 if (BuildOpts.AddStaticInitBranches && VD->isStaticLocal()) {
2908 // For static variables, we need to create a branch to track
2909 // whether or not they are initialized.
2910 if (Block) {
2911 Succ = Block;
2912 Block = nullptr;
2913 if (badCFG)
2914 return nullptr;
2915 }
2916 blockAfterStaticInit = Succ;
2917 }
2918
2919 // Destructors of temporaries in initialization expression should be called
2920 // after initialization finishes.
2921 Expr *Init = VD->getInit();
2922 if (Init) {
2923 HasTemporaries = isa<ExprWithCleanups>(Init);
2924
2925 if (BuildOpts.AddTemporaryDtors && HasTemporaries) {
2926 // Generate destructors for temporaries in initialization expression.
2927 TempDtorContext Context;
2928 VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(),
2929 /*ExternallyDestructed=*/true, Context);
2930 }
2931 }
2932
2933 autoCreateBlock();
2934 appendStmt(Block, DS);
2935
2936 findConstructionContexts(
2937 ConstructionContextLayer::create(cfg->getBumpVectorContext(), DS),
2938 Init);
2939
2940 // Keep track of the last non-null block, as 'Block' can be nulled out
2941 // if the initializer expression is something like a 'while' in a
2942 // statement-expression.
2943 CFGBlock *LastBlock = Block;
2944
2945 if (Init) {
2946 if (HasTemporaries) {
2947 // For expression with temporaries go directly to subexpression to omit
2948 // generating destructors for the second time.
2949 ExprWithCleanups *EC = cast<ExprWithCleanups>(Init);
2950 if (CFGBlock *newBlock = Visit(EC->getSubExpr()))
2951 LastBlock = newBlock;
2952 }
2953 else {
2954 if (CFGBlock *newBlock = Visit(Init))
2955 LastBlock = newBlock;
2956 }
2957 }
2958
2959 // If the type of VD is a VLA, then we must process its size expressions.
2960 // FIXME: This does not find the VLA if it is embedded in other types,
2961 // like here: `int (*p_vla)[x];`
2962 for (const VariableArrayType* VA = FindVA(VD->getType().getTypePtr());
2963 VA != nullptr; VA = FindVA(VA->getElementType().getTypePtr())) {
2964 if (CFGBlock *newBlock = addStmt(VA->getSizeExpr()))
2965 LastBlock = newBlock;
2966 }
2967
2968 maybeAddScopeBeginForVarDecl(Block, VD, DS);
2969
2970 // Remove variable from local scope.
2971 if (ScopePos && VD == *ScopePos)
2972 ++ScopePos;
2973
2974 CFGBlock *B = LastBlock;
2975 if (blockAfterStaticInit) {
2976 Succ = B;
2977 Block = createBlock(false);
2978 Block->setTerminator(DS);
2979 addSuccessor(Block, blockAfterStaticInit);
2980 addSuccessor(Block, B);
2981 B = Block;
2982 }
2983
2984 return B;
2985 }
2986
VisitIfStmt(IfStmt * I)2987 CFGBlock *CFGBuilder::VisitIfStmt(IfStmt *I) {
2988 // We may see an if statement in the middle of a basic block, or it may be the
2989 // first statement we are processing. In either case, we create a new basic
2990 // block. First, we create the blocks for the then...else statements, and
2991 // then we create the block containing the if statement. If we were in the
2992 // middle of a block, we stop processing that block. That block is then the
2993 // implicit successor for the "then" and "else" clauses.
2994
2995 // Save local scope position because in case of condition variable ScopePos
2996 // won't be restored when traversing AST.
2997 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
2998
2999 // Create local scope for C++17 if init-stmt if one exists.
3000 if (Stmt *Init = I->getInit())
3001 addLocalScopeForStmt(Init);
3002
3003 // Create local scope for possible condition variable.
3004 // Store scope position. Add implicit destructor.
3005 if (VarDecl *VD = I->getConditionVariable())
3006 addLocalScopeForVarDecl(VD);
3007
3008 addAutomaticObjHandling(ScopePos, save_scope_pos.get(), I);
3009
3010 // The block we were processing is now finished. Make it the successor
3011 // block.
3012 if (Block) {
3013 Succ = Block;
3014 if (badCFG)
3015 return nullptr;
3016 }
3017
3018 // Process the false branch.
3019 CFGBlock *ElseBlock = Succ;
3020
3021 if (Stmt *Else = I->getElse()) {
3022 SaveAndRestore<CFGBlock*> sv(Succ);
3023
3024 // NULL out Block so that the recursive call to Visit will
3025 // create a new basic block.
3026 Block = nullptr;
3027
3028 // If branch is not a compound statement create implicit scope
3029 // and add destructors.
3030 if (!isa<CompoundStmt>(Else))
3031 addLocalScopeAndDtors(Else);
3032
3033 ElseBlock = addStmt(Else);
3034
3035 if (!ElseBlock) // Can occur when the Else body has all NullStmts.
3036 ElseBlock = sv.get();
3037 else if (Block) {
3038 if (badCFG)
3039 return nullptr;
3040 }
3041 }
3042
3043 // Process the true branch.
3044 CFGBlock *ThenBlock;
3045 {
3046 Stmt *Then = I->getThen();
3047 assert(Then);
3048 SaveAndRestore<CFGBlock*> sv(Succ);
3049 Block = nullptr;
3050
3051 // If branch is not a compound statement create implicit scope
3052 // and add destructors.
3053 if (!isa<CompoundStmt>(Then))
3054 addLocalScopeAndDtors(Then);
3055
3056 ThenBlock = addStmt(Then);
3057
3058 if (!ThenBlock) {
3059 // We can reach here if the "then" body has all NullStmts.
3060 // Create an empty block so we can distinguish between true and false
3061 // branches in path-sensitive analyses.
3062 ThenBlock = createBlock(false);
3063 addSuccessor(ThenBlock, sv.get());
3064 } else if (Block) {
3065 if (badCFG)
3066 return nullptr;
3067 }
3068 }
3069
3070 // Specially handle "if (expr1 || ...)" and "if (expr1 && ...)" by
3071 // having these handle the actual control-flow jump. Note that
3072 // if we introduce a condition variable, e.g. "if (int x = exp1 || exp2)"
3073 // we resort to the old control-flow behavior. This special handling
3074 // removes infeasible paths from the control-flow graph by having the
3075 // control-flow transfer of '&&' or '||' go directly into the then/else
3076 // blocks directly.
3077 BinaryOperator *Cond =
3078 I->getConditionVariable()
3079 ? nullptr
3080 : dyn_cast<BinaryOperator>(I->getCond()->IgnoreParens());
3081 CFGBlock *LastBlock;
3082 if (Cond && Cond->isLogicalOp())
3083 LastBlock = VisitLogicalOperator(Cond, I, ThenBlock, ElseBlock).first;
3084 else {
3085 // Now create a new block containing the if statement.
3086 Block = createBlock(false);
3087
3088 // Set the terminator of the new block to the If statement.
3089 Block->setTerminator(I);
3090
3091 // See if this is a known constant.
3092 const TryResult &KnownVal = tryEvaluateBool(I->getCond());
3093
3094 // Add the successors. If we know that specific branches are
3095 // unreachable, inform addSuccessor() of that knowledge.
3096 addSuccessor(Block, ThenBlock, /* IsReachable = */ !KnownVal.isFalse());
3097 addSuccessor(Block, ElseBlock, /* IsReachable = */ !KnownVal.isTrue());
3098
3099 // Add the condition as the last statement in the new block. This may
3100 // create new blocks as the condition may contain control-flow. Any newly
3101 // created blocks will be pointed to be "Block".
3102 LastBlock = addStmt(I->getCond());
3103
3104 // If the IfStmt contains a condition variable, add it and its
3105 // initializer to the CFG.
3106 if (const DeclStmt* DS = I->getConditionVariableDeclStmt()) {
3107 autoCreateBlock();
3108 LastBlock = addStmt(const_cast<DeclStmt *>(DS));
3109 }
3110 }
3111
3112 // Finally, if the IfStmt contains a C++17 init-stmt, add it to the CFG.
3113 if (Stmt *Init = I->getInit()) {
3114 autoCreateBlock();
3115 LastBlock = addStmt(Init);
3116 }
3117
3118 return LastBlock;
3119 }
3120
VisitReturnStmt(Stmt * S)3121 CFGBlock *CFGBuilder::VisitReturnStmt(Stmt *S) {
3122 // If we were in the middle of a block we stop processing that block.
3123 //
3124 // NOTE: If a "return" or "co_return" appears in the middle of a block, this
3125 // means that the code afterwards is DEAD (unreachable). We still keep
3126 // a basic block for that code; a simple "mark-and-sweep" from the entry
3127 // block will be able to report such dead blocks.
3128 assert(isa<ReturnStmt>(S) || isa<CoreturnStmt>(S));
3129
3130 // Create the new block.
3131 Block = createBlock(false);
3132
3133 addAutomaticObjHandling(ScopePos, LocalScope::const_iterator(), S);
3134
3135 if (auto *R = dyn_cast<ReturnStmt>(S))
3136 findConstructionContexts(
3137 ConstructionContextLayer::create(cfg->getBumpVectorContext(), R),
3138 R->getRetValue());
3139
3140 // If the one of the destructors does not return, we already have the Exit
3141 // block as a successor.
3142 if (!Block->hasNoReturnElement())
3143 addSuccessor(Block, &cfg->getExit());
3144
3145 // Add the return statement to the block.
3146 appendStmt(Block, S);
3147
3148 // Visit children
3149 if (ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) {
3150 if (Expr *O = RS->getRetValue())
3151 return Visit(O, AddStmtChoice::AlwaysAdd, /*ExternallyDestructed=*/true);
3152 return Block;
3153 } else { // co_return
3154 return VisitChildren(S);
3155 }
3156 }
3157
VisitSEHExceptStmt(SEHExceptStmt * ES)3158 CFGBlock *CFGBuilder::VisitSEHExceptStmt(SEHExceptStmt *ES) {
3159 // SEHExceptStmt are treated like labels, so they are the first statement in a
3160 // block.
3161
3162 // Save local scope position because in case of exception variable ScopePos
3163 // won't be restored when traversing AST.
3164 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
3165
3166 addStmt(ES->getBlock());
3167 CFGBlock *SEHExceptBlock = Block;
3168 if (!SEHExceptBlock)
3169 SEHExceptBlock = createBlock();
3170
3171 appendStmt(SEHExceptBlock, ES);
3172
3173 // Also add the SEHExceptBlock as a label, like with regular labels.
3174 SEHExceptBlock->setLabel(ES);
3175
3176 // Bail out if the CFG is bad.
3177 if (badCFG)
3178 return nullptr;
3179
3180 // We set Block to NULL to allow lazy creation of a new block (if necessary).
3181 Block = nullptr;
3182
3183 return SEHExceptBlock;
3184 }
3185
VisitSEHFinallyStmt(SEHFinallyStmt * FS)3186 CFGBlock *CFGBuilder::VisitSEHFinallyStmt(SEHFinallyStmt *FS) {
3187 return VisitCompoundStmt(FS->getBlock(), /*ExternallyDestructed=*/false);
3188 }
3189
VisitSEHLeaveStmt(SEHLeaveStmt * LS)3190 CFGBlock *CFGBuilder::VisitSEHLeaveStmt(SEHLeaveStmt *LS) {
3191 // "__leave" is a control-flow statement. Thus we stop processing the current
3192 // block.
3193 if (badCFG)
3194 return nullptr;
3195
3196 // Now create a new block that ends with the __leave statement.
3197 Block = createBlock(false);
3198 Block->setTerminator(LS);
3199
3200 // If there is no target for the __leave, then we are looking at an incomplete
3201 // AST. This means that the CFG cannot be constructed.
3202 if (SEHLeaveJumpTarget.block) {
3203 addAutomaticObjHandling(ScopePos, SEHLeaveJumpTarget.scopePosition, LS);
3204 addSuccessor(Block, SEHLeaveJumpTarget.block);
3205 } else
3206 badCFG = true;
3207
3208 return Block;
3209 }
3210
VisitSEHTryStmt(SEHTryStmt * Terminator)3211 CFGBlock *CFGBuilder::VisitSEHTryStmt(SEHTryStmt *Terminator) {
3212 // "__try"/"__except"/"__finally" is a control-flow statement. Thus we stop
3213 // processing the current block.
3214 CFGBlock *SEHTrySuccessor = nullptr;
3215
3216 if (Block) {
3217 if (badCFG)
3218 return nullptr;
3219 SEHTrySuccessor = Block;
3220 } else SEHTrySuccessor = Succ;
3221
3222 // FIXME: Implement __finally support.
3223 if (Terminator->getFinallyHandler())
3224 return NYS();
3225
3226 CFGBlock *PrevSEHTryTerminatedBlock = TryTerminatedBlock;
3227
3228 // Create a new block that will contain the __try statement.
3229 CFGBlock *NewTryTerminatedBlock = createBlock(false);
3230
3231 // Add the terminator in the __try block.
3232 NewTryTerminatedBlock->setTerminator(Terminator);
3233
3234 if (SEHExceptStmt *Except = Terminator->getExceptHandler()) {
3235 // The code after the try is the implicit successor if there's an __except.
3236 Succ = SEHTrySuccessor;
3237 Block = nullptr;
3238 CFGBlock *ExceptBlock = VisitSEHExceptStmt(Except);
3239 if (!ExceptBlock)
3240 return nullptr;
3241 // Add this block to the list of successors for the block with the try
3242 // statement.
3243 addSuccessor(NewTryTerminatedBlock, ExceptBlock);
3244 }
3245 if (PrevSEHTryTerminatedBlock)
3246 addSuccessor(NewTryTerminatedBlock, PrevSEHTryTerminatedBlock);
3247 else
3248 addSuccessor(NewTryTerminatedBlock, &cfg->getExit());
3249
3250 // The code after the try is the implicit successor.
3251 Succ = SEHTrySuccessor;
3252
3253 // Save the current "__try" context.
3254 SaveAndRestore<CFGBlock *> save_try(TryTerminatedBlock,
3255 NewTryTerminatedBlock);
3256 cfg->addTryDispatchBlock(TryTerminatedBlock);
3257
3258 // Save the current value for the __leave target.
3259 // All __leaves should go to the code following the __try
3260 // (FIXME: or if the __try has a __finally, to the __finally.)
3261 SaveAndRestore<JumpTarget> save_break(SEHLeaveJumpTarget);
3262 SEHLeaveJumpTarget = JumpTarget(SEHTrySuccessor, ScopePos);
3263
3264 assert(Terminator->getTryBlock() && "__try must contain a non-NULL body");
3265 Block = nullptr;
3266 return addStmt(Terminator->getTryBlock());
3267 }
3268
VisitLabelStmt(LabelStmt * L)3269 CFGBlock *CFGBuilder::VisitLabelStmt(LabelStmt *L) {
3270 // Get the block of the labeled statement. Add it to our map.
3271 addStmt(L->getSubStmt());
3272 CFGBlock *LabelBlock = Block;
3273
3274 if (!LabelBlock) // This can happen when the body is empty, i.e.
3275 LabelBlock = createBlock(); // scopes that only contains NullStmts.
3276
3277 assert(LabelMap.find(L->getDecl()) == LabelMap.end() &&
3278 "label already in map");
3279 LabelMap[L->getDecl()] = JumpTarget(LabelBlock, ScopePos);
3280
3281 // Labels partition blocks, so this is the end of the basic block we were
3282 // processing (L is the block's label). Because this is label (and we have
3283 // already processed the substatement) there is no extra control-flow to worry
3284 // about.
3285 LabelBlock->setLabel(L);
3286 if (badCFG)
3287 return nullptr;
3288
3289 // We set Block to NULL to allow lazy creation of a new block (if necessary);
3290 Block = nullptr;
3291
3292 // This block is now the implicit successor of other blocks.
