1 //===- ThreadSafety.cpp ----------------------------------------*- C++ --*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // A intra-procedural analysis for thread safety (e.g. deadlocks and race
11 // conditions), based off of an annotation system.
12 //
13 // See http://clang.llvm.org/docs/ThreadSafetyAnalysis.html
14 // for more information.
15 //
16 //===----------------------------------------------------------------------===//
17
18 #include "clang/AST/Attr.h"
19 #include "clang/AST/DeclCXX.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/StmtCXX.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
24 #include "clang/Analysis/Analyses/ThreadSafety.h"
25 #include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
26 #include "clang/Analysis/Analyses/ThreadSafetyLogical.h"
27 #include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
28 #include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
29 #include "clang/Analysis/AnalysisContext.h"
30 #include "clang/Analysis/CFG.h"
31 #include "clang/Analysis/CFGStmtMap.h"
32 #include "clang/Basic/OperatorKinds.h"
33 #include "clang/Basic/SourceLocation.h"
34 #include "clang/Basic/SourceManager.h"
35 #include "llvm/ADT/BitVector.h"
36 #include "llvm/ADT/FoldingSet.h"
37 #include "llvm/ADT/ImmutableMap.h"
38 #include "llvm/ADT/PostOrderIterator.h"
39 #include "llvm/ADT/SmallVector.h"
40 #include "llvm/ADT/StringRef.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include <algorithm>
43 #include <ostream>
44 #include <sstream>
45 #include <utility>
46 #include <vector>
47
48
49 namespace clang {
50 namespace threadSafety {
51
52 // Key method definition
~ThreadSafetyHandler()53 ThreadSafetyHandler::~ThreadSafetyHandler() {}
54
55 class TILPrinter :
56 public til::PrettyPrinter<TILPrinter, llvm::raw_ostream> {};
57
58
59 /// Issue a warning about an invalid lock expression
warnInvalidLock(ThreadSafetyHandler & Handler,const Expr * MutexExp,const NamedDecl * D,const Expr * DeclExp,StringRef Kind)60 static void warnInvalidLock(ThreadSafetyHandler &Handler,
61 const Expr *MutexExp, const NamedDecl *D,
62 const Expr *DeclExp, StringRef Kind) {
63 SourceLocation Loc;
64 if (DeclExp)
65 Loc = DeclExp->getExprLoc();
66
67 // FIXME: add a note about the attribute location in MutexExp or D
68 if (Loc.isValid())
69 Handler.handleInvalidLockExp(Kind, Loc);
70 }
71
72
73 /// \brief A set of CapabilityInfo objects, which are compiled from the
74 /// requires attributes on a function.
75 class CapExprSet : public SmallVector<CapabilityExpr, 4> {
76 public:
77 /// \brief Push M onto list, but discard duplicates.
push_back_nodup(const CapabilityExpr & CapE)78 void push_back_nodup(const CapabilityExpr &CapE) {
79 iterator It = std::find_if(begin(), end(),
80 [=](const CapabilityExpr &CapE2) {
81 return CapE.equals(CapE2);
82 });
83 if (It == end())
84 push_back(CapE);
85 }
86 };
87
88 class FactManager;
89 class FactSet;
90
91 /// \brief This is a helper class that stores a fact that is known at a
92 /// particular point in program execution. Currently, a fact is a capability,
93 /// along with additional information, such as where it was acquired, whether
94 /// it is exclusive or shared, etc.
95 ///
96 /// FIXME: this analysis does not currently support either re-entrant
97 /// locking or lock "upgrading" and "downgrading" between exclusive and
98 /// shared.
99 class FactEntry : public CapabilityExpr {
100 private:
101 LockKind LKind; ///< exclusive or shared
102 SourceLocation AcquireLoc; ///< where it was acquired.
103 bool Asserted; ///< true if the lock was asserted
104
105 public:
FactEntry(const CapabilityExpr & CE,LockKind LK,SourceLocation Loc,bool Asrt)106 FactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
107 bool Asrt)
108 : CapabilityExpr(CE), LKind(LK), AcquireLoc(Loc), Asserted(Asrt) {}
109
~FactEntry()110 virtual ~FactEntry() {}
111
kind() const112 LockKind kind() const { return LKind; }
loc() const113 SourceLocation loc() const { return AcquireLoc; }
asserted() const114 bool asserted() const { return Asserted; }
115
116 virtual void
117 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
118 SourceLocation JoinLoc, LockErrorKind LEK,
119 ThreadSafetyHandler &Handler) const = 0;
120 virtual void handleUnlock(FactSet &FSet, FactManager &FactMan,
121 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
122 bool FullyRemove, ThreadSafetyHandler &Handler,
123 StringRef DiagKind) const = 0;
124
125 // Return true if LKind >= LK, where exclusive > shared
isAtLeast(LockKind LK)126 bool isAtLeast(LockKind LK) {
127 return (LKind == LK_Exclusive) || (LK == LK_Shared);
128 }
129 };
130
131
132 typedef unsigned short FactID;
133
134 /// \brief FactManager manages the memory for all facts that are created during
135 /// the analysis of a single routine.
136 class FactManager {
137 private:
138 std::vector<std::unique_ptr<FactEntry>> Facts;
139
140 public:
newFact(std::unique_ptr<FactEntry> Entry)141 FactID newFact(std::unique_ptr<FactEntry> Entry) {
142 Facts.push_back(std::move(Entry));
143 return static_cast<unsigned short>(Facts.size() - 1);
144 }
145
operator [](FactID F) const146 const FactEntry &operator[](FactID F) const { return *Facts[F]; }
operator [](FactID F)147 FactEntry &operator[](FactID F) { return *Facts[F]; }
148 };
149
150
151 /// \brief A FactSet is the set of facts that are known to be true at a
152 /// particular program point. FactSets must be small, because they are
153 /// frequently copied, and are thus implemented as a set of indices into a
154 /// table maintained by a FactManager. A typical FactSet only holds 1 or 2
155 /// locks, so we can get away with doing a linear search for lookup. Note
156 /// that a hashtable or map is inappropriate in this case, because lookups
157 /// may involve partial pattern matches, rather than exact matches.