3293 Succ = LabelBlock;
3294
3295 return LabelBlock;
3296 }
3297
VisitBlockExpr(BlockExpr * E,AddStmtChoice asc)3298 CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) {
3299 CFGBlock *LastBlock = VisitNoRecurse(E, asc);
3300 for (const BlockDecl::Capture &CI : E->getBlockDecl()->captures()) {
3301 if (Expr *CopyExpr = CI.getCopyExpr()) {
3302 CFGBlock *Tmp = Visit(CopyExpr);
3303 if (Tmp)
3304 LastBlock = Tmp;
3305 }
3306 }
3307 return LastBlock;
3308 }
3309
VisitLambdaExpr(LambdaExpr * E,AddStmtChoice asc)3310 CFGBlock *CFGBuilder::VisitLambdaExpr(LambdaExpr *E, AddStmtChoice asc) {
3311 CFGBlock *LastBlock = VisitNoRecurse(E, asc);
3312 for (LambdaExpr::capture_init_iterator it = E->capture_init_begin(),
3313 et = E->capture_init_end(); it != et; ++it) {
3314 if (Expr *Init = *it) {
3315 CFGBlock *Tmp = Visit(Init);
3316 if (Tmp)
3317 LastBlock = Tmp;
3318 }
3319 }
3320 return LastBlock;
3321 }
3322
VisitGotoStmt(GotoStmt * G)3323 CFGBlock *CFGBuilder::VisitGotoStmt(GotoStmt *G) {
3324 // Goto is a control-flow statement. Thus we stop processing the current
3325 // block and create a new one.
3326
3327 Block = createBlock(false);
3328 Block->setTerminator(G);
3329
3330 // If we already know the mapping to the label block add the successor now.
3331 LabelMapTy::iterator I = LabelMap.find(G->getLabel());
3332
3333 if (I == LabelMap.end())
3334 // We will need to backpatch this block later.
3335 BackpatchBlocks.push_back(JumpSource(Block, ScopePos));
3336 else {
3337 JumpTarget JT = I->second;
3338 addAutomaticObjHandling(ScopePos, JT.scopePosition, G);
3339 addSuccessor(Block, JT.block);
3340 }
3341
3342 return Block;
3343 }
3344
VisitGCCAsmStmt(GCCAsmStmt * G,AddStmtChoice asc)3345 CFGBlock *CFGBuilder::VisitGCCAsmStmt(GCCAsmStmt *G, AddStmtChoice asc) {
3346 // Goto is a control-flow statement. Thus we stop processing the current
3347 // block and create a new one.
3348
3349 if (!G->isAsmGoto())
3350 return VisitStmt(G, asc);
3351
3352 if (Block) {
3353 Succ = Block;
3354 if (badCFG)
3355 return nullptr;
3356 }
3357 Block = createBlock();
3358 Block->setTerminator(G);
3359 // We will backpatch this block later for all the labels.
3360 BackpatchBlocks.push_back(JumpSource(Block, ScopePos));
3361 // Save "Succ" in BackpatchBlocks. In the backpatch processing, "Succ" is
3362 // used to avoid adding "Succ" again.
3363 BackpatchBlocks.push_back(JumpSource(Succ, ScopePos));
3364 return VisitChildren(G);
3365 }
3366
VisitForStmt(ForStmt * F)3367 CFGBlock *CFGBuilder::VisitForStmt(ForStmt *F) {
3368 CFGBlock *LoopSuccessor = nullptr;
3369
3370 // Save local scope position because in case of condition variable ScopePos
3371 // won't be restored when traversing AST.
3372 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
3373
3374 // Create local scope for init statement and possible condition variable.
3375 // Add destructor for init statement and condition variable.
3376 // Store scope position for continue statement.
3377 if (Stmt *Init = F->getInit())
3378 addLocalScopeForStmt(Init);
3379 LocalScope::const_iterator LoopBeginScopePos = ScopePos;
3380
3381 if (VarDecl *VD = F->getConditionVariable())
3382 addLocalScopeForVarDecl(VD);
3383 LocalScope::const_iterator ContinueScopePos = ScopePos;
3384
3385 addAutomaticObjHandling(ScopePos, save_scope_pos.get(), F);
3386
3387 addLoopExit(F);
3388
3389 // "for" is a control-flow statement. Thus we stop processing the current
3390 // block.
3391 if (Block) {
3392 if (badCFG)
3393 return nullptr;
3394 LoopSuccessor = Block;
3395 } else
3396 LoopSuccessor = Succ;
3397
3398 // Save the current value for the break targets.
3399 // All breaks should go to the code following the loop.
3400 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
3401 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
3402
3403 CFGBlock *BodyBlock = nullptr, *TransitionBlock = nullptr;
3404
3405 // Now create the loop body.
3406 {
3407 assert(F->getBody());
3408
3409 // Save the current values for Block, Succ, continue and break targets.
3410 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
3411 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget);
3412
3413 // Create an empty block to represent the transition block for looping back
3414 // to the head of the loop. If we have increment code, it will
3415 // go in this block as well.
3416 Block = Succ = TransitionBlock = createBlock(false);
3417 TransitionBlock->setLoopTarget(F);
3418
3419 if (Stmt *I = F->getInc()) {
3420 // Generate increment code in its own basic block. This is the target of
3421 // continue statements.
3422 Succ = addStmt(I);
3423 }
3424
3425 // Finish up the increment (or empty) block if it hasn't been already.
3426 if (Block) {
3427 assert(Block == Succ);
3428 if (badCFG)
3429 return nullptr;
3430 Block = nullptr;
3431 }
3432
3433 // The starting block for the loop increment is the block that should
3434 // represent the 'loop target' for looping back to the start of the loop.
3435 ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos);
3436 ContinueJumpTarget.block->setLoopTarget(F);
3437
3438 // Loop body should end with destructor of Condition variable (if any).
3439 addAutomaticObjHandling(ScopePos, LoopBeginScopePos, F);
3440
3441 // If body is not a compound statement create implicit scope
3442 // and add destructors.
3443 if (!isa<CompoundStmt>(F->getBody()))
3444 addLocalScopeAndDtors(F->getBody());
3445
3446 // Now populate the body block, and in the process create new blocks as we
3447 // walk the body of the loop.
3448 BodyBlock = addStmt(F->getBody());
3449
3450 if (!BodyBlock) {
3451 // In the case of "for (...;...;...);" we can have a null BodyBlock.
3452 // Use the continue jump target as the proxy for the body.
3453 BodyBlock = ContinueJumpTarget.block;
3454 }
3455 else if (badCFG)
3456 return nullptr;
3457 }
3458
3459 // Because of short-circuit evaluation, the condition of the loop can span
3460 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
3461 // evaluate the condition.
3462 CFGBlock *EntryConditionBlock = nullptr, *ExitConditionBlock = nullptr;
3463
3464 do {
3465 Expr *C = F->getCond();
3466 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
3467
3468 // Specially handle logical operators, which have a slightly
3469 // more optimal CFG representation.
3470 if (BinaryOperator *Cond =
3471 dyn_cast_or_null<BinaryOperator>(C ? C->IgnoreParens() : nullptr))
3472 if (Cond->isLogicalOp()) {
3473 std::tie(EntryConditionBlock, ExitConditionBlock) =
3474 VisitLogicalOperator(Cond, F, BodyBlock, LoopSuccessor);
3475 break;
3476 }
3477
3478 // The default case when not handling logical operators.
3479 EntryConditionBlock = ExitConditionBlock = createBlock(false);
3480 ExitConditionBlock->setTerminator(F);
3481
3482 // See if this is a known constant.
3483 TryResult KnownVal(true);
3484
3485 if (C) {
3486 // Now add the actual condition to the condition block.
3487 // Because the condition itself may contain control-flow, new blocks may
3488 // be created. Thus we update "Succ" after adding the condition.
3489 Block = ExitConditionBlock;
3490 EntryConditionBlock = addStmt(C);
3491
3492 // If this block contains a condition variable, add both the condition
3493 // variable and initializer to the CFG.
3494 if (VarDecl *VD = F->getConditionVariable()) {
3495 if (Expr *Init = VD->getInit()) {
3496 autoCreateBlock();
3497 const DeclStmt *DS = F->getConditionVariableDeclStmt();
3498 assert(DS->isSingleDecl());
3499 findConstructionContexts(
3500 ConstructionContextLayer::create(cfg->getBumpVectorContext(), DS),
3501 Init);
3502 appendStmt(Block, DS);
3503 EntryConditionBlock = addStmt(Init);
3504 assert(Block == EntryConditionBlock);
3505 maybeAddScopeBeginForVarDecl(EntryConditionBlock, VD, C);
3506 }
3507 }
3508
3509 if (Block && badCFG)
3510 return nullptr;
3511
3512 KnownVal = tryEvaluateBool(C);
3513 }
3514
3515 // Add the loop body entry as a successor to the condition.
3516 addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? nullptr : BodyBlock);
3517 // Link up the condition block with the code that follows the loop. (the
3518 // false branch).
3519 addSuccessor(ExitConditionBlock,
3520 KnownVal.isTrue() ? nullptr : LoopSuccessor);
3521 } while (false);
3522
3523 // Link up the loop-back block to the entry condition block.
3524 addSuccessor(TransitionBlock, EntryConditionBlock);
3525
3526 // The condition block is the implicit successor for any code above the loop.
3527 Succ = EntryConditionBlock;
3528
3529 // If the loop contains initialization, create a new block for those
3530 // statements. This block can also contain statements that precede the loop.
3531 if (Stmt *I = F->getInit()) {
3532 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
3533 ScopePos = LoopBeginScopePos;
3534 Block = createBlock();
3535 return addStmt(I);
3536 }
3537
3538 // There is no loop initialization. We are thus basically a while loop.
3539 // NULL out Block to force lazy block construction.
3540 Block = nullptr;
3541 Succ = EntryConditionBlock;
3542 return EntryConditionBlock;
3543 }
3544
3545 CFGBlock *
VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr * MTE,AddStmtChoice asc)3546 CFGBuilder::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE,
3547 AddStmtChoice asc) {
3548 findConstructionContexts(
3549 ConstructionContextLayer::create(cfg->getBumpVectorContext(), MTE),
3550 MTE->getSubExpr());
3551
3552 return VisitStmt(MTE, asc);
3553 }
3554
VisitMemberExpr(MemberExpr * M,AddStmtChoice asc)3555 CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) {
3556 if (asc.alwaysAdd(*this, M)) {
3557 autoCreateBlock();
3558 appendStmt(Block, M);
3559 }
3560 return Visit(M->getBase());
3561 }
3562
VisitObjCForCollectionStmt(ObjCForCollectionStmt * S)3563 CFGBlock *CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
3564 // Objective-C fast enumeration 'for' statements:
3565 // http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC
3566 //
3567 // for ( Type newVariable in collection_expression ) { statements }
3568 //
3569 // becomes:
3570 //
3571 // prologue:
3572 // 1. collection_expression
3573 // T. jump to loop_entry
3574 // loop_entry:
3575 // 1. side-effects of element expression
3576 // 1. ObjCForCollectionStmt [performs binding to newVariable]
3577 // T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil]
3578 // TB:
3579 // statements
3580 // T. jump to loop_entry
3581 // FB:
3582 // what comes after
3583 //
3584 // and
3585 //
3586 // Type existingItem;
3587 // for ( existingItem in expression ) { statements }
3588 //
3589 // becomes:
3590 //
3591 // the same with newVariable replaced with existingItem; the binding works
3592 // the same except that for one ObjCForCollectionStmt::getElement() returns
3593 // a DeclStmt and the other returns a DeclRefExpr.
3594
3595 CFGBlock *LoopSuccessor = nullptr;
3596
3597 if (Block) {
3598 if (badCFG)
3599 return nullptr;
3600 LoopSuccessor = Block;
3601 Block = nullptr;
3602 } else
3603 LoopSuccessor = Succ;
3604
3605 // Build the condition blocks.
3606 CFGBlock *ExitConditionBlock = createBlock(false);
3607
3608 // Set the terminator for the "exit" condition block.
3609 ExitConditionBlock->setTerminator(S);
3610
3611 // The last statement in the block should be the ObjCForCollectionStmt, which
3612 // performs the actual binding to 'element' and determines if there are any
3613 // more items in the collection.
3614 appendStmt(ExitConditionBlock, S);
3615 Block = ExitConditionBlock;
3616
3617 // Walk the 'element' expression to see if there are any side-effects. We
3618 // generate new blocks as necessary. We DON'T add the statement by default to
3619 // the CFG unless it contains control-flow.
3620 CFGBlock *EntryConditionBlock = Visit(S->getElement(),
3621 AddStmtChoice::NotAlwaysAdd);
3622 if (Block) {
3623 if (badCFG)
3624 return nullptr;
3625 Block = nullptr;
3626 }
3627
3628 // The condition block is the implicit successor for the loop body as well as
3629 // any code above the loop.
3630 Succ = EntryConditionBlock;
3631
3632 // Now create the true branch.
3633 {
3634 // Save the current values for Succ, continue and break targets.
3635 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
3636 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
3637 save_break(BreakJumpTarget);
3638
3639 // Add an intermediate block between the BodyBlock and the
3640 // EntryConditionBlock to represent the "loop back" transition, for looping
3641 // back to the head of the loop.
3642 CFGBlock *LoopBackBlock = nullptr;
3643 Succ = LoopBackBlock = createBlock();
3644 LoopBackBlock->setLoopTarget(S);
3645
3646 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
3647 ContinueJumpTarget = JumpTarget(Succ, ScopePos);
3648
3649 CFGBlock *BodyBlock = addStmt(S->getBody());
3650
3651 if (!BodyBlock)
3652 BodyBlock = ContinueJumpTarget.block; // can happen for "for (X in Y) ;"
3653 else if (Block) {
3654 if (badCFG)
3655 return nullptr;
3656 }
3657
3658 // This new body block is a successor to our "exit" condition block.
3659 addSuccessor(ExitConditionBlock, BodyBlock);
3660 }
3661
3662 // Link up the condition block with the code that follows the loop.
3663 // (the false branch).
3664 addSuccessor(ExitConditionBlock, LoopSuccessor);
3665
3666 // Now create a prologue block to contain the collection expression.
3667 Block = createBlock();
3668 return addStmt(S->getCollection());
3669 }
3670
VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt * S)3671 CFGBlock *CFGBuilder::VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S) {
3672 // Inline the body.
3673 return addStmt(S->getSubStmt());
3674 // TODO: consider adding cleanups for the end of @autoreleasepool scope.
3675 }
3676
VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt * S)3677 CFGBlock *CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S) {
3678 // FIXME: Add locking 'primitives' to CFG for @synchronized.
3679
3680 // Inline the body.
3681 CFGBlock *SyncBlock = addStmt(S->getSynchBody());
3682
3683 // The sync body starts its own basic block. This makes it a little easier
3684 // for diagnostic clients.
3685 if (SyncBlock) {
3686 if (badCFG)
3687 return nullptr;
3688
3689 Block = nullptr;
3690 Succ = SyncBlock;
3691 }
3692
3693 // Add the @synchronized to the CFG.
3694 autoCreateBlock();
3695 appendStmt(Block, S);
3696
3697 // Inline the sync expression.
3698 return addStmt(S->getSynchExpr());
3699 }
3700
VisitObjCAtTryStmt(ObjCAtTryStmt * S)3701 CFGBlock *CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
3702 // FIXME
3703 return NYS();
3704 }
3705
VisitPseudoObjectExpr(PseudoObjectExpr * E)3706 CFGBlock *CFGBuilder::VisitPseudoObjectExpr(PseudoObjectExpr *E) {
3707 autoCreateBlock();
3708
3709 // Add the PseudoObject as the last thing.
3710 appendStmt(Block, E);
3711
3712 CFGBlock *lastBlock = Block;
3713
3714 // Before that, evaluate all of the semantics in order. In
3715 // CFG-land, that means appending them in reverse order.
3716 for (unsigned i = E->getNumSemanticExprs(); i != 0; ) {
3717 Expr *Semantic = E->getSemanticExpr(--i);
3718
3719 // If the semantic is an opaque value, we're being asked to bind
3720 // it to its source expression.
3721 if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
3722 Semantic = OVE->getSourceExpr();
3723
3724 if (CFGBlock *B = Visit(Semantic))
3725 lastBlock = B;
3726 }
3727
3728 return lastBlock;
3729 }
3730
VisitWhileStmt(WhileStmt * W)3731 CFGBlock *CFGBuilder::VisitWhileStmt(WhileStmt *W) {
3732 CFGBlock *LoopSuccessor = nullptr;
3733
3734 // Save local scope position because in case of condition variable ScopePos
3735 // won't be restored when traversing AST.