158 class FactSet {
159 private:
160 typedef SmallVector<FactID, 4> FactVec;
161
162 FactVec FactIDs;
163
164 public:
165 typedef FactVec::iterator iterator;
166 typedef FactVec::const_iterator const_iterator;
167
begin()168 iterator begin() { return FactIDs.begin(); }
begin() const169 const_iterator begin() const { return FactIDs.begin(); }
170
end()171 iterator end() { return FactIDs.end(); }
end() const172 const_iterator end() const { return FactIDs.end(); }
173
isEmpty() const174 bool isEmpty() const { return FactIDs.size() == 0; }
175
176 // Return true if the set contains only negative facts
isEmpty(FactManager & FactMan) const177 bool isEmpty(FactManager &FactMan) const {
178 for (FactID FID : *this) {
179 if (!FactMan[FID].negative())
180 return false;
181 }
182 return true;
183 }
184
addLockByID(FactID ID)185 void addLockByID(FactID ID) { FactIDs.push_back(ID); }
186
addLock(FactManager & FM,std::unique_ptr<FactEntry> Entry)187 FactID addLock(FactManager &FM, std::unique_ptr<FactEntry> Entry) {
188 FactID F = FM.newFact(std::move(Entry));
189 FactIDs.push_back(F);
190 return F;
191 }
192
removeLock(FactManager & FM,const CapabilityExpr & CapE)193 bool removeLock(FactManager& FM, const CapabilityExpr &CapE) {
194 unsigned n = FactIDs.size();
195 if (n == 0)
196 return false;
197
198 for (unsigned i = 0; i < n-1; ++i) {
199 if (FM[FactIDs[i]].matches(CapE)) {
200 FactIDs[i] = FactIDs[n-1];
201 FactIDs.pop_back();
202 return true;
203 }
204 }
205 if (FM[FactIDs[n-1]].matches(CapE)) {
206 FactIDs.pop_back();
207 return true;
208 }
209 return false;
210 }
211
findLockIter(FactManager & FM,const CapabilityExpr & CapE)212 iterator findLockIter(FactManager &FM, const CapabilityExpr &CapE) {
213 return std::find_if(begin(), end(), [&](FactID ID) {
214 return FM[ID].matches(CapE);
215 });
216 }
217
findLock(FactManager & FM,const CapabilityExpr & CapE) const218 FactEntry *findLock(FactManager &FM, const CapabilityExpr &CapE) const {
219 auto I = std::find_if(begin(), end(), [&](FactID ID) {
220 return FM[ID].matches(CapE);
221 });
222 return I != end() ? &FM[*I] : nullptr;
223 }
224
findLockUniv(FactManager & FM,const CapabilityExpr & CapE) const225 FactEntry *findLockUniv(FactManager &FM, const CapabilityExpr &CapE) const {
226 auto I = std::find_if(begin(), end(), [&](FactID ID) -> bool {
227 return FM[ID].matchesUniv(CapE);
228 });
229 return I != end() ? &FM[*I] : nullptr;
230 }
231
findPartialMatch(FactManager & FM,const CapabilityExpr & CapE) const232 FactEntry *findPartialMatch(FactManager &FM,
233 const CapabilityExpr &CapE) const {
234 auto I = std::find_if(begin(), end(), [&](FactID ID) {
235 return FM[ID].partiallyMatches(CapE);
236 });
237 return I != end() ? &FM[*I] : nullptr;
238 }
239 };
240
241
242 typedef llvm::ImmutableMap<const NamedDecl*, unsigned> LocalVarContext;
243 class LocalVariableMap;
244
245 /// A side (entry or exit) of a CFG node.
246 enum CFGBlockSide { CBS_Entry, CBS_Exit };
247
248 /// CFGBlockInfo is a struct which contains all the information that is
249 /// maintained for each block in the CFG. See LocalVariableMap for more
250 /// information about the contexts.
251 struct CFGBlockInfo {
252 FactSet EntrySet; // Lockset held at entry to block
253 FactSet ExitSet; // Lockset held at exit from block
254 LocalVarContext EntryContext; // Context held at entry to block
255 LocalVarContext ExitContext; // Context held at exit from block
256 SourceLocation EntryLoc; // Location of first statement in block
257 SourceLocation ExitLoc; // Location of last statement in block.
258 unsigned EntryIndex; // Used to replay contexts later
259 bool Reachable; // Is this block reachable?
260
getSetclang::threadSafety::CFGBlockInfo261 const FactSet &getSet(CFGBlockSide Side) const {
262 return Side == CBS_Entry ? EntrySet : ExitSet;
263 }
getLocationclang::threadSafety::CFGBlockInfo264 SourceLocation getLocation(CFGBlockSide Side) const {
265 return Side == CBS_Entry ? EntryLoc : ExitLoc;
266 }
267
268 private:
CFGBlockInfoclang::threadSafety::CFGBlockInfo269 CFGBlockInfo(LocalVarContext EmptyCtx)
270 : EntryContext(EmptyCtx), ExitContext(EmptyCtx), Reachable(false)
271 { }
272
273 public:
274 static CFGBlockInfo getEmptyBlockInfo(LocalVariableMap &M);
275 };
276
277
278
279 // A LocalVariableMap maintains a map from local variables to their currently
280 // valid definitions. It provides SSA-like functionality when traversing the
281 // CFG. Like SSA, each definition or assignment to a variable is assigned a
282 // unique name (an integer), which acts as the SSA name for that definition.
283 // The total set of names is shared among all CFG basic blocks.
284 // Unlike SSA, we do not rewrite expressions to replace local variables declrefs
285 // with their SSA-names. Instead, we compute a Context for each point in the
286 // code, which maps local variables to the appropriate SSA-name. This map
287 // changes with each assignment.
288 //
289 // The map is computed in a single pass over the CFG. Subsequent analyses can
290 // then query the map to find the appropriate Context for a statement, and use
291 // that Context to look up the definitions of variables.
292 class LocalVariableMap {
293 public:
294 typedef LocalVarContext Context;
295
296 /// A VarDefinition consists of an expression, representing the value of the
297 /// variable, along with the context in which that expression should be
298 /// interpreted. A reference VarDefinition does not itself contain this
299 /// information, but instead contains a pointer to a previous VarDefinition.
300 struct VarDefinition {
301 public:
302 friend class LocalVariableMap;
303
304 const NamedDecl *Dec; // The original declaration for this variable.
305 const Expr *Exp; // The expression for this variable, OR
306 unsigned Ref; // Reference to another VarDefinition
307 Context Ctx; // The map with which Exp should be interpreted.
308
isReferenceclang::threadSafety::LocalVariableMap::VarDefinition309 bool isReference() { return !Exp; }
310
311 private:
312 // Create ordinary variable definition
VarDefinitionclang::threadSafety::LocalVariableMap::VarDefinition313 VarDefinition(const NamedDecl *D, const Expr *E, Context C)
314 : Dec(D), Exp(E), Ref(0), Ctx(C)
315 { }
316
317 // Create reference to previous definition
VarDefinitionclang::threadSafety::LocalVariableMap::VarDefinition318 VarDefinition(const NamedDecl *D, unsigned R, Context C)
319 : Dec(D), Exp(nullptr), Ref(R), Ctx(C)
320 { }
321 };
322
323 private:
324 Context::Factory ContextFactory;
325 std::vector<VarDefinition> VarDefinitions;
326 std::vector<unsigned> CtxIndices;
327 std::vector<std::pair<Stmt*, Context> > SavedContexts;
328
329 public:
LocalVariableMap()330 LocalVariableMap() {
331 // index 0 is a placeholder for undefined variables (aka phi-nodes).
332 VarDefinitions.push_back(VarDefinition(nullptr, 0u, getEmptyContext()));
333 }
334
335 /// Look up a definition, within the given context.
lookup(const NamedDecl * D,Context Ctx)336 const VarDefinition* lookup(const NamedDecl *D, Context Ctx) {
337 const unsigned *i = Ctx.lookup(D);
338 if (!i)
339 return nullptr;
340 assert(*i < VarDefinitions.size());
341 return &VarDefinitions[*i];
342 }
343
344 /// Look up the definition for D within the given context. Returns
345 /// NULL if the expression is not statically known. If successful, also
346 /// modifies Ctx to hold the context of the return Expr.
lookupExpr(const NamedDecl * D,Context & Ctx)347 const Expr* lookupExpr(const NamedDecl *D, Context &Ctx) {
348 const unsigned *P = Ctx.lookup(D);
349 if (!P)
350 return nullptr;
351
352 unsigned i = *P;
353 while (i > 0) {
354 if (VarDefinitions[i].Exp) {
355 Ctx = VarDefinitions[i].Ctx;
356 return VarDefinitions[i].Exp;
357 }
358 i = VarDefinitions[i].Ref;
359 }
360 return nullptr;
361 }
362
getEmptyContext()363 Context getEmptyContext() { return ContextFactory.getEmptyMap(); }
364
365 /// Return the next context after processing S. This function is used by
366 /// clients of the class to get the appropriate context when traversing the
367 /// CFG. It must be called for every assignment or DeclStmt.