3736 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
3737
3738 // Create local scope for possible condition variable.
3739 // Store scope position for continue statement.
3740 LocalScope::const_iterator LoopBeginScopePos = ScopePos;
3741 if (VarDecl *VD = W->getConditionVariable()) {
3742 addLocalScopeForVarDecl(VD);
3743 addAutomaticObjHandling(ScopePos, LoopBeginScopePos, W);
3744 }
3745 addLoopExit(W);
3746
3747 // "while" is a control-flow statement. Thus we stop processing the current
3748 // block.
3749 if (Block) {
3750 if (badCFG)
3751 return nullptr;
3752 LoopSuccessor = Block;
3753 Block = nullptr;
3754 } else {
3755 LoopSuccessor = Succ;
3756 }
3757
3758 CFGBlock *BodyBlock = nullptr, *TransitionBlock = nullptr;
3759
3760 // Process the loop body.
3761 {
3762 assert(W->getBody());
3763
3764 // Save the current values for Block, Succ, continue and break targets.
3765 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
3766 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
3767 save_break(BreakJumpTarget);
3768
3769 // Create an empty block to represent the transition block for looping back
3770 // to the head of the loop.
3771 Succ = TransitionBlock = createBlock(false);
3772 TransitionBlock->setLoopTarget(W);
3773 ContinueJumpTarget = JumpTarget(Succ, LoopBeginScopePos);
3774
3775 // All breaks should go to the code following the loop.
3776 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
3777
3778 // Loop body should end with destructor of Condition variable (if any).
3779 addAutomaticObjHandling(ScopePos, LoopBeginScopePos, W);
3780
3781 // If body is not a compound statement create implicit scope
3782 // and add destructors.
3783 if (!isa<CompoundStmt>(W->getBody()))
3784 addLocalScopeAndDtors(W->getBody());
3785
3786 // Create the body. The returned block is the entry to the loop body.
3787 BodyBlock = addStmt(W->getBody());
3788
3789 if (!BodyBlock)
3790 BodyBlock = ContinueJumpTarget.block; // can happen for "while(...) ;"
3791 else if (Block && badCFG)
3792 return nullptr;
3793 }
3794
3795 // Because of short-circuit evaluation, the condition of the loop can span
3796 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
3797 // evaluate the condition.
3798 CFGBlock *EntryConditionBlock = nullptr, *ExitConditionBlock = nullptr;
3799
3800 do {
3801 Expr *C = W->getCond();
3802
3803 // Specially handle logical operators, which have a slightly
3804 // more optimal CFG representation.
3805 if (BinaryOperator *Cond = dyn_cast<BinaryOperator>(C->IgnoreParens()))
3806 if (Cond->isLogicalOp()) {
3807 std::tie(EntryConditionBlock, ExitConditionBlock) =
3808 VisitLogicalOperator(Cond, W, BodyBlock, LoopSuccessor);
3809 break;
3810 }
3811
3812 // The default case when not handling logical operators.
3813 ExitConditionBlock = createBlock(false);
3814 ExitConditionBlock->setTerminator(W);
3815
3816 // Now add the actual condition to the condition block.
3817 // Because the condition itself may contain control-flow, new blocks may
3818 // be created. Thus we update "Succ" after adding the condition.
3819 Block = ExitConditionBlock;
3820 Block = EntryConditionBlock = addStmt(C);
3821
3822 // If this block contains a condition variable, add both the condition
3823 // variable and initializer to the CFG.
3824 if (VarDecl *VD = W->getConditionVariable()) {
3825 if (Expr *Init = VD->getInit()) {
3826 autoCreateBlock();
3827 const DeclStmt *DS = W->getConditionVariableDeclStmt();
3828 assert(DS->isSingleDecl());
3829 findConstructionContexts(
3830 ConstructionContextLayer::create(cfg->getBumpVectorContext(),
3831 const_cast<DeclStmt *>(DS)),
3832 Init);
3833 appendStmt(Block, DS);
3834 EntryConditionBlock = addStmt(Init);
3835 assert(Block == EntryConditionBlock);
3836 maybeAddScopeBeginForVarDecl(EntryConditionBlock, VD, C);
3837 }
3838 }
3839
3840 if (Block && badCFG)
3841 return nullptr;
3842
3843 // See if this is a known constant.
3844 const TryResult& KnownVal = tryEvaluateBool(C);
3845
3846 // Add the loop body entry as a successor to the condition.
3847 addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? nullptr : BodyBlock);
3848 // Link up the condition block with the code that follows the loop. (the
3849 // false branch).
3850 addSuccessor(ExitConditionBlock,
3851 KnownVal.isTrue() ? nullptr : LoopSuccessor);
3852 } while(false);
3853
3854 // Link up the loop-back block to the entry condition block.
3855 addSuccessor(TransitionBlock, EntryConditionBlock);
3856
3857 // There can be no more statements in the condition block since we loop back
3858 // to this block. NULL out Block to force lazy creation of another block.
3859 Block = nullptr;
3860
3861 // Return the condition block, which is the dominating block for the loop.
3862 Succ = EntryConditionBlock;
3863 return EntryConditionBlock;
3864 }
3865
VisitObjCAtCatchStmt(ObjCAtCatchStmt * S)3866 CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
3867 // FIXME: For now we pretend that @catch and the code it contains does not
3868 // exit.
3869 return Block;
3870 }
3871
VisitObjCAtThrowStmt(ObjCAtThrowStmt * S)3872 CFGBlock *CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) {
3873 // FIXME: This isn't complete. We basically treat @throw like a return
3874 // statement.
3875
3876 // If we were in the middle of a block we stop processing that block.
3877 if (badCFG)
3878 return nullptr;
3879
3880 // Create the new block.
3881 Block = createBlock(false);
3882
3883 // The Exit block is the only successor.
3884 addSuccessor(Block, &cfg->getExit());
3885
3886 // Add the statement to the block. This may create new blocks if S contains
3887 // control-flow (short-circuit operations).
3888 return VisitStmt(S, AddStmtChoice::AlwaysAdd);
3889 }
3890
VisitObjCMessageExpr(ObjCMessageExpr * ME,AddStmtChoice asc)3891 CFGBlock *CFGBuilder::VisitObjCMessageExpr(ObjCMessageExpr *ME,
3892 AddStmtChoice asc) {
3893 findConstructionContextsForArguments(ME);
3894
3895 autoCreateBlock();
3896 appendObjCMessage(Block, ME);
3897
3898 return VisitChildren(ME);
3899 }
3900
VisitCXXThrowExpr(CXXThrowExpr * T)3901 CFGBlock *CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr *T) {
3902 // If we were in the middle of a block we stop processing that block.
3903 if (badCFG)
3904 return nullptr;
3905
3906 // Create the new block.
3907 Block = createBlock(false);
3908
3909 if (TryTerminatedBlock)
3910 // The current try statement is the only successor.
3911 addSuccessor(Block, TryTerminatedBlock);
3912 else
3913 // otherwise the Exit block is the only successor.
3914 addSuccessor(Block, &cfg->getExit());
3915
3916 // Add the statement to the block. This may create new blocks if S contains
3917 // control-flow (short-circuit operations).
3918 return VisitStmt(T, AddStmtChoice::AlwaysAdd);
3919 }
3920
VisitDoStmt(DoStmt * D)3921 CFGBlock *CFGBuilder::VisitDoStmt(DoStmt *D) {
3922 CFGBlock *LoopSuccessor = nullptr;
3923
3924 addLoopExit(D);
3925
3926 // "do...while" is a control-flow statement. Thus we stop processing the
3927 // current block.
3928 if (Block) {
3929 if (badCFG)
3930 return nullptr;
3931 LoopSuccessor = Block;
3932 } else
3933 LoopSuccessor = Succ;
3934
3935 // Because of short-circuit evaluation, the condition of the loop can span
3936 // multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
3937 // evaluate the condition.
3938 CFGBlock *ExitConditionBlock = createBlock(false);
3939 CFGBlock *EntryConditionBlock = ExitConditionBlock;
3940
3941 // Set the terminator for the "exit" condition block.
3942 ExitConditionBlock->setTerminator(D);
3943
3944 // Now add the actual condition to the condition block. Because the condition
3945 // itself may contain control-flow, new blocks may be created.
3946 if (Stmt *C = D->getCond()) {
3947 Block = ExitConditionBlock;
3948 EntryConditionBlock = addStmt(C);
3949 if (Block) {
3950 if (badCFG)
3951 return nullptr;
3952 }
3953 }
3954
3955 // The condition block is the implicit successor for the loop body.
3956 Succ = EntryConditionBlock;
3957
3958 // See if this is a known constant.
3959 const TryResult &KnownVal = tryEvaluateBool(D->getCond());
3960
3961 // Process the loop body.
3962 CFGBlock *BodyBlock = nullptr;
3963 {
3964 assert(D->getBody());
3965
3966 // Save the current values for Block, Succ, and continue and break targets
3967 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
3968 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
3969 save_break(BreakJumpTarget);
3970
3971 // All continues within this loop should go to the condition block
3972 ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos);
3973
3974 // All breaks should go to the code following the loop.
3975 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
3976
3977 // NULL out Block to force lazy instantiation of blocks for the body.
3978 Block = nullptr;
3979
3980 // If body is not a compound statement create implicit scope
3981 // and add destructors.
3982 if (!isa<CompoundStmt>(D->getBody()))
3983 addLocalScopeAndDtors(D->getBody());
3984
3985 // Create the body. The returned block is the entry to the loop body.
3986 BodyBlock = addStmt(D->getBody());
3987
3988 if (!BodyBlock)
3989 BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)"
3990 else if (Block) {
3991 if (badCFG)
3992 return nullptr;
3993 }
3994
3995 // Add an intermediate block between the BodyBlock and the
3996 // ExitConditionBlock to represent the "loop back" transition. Create an
3997 // empty block to represent the transition block for looping back to the
3998 // head of the loop.
3999 // FIXME: Can we do this more efficiently without adding another block?
4000 Block = nullptr;
4001 Succ = BodyBlock;
4002 CFGBlock *LoopBackBlock = createBlock();
4003 LoopBackBlock->setLoopTarget(D);
4004
4005 if (!KnownVal.isFalse())
4006 // Add the loop body entry as a successor to the condition.
4007 addSuccessor(ExitConditionBlock, LoopBackBlock);
4008 else
4009 addSuccessor(ExitConditionBlock, nullptr);
4010 }
4011
4012 // Link up the condition block with the code that follows the loop.
4013 // (the false branch).
4014 addSuccessor(ExitConditionBlock, KnownVal.isTrue() ? nullptr : LoopSuccessor);
4015
4016 // There can be no more statements in the body block(s) since we loop back to
4017 // the body. NULL out Block to force lazy creation of another block.
4018 Block = nullptr;
4019
4020 // Return the loop body, which is the dominating block for the loop.
4021 Succ = BodyBlock;
4022 return BodyBlock;
4023 }
4024
VisitContinueStmt(ContinueStmt * C)4025 CFGBlock *CFGBuilder::VisitContinueStmt(ContinueStmt *C) {
4026 // "continue" is a control-flow statement. Thus we stop processing the
4027 // current block.
4028 if (badCFG)
4029 return nullptr;
4030
4031 // Now create a new block that ends with the continue statement.
4032 Block = createBlock(false);
4033 Block->setTerminator(C);
4034
4035 // If there is no target for the continue, then we are looking at an
4036 // incomplete AST. This means the CFG cannot be constructed.
4037 if (ContinueJumpTarget.block) {
4038 addAutomaticObjHandling(ScopePos, ContinueJumpTarget.scopePosition, C);
4039 addSuccessor(Block, ContinueJumpTarget.block);
4040 } else
4041 badCFG = true;
4042
4043 return Block;
4044 }
4045
VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr * E,AddStmtChoice asc)4046 CFGBlock *CFGBuilder::VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E,
4047 AddStmtChoice asc) {
4048 if (asc.alwaysAdd(*this, E)) {
4049 autoCreateBlock();
4050 appendStmt(Block, E);
4051 }
4052
4053 // VLA types have expressions that must be evaluated.
4054 // Evaluation is done only for `sizeof`.
4055
4056 if (E->getKind() != UETT_SizeOf)
4057 return Block;
4058
4059 CFGBlock *lastBlock = Block;
4060
4061 if (E->isArgumentType()) {
4062 for (const VariableArrayType *VA =FindVA(E->getArgumentType().getTypePtr());
4063 VA != nullptr; VA = FindVA(VA->getElementType().getTypePtr()))
4064 lastBlock = addStmt(VA->getSizeExpr());
4065 }
4066 return lastBlock;
4067 }
4068
4069 /// VisitStmtExpr - Utility method to handle (nested) statement
4070 /// expressions (a GCC extension).
VisitStmtExpr(StmtExpr * SE,AddStmtChoice asc)4071 CFGBlock *CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) {
4072 if (asc.alwaysAdd(*this, SE)) {
4073 autoCreateBlock();
4074 appendStmt(Block, SE);
4075 }
4076 return VisitCompoundStmt(SE->getSubStmt(), /*ExternallyDestructed=*/true);
4077 }
4078
VisitSwitchStmt(SwitchStmt * Terminator)4079 CFGBlock *CFGBuilder::VisitSwitchStmt(SwitchStmt *Terminator) {
4080 // "switch" is a control-flow statement. Thus we stop processing the current
4081 // block.
4082 CFGBlock *SwitchSuccessor = nullptr;
4083
4084 // Save local scope position because in case of condition variable ScopePos
4085 // won't be restored when traversing AST.
4086 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
4087
4088 // Create local scope for C++17 switch init-stmt if one exists.
4089 if (Stmt *Init = Terminator->getInit())
4090 addLocalScopeForStmt(Init);
4091
4092 // Create local scope for possible condition variable.
4093 // Store scope position. Add implicit destructor.
4094 if (VarDecl *VD = Terminator->getConditionVariable())
4095 addLocalScopeForVarDecl(VD);
4096
4097 addAutomaticObjHandling(ScopePos, save_scope_pos.get(), Terminator);
4098
4099 if (Block) {
4100 if (badCFG)
4101 return nullptr;
4102 SwitchSuccessor = Block;
4103 } else SwitchSuccessor = Succ;
4104
4105 // Save the current "switch" context.
4106 SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock),
4107 save_default(DefaultCaseBlock);
4108 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
4109
4110 // Set the "default" case to be the block after the switch statement. If the
4111 // switch statement contains a "default:", this value will be overwritten with
4112 // the block for that code.
4113 DefaultCaseBlock = SwitchSuccessor;
4114
4115 // Create a new block that will contain the switch statement.
4116 SwitchTerminatedBlock = createBlock(false);
4117
4118 // Now process the switch body. The code after the switch is the implicit
4119 // successor.
4120 Succ = SwitchSuccessor;
4121 BreakJumpTarget = JumpTarget(SwitchSuccessor, ScopePos);
4122
4123 // When visiting the body, the case statements should automatically get linked
4124 // up to the switch. We also don't keep a pointer to the body, since all
4125 // control-flow from the switch goes to case/default statements.
4126 assert(Terminator->getBody() && "switch must contain a non-NULL body");
4127 Block = nullptr;
4128
4129 // For pruning unreachable case statements, save the current state
4130 // for tracking the condition value.
4131 SaveAndRestore<bool> save_switchExclusivelyCovered(switchExclusivelyCovered,
4132 false);
4133
4134 // Determine if the switch condition can be explicitly evaluated.
4135 assert(Terminator->getCond() && "switch condition must be non-NULL");
4136 Expr::EvalResult result;
4137 bool b = tryEvaluate(Terminator->getCond(), result);
4138 SaveAndRestore<Expr::EvalResult*> save_switchCond(switchCond,
4139 b ? &result : nullptr);
4140
4141 // If body is not a compound statement create implicit scope
4142 // and add destructors.
4143 if (!isa<CompoundStmt>(Terminator->getBody()))
4144 addLocalScopeAndDtors(Terminator->getBody());
4145
4146 addStmt(Terminator->getBody());
4147 if (Block) {
4148 if (badCFG)
4149 return nullptr;
4150 }
4151
4152 // If we have no "default:" case, the default transition is to the code
4153 // following the switch body. Moreover, take into account if all the
4154 // cases of a switch are covered (e.g., switching on an enum value).