getNextContext(unsigned & CtxIndex,Stmt * S,Context C)368 Context getNextContext(unsigned &CtxIndex, Stmt *S, Context C) {
369 if (SavedContexts[CtxIndex+1].first == S) {
370 CtxIndex++;
371 Context Result = SavedContexts[CtxIndex].second;
372 return Result;
373 }
374 return C;
375 }
376
dumpVarDefinitionName(unsigned i)377 void dumpVarDefinitionName(unsigned i) {
378 if (i == 0) {
379 llvm::errs() << "Undefined";
380 return;
381 }
382 const NamedDecl *Dec = VarDefinitions[i].Dec;
383 if (!Dec) {
384 llvm::errs() << "<<NULL>>";
385 return;
386 }
387 Dec->printName(llvm::errs());
388 llvm::errs() << "." << i << " " << ((const void*) Dec);
389 }
390
391 /// Dumps an ASCII representation of the variable map to llvm::errs()
dump()392 void dump() {
393 for (unsigned i = 1, e = VarDefinitions.size(); i < e; ++i) {
394 const Expr *Exp = VarDefinitions[i].Exp;
395 unsigned Ref = VarDefinitions[i].Ref;
396
397 dumpVarDefinitionName(i);
398 llvm::errs() << " = ";
399 if (Exp) Exp->dump();
400 else {
401 dumpVarDefinitionName(Ref);
402 llvm::errs() << "\n";
403 }
404 }
405 }
406
407 /// Dumps an ASCII representation of a Context to llvm::errs()
dumpContext(Context C)408 void dumpContext(Context C) {
409 for (Context::iterator I = C.begin(), E = C.end(); I != E; ++I) {
410 const NamedDecl *D = I.getKey();
411 D->printName(llvm::errs());
412 const unsigned *i = C.lookup(D);
413 llvm::errs() << " -> ";
414 dumpVarDefinitionName(*i);
415 llvm::errs() << "\n";
416 }
417 }
418
419 /// Builds the variable map.
420 void traverseCFG(CFG *CFGraph, const PostOrderCFGView *SortedGraph,
421 std::vector<CFGBlockInfo> &BlockInfo);
422
423 protected:
424 // Get the current context index
getContextIndex()425 unsigned getContextIndex() { return SavedContexts.size()-1; }
426
427 // Save the current context for later replay
saveContext(Stmt * S,Context C)428 void saveContext(Stmt *S, Context C) {
429 SavedContexts.push_back(std::make_pair(S,C));
430 }
431
432 // Adds a new definition to the given context, and returns a new context.
433 // This method should be called when declaring a new variable.
addDefinition(const NamedDecl * D,const Expr * Exp,Context Ctx)434 Context addDefinition(const NamedDecl *D, const Expr *Exp, Context Ctx) {
435 assert(!Ctx.contains(D));
436 unsigned newID = VarDefinitions.size();
437 Context NewCtx = ContextFactory.add(Ctx, D, newID);
438 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
439 return NewCtx;
440 }
441
442 // Add a new reference to an existing definition.
addReference(const NamedDecl * D,unsigned i,Context Ctx)443 Context addReference(const NamedDecl *D, unsigned i, Context Ctx) {
444 unsigned newID = VarDefinitions.size();
445 Context NewCtx = ContextFactory.add(Ctx, D, newID);
446 VarDefinitions.push_back(VarDefinition(D, i, Ctx));
447 return NewCtx;
448 }
449
450 // Updates a definition only if that definition is already in the map.
451 // This method should be called when assigning to an existing variable.
updateDefinition(const NamedDecl * D,Expr * Exp,Context Ctx)452 Context updateDefinition(const NamedDecl *D, Expr *Exp, Context Ctx) {
453 if (Ctx.contains(D)) {
454 unsigned newID = VarDefinitions.size();
455 Context NewCtx = ContextFactory.remove(Ctx, D);
456 NewCtx = ContextFactory.add(NewCtx, D, newID);
457 VarDefinitions.push_back(VarDefinition(D, Exp, Ctx));
458 return NewCtx;
459 }
460 return Ctx;
461 }
462
463 // Removes a definition from the context, but keeps the variable name
464 // as a valid variable. The index 0 is a placeholder for cleared definitions.
clearDefinition(const NamedDecl * D,Context Ctx)465 Context clearDefinition(const NamedDecl *D, Context Ctx) {
466 Context NewCtx = Ctx;
467 if (NewCtx.contains(D)) {
468 NewCtx = ContextFactory.remove(NewCtx, D);
469 NewCtx = ContextFactory.add(NewCtx, D, 0);
470 }
471 return NewCtx;
472 }
473
474 // Remove a definition entirely frmo the context.
removeDefinition(const NamedDecl * D,Context Ctx)475 Context removeDefinition(const NamedDecl *D, Context Ctx) {
476 Context NewCtx = Ctx;
477 if (NewCtx.contains(D)) {
478 NewCtx = ContextFactory.remove(NewCtx, D);
479 }
480 return NewCtx;
481 }
482
483 Context intersectContexts(Context C1, Context C2);
484 Context createReferenceContext(Context C);
485 void intersectBackEdge(Context C1, Context C2);
486
487 friend class VarMapBuilder;
488 };
489
490
491 // This has to be defined after LocalVariableMap.
getEmptyBlockInfo(LocalVariableMap & M)492 CFGBlockInfo CFGBlockInfo::getEmptyBlockInfo(LocalVariableMap &M) {
493 return CFGBlockInfo(M.getEmptyContext());
494 }
495
496
497 /// Visitor which builds a LocalVariableMap
498 class VarMapBuilder : public StmtVisitor<VarMapBuilder> {
499 public:
500 LocalVariableMap* VMap;
501 LocalVariableMap::Context Ctx;
502
VarMapBuilder(LocalVariableMap * VM,LocalVariableMap::Context C)503 VarMapBuilder(LocalVariableMap *VM, LocalVariableMap::Context C)
504 : VMap(VM), Ctx(C) {}
505
506 void VisitDeclStmt(DeclStmt *S);
507 void VisitBinaryOperator(BinaryOperator *BO);
508 };
509
510
511 // Add new local variables to the variable map
VisitDeclStmt(DeclStmt * S)512 void VarMapBuilder::VisitDeclStmt(DeclStmt *S) {
513 bool modifiedCtx = false;
514 DeclGroupRef DGrp = S->getDeclGroup();
515 for (const auto *D : DGrp) {
516 if (const auto *VD = dyn_cast_or_null<VarDecl>(D)) {
517 const Expr *E = VD->getInit();
518
519 // Add local variables with trivial type to the variable map
520 QualType T = VD->getType();
521 if (T.isTrivialType(VD->getASTContext())) {
522 Ctx = VMap->addDefinition(VD, E, Ctx);
523 modifiedCtx = true;
524 }
525 }
526 }
527 if (modifiedCtx)
528 VMap->saveContext(S, Ctx);
529 }
530
531 // Update local variable definitions in variable map
VisitBinaryOperator(BinaryOperator * BO)532 void VarMapBuilder::VisitBinaryOperator(BinaryOperator *BO) {
533 if (!BO->isAssignmentOp())
534 return;
535
536 Expr *LHSExp = BO->getLHS()->IgnoreParenCasts();
537
538 // Update the variable map and current context.