4155 //
4156 // Note: We add a successor to a switch that is considered covered yet has no
4157 // case statements if the enumeration has no enumerators.
4158 bool SwitchAlwaysHasSuccessor = false;
4159 SwitchAlwaysHasSuccessor |= switchExclusivelyCovered;
4160 SwitchAlwaysHasSuccessor |= Terminator->isAllEnumCasesCovered() &&
4161 Terminator->getSwitchCaseList();
4162 addSuccessor(SwitchTerminatedBlock, DefaultCaseBlock,
4163 !SwitchAlwaysHasSuccessor);
4164
4165 // Add the terminator and condition in the switch block.
4166 SwitchTerminatedBlock->setTerminator(Terminator);
4167 Block = SwitchTerminatedBlock;
4168 CFGBlock *LastBlock = addStmt(Terminator->getCond());
4169
4170 // If the SwitchStmt contains a condition variable, add both the
4171 // SwitchStmt and the condition variable initialization to the CFG.
4172 if (VarDecl *VD = Terminator->getConditionVariable()) {
4173 if (Expr *Init = VD->getInit()) {
4174 autoCreateBlock();
4175 appendStmt(Block, Terminator->getConditionVariableDeclStmt());
4176 LastBlock = addStmt(Init);
4177 maybeAddScopeBeginForVarDecl(LastBlock, VD, Init);
4178 }
4179 }
4180
4181 // Finally, if the SwitchStmt contains a C++17 init-stmt, add it to the CFG.
4182 if (Stmt *Init = Terminator->getInit()) {
4183 autoCreateBlock();
4184 LastBlock = addStmt(Init);
4185 }
4186
4187 return LastBlock;
4188 }
4189
shouldAddCase(bool & switchExclusivelyCovered,const Expr::EvalResult * switchCond,const CaseStmt * CS,ASTContext & Ctx)4190 static bool shouldAddCase(bool &switchExclusivelyCovered,
4191 const Expr::EvalResult *switchCond,
4192 const CaseStmt *CS,
4193 ASTContext &Ctx) {
4194 if (!switchCond)
4195 return true;
4196
4197 bool addCase = false;
4198
4199 if (!switchExclusivelyCovered) {
4200 if (switchCond->Val.isInt()) {
4201 // Evaluate the LHS of the case value.
4202 const llvm::APSInt &lhsInt = CS->getLHS()->EvaluateKnownConstInt(Ctx);
4203 const llvm::APSInt &condInt = switchCond->Val.getInt();
4204
4205 if (condInt == lhsInt) {
4206 addCase = true;
4207 switchExclusivelyCovered = true;
4208 }
4209 else if (condInt > lhsInt) {
4210 if (const Expr *RHS = CS->getRHS()) {
4211 // Evaluate the RHS of the case value.
4212 const llvm::APSInt &V2 = RHS->EvaluateKnownConstInt(Ctx);
4213 if (V2 >= condInt) {
4214 addCase = true;
4215 switchExclusivelyCovered = true;
4216 }
4217 }
4218 }
4219 }
4220 else
4221 addCase = true;
4222 }
4223 return addCase;
4224 }
4225
VisitCaseStmt(CaseStmt * CS)4226 CFGBlock *CFGBuilder::VisitCaseStmt(CaseStmt *CS) {
4227 // CaseStmts are essentially labels, so they are the first statement in a
4228 // block.
4229 CFGBlock *TopBlock = nullptr, *LastBlock = nullptr;
4230
4231 if (Stmt *Sub = CS->getSubStmt()) {
4232 // For deeply nested chains of CaseStmts, instead of doing a recursion
4233 // (which can blow out the stack), manually unroll and create blocks
4234 // along the way.
4235 while (isa<CaseStmt>(Sub)) {
4236 CFGBlock *currentBlock = createBlock(false);
4237 currentBlock->setLabel(CS);
4238
4239 if (TopBlock)
4240 addSuccessor(LastBlock, currentBlock);
4241 else
4242 TopBlock = currentBlock;
4243
4244 addSuccessor(SwitchTerminatedBlock,
4245 shouldAddCase(switchExclusivelyCovered, switchCond,
4246 CS, *Context)
4247 ? currentBlock : nullptr);
4248
4249 LastBlock = currentBlock;
4250 CS = cast<CaseStmt>(Sub);
4251 Sub = CS->getSubStmt();
4252 }
4253
4254 addStmt(Sub);
4255 }
4256
4257 CFGBlock *CaseBlock = Block;
4258 if (!CaseBlock)
4259 CaseBlock = createBlock();
4260
4261 // Cases statements partition blocks, so this is the top of the basic block we
4262 // were processing (the "case XXX:" is the label).
4263 CaseBlock->setLabel(CS);
4264
4265 if (badCFG)
4266 return nullptr;
4267
4268 // Add this block to the list of successors for the block with the switch
4269 // statement.
4270 assert(SwitchTerminatedBlock);
4271 addSuccessor(SwitchTerminatedBlock, CaseBlock,
4272 shouldAddCase(switchExclusivelyCovered, switchCond,
4273 CS, *Context));
4274
4275 // We set Block to NULL to allow lazy creation of a new block (if necessary)
4276 Block = nullptr;
4277
4278 if (TopBlock) {
4279 addSuccessor(LastBlock, CaseBlock);
4280 Succ = TopBlock;
4281 } else {
4282 // This block is now the implicit successor of other blocks.
4283 Succ = CaseBlock;
4284 }
4285
4286 return Succ;
4287 }
4288
VisitDefaultStmt(DefaultStmt * Terminator)4289 CFGBlock *CFGBuilder::VisitDefaultStmt(DefaultStmt *Terminator) {
4290 if (Terminator->getSubStmt())
4291 addStmt(Terminator->getSubStmt());
4292
4293 DefaultCaseBlock = Block;
4294
4295 if (!DefaultCaseBlock)
4296 DefaultCaseBlock = createBlock();
4297
4298 // Default statements partition blocks, so this is the top of the basic block
4299 // we were processing (the "default:" is the label).
4300 DefaultCaseBlock->setLabel(Terminator);
4301
4302 if (badCFG)
4303 return nullptr;
4304
4305 // Unlike case statements, we don't add the default block to the successors
4306 // for the switch statement immediately. This is done when we finish
4307 // processing the switch statement. This allows for the default case
4308 // (including a fall-through to the code after the switch statement) to always
4309 // be the last successor of a switch-terminated block.
4310
4311 // We set Block to NULL to allow lazy creation of a new block (if necessary)
4312 Block = nullptr;
4313
4314 // This block is now the implicit successor of other blocks.
4315 Succ = DefaultCaseBlock;
4316
4317 return DefaultCaseBlock;
4318 }
4319
VisitCXXTryStmt(CXXTryStmt * Terminator)4320 CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) {
4321 // "try"/"catch" is a control-flow statement. Thus we stop processing the
4322 // current block.
4323 CFGBlock *TrySuccessor = nullptr;
4324
4325 if (Block) {
4326 if (badCFG)
4327 return nullptr;
4328 TrySuccessor = Block;
4329 } else TrySuccessor = Succ;
4330
4331 CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock;
4332
4333 // Create a new block that will contain the try statement.
4334 CFGBlock *NewTryTerminatedBlock = createBlock(false);
4335 // Add the terminator in the try block.
4336 NewTryTerminatedBlock->setTerminator(Terminator);
4337
4338 bool HasCatchAll = false;
4339 for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) {
4340 // The code after the try is the implicit successor.
4341 Succ = TrySuccessor;
4342 CXXCatchStmt *CS = Terminator->getHandler(h);
4343 if (CS->getExceptionDecl() == nullptr) {
4344 HasCatchAll = true;
4345 }
4346 Block = nullptr;
4347 CFGBlock *CatchBlock = VisitCXXCatchStmt(CS);
4348 if (!CatchBlock)
4349 return nullptr;
4350 // Add this block to the list of successors for the block with the try
4351 // statement.
4352 addSuccessor(NewTryTerminatedBlock, CatchBlock);
4353 }
4354 if (!HasCatchAll) {
4355 if (PrevTryTerminatedBlock)
4356 addSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock);
4357 else
4358 addSuccessor(NewTryTerminatedBlock, &cfg->getExit());
4359 }
4360
4361 // The code after the try is the implicit successor.
4362 Succ = TrySuccessor;
4363
4364 // Save the current "try" context.
4365 SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock, NewTryTerminatedBlock);
4366 cfg->addTryDispatchBlock(TryTerminatedBlock);
4367
4368 assert(Terminator->getTryBlock() && "try must contain a non-NULL body");
4369 Block = nullptr;
4370 return addStmt(Terminator->getTryBlock());
4371 }
4372
VisitCXXCatchStmt(CXXCatchStmt * CS)4373 CFGBlock *CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt *CS) {
4374 // CXXCatchStmt are treated like labels, so they are the first statement in a
4375 // block.
4376
4377 // Save local scope position because in case of exception variable ScopePos
4378 // won't be restored when traversing AST.
4379 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
4380
4381 // Create local scope for possible exception variable.
4382 // Store scope position. Add implicit destructor.
4383 if (VarDecl *VD = CS->getExceptionDecl()) {
4384 LocalScope::const_iterator BeginScopePos = ScopePos;
4385 addLocalScopeForVarDecl(VD);
4386 addAutomaticObjHandling(ScopePos, BeginScopePos, CS);
4387 }
4388
4389 if (CS->getHandlerBlock())
4390 addStmt(CS->getHandlerBlock());
4391
4392 CFGBlock *CatchBlock = Block;
4393 if (!CatchBlock)
4394 CatchBlock = createBlock();
4395
4396 // CXXCatchStmt is more than just a label. They have semantic meaning
4397 // as well, as they implicitly "initialize" the catch variable. Add
4398 // it to the CFG as a CFGElement so that the control-flow of these
4399 // semantics gets captured.
4400 appendStmt(CatchBlock, CS);
4401
4402 // Also add the CXXCatchStmt as a label, to mirror handling of regular
4403 // labels.
4404 CatchBlock->setLabel(CS);
4405
4406 // Bail out if the CFG is bad.
4407 if (badCFG)
4408 return nullptr;
4409
4410 // We set Block to NULL to allow lazy creation of a new block (if necessary)
4411 Block = nullptr;
4412
4413 return CatchBlock;
4414 }
4415
VisitCXXForRangeStmt(CXXForRangeStmt * S)4416 CFGBlock *CFGBuilder::VisitCXXForRangeStmt(CXXForRangeStmt *S) {
4417 // C++0x for-range statements are specified as [stmt.ranged]:
4418 //
4419 // {
4420 // auto && __range = range-init;
4421 // for ( auto __begin = begin-expr,
4422 // __end = end-expr;
4423 // __begin != __end;
4424 // ++__begin ) {
4425 // for-range-declaration = *__begin;
4426 // statement
4427 // }
4428 // }
4429
4430 // Save local scope position before the addition of the implicit variables.
4431 SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
4432
4433 // Create local scopes and destructors for range, begin and end variables.
4434 if (Stmt *Range = S->getRangeStmt())
4435 addLocalScopeForStmt(Range);
4436 if (Stmt *Begin = S->getBeginStmt())
4437 addLocalScopeForStmt(Begin);
4438 if (Stmt *End = S->getEndStmt())
4439 addLocalScopeForStmt(End);
4440 addAutomaticObjHandling(ScopePos, save_scope_pos.get(), S);
4441
4442 LocalScope::const_iterator ContinueScopePos = ScopePos;
4443
4444 // "for" is a control-flow statement. Thus we stop processing the current
4445 // block.
4446 CFGBlock *LoopSuccessor = nullptr;
4447 if (Block) {
4448 if (badCFG)
4449 return nullptr;
4450 LoopSuccessor = Block;
4451 } else
4452 LoopSuccessor = Succ;
4453
4454 // Save the current value for the break targets.
4455 // All breaks should go to the code following the loop.
4456 SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
4457 BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
4458
4459 // The block for the __begin != __end expression.
4460 CFGBlock *ConditionBlock = createBlock(false);
4461 ConditionBlock->setTerminator(S);
4462
4463 // Now add the actual condition to the condition block.
4464 if (Expr *C = S->getCond()) {
4465 Block = ConditionBlock;
4466 CFGBlock *BeginConditionBlock = addStmt(C);
4467 if (badCFG)
4468 return nullptr;
4469 assert(BeginConditionBlock == ConditionBlock &&
4470 "condition block in for-range was unexpectedly complex");
4471 (void)BeginConditionBlock;
4472 }
4473
4474 // The condition block is the implicit successor for the loop body as well as
4475 // any code above the loop.
4476 Succ = ConditionBlock;
4477
4478 // See if this is a known constant.
4479 TryResult KnownVal(true);
4480
4481 if (S->getCond())
4482 KnownVal = tryEvaluateBool(S->getCond());
4483
4484 // Now create the loop body.
4485 {
4486 assert(S->getBody());
4487
4488 // Save the current values for Block, Succ, and continue targets.
4489 SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
4490 SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget);
4491
4492 // Generate increment code in its own basic block. This is the target of
4493 // continue statements.
4494 Block = nullptr;
4495 Succ = addStmt(S->getInc());
4496 if (badCFG)
4497 return nullptr;
4498 ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos);
4499
4500 // The starting block for the loop increment is the block that should
4501 // represent the 'loop target' for looping back to the start of the loop.
4502 ContinueJumpTarget.block->setLoopTarget(S);
4503
4504 // Finish up the increment block and prepare to start the loop body.
4505 assert(Block);
4506 if (badCFG)
4507 return nullptr;
4508 Block = nullptr;
4509
4510 // Add implicit scope and dtors for loop variable.
4511 addLocalScopeAndDtors(S->getLoopVarStmt());
4512
4513 // If body is not a compound statement create implicit scope
4514 // and add destructors.
4515 if (!isa<CompoundStmt>(S->getBody()))
4516 addLocalScopeAndDtors(S->getBody());
4517
4518 // Populate a new block to contain the loop body and loop variable.
4519 addStmt(S->getBody());
4520
4521 if (badCFG)
4522 return nullptr;
4523 CFGBlock *LoopVarStmtBlock = addStmt(S->getLoopVarStmt());
4524 if (badCFG)
4525 return nullptr;
4526
4527 // This new body block is a successor to our condition block.
4528 addSuccessor(ConditionBlock,
4529 KnownVal.isFalse() ? nullptr : LoopVarStmtBlock);
4530 }
4531
4532 // Link up the condition block with the code that follows the loop (the
4533 // false branch).
4534 addSuccessor(ConditionBlock, KnownVal.isTrue() ? nullptr : LoopSuccessor);
4535
4536 // Add the initialization statements.
4537 Block = createBlock();
4538 addStmt(S->getBeginStmt());
4539 addStmt(S->getEndStmt());
4540 CFGBlock *Head = addStmt(S->getRangeStmt());
4541 if (S->getInit())
4542 Head = addStmt(S->getInit());
4543 return Head;
4544 }
4545
VisitExprWithCleanups(ExprWithCleanups * E,AddStmtChoice asc,bool ExternallyDestructed)4546 CFGBlock *CFGBuilder::VisitExprWithCleanups(ExprWithCleanups *E,
4547 AddStmtChoice asc, bool ExternallyDestructed) {
4548 if (BuildOpts.AddTemporaryDtors) {
4549 // If adding implicit destructors visit the full expression for adding
4550 // destructors of temporaries.
4551 TempDtorContext Context;
4552 VisitForTemporaryDtors(E->getSubExpr(), ExternallyDestructed, Context);
4553
4554 // Full expression has to be added as CFGStmt so it will be sequenced
4555 // before destructors of it's temporaries.
4556 asc = asc.withAlwaysAdd(true);
4557 }
4558 return Visit(E->getSubExpr(), asc);
4559 }
4560
VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr * E,AddStmtChoice asc)4561 CFGBlock *CFGBuilder::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E,
4562 AddStmtChoice asc) {
4563 if (asc.alwaysAdd(*this, E)) {
4564 autoCreateBlock();
4565 appendStmt(Block, E);
4566
4567 findConstructionContexts(
4568 ConstructionContextLayer::create(cfg->getBumpVectorContext(), E),
4569 E->getSubExpr());
4570
4571 // We do not want to propagate the AlwaysAdd property.
4572 asc = asc.withAlwaysAdd(false);
4573 }
4574 return Visit(E->getSubExpr(), asc);
4575 }
4576
VisitCXXConstructExpr(CXXConstructExpr * C,AddStmtChoice asc)4577 CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
4578 AddStmtChoice asc) {
4579 // If the constructor takes objects as arguments by value, we need to properly
4580 // construct these objects. Construction contexts we find here aren't for the
4581 // constructor C, they're for its arguments only.
4582 findConstructionContextsForArguments(C);
4583
4584 autoCreateBlock();
4585 appendConstructor(Block, C);
4586
4587 return VisitChildren(C);
4588 }
4589
VisitCXXNewExpr(CXXNewExpr * NE,AddStmtChoice asc)4590 CFGBlock *CFGBuilder::VisitCXXNewExpr(CXXNewExpr *NE,
4591 AddStmtChoice asc) {
4592 autoCreateBlock();
4593 appendStmt(Block, NE);
4594
4595 findConstructionContexts(
4596 ConstructionContextLayer::create(cfg->getBumpVectorContext(), NE),
4597 const_cast<CXXConstructExpr *>(NE->getConstructExpr()));
4598
4599 if (NE->getInitializer())
4600 Block = Visit(NE->getInitializer());
4601
4602 if (BuildOpts.AddCXXNewAllocator)
4603 appendNewAllocator(Block, NE);
4604
4605 if (NE->isArray() && *NE->getArraySize())
4606 Block = Visit(*NE->getArraySize());
4607
4608 for (CXXNewExpr::arg_iterator I = NE->placement_arg_begin(),
4609 E = NE->placement_arg_end(); I != E; ++I)
4610 Block = Visit(*I);
4611
4612 return Block;
4613 }
4614
VisitCXXDeleteExpr(CXXDeleteExpr * DE,AddStmtChoice asc)4615 CFGBlock *CFGBuilder::VisitCXXDeleteExpr(CXXDeleteExpr *DE,
4616 AddStmtChoice asc) {
4617 autoCreateBlock();
4618 appendStmt(Block, DE);
4619 QualType DTy = DE->getDestroyedType();
4620 if (!DTy.isNull()) {
4621 DTy = DTy.getNonReferenceType();
4622 CXXRecordDecl *RD = Context->getBaseElementType(DTy)->getAsCXXRecordDecl();
4623 if (RD) {
4624 if (RD->isCompleteDefinition() && !RD->hasTrivialDestructor())
4625 appendDeleteDtor(Block, RD, DE);
4626 }
4627 }
4628
4629 return VisitChildren(DE);
4630 }
4631
VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr * E,AddStmtChoice asc)4632 CFGBlock *CFGBuilder::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
4633 AddStmtChoice asc) {
4634 if (asc.alwaysAdd(*this, E)) {
4635 autoCreateBlock();
4636 appendStmt(Block, E);
4637 // We do not want to propagate the AlwaysAdd property.
4638 asc = asc.withAlwaysAdd(false);
4639 }
4640 return Visit(E->getSubExpr(), asc);
4641 }
4642
VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr * C,AddStmtChoice asc)4643 CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C,
4644 AddStmtChoice asc) {
4645 // If the constructor takes objects as arguments by value, we need to properly
4646 // construct these objects. Construction contexts we find here aren't for the
4647 // constructor C, they're for its arguments only.
4648 findConstructionContextsForArguments(C);
4649
4650 autoCreateBlock();
4651 appendConstructor(Block, C);
4652 return VisitChildren(C);
4653 }
4654
VisitImplicitCastExpr(ImplicitCastExpr * E,AddStmtChoice asc)4655 CFGBlock *CFGBuilder::VisitImplicitCastExpr(ImplicitCastExpr *E,
4656 AddStmtChoice asc) {
4657 if (asc.alwaysAdd(*this, E)) {
4658 autoCreateBlock();
4659 appendStmt(Block, E);
4660 }
4661
4662 if (E->getCastKind() == CK_IntegralToBoolean)
4663 tryEvaluateBool(E->getSubExpr()->IgnoreParens());
4664
4665 return Visit(E->getSubExpr(), AddStmtChoice());
4666 }
4667
VisitConstantExpr(ConstantExpr * E,AddStmtChoice asc)4668 CFGBlock *CFGBuilder::VisitConstantExpr(ConstantExpr *E, AddStmtChoice asc) {
4669 return Visit(E->getSubExpr(), AddStmtChoice());
4670 }
4671
VisitIndirectGotoStmt(IndirectGotoStmt * I)4672 CFGBlock *CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt *I) {
4673 // Lazily create the indirect-goto dispatch block if there isn't one already.
4674 CFGBlock *IBlock = cfg->getIndirectGotoBlock();
4675
4676 if (!IBlock) {
4677 IBlock = createBlock(false);
4678 cfg->setIndirectGotoBlock(IBlock);
4679 }
4680
4681 // IndirectGoto is a control-flow statement. Thus we stop processing the
4682 // current block and create a new one.
4683 if (badCFG)
4684 return nullptr;
4685
4686 Block = createBlock(false);
4687 Block->setTerminator(I);
4688 addSuccessor(Block, IBlock);
4689 return addStmt(I->getTarget());
4690 }
4691
VisitForTemporaryDtors(Stmt * E,bool ExternallyDestructed,TempDtorContext & Context)4692 CFGBlock *CFGBuilder::VisitForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
4693 TempDtorContext &Context) {
4694 assert(BuildOpts.AddImplicitDtors && BuildOpts.AddTemporaryDtors);
4695
4696 tryAgain:
4697 if (!E) {
4698 badCFG = true;
4699 return nullptr;
4700 }
4701 switch (E->getStmtClass()) {
4702 default:
4703 return VisitChildrenForTemporaryDtors(E, false, Context);
4704
4705 case Stmt::InitListExprClass:
4706 return VisitChildrenForTemporaryDtors(E, ExternallyDestructed, Context);
4707
4708 case Stmt::BinaryOperatorClass:
4709 return VisitBinaryOperatorForTemporaryDtors(cast<BinaryOperator>(E),
4710 ExternallyDestructed,
4711 Context);
4712
4713 case Stmt::CXXBindTemporaryExprClass:
4714 return VisitCXXBindTemporaryExprForTemporaryDtors(
4715 cast<CXXBindTemporaryExpr>(E), ExternallyDestructed, Context);
4716
4717 case Stmt::BinaryConditionalOperatorClass:
4718 case Stmt::ConditionalOperatorClass:
4719 return VisitConditionalOperatorForTemporaryDtors(
4720 cast<AbstractConditionalOperator>(E), ExternallyDestructed, Context);
4721
4722 case Stmt::ImplicitCastExprClass:
4723 // For implicit cast we want ExternallyDestructed to be passed further.
4724 E = cast<CastExpr>(E)->getSubExpr();
4725 goto tryAgain;
4726
4727 case Stmt::CXXFunctionalCastExprClass:
4728 // For functional cast we want ExternallyDestructed to be passed further.
4729 E = cast<CXXFunctionalCastExpr>(E)->getSubExpr();
4730 goto tryAgain;
4731
4732 case Stmt::ConstantExprClass:
4733 E = cast<ConstantExpr>(E)->getSubExpr();
4734 goto tryAgain;
4735
4736 case Stmt::ParenExprClass:
4737 E = cast<ParenExpr>(E)->getSubExpr();
4738 goto tryAgain;
4739
4740 case Stmt::MaterializeTemporaryExprClass: {
4741 const MaterializeTemporaryExpr* MTE = cast<MaterializeTemporaryExpr>(E);
4742 ExternallyDestructed = (MTE->getStorageDuration() != SD_FullExpression);
4743 SmallVector<const Expr *, 2> CommaLHSs;
4744 SmallVector<SubobjectAdjustment, 2> Adjustments;
4745 // Find the expression whose lifetime needs to be extended.
4746 E = const_cast<Expr *>(
4747 cast<MaterializeTemporaryExpr>(E)
4748 ->getSubExpr()
4749 ->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments));
4750 // Visit the skipped comma operator left-hand sides for other temporaries.
4751 for (const Expr *CommaLHS : CommaLHSs) {
4752 VisitForTemporaryDtors(const_cast<Expr *>(CommaLHS),
4753 /*ExternallyDestructed=*/false, Context);
4754 }
4755 goto tryAgain;
4756 }
4757
4758 case Stmt::BlockExprClass:
4759 // Don't recurse into blocks; their subexpressions don't get evaluated
4760 // here.
4761 return Block;
4762
4763 case Stmt::LambdaExprClass: {
4764 // For lambda expressions, only recurse into the capture initializers,
4765 // and not the body.
4766 auto *LE = cast<LambdaExpr>(E);
4767 CFGBlock *B = Block;
4768 for (Expr *Init : LE->capture_inits()) {
4769 if (Init) {
4770 if (CFGBlock *R = VisitForTemporaryDtors(
4771 Init, /*ExternallyDestructed=*/true, Context))
4772 B = R;
4773 }
4774 }
4775 return B;
4776 }
4777
4778 case Stmt::StmtExprClass:
4779 // Don't recurse into statement expressions; any cleanups inside them
4780 // will be wrapped in their own ExprWithCleanups.
4781 return Block;
4782
4783 case Stmt::CXXDefaultArgExprClass:
4784 E = cast<CXXDefaultArgExpr>(E)->getExpr();
4785 goto tryAgain;
4786
4787 case Stmt::CXXDefaultInitExprClass:
4788 E = cast<CXXDefaultInitExpr>(E)->getExpr();
4789 goto tryAgain;
4790 }
4791 }
4792
VisitChildrenForTemporaryDtors(Stmt * E,bool ExternallyDestructed,TempDtorContext & Context)4793 CFGBlock *CFGBuilder::VisitChildrenForTemporaryDtors(Stmt *E,
4794 bool ExternallyDestructed,
4795 TempDtorContext &Context) {
4796 if (isa<LambdaExpr>(E)) {
4797 // Do not visit the children of lambdas; they have their own CFGs.
4798 return Block;
4799 }
4800
4801 // When visiting children for destructors we want to visit them in reverse
4802 // order that they will appear in the CFG. Because the CFG is built
4803 // bottom-up, this means we visit them in their natural order, which
4804 // reverses them in the CFG.
4805 CFGBlock *B = Block;
4806 for (Stmt *Child : E->children())
4807 if (Child)
4808 if (CFGBlock *R = VisitForTemporaryDtors(Child, ExternallyDestructed, Context))
4809 B = R;
4810
4811 return B;
4812 }
4813
VisitBinaryOperatorForTemporaryDtors(BinaryOperator * E,bool ExternallyDestructed,TempDtorContext & Context)4814 CFGBlock *CFGBuilder::VisitBinaryOperatorForTemporaryDtors(
4815 BinaryOperator *E, bool ExternallyDestructed, TempDtorContext &Context) {
4816 if (E->isCommaOp()) {
4817 // For the comma operator, the LHS expression is evaluated before the RHS
4818 // expression, so prepend temporary destructors for the LHS first.
4819 CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS(), false, Context);
4820 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS(), ExternallyDestructed, Context);
4821 return RHSBlock ? RHSBlock : LHSBlock;
4822 }
4823
4824 if (E->isLogicalOp()) {
4825 VisitForTemporaryDtors(E->getLHS(), false, Context);
4826 TryResult RHSExecuted = tryEvaluateBool(E->getLHS());
4827 if (RHSExecuted.isKnown() && E->getOpcode() == BO_LOr)
4828 RHSExecuted.negate();
4829
4830 // We do not know at CFG-construction time whether the right-hand-side was
4831 // executed, thus we add a branch node that depends on the temporary
4832 // constructor call.
4833 TempDtorContext RHSContext(
4834 bothKnownTrue(Context.KnownExecuted, RHSExecuted));
4835 VisitForTemporaryDtors(E->getRHS(), false, RHSContext);
4836 InsertTempDtorDecisionBlock(RHSContext);
4837
4838 return Block;
4839 }
4840
4841 if (E->isAssignmentOp()) {
4842 // For assignment operators, the RHS expression is evaluated before the LHS
4843 // expression, so prepend temporary destructors for the RHS first.
4844 CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS(), false, Context);
4845 CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS(), false, Context);
4846 return LHSBlock ? LHSBlock : RHSBlock;
4847 }
4848
4849 // Any other operator is visited normally.
4850 return VisitChildrenForTemporaryDtors(E, ExternallyDestructed, Context);
4851 }
4852
VisitCXXBindTemporaryExprForTemporaryDtors(CXXBindTemporaryExpr * E,bool ExternallyDestructed,TempDtorContext & Context)4853 CFGBlock *CFGBuilder::VisitCXXBindTemporaryExprForTemporaryDtors(
4854 CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context) {
4855 // First add destructors for temporaries in subexpression.
4856 // Because VisitCXXBindTemporaryExpr calls setDestructed:
4857 CFGBlock *B = VisitForTemporaryDtors(E->getSubExpr(), true, Context);
4858 if (!ExternallyDestructed) {
4859 // If lifetime of temporary is not prolonged (by assigning to constant
4860 // reference) add destructor for it.
4861
4862 const CXXDestructorDecl *Dtor = E->getTemporary()->getDestructor();
4863
4864 if (Dtor->getParent()->isAnyDestructorNoReturn()) {
4865 // If the destructor is marked as a no-return destructor, we need to
4866 // create a new block for the destructor which does not have as a
4867 // successor anything built thus far. Control won't flow out of this
4868 // block.
4869 if (B) Succ = B;
4870 Block = createNoReturnBlock();
4871 } else if (Context.needsTempDtorBranch()) {
4872 // If we need to introduce a branch, we add a new block that we will hook
4873 // up to a decision block later.
4874 if (B) Succ = B;
4875 Block = createBlock();
4876 } else {
4877 autoCreateBlock();
4878 }
4879 if (Context.needsTempDtorBranch()) {
4880 Context.setDecisionPoint(Succ, E);
4881 }
4882 appendTemporaryDtor(Block, E);
4883
4884 B = Block;
4885 }
4886 return B;
4887 }
4888
InsertTempDtorDecisionBlock(const TempDtorContext & Context,CFGBlock * FalseSucc)4889 void CFGBuilder::InsertTempDtorDecisionBlock(const TempDtorContext &Context,
4890 CFGBlock *FalseSucc) {
4891 if (!Context.TerminatorExpr) {
4892 // If no temporary was found, we do not need to insert a decision point.
4893 return;
4894 }
4895 assert(Context.TerminatorExpr);
4896 CFGBlock *Decision = createBlock(false);
4897 Decision->setTerminator(CFGTerminator(Context.TerminatorExpr,
4898 CFGTerminator::TemporaryDtorsBranch));
4899 addSuccessor(Decision, Block, !Context.KnownExecuted.isFalse());
4900 addSuccessor(Decision, FalseSucc ? FalseSucc : Context.Succ,
4901 !Context.KnownExecuted.isTrue());
4902 Block = Decision;
4903 }
4904
VisitConditionalOperatorForTemporaryDtors(AbstractConditionalOperator * E,bool ExternallyDestructed,TempDtorContext & Context)4905 CFGBlock *CFGBuilder::VisitConditionalOperatorForTemporaryDtors(
4906 AbstractConditionalOperator *E, bool ExternallyDestructed,
4907 TempDtorContext &Context) {
4908 VisitForTemporaryDtors(E->getCond(), false, Context);
4909 CFGBlock *ConditionBlock = Block;
4910 CFGBlock *ConditionSucc = Succ;
4911 TryResult ConditionVal = tryEvaluateBool(E->getCond());
4912 TryResult NegatedVal = ConditionVal;
4913 if (NegatedVal.isKnown()) NegatedVal.negate();
4914
4915 TempDtorContext TrueContext(
4916 bothKnownTrue(Context.KnownExecuted, ConditionVal));
4917 VisitForTemporaryDtors(E->getTrueExpr(), ExternallyDestructed, TrueContext);
4918 CFGBlock *TrueBlock = Block;
4919
4920 Block = ConditionBlock;
4921 Succ = ConditionSucc;
4922 TempDtorContext FalseContext(
4923 bothKnownTrue(Context.KnownExecuted, NegatedVal));
4924 VisitForTemporaryDtors(E->getFalseExpr(), ExternallyDestructed, FalseContext);
4925
4926 if (TrueContext.TerminatorExpr && FalseContext.TerminatorExpr) {
4927 InsertTempDtorDecisionBlock(FalseContext, TrueBlock);
4928 } else if (TrueContext.TerminatorExpr) {
4929 Block = TrueBlock;
4930 InsertTempDtorDecisionBlock(TrueContext);
4931 } else {
4932 InsertTempDtorDecisionBlock(FalseContext);
4933 }
4934 return Block;
4935 }
4936
VisitOMPExecutableDirective(OMPExecutableDirective * D,AddStmtChoice asc)4937 CFGBlock *CFGBuilder::VisitOMPExecutableDirective(OMPExecutableDirective *D,
4938 AddStmtChoice asc) {
4939 if (asc.alwaysAdd(*this, D)) {
4940 autoCreateBlock();
4941 appendStmt(Block, D);
4942 }
4943
4944 // Iterate over all used expression in clauses.