539 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHSExp)) {
540 ValueDecl *VDec = DRE->getDecl();
541 if (Ctx.lookup(VDec)) {
542 if (BO->getOpcode() == BO_Assign)
543 Ctx = VMap->updateDefinition(VDec, BO->getRHS(), Ctx);
544 else
545 // FIXME -- handle compound assignment operators
546 Ctx = VMap->clearDefinition(VDec, Ctx);
547 VMap->saveContext(BO, Ctx);
548 }
549 }
550 }
551
552
553 // Computes the intersection of two contexts. The intersection is the
554 // set of variables which have the same definition in both contexts;
555 // variables with different definitions are discarded.
556 LocalVariableMap::Context
intersectContexts(Context C1,Context C2)557 LocalVariableMap::intersectContexts(Context C1, Context C2) {
558 Context Result = C1;
559 for (const auto &P : C1) {
560 const NamedDecl *Dec = P.first;
561 const unsigned *i2 = C2.lookup(Dec);
562 if (!i2) // variable doesn't exist on second path
563 Result = removeDefinition(Dec, Result);
564 else if (*i2 != P.second) // variable exists, but has different definition
565 Result = clearDefinition(Dec, Result);
566 }
567 return Result;
568 }
569
570 // For every variable in C, create a new variable that refers to the
571 // definition in C. Return a new context that contains these new variables.
572 // (We use this for a naive implementation of SSA on loop back-edges.)
createReferenceContext(Context C)573 LocalVariableMap::Context LocalVariableMap::createReferenceContext(Context C) {
574 Context Result = getEmptyContext();
575 for (const auto &P : C)
576 Result = addReference(P.first, P.second, Result);
577 return Result;
578 }
579
580 // This routine also takes the intersection of C1 and C2, but it does so by
581 // altering the VarDefinitions. C1 must be the result of an earlier call to
582 // createReferenceContext.
intersectBackEdge(Context C1,Context C2)583 void LocalVariableMap::intersectBackEdge(Context C1, Context C2) {
584 for (const auto &P : C1) {
585 unsigned i1 = P.second;
586 VarDefinition *VDef = &VarDefinitions[i1];
587 assert(VDef->isReference());
588
589 const unsigned *i2 = C2.lookup(P.first);
590 if (!i2 || (*i2 != i1))
591 VDef->Ref = 0; // Mark this variable as undefined
592 }
593 }
594
595
596 // Traverse the CFG in topological order, so all predecessors of a block
597 // (excluding back-edges) are visited before the block itself. At
598 // each point in the code, we calculate a Context, which holds the set of
599 // variable definitions which are visible at that point in execution.
600 // Visible variables are mapped to their definitions using an array that
601 // contains all definitions.
602 //
603 // At join points in the CFG, the set is computed as the intersection of
604 // the incoming sets along each edge, E.g.
605 //
606 // { Context | VarDefinitions }
607 // int x = 0; { x -> x1 | x1 = 0 }
608 // int y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
609 // if (b) x = 1; { x -> x2, y -> y1 | x2 = 1, y1 = 0, ... }
610 // else x = 2; { x -> x3, y -> y1 | x3 = 2, x2 = 1, ... }
611 // ... { y -> y1 (x is unknown) | x3 = 2, x2 = 1, ... }
612 //
613 // This is essentially a simpler and more naive version of the standard SSA
614 // algorithm. Those definitions that remain in the intersection are from blocks
615 // that strictly dominate the current block. We do not bother to insert proper
616 // phi nodes, because they are not used in our analysis; instead, wherever
617 // a phi node would be required, we simply remove that definition from the
618 // context (E.g. x above).
619 //
620 // The initial traversal does not capture back-edges, so those need to be
621 // handled on a separate pass. Whenever the first pass encounters an
622 // incoming back edge, it duplicates the context, creating new definitions
623 // that refer back to the originals. (These correspond to places where SSA
624 // might have to insert a phi node.) On the second pass, these definitions are
625 // set to NULL if the variable has changed on the back-edge (i.e. a phi
626 // node was actually required.) E.g.
627 //
628 // { Context | VarDefinitions }
629 // int x = 0, y = 0; { x -> x1, y -> y1 | y1 = 0, x1 = 0 }
630 // while (b) { x -> x2, y -> y1 | [1st:] x2=x1; [2nd:] x2=NULL; }
631 // x = x+1; { x -> x3, y -> y1 | x3 = x2 + 1, ... }
632 // ... { y -> y1 | x3 = 2, x2 = 1, ... }
633 //
traverseCFG(CFG * CFGraph,const PostOrderCFGView * SortedGraph,std::vector<CFGBlockInfo> & BlockInfo)634 void LocalVariableMap::traverseCFG(CFG *CFGraph,
635 const PostOrderCFGView *SortedGraph,
636 std::vector<CFGBlockInfo> &BlockInfo) {
637 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
638
639 CtxIndices.resize(CFGraph->getNumBlockIDs());
640
641 for (const auto *CurrBlock : *SortedGraph) {
642 int CurrBlockID = CurrBlock->getBlockID();
643 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
644
645 VisitedBlocks.insert(CurrBlock);
646
647 // Calculate the entry context for the current block
648 bool HasBackEdges = false;
649 bool CtxInit = true;
650 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
651 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
652 // if *PI -> CurrBlock is a back edge, so skip it
653 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI)) {
654 HasBackEdges = true;
655 continue;
656 }
657
658 int PrevBlockID = (*PI)->getBlockID();
659 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
660
661 if (CtxInit) {
662 CurrBlockInfo->EntryContext = PrevBlockInfo->ExitContext;
663 CtxInit = false;
664 }
665 else {
666 CurrBlockInfo->EntryContext =
667 intersectContexts(CurrBlockInfo->EntryContext,
668 PrevBlockInfo->ExitContext);
669 }
670 }
671
672 // Duplicate the context if we have back-edges, so we can call
673 // intersectBackEdges later.
674 if (HasBackEdges)
675 CurrBlockInfo->EntryContext =
676 createReferenceContext(CurrBlockInfo->EntryContext);
677
678 // Create a starting context index for the current block
679 saveContext(nullptr, CurrBlockInfo->EntryContext);
680 CurrBlockInfo->EntryIndex = getContextIndex();
681
682 // Visit all the statements in the basic block.
683 VarMapBuilder VMapBuilder(this, CurrBlockInfo->EntryContext);
684 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
685 BE = CurrBlock->end(); BI != BE; ++BI) {
686 switch (BI->getKind()) {
687 case CFGElement::Statement: {
688 CFGStmt CS = BI->castAs<CFGStmt>();
689 VMapBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
690 break;
691 }
692 default:
693 break;
694 }
695 }
696 CurrBlockInfo->ExitContext = VMapBuilder.Ctx;
697
698 // Mark variables on back edges as "unknown" if they've been changed.
699 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
700 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
701 // if CurrBlock -> *SI is *not* a back edge
702 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
703 continue;
704
705 CFGBlock *FirstLoopBlock = *SI;
706 Context LoopBegin = BlockInfo[FirstLoopBlock->getBlockID()].EntryContext;
707 Context LoopEnd = CurrBlockInfo->ExitContext;
708 intersectBackEdge(LoopBegin, LoopEnd);
709 }
710 }
711
712 // Put an extra entry at the end of the indexed context array
713 unsigned exitID = CFGraph->getExit().getBlockID();
714 saveContext(nullptr, BlockInfo[exitID].ExitContext);
715 }
716
717 /// Find the appropriate source locations to use when producing diagnostics for
718 /// each block in the CFG.
findBlockLocations(CFG * CFGraph,const PostOrderCFGView * SortedGraph,std::vector<CFGBlockInfo> & BlockInfo)719 static void findBlockLocations(CFG *CFGraph,
720 const PostOrderCFGView *SortedGraph,
721 std::vector<CFGBlockInfo> &BlockInfo) {
722 for (const auto *CurrBlock : *SortedGraph) {
723 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlock->getBlockID()];
724
725 // Find the source location of the last statement in the block, if the
726 // block is not empty.