4945 CFGBlock *B = Block;
4946
4947 // Reverse the elements to process them in natural order. Iterators are not
4948 // bidirectional, so we need to create temp vector.
4949 SmallVector<Stmt *, 8> Used(
4950 OMPExecutableDirective::used_clauses_children(D->clauses()));
4951 for (Stmt *S : llvm::reverse(Used)) {
4952 assert(S && "Expected non-null used-in-clause child.");
4953 if (CFGBlock *R = Visit(S))
4954 B = R;
4955 }
4956 // Visit associated structured block if any.
4957 if (!D->isStandaloneDirective()) {
4958 Stmt *S = D->getRawStmt();
4959 if (!isa<CompoundStmt>(S))
4960 addLocalScopeAndDtors(S);
4961 if (CFGBlock *R = addStmt(S))
4962 B = R;
4963 }
4964
4965 return B;
4966 }
4967
4968 /// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has
4969 /// no successors or predecessors. If this is the first block created in the
4970 /// CFG, it is automatically set to be the Entry and Exit of the CFG.
createBlock()4971 CFGBlock *CFG::createBlock() {
4972 bool first_block = begin() == end();
4973
4974 // Create the block.
4975 CFGBlock *Mem = getAllocator().Allocate<CFGBlock>();
4976 new (Mem) CFGBlock(NumBlockIDs++, BlkBVC, this);
4977 Blocks.push_back(Mem, BlkBVC);
4978
4979 // If this is the first block, set it as the Entry and Exit.
4980 if (first_block)
4981 Entry = Exit = &back();
4982
4983 // Return the block.
4984 return &back();
4985 }
4986
4987 /// buildCFG - Constructs a CFG from an AST.
buildCFG(const Decl * D,Stmt * Statement,ASTContext * C,const BuildOptions & BO)4988 std::unique_ptr<CFG> CFG::buildCFG(const Decl *D, Stmt *Statement,
4989 ASTContext *C, const BuildOptions &BO) {
4990 CFGBuilder Builder(C, BO);
4991 return Builder.buildCFG(D, Statement);
4992 }
4993
isLinear() const4994 bool CFG::isLinear() const {
4995 // Quick path: if we only have the ENTRY block, the EXIT block, and some code
4996 // in between, then we have no room for control flow.
4997 if (size() <= 3)
4998 return true;
4999
5000 // Traverse the CFG until we find a branch.
5001 // TODO: While this should still be very fast,
5002 // maybe we should cache the answer.
5003 llvm::SmallPtrSet<const CFGBlock *, 4> Visited;
5004 const CFGBlock *B = Entry;
5005 while (B != Exit) {
5006 auto IteratorAndFlag = Visited.insert(B);
5007 if (!IteratorAndFlag.second) {
5008 // We looped back to a block that we've already visited. Not linear.
5009 return false;
5010 }
5011
5012 // Iterate over reachable successors.
5013 const CFGBlock *FirstReachableB = nullptr;
5014 for (const CFGBlock::AdjacentBlock &AB : B->succs()) {
5015 if (!AB.isReachable())
5016 continue;
5017
5018 if (FirstReachableB == nullptr) {
5019 FirstReachableB = &*AB;
5020 } else {
5021 // We've encountered a branch. It's not a linear CFG.
5022 return false;
5023 }
5024 }
5025
5026 if (!FirstReachableB) {
5027 // We reached a dead end. EXIT is unreachable. This is linear enough.
5028 return true;
5029 }
5030
5031 // There's only one way to move forward. Proceed.
5032 B = FirstReachableB;
5033 }
5034
5035 // We reached EXIT and found no branches.
5036 return true;
5037 }
5038
5039 const CXXDestructorDecl *
getDestructorDecl(ASTContext & astContext) const5040 CFGImplicitDtor::getDestructorDecl(ASTContext &astContext) const {
5041 switch (getKind()) {
5042 case CFGElement::Initializer:
5043 case CFGElement::NewAllocator:
5044 case CFGElement::LoopExit:
5045 case CFGElement::LifetimeEnds:
5046 case CFGElement::Statement:
5047 case CFGElement::Constructor:
5048 case CFGElement::CXXRecordTypedCall:
5049 case CFGElement::ScopeBegin:
5050 case CFGElement::ScopeEnd:
5051 llvm_unreachable("getDestructorDecl should only be used with "
5052 "ImplicitDtors");
5053 case CFGElement::AutomaticObjectDtor: {
5054 const VarDecl *var = castAs<CFGAutomaticObjDtor>().getVarDecl();
5055 QualType ty = var->getType();
5056
5057 // FIXME: See CFGBuilder::addLocalScopeForVarDecl.
5058 //
5059 // Lifetime-extending constructs are handled here. This works for a single
5060 // temporary in an initializer expression.
5061 if (ty->isReferenceType()) {
5062 if (const Expr *Init = var->getInit()) {
5063 ty = getReferenceInitTemporaryType(Init);
5064 }
5065 }
5066
5067 while (const ArrayType *arrayType = astContext.getAsArrayType(ty)) {
5068 ty = arrayType->getElementType();
5069 }
5070
5071 // The situation when the type of the lifetime-extending reference
5072 // does not correspond to the type of the object is supposed
5073 // to be handled by now. In particular, 'ty' is now the unwrapped
5074 // record type.
5075 const CXXRecordDecl *classDecl = ty->getAsCXXRecordDecl();
5076 assert(classDecl);
5077 return classDecl->getDestructor();
5078 }
5079 case CFGElement::DeleteDtor: {
5080 const CXXDeleteExpr *DE = castAs<CFGDeleteDtor>().getDeleteExpr();
5081 QualType DTy = DE->getDestroyedType();
5082 DTy = DTy.getNonReferenceType();
5083 const CXXRecordDecl *classDecl =
5084 astContext.getBaseElementType(DTy)->getAsCXXRecordDecl();
5085 return classDecl->getDestructor();
5086 }
5087 case CFGElement::TemporaryDtor: {
5088 const CXXBindTemporaryExpr *bindExpr =
5089 castAs<CFGTemporaryDtor>().getBindTemporaryExpr();
5090 const CXXTemporary *temp = bindExpr->getTemporary();
5091 return temp->getDestructor();
5092 }
5093 case CFGElement::BaseDtor:
5094 case CFGElement::MemberDtor:
5095 // Not yet supported.
5096 return nullptr;
5097 }
5098 llvm_unreachable("getKind() returned bogus value");
5099 }
5100
5101 //===----------------------------------------------------------------------===//
5102 // CFGBlock operations.
5103 //===----------------------------------------------------------------------===//
5104
AdjacentBlock(CFGBlock * B,bool IsReachable)5105 CFGBlock::AdjacentBlock::AdjacentBlock(CFGBlock *B, bool IsReachable)
5106 : ReachableBlock(IsReachable ? B : nullptr),
5107 UnreachableBlock(!IsReachable ? B : nullptr,
5108 B && IsReachable ? AB_Normal : AB_Unreachable) {}
5109
AdjacentBlock(CFGBlock * B,CFGBlock * AlternateBlock)5110 CFGBlock::AdjacentBlock::AdjacentBlock(CFGBlock *B, CFGBlock *AlternateBlock)
5111 : ReachableBlock(B),
5112 UnreachableBlock(B == AlternateBlock ? nullptr : AlternateBlock,
5113 B == AlternateBlock ? AB_Alternate : AB_Normal) {}
5114
addSuccessor(AdjacentBlock Succ,BumpVectorContext & C)5115 void CFGBlock::addSuccessor(AdjacentBlock Succ,
5116 BumpVectorContext &C) {
5117 if (CFGBlock *B = Succ.getReachableBlock())
5118 B->Preds.push_back(AdjacentBlock(this, Succ.isReachable()), C);
5119
5120 if (CFGBlock *UnreachableB = Succ.getPossiblyUnreachableBlock())
5121 UnreachableB->Preds.push_back(AdjacentBlock(this, false), C);
5122
5123 Succs.push_back(Succ, C);
5124 }
5125
FilterEdge(const CFGBlock::FilterOptions & F,const CFGBlock * From,const CFGBlock * To)5126 bool CFGBlock::FilterEdge(const CFGBlock::FilterOptions &F,
5127 const CFGBlock *From, const CFGBlock *To) {
5128 if (F.IgnoreNullPredecessors && !From)
5129 return true;
5130
5131 if (To && From && F.IgnoreDefaultsWithCoveredEnums) {
5132 // If the 'To' has no label or is labeled but the label isn't a
5133 // CaseStmt then filter this edge.
5134 if (const SwitchStmt *S =
5135 dyn_cast_or_null<SwitchStmt>(From->getTerminatorStmt())) {
5136 if (S->isAllEnumCasesCovered()) {
5137 const Stmt *L = To->getLabel();
5138 if (!L || !isa<CaseStmt>(L))
5139 return true;
5140 }
5141 }
5142 }
5143
5144 return false;
5145 }
5146
5147 //===----------------------------------------------------------------------===//
5148 // CFG pretty printing
5149 //===----------------------------------------------------------------------===//
5150
5151 namespace {
5152
5153 class StmtPrinterHelper : public PrinterHelper {
5154 using StmtMapTy = llvm::DenseMap<const Stmt *, std::pair<unsigned, unsigned>>;
5155 using DeclMapTy = llvm::DenseMap<const Decl *, std::pair<unsigned, unsigned>>;
5156
5157 StmtMapTy StmtMap;
5158 DeclMapTy DeclMap;
5159 signed currentBlock = 0;
5160 unsigned currStmt = 0;
5161 const LangOptions &LangOpts;
5162
5163 public:
StmtPrinterHelper(const CFG * cfg,const LangOptions & LO)5164 StmtPrinterHelper(const CFG* cfg, const LangOptions &LO)
5165 : LangOpts(LO) {
5166 if (!cfg)
5167 return;
5168 for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) {
5169 unsigned j = 1;
5170 for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ;
5171 BI != BEnd; ++BI, ++j ) {
5172 if (Optional<CFGStmt> SE = BI->getAs<CFGStmt>()) {
5173 const Stmt *stmt= SE->getStmt();
5174 std::pair<unsigned, unsigned> P((*I)->getBlockID(), j);
5175 StmtMap[stmt] = P;
5176
5177 switch (stmt->getStmtClass()) {
5178 case Stmt::DeclStmtClass:
5179 DeclMap[cast<DeclStmt>(stmt)->getSingleDecl()] = P;
5180 break;
5181 case Stmt::IfStmtClass: {
5182 const VarDecl *var = cast<IfStmt>(stmt)->getConditionVariable();
5183 if (var)
5184 DeclMap[var] = P;
5185 break;
5186 }
5187 case Stmt::ForStmtClass: {
5188 const VarDecl *var = cast<ForStmt>(stmt)->getConditionVariable();
5189 if (var)
5190 DeclMap[var] = P;
5191 break;
5192 }
5193 case Stmt::WhileStmtClass: {
5194 const VarDecl *var =
5195 cast<WhileStmt>(stmt)->getConditionVariable();
5196 if (var)
5197 DeclMap[var] = P;
5198 break;
5199 }
5200 case Stmt::SwitchStmtClass: {
5201 const VarDecl *var =
5202 cast<SwitchStmt>(stmt)->getConditionVariable();
5203 if (var)
5204 DeclMap[var] = P;
5205 break;
5206 }
5207 case Stmt::CXXCatchStmtClass: {
5208 const VarDecl *var =
5209 cast<CXXCatchStmt>(stmt)->getExceptionDecl();
5210 if (var)
5211 DeclMap[var] = P;
5212 break;
5213 }
5214 default:
5215 break;
5216 }
5217 }
5218 }
5219 }
5220 }
5221
5222 ~StmtPrinterHelper() override = default;
5223
getLangOpts() const5224 const LangOptions &getLangOpts() const { return LangOpts; }
setBlockID(signed i)5225 void setBlockID(signed i) { currentBlock = i; }
setStmtID(unsigned i)5226 void setStmtID(unsigned i) { currStmt = i; }
5227
handledStmt(Stmt * S,raw_ostream & OS)5228 bool handledStmt(Stmt *S, raw_ostream &OS) override {
5229 StmtMapTy::iterator I = StmtMap.find(S);
5230
5231 if (I == StmtMap.end())
5232 return false;
5233
5234 if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock
5235 && I->second.second == currStmt) {
5236 return false;
5237 }
5238
5239 OS << "[B" << I->second.first << "." << I->second.second << "]";
5240 return true;
5241 }
5242
handleDecl(const Decl * D,raw_ostream & OS)5243 bool handleDecl(const Decl *D, raw_ostream &OS) {
5244 DeclMapTy::iterator I = DeclMap.find(D);
5245
5246 if (I == DeclMap.end())
5247 return false;
5248
5249 if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock
5250 && I->second.second == currStmt) {
5251 return false;
5252 }
5253
5254 OS << "[B" << I->second.first << "." << I->second.second << "]";
5255 return true;
5256 }
5257 };
5258
5259 class CFGBlockTerminatorPrint
5260 : public StmtVisitor<CFGBlockTerminatorPrint,void> {
5261 raw_ostream &OS;
5262 StmtPrinterHelper* Helper;
5263 PrintingPolicy Policy;
5264
5265 public:
CFGBlockTerminatorPrint(raw_ostream & os,StmtPrinterHelper * helper,const PrintingPolicy & Policy)5266 CFGBlockTerminatorPrint(raw_ostream &os, StmtPrinterHelper* helper,
5267 const PrintingPolicy &Policy)
5268 : OS(os), Helper(helper), Policy(Policy) {
5269 this->Policy.IncludeNewlines = false;
5270 }
5271
VisitIfStmt(IfStmt * I)5272 void VisitIfStmt(IfStmt *I) {
5273 OS << "if ";
5274 if (Stmt *C = I->getCond())
5275 C->printPretty(OS, Helper, Policy);
5276 }
5277
5278 // Default case.
VisitStmt(Stmt * Terminator)5279 void VisitStmt(Stmt *Terminator) {
5280 Terminator->printPretty(OS, Helper, Policy);
5281 }
5282
VisitDeclStmt(DeclStmt * DS)5283 void VisitDeclStmt(DeclStmt *DS) {
5284 VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
5285 OS << "static init " << VD->getName();
5286 }
5287
VisitForStmt(ForStmt * F)5288 void VisitForStmt(ForStmt *F) {
5289 OS << "for (" ;
5290 if (F->getInit())
5291 OS << "...";
5292 OS << "; ";
5293 if (Stmt *C = F->getCond())
5294 C->printPretty(OS, Helper, Policy);
5295 OS << "; ";
5296 if (F->getInc())
5297 OS << "...";
5298 OS << ")";
5299 }
5300
VisitWhileStmt(WhileStmt * W)5301 void VisitWhileStmt(WhileStmt *W) {
5302 OS << "while " ;
5303 if (Stmt *C = W->getCond())
5304 C->printPretty(OS, Helper, Policy);
5305 }
5306
VisitDoStmt(DoStmt * D)5307 void VisitDoStmt(DoStmt *D) {
5308 OS << "do ... while ";
5309 if (Stmt *C = D->getCond())
5310 C->printPretty(OS, Helper, Policy);
5311 }
5312
VisitSwitchStmt(SwitchStmt * Terminator)5313 void VisitSwitchStmt(SwitchStmt *Terminator) {
5314 OS << "switch ";
5315 Terminator->getCond()->printPretty(OS, Helper, Policy);
5316 }
5317
VisitCXXTryStmt(CXXTryStmt * CS)5318 void VisitCXXTryStmt(CXXTryStmt *CS) {
5319 OS << "try ...";
5320 }
5321
VisitSEHTryStmt(SEHTryStmt * CS)5322 void VisitSEHTryStmt(SEHTryStmt *CS) {
5323 OS << "__try ...";
5324 }
5325
VisitAbstractConditionalOperator(AbstractConditionalOperator * C)5326 void VisitAbstractConditionalOperator(AbstractConditionalOperator* C) {
5327 if (Stmt *Cond = C->getCond())
5328 Cond->printPretty(OS, Helper, Policy);
5329 OS << " ? ... : ...";
5330 }
5331
VisitChooseExpr(ChooseExpr * C)5332 void VisitChooseExpr(ChooseExpr *C) {
5333 OS << "__builtin_choose_expr( ";
5334 if (Stmt *Cond = C->getCond())
5335 Cond->printPretty(OS, Helper, Policy);
5336 OS << " )";
5337 }
5338
VisitIndirectGotoStmt(IndirectGotoStmt * I)5339 void VisitIndirectGotoStmt(IndirectGotoStmt *I) {
5340 OS << "goto *";
5341 if (Stmt *T = I->getTarget())
5342 T->printPretty(OS, Helper, Policy);
5343 }
5344
VisitBinaryOperator(BinaryOperator * B)5345 void VisitBinaryOperator(BinaryOperator* B) {
5346 if (!B->isLogicalOp()) {
5347 VisitExpr(B);
5348 return;
5349 }
5350
5351 if (B->getLHS())
5352 B->getLHS()->printPretty(OS, Helper, Policy);
5353
5354 switch (B->getOpcode()) {
5355 case BO_LOr:
5356 OS << " || ...";
5357 return;
5358 case BO_LAnd:
5359 OS << " && ...";
5360 return;
5361 default:
5362 llvm_unreachable("Invalid logical operator.");
5363 }
5364 }
5365
VisitExpr(Expr * E)5366 void VisitExpr(Expr *E) {
5367 E->printPretty(OS, Helper, Policy);
5368 }
5369
5370 public:
print(CFGTerminator T)5371 void print(CFGTerminator T) {
5372 switch (T.getKind()) {
5373 case CFGTerminator::StmtBranch:
5374 Visit(T.getStmt());
5375 break;
5376 case CFGTerminator::TemporaryDtorsBranch:
5377 OS << "(Temp Dtor) ";
5378 Visit(T.getStmt());
5379 break;
5380 case CFGTerminator::VirtualBaseBranch:
5381 OS << "(See if most derived ctor has already initialized vbases)";
5382 break;
5383 }
5384 }
5385 };
5386
5387 } // namespace
5388
print_initializer(raw_ostream & OS,StmtPrinterHelper & Helper,const CXXCtorInitializer * I)5389 static void print_initializer(raw_ostream &OS, StmtPrinterHelper &Helper,
5390 const CXXCtorInitializer *I) {
5391 if (I->isBaseInitializer())
5392 OS << I->getBaseClass()->getAsCXXRecordDecl()->getName();
5393 else if (I->isDelegatingInitializer())
5394 OS << I->getTypeSourceInfo()->getType()->getAsCXXRecordDecl()->getName();
5395 else
5396 OS << I->getAnyMember()->getName();
5397 OS << "(";
5398 if (Expr *IE = I->getInit())
5399 IE->printPretty(OS, &Helper, PrintingPolicy(Helper.getLangOpts()));
5400 OS << ")";
5401
5402 if (I->isBaseInitializer())
5403 OS << " (Base initializer)";
5404 else if (I->isDelegatingInitializer())
5405 OS << " (Delegating initializer)";
5406 else
5407 OS << " (Member initializer)";
5408 }
5409
print_construction_context(raw_ostream & OS,StmtPrinterHelper & Helper,const ConstructionContext * CC)5410 static void print_construction_context(raw_ostream &OS,
5411 StmtPrinterHelper &Helper,
5412 const ConstructionContext *CC) {
5413 SmallVector<const Stmt *, 3> Stmts;
5414 switch (CC->getKind()) {
5415 case ConstructionContext::SimpleConstructorInitializerKind: {
5416 OS << ", ";
5417 const auto *SICC = cast<SimpleConstructorInitializerConstructionContext>(CC);
5418 print_initializer(OS, Helper, SICC->getCXXCtorInitializer());
5419 return;
5420 }
5421 case ConstructionContext::CXX17ElidedCopyConstructorInitializerKind: {
5422 OS << ", ";
5423 const auto *CICC =
5424 cast<CXX17ElidedCopyConstructorInitializerConstructionContext>(CC);
5425 print_initializer(OS, Helper, CICC->getCXXCtorInitializer());
5426 Stmts.push_back(CICC->getCXXBindTemporaryExpr());
5427 break;
5428 }
5429 case ConstructionContext::SimpleVariableKind: {
5430 const auto *SDSCC = cast<SimpleVariableConstructionContext>(CC);
5431 Stmts.push_back(SDSCC->getDeclStmt());
5432 break;
5433 }
5434 case ConstructionContext::CXX17ElidedCopyVariableKind: {
5435 const auto *CDSCC = cast<CXX17ElidedCopyVariableConstructionContext>(CC);
5436 Stmts.push_back(CDSCC->getDeclStmt());
5437 Stmts.push_back(CDSCC->getCXXBindTemporaryExpr());
5438 break;
5439 }
5440 case ConstructionContext::NewAllocatedObjectKind: {
5441 const auto *NECC = cast<NewAllocatedObjectConstructionContext>(CC);
5442 Stmts.push_back(NECC->getCXXNewExpr());
5443 break;
5444 }
5445 case ConstructionContext::SimpleReturnedValueKind: {
5446 const auto *RSCC = cast<SimpleReturnedValueConstructionContext>(CC);
5447 Stmts.push_back(RSCC->getReturnStmt());
5448 break;
5449 }
5450 case ConstructionContext::CXX17ElidedCopyReturnedValueKind: {
5451 const auto *RSCC =
5452 cast<CXX17ElidedCopyReturnedValueConstructionContext>(CC);
5453 Stmts.push_back(RSCC->getReturnStmt());
5454 Stmts.push_back(RSCC->getCXXBindTemporaryExpr());
5455 break;
5456 }
5457 case ConstructionContext::SimpleTemporaryObjectKind: {
5458 const auto *TOCC = cast<SimpleTemporaryObjectConstructionContext>(CC);
5459 Stmts.push_back(TOCC->getCXXBindTemporaryExpr());
5460 Stmts.push_back(TOCC->getMaterializedTemporaryExpr());
5461 break;
5462 }
5463 case ConstructionContext::ElidedTemporaryObjectKind: {
5464 const auto *TOCC = cast<ElidedTemporaryObjectConstructionContext>(CC);
5465 Stmts.push_back(TOCC->getCXXBindTemporaryExpr());
5466 Stmts.push_back(TOCC->getMaterializedTemporaryExpr());
5467 Stmts.push_back(TOCC->getConstructorAfterElision());
5468 break;
5469 }
5470 case ConstructionContext::ArgumentKind: {
5471 const auto *ACC = cast<ArgumentConstructionContext>(CC);
5472 if (const Stmt *BTE = ACC->getCXXBindTemporaryExpr()) {
5473 OS << ", ";
5474 Helper.handledStmt(const_cast<Stmt *>(BTE), OS);
5475 }
5476 OS << ", ";
5477 Helper.handledStmt(const_cast<Expr *>(ACC->getCallLikeExpr()), OS);
5478 OS << "+" << ACC->getIndex();
5479 return;
5480 }
5481 }
5482 for (auto I: Stmts)
5483 if (I) {
5484 OS << ", ";
5485 Helper.handledStmt(const_cast<Stmt *>(I), OS);
5486 }
5487 }
5488
5489 static void print_elem(raw_ostream &OS, StmtPrinterHelper &Helper,
5490 const CFGElement &E);
5491
dumpToStream(llvm::raw_ostream & OS) const5492 void CFGElement::dumpToStream(llvm::raw_ostream &OS) const {
5493 StmtPrinterHelper Helper(nullptr, {});
5494 print_elem(OS, Helper, *this);
5495 }
5496
print_elem(raw_ostream & OS,StmtPrinterHelper & Helper,const CFGElement & E)5497 static void print_elem(raw_ostream &OS, StmtPrinterHelper &Helper,
5498 const CFGElement &E) {
5499 switch (E.getKind()) {
5500 case CFGElement::Kind::Statement:
5501 case CFGElement::Kind::CXXRecordTypedCall:
5502 case CFGElement::Kind::Constructor: {
5503 CFGStmt CS = E.castAs<CFGStmt>();
5504 const Stmt *S = CS.getStmt();
5505 assert(S != nullptr && "Expecting non-null Stmt");
5506
5507 // special printing for statement-expressions.
5508 if (const StmtExpr *SE = dyn_cast<StmtExpr>(S)) {
5509 const CompoundStmt *Sub = SE->getSubStmt();
5510
5511 auto Children = Sub->children();
5512 if (Children.begin() != Children.end()) {
5513 OS << "({ ... ; ";
5514 Helper.handledStmt(*SE->getSubStmt()->body_rbegin(),OS);
5515 OS << " })\n";
5516 return;
5517 }
5518 }
5519 // special printing for comma expressions.
5520 if (const BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
5521 if (B->getOpcode() == BO_Comma) {
5522 OS << "... , ";
5523 Helper.handledStmt(B->getRHS(),OS);
5524 OS << '\n';
5525 return;
5526 }
5527 }
5528 S->printPretty(OS, &Helper, PrintingPolicy(Helper.getLangOpts()));
5529
5530 if (auto VTC = E.getAs<CFGCXXRecordTypedCall>()) {
5531 if (isa<CXXOperatorCallExpr>(S))
5532 OS << " (OperatorCall)";
5533 OS << " (CXXRecordTypedCall";
5534 print_construction_context(OS, Helper, VTC->getConstructionContext());
5535 OS << ")";
5536 } else if (isa<CXXOperatorCallExpr>(S)) {
5537 OS << " (OperatorCall)";
5538 } else if (isa<CXXBindTemporaryExpr>(S)) {
5539 OS << " (BindTemporary)";
5540 } else if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(S)) {
5541 OS << " (CXXConstructExpr";
5542 if (Optional<CFGConstructor> CE = E.getAs<CFGConstructor>()) {
5543 print_construction_context(OS, Helper, CE->getConstructionContext());
5544 }
5545 OS << ", " << CCE->getType().getAsString() << ")";
5546 } else if (const CastExpr *CE = dyn_cast<CastExpr>(S)) {
5547 OS << " (" << CE->getStmtClassName() << ", "
5548 << CE->getCastKindName()
5549 << ", " << CE->getType().getAsString()
5550 << ")";
5551 }
5552
5553 // Expressions need a newline.
5554 if (isa<Expr>(S))
5555 OS << '\n';
5556
5557 break;
5558 }
5559
5560 case CFGElement::Kind::Initializer:
5561 print_initializer(OS, Helper, E.castAs<CFGInitializer>().getInitializer());
5562 OS << '\n';
5563 break;
5564
5565 case CFGElement::Kind::AutomaticObjectDtor: {
5566 CFGAutomaticObjDtor DE = E.castAs<CFGAutomaticObjDtor>();
5567 const VarDecl *VD = DE.getVarDecl();
5568 Helper.handleDecl(VD, OS);
5569
5570 QualType T = VD->getType();
5571 if (T->isReferenceType())
5572 T = getReferenceInitTemporaryType(VD->getInit(), nullptr);
5573
5574 OS << ".~";
5575 T.getUnqualifiedType().print(OS, PrintingPolicy(Helper.getLangOpts()));
5576 OS << "() (Implicit destructor)\n";
5577 break;
5578 }
5579
5580 case CFGElement::Kind::LifetimeEnds:
5581 Helper.handleDecl(E.castAs<CFGLifetimeEnds>().getVarDecl(), OS);
5582 OS << " (Lifetime ends)\n";
5583 break;
5584
5585 case CFGElement::Kind::LoopExit:
5586 OS << E.castAs<CFGLoopExit>().getLoopStmt()->getStmtClassName() << " (LoopExit)\n";
5587 break;
5588
5589 case CFGElement::Kind::ScopeBegin:
5590 OS << "CFGScopeBegin(";
5591 if (const VarDecl *VD = E.castAs<CFGScopeBegin>().getVarDecl())
5592 OS << VD->getQualifiedNameAsString();
5593 OS << ")\n";
5594 break;
5595
5596 case CFGElement::Kind::ScopeEnd:
5597 OS << "CFGScopeEnd(";
5598 if (const VarDecl *VD = E.castAs<CFGScopeEnd>().getVarDecl())
5599 OS << VD->getQualifiedNameAsString();
5600 OS << ")\n";
5601 break;
5602
5603 case CFGElement::Kind::NewAllocator:
5604 OS << "CFGNewAllocator(";
5605 if (const CXXNewExpr *AllocExpr = E.castAs<CFGNewAllocator>().getAllocatorExpr())
5606 AllocExpr->getType().print(OS, PrintingPolicy(Helper.getLangOpts()));
5607 OS << ")\n";
5608 break;
5609
5610 case CFGElement::Kind::DeleteDtor: {
5611 CFGDeleteDtor DE = E.castAs<CFGDeleteDtor>();
5612 const CXXRecordDecl *RD = DE.getCXXRecordDecl();
5613 if (!RD)
5614 return;
5615 CXXDeleteExpr *DelExpr =
5616 const_cast<CXXDeleteExpr*>(DE.getDeleteExpr());
5617 Helper.handledStmt(cast<Stmt>(DelExpr->getArgument()), OS);
5618 OS << "->~" << RD->getName().str() << "()";
5619 OS << " (Implicit destructor)\n";
5620 break;
5621 }
5622
5623 case CFGElement::Kind::BaseDtor: {
5624 const CXXBaseSpecifier *BS = E.castAs<CFGBaseDtor>().getBaseSpecifier();
5625 OS << "~" << BS->getType()->getAsCXXRecordDecl()->getName() << "()";
5626 OS << " (Base object destructor)\n";
5627 break;
5628 }
5629
5630 case CFGElement::Kind::MemberDtor: {
5631 const FieldDecl *FD = E.castAs<CFGMemberDtor>().getFieldDecl();
5632 const Type *T = FD->getType()->getBaseElementTypeUnsafe();
5633 OS << "this->" << FD->getName();
5634 OS << ".~" << T->getAsCXXRecordDecl()->getName() << "()";
5635 OS << " (Member object destructor)\n";
5636 break;
5637 }
5638
5639 case CFGElement::Kind::TemporaryDtor: {
5640 const CXXBindTemporaryExpr *BT = E.castAs<CFGTemporaryDtor>().getBindTemporaryExpr();
5641 OS << "~";
5642 BT->getType().print(OS, PrintingPolicy(Helper.getLangOpts()));
5643 OS << "() (Temporary object destructor)\n";
5644 break;
5645 }
5646 }
5647 }
5648
print_block(raw_ostream & OS,const CFG * cfg,const CFGBlock & B,StmtPrinterHelper & Helper,bool print_edges,bool ShowColors)5649 static void print_block(raw_ostream &OS, const CFG* cfg,
5650 const CFGBlock &B,
5651 StmtPrinterHelper &Helper, bool print_edges,
5652 bool ShowColors) {
5653 Helper.setBlockID(B.getBlockID());
5654
5655 // Print the header.
5656 if (ShowColors)
5657 OS.changeColor(raw_ostream::YELLOW, true);
5658
5659 OS << "\n [B" << B.getBlockID();
5660
5661 if (&B == &cfg->getEntry())
5662 OS << " (ENTRY)]\n";
5663 else if (&B == &cfg->getExit())
5664 OS << " (EXIT)]\n";
5665 else if (&B == cfg->getIndirectGotoBlock())
5666 OS << " (INDIRECT GOTO DISPATCH)]\n";
5667 else if (B.hasNoReturnElement())
5668 OS << " (NORETURN)]\n";
5669 else
5670 OS << "]\n";
5671
5672 if (ShowColors)
5673 OS.resetColor();
5674
5675 // Print the label of this block.