727 if (const Stmt *S = CurrBlock->getTerminator()) {
728 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc = S->getLocStart();
729 } else {
730 for (CFGBlock::const_reverse_iterator BI = CurrBlock->rbegin(),
731 BE = CurrBlock->rend(); BI != BE; ++BI) {
732 // FIXME: Handle other CFGElement kinds.
733 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
734 CurrBlockInfo->ExitLoc = CS->getStmt()->getLocStart();
735 break;
736 }
737 }
738 }
739
740 if (!CurrBlockInfo->ExitLoc.isInvalid()) {
741 // This block contains at least one statement. Find the source location
742 // of the first statement in the block.
743 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
744 BE = CurrBlock->end(); BI != BE; ++BI) {
745 // FIXME: Handle other CFGElement kinds.
746 if (Optional<CFGStmt> CS = BI->getAs<CFGStmt>()) {
747 CurrBlockInfo->EntryLoc = CS->getStmt()->getLocStart();
748 break;
749 }
750 }
751 } else if (CurrBlock->pred_size() == 1 && *CurrBlock->pred_begin() &&
752 CurrBlock != &CFGraph->getExit()) {
753 // The block is empty, and has a single predecessor. Use its exit
754 // location.
755 CurrBlockInfo->EntryLoc = CurrBlockInfo->ExitLoc =
756 BlockInfo[(*CurrBlock->pred_begin())->getBlockID()].ExitLoc;
757 }
758 }
759 }
760
761 class LockableFactEntry : public FactEntry {
762 private:
763 bool Managed; ///< managed by ScopedLockable object
764
765 public:
LockableFactEntry(const CapabilityExpr & CE,LockKind LK,SourceLocation Loc,bool Mng=false,bool Asrt=false)766 LockableFactEntry(const CapabilityExpr &CE, LockKind LK, SourceLocation Loc,
767 bool Mng = false, bool Asrt = false)
768 : FactEntry(CE, LK, Loc, Asrt), Managed(Mng) {}
769
770 void
handleRemovalFromIntersection(const FactSet & FSet,FactManager & FactMan,SourceLocation JoinLoc,LockErrorKind LEK,ThreadSafetyHandler & Handler) const771 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
772 SourceLocation JoinLoc, LockErrorKind LEK,
773 ThreadSafetyHandler &Handler) const override {
774 if (!Managed && !asserted() && !negative() && !isUniversal()) {
775 Handler.handleMutexHeldEndOfScope("mutex", toString(), loc(), JoinLoc,
776 LEK);
777 }
778 }
779
handleUnlock(FactSet & FSet,FactManager & FactMan,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,ThreadSafetyHandler & Handler,StringRef DiagKind) const780 void handleUnlock(FactSet &FSet, FactManager &FactMan,
781 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
782 bool FullyRemove, ThreadSafetyHandler &Handler,
783 StringRef DiagKind) const override {
784 FSet.removeLock(FactMan, Cp);
785 if (!Cp.negative()) {
786 FSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
787 !Cp, LK_Exclusive, UnlockLoc));
788 }
789 }
790 };
791
792 class ScopedLockableFactEntry : public FactEntry {
793 private:
794 SmallVector<const til::SExpr *, 4> UnderlyingMutexes;
795
796 public:
ScopedLockableFactEntry(const CapabilityExpr & CE,SourceLocation Loc,const CapExprSet & Excl,const CapExprSet & Shrd)797 ScopedLockableFactEntry(const CapabilityExpr &CE, SourceLocation Loc,
798 const CapExprSet &Excl, const CapExprSet &Shrd)
799 : FactEntry(CE, LK_Exclusive, Loc, false) {
800 for (const auto &M : Excl)
801 UnderlyingMutexes.push_back(M.sexpr());
802 for (const auto &M : Shrd)
803 UnderlyingMutexes.push_back(M.sexpr());
804 }
805
806 void
handleRemovalFromIntersection(const FactSet & FSet,FactManager & FactMan,SourceLocation JoinLoc,LockErrorKind LEK,ThreadSafetyHandler & Handler) const807 handleRemovalFromIntersection(const FactSet &FSet, FactManager &FactMan,
808 SourceLocation JoinLoc, LockErrorKind LEK,
809 ThreadSafetyHandler &Handler) const override {
810 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
811 if (FSet.findLock(FactMan, CapabilityExpr(UnderlyingMutex, false))) {
812 // If this scoped lock manages another mutex, and if the underlying
813 // mutex is still held, then warn about the underlying mutex.
814 Handler.handleMutexHeldEndOfScope(
815 "mutex", sx::toString(UnderlyingMutex), loc(), JoinLoc, LEK);
816 }
817 }
818 }
819
handleUnlock(FactSet & FSet,FactManager & FactMan,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,ThreadSafetyHandler & Handler,StringRef DiagKind) const820 void handleUnlock(FactSet &FSet, FactManager &FactMan,
821 const CapabilityExpr &Cp, SourceLocation UnlockLoc,
822 bool FullyRemove, ThreadSafetyHandler &Handler,
823 StringRef DiagKind) const override {
824 assert(!Cp.negative() && "Managing object cannot be negative.");
825 for (const til::SExpr *UnderlyingMutex : UnderlyingMutexes) {
826 CapabilityExpr UnderCp(UnderlyingMutex, false);
827 auto UnderEntry = llvm::make_unique<LockableFactEntry>(
828 !UnderCp, LK_Exclusive, UnlockLoc);
829
830 if (FullyRemove) {
831 // We're destroying the managing object.
832 // Remove the underlying mutex if it exists; but don't warn.
833 if (FSet.findLock(FactMan, UnderCp)) {
834 FSet.removeLock(FactMan, UnderCp);
835 FSet.addLock(FactMan, std::move(UnderEntry));
836 }
837 } else {
838 // We're releasing the underlying mutex, but not destroying the
839 // managing object. Warn on dual release.
840 if (!FSet.findLock(FactMan, UnderCp)) {
841 Handler.handleUnmatchedUnlock(DiagKind, UnderCp.toString(),
842 UnlockLoc);
843 }
844 FSet.removeLock(FactMan, UnderCp);
845 FSet.addLock(FactMan, std::move(UnderEntry));
846 }
847 }
848 if (FullyRemove)
849 FSet.removeLock(FactMan, Cp);
850 }
851 };
852
853 /// \brief Class which implements the core thread safety analysis routines.
854 class ThreadSafetyAnalyzer {
855 friend class BuildLockset;
856
857 llvm::BumpPtrAllocator Bpa;
858 threadSafety::til::MemRegionRef Arena;
859 threadSafety::SExprBuilder SxBuilder;
860
861 ThreadSafetyHandler &Handler;
862 const CXXMethodDecl *CurrentMethod;
863 LocalVariableMap LocalVarMap;
864 FactManager FactMan;
865 std::vector<CFGBlockInfo> BlockInfo;
866
867 public:
ThreadSafetyAnalyzer(ThreadSafetyHandler & H)868 ThreadSafetyAnalyzer(ThreadSafetyHandler &H)
869 : Arena(&Bpa), SxBuilder(Arena), Handler(H) {}
870
871 bool inCurrentScope(const CapabilityExpr &CapE);
872
873 void addLock(FactSet &FSet, std::unique_ptr<FactEntry> Entry,
874 StringRef DiagKind, bool ReqAttr = false);
875 void removeLock(FactSet &FSet, const CapabilityExpr &CapE,
876 SourceLocation UnlockLoc, bool FullyRemove, LockKind Kind,
877 StringRef DiagKind);
878
879 template <typename AttrType>
880 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
881 const NamedDecl *D, VarDecl *SelfDecl = nullptr);
882
883 template <class AttrType>
884 void getMutexIDs(CapExprSet &Mtxs, AttrType *Attr, Expr *Exp,
885 const NamedDecl *D,
886 const CFGBlock *PredBlock, const CFGBlock *CurrBlock,
887 Expr *BrE, bool Neg);
888
889 const CallExpr* getTrylockCallExpr(const Stmt *Cond, LocalVarContext C,
890 bool &Negate);
891
892 void getEdgeLockset(FactSet &Result, const FactSet &ExitSet,
893 const CFGBlock* PredBlock,
894 const CFGBlock *CurrBlock);
895
896 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
897 SourceLocation JoinLoc,
898 LockErrorKind LEK1, LockErrorKind LEK2,
899 bool Modify=true);
900
intersectAndWarn(FactSet & FSet1,const FactSet & FSet2,SourceLocation JoinLoc,LockErrorKind LEK1,bool Modify=true)901 void intersectAndWarn(FactSet &FSet1, const FactSet &FSet2,
902 SourceLocation JoinLoc, LockErrorKind LEK1,
903 bool Modify=true) {
904 intersectAndWarn(FSet1, FSet2, JoinLoc, LEK1, LEK1, Modify);
905 }
906
907 void runAnalysis(AnalysisDeclContext &AC);
908 };
909
910 /// \brief Gets the value decl pointer from DeclRefExprs or MemberExprs.
getValueDecl(const Expr * Exp)911 static const ValueDecl *getValueDecl(const Expr *Exp) {
912 if (const auto *CE = dyn_cast<ImplicitCastExpr>(Exp))
913 return getValueDecl(CE->getSubExpr());
914
915 if (const auto *DR = dyn_cast<DeclRefExpr>(Exp))
916 return DR->getDecl();
917
918 if (const auto *ME = dyn_cast<MemberExpr>(Exp))
919 return ME->getMemberDecl();
920
921 return nullptr;
922 }
923
924 template <typename Ty>
925 class has_arg_iterator_range {
926 typedef char yes[1];
927 typedef char no[2];
928
929 template <typename Inner>
930 static yes& test(Inner *I, decltype(I->args()) * = nullptr);
931
932 template <typename>
933 static no& test(...);
934
935 public:
936 static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
937 };
938
ClassifyDiagnostic(const CapabilityAttr * A)939 static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
940 return A->getName();
941 }
942
ClassifyDiagnostic(QualType VDT)943 static StringRef ClassifyDiagnostic(QualType VDT) {
944 // We need to look at the declaration of the type of the value to determine
945 // which it is. The type should either be a record or a typedef, or a pointer
946 // or reference thereof.
947 if (const auto *RT = VDT->getAs<RecordType>()) {
948 if (const auto *RD = RT->getDecl())
949 if (const auto *CA = RD->getAttr<CapabilityAttr>())
950 return ClassifyDiagnostic(CA);
951 } else if (const auto *TT = VDT->getAs<TypedefType>()) {
952 if (const auto *TD = TT->getDecl())
953 if (const auto *CA = TD->getAttr<CapabilityAttr>())
954 return ClassifyDiagnostic(CA);
955 } else if (VDT->isPointerType() || VDT->isReferenceType())
956 return ClassifyDiagnostic(VDT->getPointeeType());
957
958 return "mutex";
959 }
960
ClassifyDiagnostic(const ValueDecl * VD)961 static StringRef ClassifyDiagnostic(const ValueDecl *VD) {
962 assert(VD && "No ValueDecl passed");
963
964 // The ValueDecl is the declaration of a mutex or role (hopefully).
965 return ClassifyDiagnostic(VD->getType());
966 }
967
968 template <typename AttrTy>
969 static typename std::enable_if<!has_arg_iterator_range<AttrTy>::value,
970 StringRef>::type
ClassifyDiagnostic(const AttrTy * A)971 ClassifyDiagnostic(const AttrTy *A) {
972 if (const ValueDecl *VD = getValueDecl(A->getArg()))
973 return ClassifyDiagnostic(VD);
974 return "mutex";
975 }
976
977 template <typename AttrTy>
978 static typename std::enable_if<has_arg_iterator_range<AttrTy>::value,
979 StringRef>::type
ClassifyDiagnostic(const AttrTy * A)980 ClassifyDiagnostic(const AttrTy *A) {
981 for (const auto *Arg : A->args()) {
982 if (const ValueDecl *VD = getValueDecl(Arg))
983 return ClassifyDiagnostic(VD);
984 }
985 return "mutex";
986 }
987
988
inCurrentScope(const CapabilityExpr & CapE)989 inline bool ThreadSafetyAnalyzer::inCurrentScope(const CapabilityExpr &CapE) {
990 if (!CurrentMethod)
991 return false;
992 if (auto *P = dyn_cast_or_null<til::Project>(CapE.sexpr())) {
993 auto *VD = P->clangDecl();
994 if (VD)
995 return VD->getDeclContext() == CurrentMethod->getDeclContext();
996 }
997 return false;
998 }
999
1000
1001 /// \brief Add a new lock to the lockset, warning if the lock is already there.
1002 /// \param ReqAttr -- true if this is part of an initial Requires attribute.
addLock(FactSet & FSet,std::unique_ptr<FactEntry> Entry,StringRef DiagKind,bool ReqAttr)1003 void ThreadSafetyAnalyzer::addLock(FactSet &FSet,
1004 std::unique_ptr<FactEntry> Entry,
1005 StringRef DiagKind, bool ReqAttr) {
1006 if (Entry->shouldIgnore())
1007 return;
1008
1009 if (!ReqAttr && !Entry->negative()) {
1010 // look for the negative capability, and remove it from the fact set.
1011 CapabilityExpr NegC = !*Entry;
1012 FactEntry *Nen = FSet.findLock(FactMan, NegC);
1013 if (Nen) {
1014 FSet.removeLock(FactMan, NegC);
1015 }
1016 else {
1017 if (inCurrentScope(*Entry) && !Entry->asserted())
1018 Handler.handleNegativeNotHeld(DiagKind, Entry->toString(),
1019 NegC.toString(), Entry->loc());
1020 }
1021 }
1022
1023 // FIXME: deal with acquired before/after annotations.
1024 // FIXME: Don't always warn when we have support for reentrant locks.
1025 if (FSet.findLock(FactMan, *Entry)) {
1026 if (!Entry->asserted())
1027 Handler.handleDoubleLock(DiagKind, Entry->toString(), Entry->loc());
1028 } else {
1029 FSet.addLock(FactMan, std::move(Entry));
1030 }
1031 }
1032
1033
1034 /// \brief Remove a lock from the lockset, warning if the lock is not there.