5676 if (Stmt *Label = const_cast<Stmt*>(B.getLabel())) {
5677 if (print_edges)
5678 OS << " ";
5679
5680 if (LabelStmt *L = dyn_cast<LabelStmt>(Label))
5681 OS << L->getName();
5682 else if (CaseStmt *C = dyn_cast<CaseStmt>(Label)) {
5683 OS << "case ";
5684 if (C->getLHS())
5685 C->getLHS()->printPretty(OS, &Helper,
5686 PrintingPolicy(Helper.getLangOpts()));
5687 if (C->getRHS()) {
5688 OS << " ... ";
5689 C->getRHS()->printPretty(OS, &Helper,
5690 PrintingPolicy(Helper.getLangOpts()));
5691 }
5692 } else if (isa<DefaultStmt>(Label))
5693 OS << "default";
5694 else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) {
5695 OS << "catch (";
5696 if (CS->getExceptionDecl())
5697 CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper.getLangOpts()),
5698 0);
5699 else
5700 OS << "...";
5701 OS << ")";
5702 } else if (SEHExceptStmt *ES = dyn_cast<SEHExceptStmt>(Label)) {
5703 OS << "__except (";
5704 ES->getFilterExpr()->printPretty(OS, &Helper,
5705 PrintingPolicy(Helper.getLangOpts()), 0);
5706 OS << ")";
5707 } else
5708 llvm_unreachable("Invalid label statement in CFGBlock.");
5709
5710 OS << ":\n";
5711 }
5712
5713 // Iterate through the statements in the block and print them.
5714 unsigned j = 1;
5715
5716 for (CFGBlock::const_iterator I = B.begin(), E = B.end() ;
5717 I != E ; ++I, ++j ) {
5718 // Print the statement # in the basic block and the statement itself.
5719 if (print_edges)
5720 OS << " ";
5721
5722 OS << llvm::format("%3d", j) << ": ";
5723
5724 Helper.setStmtID(j);
5725
5726 print_elem(OS, Helper, *I);
5727 }
5728
5729 // Print the terminator of this block.
5730 if (B.getTerminator().isValid()) {
5731 if (ShowColors)
5732 OS.changeColor(raw_ostream::GREEN);
5733
5734 OS << " T: ";
5735
5736 Helper.setBlockID(-1);
5737
5738 PrintingPolicy PP(Helper.getLangOpts());
5739 CFGBlockTerminatorPrint TPrinter(OS, &Helper, PP);
5740 TPrinter.print(B.getTerminator());
5741 OS << '\n';
5742
5743 if (ShowColors)
5744 OS.resetColor();
5745 }
5746
5747 if (print_edges) {
5748 // Print the predecessors of this block.
5749 if (!B.pred_empty()) {
5750 const raw_ostream::Colors Color = raw_ostream::BLUE;
5751 if (ShowColors)
5752 OS.changeColor(Color);
5753 OS << " Preds " ;
5754 if (ShowColors)
5755 OS.resetColor();
5756 OS << '(' << B.pred_size() << "):";
5757 unsigned i = 0;
5758
5759 if (ShowColors)
5760 OS.changeColor(Color);
5761
5762 for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end();
5763 I != E; ++I, ++i) {
5764 if (i % 10 == 8)
5765 OS << "\n ";
5766
5767 CFGBlock *B = *I;
5768 bool Reachable = true;
5769 if (!B) {
5770 Reachable = false;
5771 B = I->getPossiblyUnreachableBlock();
5772 }
5773
5774 OS << " B" << B->getBlockID();
5775 if (!Reachable)
5776 OS << "(Unreachable)";
5777 }
5778
5779 if (ShowColors)
5780 OS.resetColor();
5781
5782 OS << '\n';
5783 }
5784
5785 // Print the successors of this block.
5786 if (!B.succ_empty()) {
5787 const raw_ostream::Colors Color = raw_ostream::MAGENTA;
5788 if (ShowColors)
5789 OS.changeColor(Color);
5790 OS << " Succs ";
5791 if (ShowColors)
5792 OS.resetColor();
5793 OS << '(' << B.succ_size() << "):";
5794 unsigned i = 0;
5795
5796 if (ShowColors)
5797 OS.changeColor(Color);
5798
5799 for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end();
5800 I != E; ++I, ++i) {
5801 if (i % 10 == 8)
5802 OS << "\n ";
5803
5804 CFGBlock *B = *I;
5805
5806 bool Reachable = true;
5807 if (!B) {
5808 Reachable = false;
5809 B = I->getPossiblyUnreachableBlock();
5810 }
5811
5812 if (B) {
5813 OS << " B" << B->getBlockID();
5814 if (!Reachable)
5815 OS << "(Unreachable)";
5816 }
5817 else {
5818 OS << " NULL";
5819 }
5820 }
5821
5822 if (ShowColors)
5823 OS.resetColor();
5824 OS << '\n';
5825 }
5826 }
5827 }
5828
5829 /// dump - A simple pretty printer of a CFG that outputs to stderr.
dump(const LangOptions & LO,bool ShowColors) const5830 void CFG::dump(const LangOptions &LO, bool ShowColors) const {
5831 print(llvm::errs(), LO, ShowColors);
5832 }
5833
5834 /// print - A simple pretty printer of a CFG that outputs to an ostream.
print(raw_ostream & OS,const LangOptions & LO,bool ShowColors) const5835 void CFG::print(raw_ostream &OS, const LangOptions &LO, bool ShowColors) const {
5836 StmtPrinterHelper Helper(this, LO);
5837
5838 // Print the entry block.
5839 print_block(OS, this, getEntry(), Helper, true, ShowColors);
5840
5841 // Iterate through the CFGBlocks and print them one by one.
5842 for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) {
5843 // Skip the entry block, because we already printed it.
5844 if (&(**I) == &getEntry() || &(**I) == &getExit())
5845 continue;
5846
5847 print_block(OS, this, **I, Helper, true, ShowColors);
5848 }
5849
5850 // Print the exit block.
5851 print_block(OS, this, getExit(), Helper, true, ShowColors);
5852 OS << '\n';
5853 OS.flush();
5854 }
5855
getIndexInCFG() const5856 size_t CFGBlock::getIndexInCFG() const {
5857 return llvm::find(*getParent(), this) - getParent()->begin();
5858 }
5859
5860 /// dump - A simply pretty printer of a CFGBlock that outputs to stderr.
dump(const CFG * cfg,const LangOptions & LO,bool ShowColors) const5861 void CFGBlock::dump(const CFG* cfg, const LangOptions &LO,
5862 bool ShowColors) const {
5863 print(llvm::errs(), cfg, LO, ShowColors);
5864 }
5865
dump() const5866 LLVM_DUMP_METHOD void CFGBlock::dump() const {
5867 dump(getParent(), LangOptions(), false);
5868 }
5869
5870 /// print - A simple pretty printer of a CFGBlock that outputs to an ostream.
5871 /// Generally this will only be called from CFG::print.
print(raw_ostream & OS,const CFG * cfg,const LangOptions & LO,bool ShowColors) const5872 void CFGBlock::print(raw_ostream &OS, const CFG* cfg,
5873 const LangOptions &LO, bool ShowColors) const {
5874 StmtPrinterHelper Helper(cfg, LO);
5875 print_block(OS, cfg, *this, Helper, true, ShowColors);
5876 OS << '\n';
5877 }
5878
5879 /// printTerminator - A simple pretty printer of the terminator of a CFGBlock.
printTerminator(raw_ostream & OS,const LangOptions & LO) const5880 void CFGBlock::printTerminator(raw_ostream &OS,
5881 const LangOptions &LO) const {
5882 CFGBlockTerminatorPrint TPrinter(OS, nullptr, PrintingPolicy(LO));
5883 TPrinter.print(getTerminator());
5884 }
5885
5886 /// printTerminatorJson - Pretty-prints the terminator in JSON format.
printTerminatorJson(raw_ostream & Out,const LangOptions & LO,bool AddQuotes) const5887 void CFGBlock::printTerminatorJson(raw_ostream &Out, const LangOptions &LO,
5888 bool AddQuotes) const {
5889 std::string Buf;
5890 llvm::raw_string_ostream TempOut(Buf);
5891
5892 printTerminator(TempOut, LO);
5893
5894 Out << JsonFormat(TempOut.str(), AddQuotes);
5895 }
5896
5897 // Returns true if by simply looking at the block, we can be sure that it
5898 // results in a sink during analysis. This is useful to know when the analysis
5899 // was interrupted, and we try to figure out if it would sink eventually.
5900 // There may be many more reasons why a sink would appear during analysis
5901 // (eg. checkers may generate sinks arbitrarily), but here we only consider
5902 // sinks that would be obvious by looking at the CFG.
isImmediateSinkBlock(const CFGBlock * Blk)5903 static bool isImmediateSinkBlock(const CFGBlock *Blk) {
5904 if (Blk->hasNoReturnElement())
5905 return true;
5906
5907 // FIXME: Throw-expressions are currently generating sinks during analysis:
5908 // they're not supported yet, and also often used for actually terminating
5909 // the program. So we should treat them as sinks in this analysis as well,
5910 // at least for now, but once we have better support for exceptions,
5911 // we'd need to carefully handle the case when the throw is being
5912 // immediately caught.
5913 if (std::any_of(Blk->begin(), Blk->end(), [](const CFGElement &Elm) {
5914 if (Optional<CFGStmt> StmtElm = Elm.getAs<CFGStmt>())
5915 if (isa<CXXThrowExpr>(StmtElm->getStmt()))
5916 return true;
5917 return false;
5918 }))
5919 return true;
5920
5921 return false;
5922 }
5923
isInevitablySinking() const5924 bool CFGBlock::isInevitablySinking() const {
5925 const CFG &Cfg = *getParent();
5926
5927 const CFGBlock *StartBlk = this;
5928 if (isImmediateSinkBlock(StartBlk))
5929 return true;
5930
5931 llvm::SmallVector<const CFGBlock *, 32> DFSWorkList;
5932 llvm::SmallPtrSet<const CFGBlock *, 32> Visited;
5933
5934 DFSWorkList.push_back(StartBlk);
5935 while (!DFSWorkList.empty()) {
5936 const CFGBlock *Blk = DFSWorkList.back();
5937 DFSWorkList.pop_back();
5938 Visited.insert(Blk);
5939
5940 // If at least one path reaches the CFG exit, it means that control is
5941 // returned to the caller. For now, say that we are not sure what
5942 // happens next. If necessary, this can be improved to analyze
5943 // the parent StackFrameContext's call site in a similar manner.
5944 if (Blk == &Cfg.getExit())
5945 return false;
5946
5947 for (const auto &Succ : Blk->succs()) {
5948 if (const CFGBlock *SuccBlk = Succ.getReachableBlock()) {
5949 if (!isImmediateSinkBlock(SuccBlk) && !Visited.count(SuccBlk)) {
5950 // If the block has reachable child blocks that aren't no-return,
5951 // add them to the worklist.
5952 DFSWorkList.push_back(SuccBlk);
5953 }
5954 }
5955 }
5956 }
5957
5958 // Nothing reached the exit. It can only mean one thing: there's no return.
5959 return true;
5960 }
5961
getLastCondition() const5962 const Expr *CFGBlock::getLastCondition() const {
5963 // If the terminator is a temporary dtor or a virtual base, etc, we can't
5964 // retrieve a meaningful condition, bail out.
5965 if (Terminator.getKind() != CFGTerminator::StmtBranch)
5966 return nullptr;
5967
5968 // Also, if this method was called on a block that doesn't have 2 successors,
5969 // this block doesn't have retrievable condition.
5970 if (succ_size() < 2)
5971 return nullptr;
5972
5973 // FIXME: Is there a better condition expression we can return in this case?
5974 if (size() == 0)
5975 return nullptr;
5976
5977 auto StmtElem = rbegin()->getAs<CFGStmt>();
5978 if (!StmtElem)
5979 return nullptr;
5980
5981 const Stmt *Cond = StmtElem->getStmt();
5982 if (isa<ObjCForCollectionStmt>(Cond) || isa<DeclStmt>(Cond))
5983 return nullptr;
5984
5985 // Only ObjCForCollectionStmt is known not to be a non-Expr terminator, hence
5986 // the cast<>.
5987 return cast<Expr>(Cond)->IgnoreParens();
5988 }
5989
getTerminatorCondition(bool StripParens)5990 Stmt *CFGBlock::getTerminatorCondition(bool StripParens) {
5991 Stmt *Terminator = getTerminatorStmt();
5992 if (!Terminator)
5993 return nullptr;
5994
5995 Expr *E = nullptr;
5996
5997 switch (Terminator->getStmtClass()) {
5998 default:
5999 break;
6000
6001 case Stmt::CXXForRangeStmtClass:
6002 E = cast<CXXForRangeStmt>(Terminator)->getCond();
6003 break;
6004
6005 case Stmt::ForStmtClass:
6006 E = cast<ForStmt>(Terminator)->getCond();
6007 break;
6008
6009 case Stmt::WhileStmtClass:
6010 E = cast<WhileStmt>(Terminator)->getCond();
6011 break;
6012
6013 case Stmt::DoStmtClass:
6014 E = cast<DoStmt>(Terminator)->getCond();
6015 break;
6016
6017 case Stmt::IfStmtClass:
6018 E = cast<IfStmt>(Terminator)->getCond();
6019 break;
6020
6021 case Stmt::ChooseExprClass:
6022 E = cast<ChooseExpr>(Terminator)->getCond();
6023 break;
6024
6025 case Stmt::IndirectGotoStmtClass:
6026 E = cast<IndirectGotoStmt>(Terminator)->getTarget();
6027 break;
6028
6029 case Stmt::SwitchStmtClass:
6030 E = cast<SwitchStmt>(Terminator)->getCond();
6031 break;
6032
6033 case Stmt::BinaryConditionalOperatorClass:
6034 E = cast<BinaryConditionalOperator>(Terminator)->getCond();
6035 break;
6036
6037 case Stmt::ConditionalOperatorClass:
6038 E = cast<ConditionalOperator>(Terminator)->getCond();
6039 break;
6040
6041 case Stmt::BinaryOperatorClass: // '&&' and '||'
6042 E = cast<BinaryOperator>(Terminator)->getLHS();
6043 break;
6044
6045 case Stmt::ObjCForCollectionStmtClass:
6046 return Terminator;
6047 }
6048
6049 if (!StripParens)
6050 return E;
6051
6052 return E ? E->IgnoreParens() : nullptr;
6053 }
6054
6055 //===----------------------------------------------------------------------===//
6056 // CFG Graphviz Visualization
6057 //===----------------------------------------------------------------------===//
6058
6059 #ifndef NDEBUG
6060 static StmtPrinterHelper* GraphHelper;
6061 #endif
6062
viewCFG(const LangOptions & LO) const6063 void CFG::viewCFG(const LangOptions &LO) const {
6064 #ifndef NDEBUG
6065 StmtPrinterHelper H(this, LO);
6066 GraphHelper = &H;
6067 llvm::ViewGraph(this,"CFG");
6068 GraphHelper = nullptr;
6069 #endif
6070 }
6071
6072 namespace llvm {
6073
6074 template<>
6075 struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits {
DOTGraphTraitsllvm::DOTGraphTraits6076 DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
6077
getNodeLabelllvm::DOTGraphTraits6078 static std::string getNodeLabel(const CFGBlock *Node, const CFG* Graph) {
6079 #ifndef NDEBUG
6080 std::string OutSStr;
6081 llvm::raw_string_ostream Out(OutSStr);
6082 print_block(Out,Graph, *Node, *GraphHelper, false, false);
6083 std::string& OutStr = Out.str();
6084
6085 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
6086
6087 // Process string output to make it nicer...
6088 for (unsigned i = 0; i != OutStr.length(); ++i)
6089 if (OutStr[i] == '\n') { // Left justify
6090 OutStr[i] = '\\';
6091 OutStr.insert(OutStr.begin()+i+1, 'l');
6092 }
6093
6094 return OutStr;
6095 #else
6096 return {};
6097 #endif
6098 }
6099 };
6100
6101 } // namespace llvm
6102