1035 /// \param UnlockLoc The source location of the unlock (only used in error msg)
removeLock(FactSet & FSet,const CapabilityExpr & Cp,SourceLocation UnlockLoc,bool FullyRemove,LockKind ReceivedKind,StringRef DiagKind)1036 void ThreadSafetyAnalyzer::removeLock(FactSet &FSet, const CapabilityExpr &Cp,
1037 SourceLocation UnlockLoc,
1038 bool FullyRemove, LockKind ReceivedKind,
1039 StringRef DiagKind) {
1040 if (Cp.shouldIgnore())
1041 return;
1042
1043 const FactEntry *LDat = FSet.findLock(FactMan, Cp);
1044 if (!LDat) {
1045 Handler.handleUnmatchedUnlock(DiagKind, Cp.toString(), UnlockLoc);
1046 return;
1047 }
1048
1049 // Generic lock removal doesn't care about lock kind mismatches, but
1050 // otherwise diagnose when the lock kinds are mismatched.
1051 if (ReceivedKind != LK_Generic && LDat->kind() != ReceivedKind) {
1052 Handler.handleIncorrectUnlockKind(DiagKind, Cp.toString(),
1053 LDat->kind(), ReceivedKind, UnlockLoc);
1054 }
1055
1056 LDat->handleUnlock(FSet, FactMan, Cp, UnlockLoc, FullyRemove, Handler,
1057 DiagKind);
1058 }
1059
1060
1061 /// \brief Extract the list of mutexIDs from the attribute on an expression,
1062 /// and push them onto Mtxs, discarding any duplicates.
1063 template <typename AttrType>
getMutexIDs(CapExprSet & Mtxs,AttrType * Attr,Expr * Exp,const NamedDecl * D,VarDecl * SelfDecl)1064 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1065 Expr *Exp, const NamedDecl *D,
1066 VarDecl *SelfDecl) {
1067 if (Attr->args_size() == 0) {
1068 // The mutex held is the "this" object.
1069 CapabilityExpr Cp = SxBuilder.translateAttrExpr(nullptr, D, Exp, SelfDecl);
1070 if (Cp.isInvalid()) {
1071 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1072 return;
1073 }
1074 //else
1075 if (!Cp.shouldIgnore())
1076 Mtxs.push_back_nodup(Cp);
1077 return;
1078 }
1079
1080 for (const auto *Arg : Attr->args()) {
1081 CapabilityExpr Cp = SxBuilder.translateAttrExpr(Arg, D, Exp, SelfDecl);
1082 if (Cp.isInvalid()) {
1083 warnInvalidLock(Handler, nullptr, D, Exp, ClassifyDiagnostic(Attr));
1084 continue;
1085 }
1086 //else
1087 if (!Cp.shouldIgnore())
1088 Mtxs.push_back_nodup(Cp);
1089 }
1090 }
1091
1092
1093 /// \brief Extract the list of mutexIDs from a trylock attribute. If the
1094 /// trylock applies to the given edge, then push them onto Mtxs, discarding
1095 /// any duplicates.
1096 template <class AttrType>
getMutexIDs(CapExprSet & Mtxs,AttrType * Attr,Expr * Exp,const NamedDecl * D,const CFGBlock * PredBlock,const CFGBlock * CurrBlock,Expr * BrE,bool Neg)1097 void ThreadSafetyAnalyzer::getMutexIDs(CapExprSet &Mtxs, AttrType *Attr,
1098 Expr *Exp, const NamedDecl *D,
1099 const CFGBlock *PredBlock,
1100 const CFGBlock *CurrBlock,
1101 Expr *BrE, bool Neg) {
1102 // Find out which branch has the lock
1103 bool branch = false;
1104 if (CXXBoolLiteralExpr *BLE = dyn_cast_or_null<CXXBoolLiteralExpr>(BrE))
1105 branch = BLE->getValue();
1106 else if (IntegerLiteral *ILE = dyn_cast_or_null<IntegerLiteral>(BrE))
1107 branch = ILE->getValue().getBoolValue();
1108
1109 int branchnum = branch ? 0 : 1;
1110 if (Neg)
1111 branchnum = !branchnum;
1112
1113 // If we've taken the trylock branch, then add the lock
1114 int i = 0;
1115 for (CFGBlock::const_succ_iterator SI = PredBlock->succ_begin(),
1116 SE = PredBlock->succ_end(); SI != SE && i < 2; ++SI, ++i) {
1117 if (*SI == CurrBlock && i == branchnum)
1118 getMutexIDs(Mtxs, Attr, Exp, D);
1119 }
1120 }
1121
1122
getStaticBooleanValue(Expr * E,bool & TCond)1123 bool getStaticBooleanValue(Expr* E, bool& TCond) {
1124 if (isa<CXXNullPtrLiteralExpr>(E) || isa<GNUNullExpr>(E)) {
1125 TCond = false;
1126 return true;
1127 } else if (CXXBoolLiteralExpr *BLE = dyn_cast<CXXBoolLiteralExpr>(E)) {
1128 TCond = BLE->getValue();
1129 return true;
1130 } else if (IntegerLiteral *ILE = dyn_cast<IntegerLiteral>(E)) {
1131 TCond = ILE->getValue().getBoolValue();
1132 return true;
1133 } else if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
1134 return getStaticBooleanValue(CE->getSubExpr(), TCond);
1135 }
1136 return false;
1137 }
1138
1139
1140 // If Cond can be traced back to a function call, return the call expression.
1141 // The negate variable should be called with false, and will be set to true
1142 // if the function call is negated, e.g. if (!mu.tryLock(...))
getTrylockCallExpr(const Stmt * Cond,LocalVarContext C,bool & Negate)1143 const CallExpr* ThreadSafetyAnalyzer::getTrylockCallExpr(const Stmt *Cond,
1144 LocalVarContext C,
1145 bool &Negate) {
1146 if (!Cond)
1147 return nullptr;
1148
1149 if (const CallExpr *CallExp = dyn_cast<CallExpr>(Cond)) {
1150 return CallExp;
1151 }
1152 else if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond)) {
1153 return getTrylockCallExpr(PE->getSubExpr(), C, Negate);
1154 }
1155 else if (const ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(Cond)) {
1156 return getTrylockCallExpr(CE->getSubExpr(), C, Negate);
1157 }
1158 else if (const ExprWithCleanups* EWC = dyn_cast<ExprWithCleanups>(Cond)) {
1159 return getTrylockCallExpr(EWC->getSubExpr(), C, Negate);
1160 }
1161 else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Cond)) {
1162 const Expr *E = LocalVarMap.lookupExpr(DRE->getDecl(), C);
1163 return getTrylockCallExpr(E, C, Negate);
1164 }
1165 else if (const UnaryOperator *UOP = dyn_cast<UnaryOperator>(Cond)) {
1166 if (UOP->getOpcode() == UO_LNot) {
1167 Negate = !Negate;
1168 return getTrylockCallExpr(UOP->getSubExpr(), C, Negate);
1169 }
1170 return nullptr;
1171 }
1172 else if (const BinaryOperator *BOP = dyn_cast<BinaryOperator>(Cond)) {
1173 if (BOP->getOpcode() == BO_EQ || BOP->getOpcode() == BO_NE) {
1174 if (BOP->getOpcode() == BO_NE)
1175 Negate = !Negate;
1176
1177 bool TCond = false;
1178 if (getStaticBooleanValue(BOP->getRHS(), TCond)) {
1179 if (!TCond) Negate = !Negate;
1180 return getTrylockCallExpr(BOP->getLHS(), C, Negate);
1181 }
1182 TCond = false;
1183 if (getStaticBooleanValue(BOP->getLHS(), TCond)) {
1184 if (!TCond) Negate = !Negate;
1185 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1186 }
1187 return nullptr;
1188 }
1189 if (BOP->getOpcode() == BO_LAnd) {
1190 // LHS must have been evaluated in a different block.
1191 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1192 }
1193 if (BOP->getOpcode() == BO_LOr) {
1194 return getTrylockCallExpr(BOP->getRHS(), C, Negate);
1195 }
1196 return nullptr;
1197 }
1198 return nullptr;
1199 }
1200
1201
1202 /// \brief Find the lockset that holds on the edge between PredBlock
1203 /// and CurrBlock. The edge set is the exit set of PredBlock (passed
1204 /// as the ExitSet parameter) plus any trylocks, which are conditionally held.
getEdgeLockset(FactSet & Result,const FactSet & ExitSet,const CFGBlock * PredBlock,const CFGBlock * CurrBlock)1205 void ThreadSafetyAnalyzer::getEdgeLockset(FactSet& Result,
1206 const FactSet &ExitSet,
1207 const CFGBlock *PredBlock,
1208 const CFGBlock *CurrBlock) {
1209 Result = ExitSet;
1210
1211 const Stmt *Cond = PredBlock->getTerminatorCondition();
1212 if (!Cond)
1213 return;
1214
1215 bool Negate = false;
1216 const CFGBlockInfo *PredBlockInfo = &BlockInfo[PredBlock->getBlockID()];
1217 const LocalVarContext &LVarCtx = PredBlockInfo->ExitContext;
1218 StringRef CapDiagKind = "mutex";
1219
1220 CallExpr *Exp =
1221 const_cast<CallExpr*>(getTrylockCallExpr(Cond, LVarCtx, Negate));
1222 if (!Exp)
1223 return;
1224
1225 NamedDecl *FunDecl = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1226 if(!FunDecl || !FunDecl->hasAttrs())
1227 return;
1228
1229 CapExprSet ExclusiveLocksToAdd;
1230 CapExprSet SharedLocksToAdd;
1231
1232 // If the condition is a call to a Trylock function, then grab the attributes
1233 for (auto *Attr : FunDecl->getAttrs()) {
1234 switch (Attr->getKind()) {
1235 case attr::ExclusiveTrylockFunction: {
1236 ExclusiveTrylockFunctionAttr *A =
1237 cast<ExclusiveTrylockFunctionAttr>(Attr);
1238 getMutexIDs(ExclusiveLocksToAdd, A, Exp, FunDecl,
1239 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1240 CapDiagKind = ClassifyDiagnostic(A);
1241 break;
1242 }
1243 case attr::SharedTrylockFunction: {
1244 SharedTrylockFunctionAttr *A =
1245 cast<SharedTrylockFunctionAttr>(Attr);
1246 getMutexIDs(SharedLocksToAdd, A, Exp, FunDecl,
1247 PredBlock, CurrBlock, A->getSuccessValue(), Negate);
1248 CapDiagKind = ClassifyDiagnostic(A);
1249 break;
1250 }
1251 default:
1252 break;
1253 }
1254 }
1255
1256 // Add and remove locks.
1257 SourceLocation Loc = Exp->getExprLoc();
1258 for (const auto &ExclusiveLockToAdd : ExclusiveLocksToAdd)
1259 addLock(Result, llvm::make_unique<LockableFactEntry>(ExclusiveLockToAdd,
1260 LK_Exclusive, Loc),
1261 CapDiagKind);
1262 for (const auto &SharedLockToAdd : SharedLocksToAdd)
1263 addLock(Result, llvm::make_unique<LockableFactEntry>(SharedLockToAdd,
1264 LK_Shared, Loc),
1265 CapDiagKind);
1266 }
1267
1268 /// \brief We use this class to visit different types of expressions in
1269 /// CFGBlocks, and build up the lockset.
1270 /// An expression may cause us to add or remove locks from the lockset, or else
1271 /// output error messages related to missing locks.
1272 /// FIXME: In future, we may be able to not inherit from a visitor.
1273 class BuildLockset : public StmtVisitor<BuildLockset> {
1274 friend class ThreadSafetyAnalyzer;
1275
1276 ThreadSafetyAnalyzer *Analyzer;
1277 FactSet FSet;
1278 LocalVariableMap::Context LVarCtx;
1279 unsigned CtxIndex;
1280
1281 // helper functions
1282 void warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp, AccessKind AK,
1283 Expr *MutexExp, ProtectedOperationKind POK,
1284 StringRef DiagKind, SourceLocation Loc);
1285 void warnIfMutexHeld(const NamedDecl *D, const Expr *Exp, Expr *MutexExp,
1286 StringRef DiagKind);
1287
1288 void checkAccess(const Expr *Exp, AccessKind AK,
1289 ProtectedOperationKind POK = POK_VarAccess);
1290 void checkPtAccess(const Expr *Exp, AccessKind AK,
1291 ProtectedOperationKind POK = POK_VarAccess);
1292
1293 void handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD = nullptr);
1294
1295 public:
BuildLockset(ThreadSafetyAnalyzer * Anlzr,CFGBlockInfo & Info)1296 BuildLockset(ThreadSafetyAnalyzer *Anlzr, CFGBlockInfo &Info)
1297 : StmtVisitor<BuildLockset>(),
1298 Analyzer(Anlzr),
1299 FSet(Info.EntrySet),
1300 LVarCtx(Info.EntryContext),
1301 CtxIndex(Info.EntryIndex)
1302 {}
1303
1304 void VisitUnaryOperator(UnaryOperator *UO);
1305 void VisitBinaryOperator(BinaryOperator *BO);
1306 void VisitCastExpr(CastExpr *CE);
1307 void VisitCallExpr(CallExpr *Exp);
1308 void VisitCXXConstructExpr(CXXConstructExpr *Exp);
1309 void VisitDeclStmt(DeclStmt *S);
1310 };
1311
1312
1313 /// \brief Warn if the LSet does not contain a lock sufficient to protect access
1314 /// of at least the passed in AccessKind.
warnIfMutexNotHeld(const NamedDecl * D,const Expr * Exp,AccessKind AK,Expr * MutexExp,ProtectedOperationKind POK,StringRef DiagKind,SourceLocation Loc)1315 void BuildLockset::warnIfMutexNotHeld(const NamedDecl *D, const Expr *Exp,
1316 AccessKind AK, Expr *MutexExp,
1317 ProtectedOperationKind POK,
1318 StringRef DiagKind, SourceLocation Loc) {
1319 LockKind LK = getLockKindFromAccessKind(AK);
1320
1321 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1322 if (Cp.isInvalid()) {
1323 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1324 return;
1325 } else if (Cp.shouldIgnore()) {
1326 return;
1327 }
1328
1329 if (Cp.negative()) {
1330 // Negative capabilities act like locks excluded
1331 FactEntry *LDat = FSet.findLock(Analyzer->FactMan, !Cp);
1332 if (LDat) {
1333 Analyzer->Handler.handleFunExcludesLock(
1334 DiagKind, D->getNameAsString(), (!Cp).toString(), Loc);
1335 return;
1336 }
1337
1338 // If this does not refer to a negative capability in the same class,
1339 // then stop here.
1340 if (!Analyzer->inCurrentScope(Cp))
1341 return;
1342
1343 // Otherwise the negative requirement must be propagated to the caller.
1344 LDat = FSet.findLock(Analyzer->FactMan, Cp);
1345 if (!LDat) {
1346 Analyzer->Handler.handleMutexNotHeld("", D, POK, Cp.toString(),
1347 LK_Shared, Loc);
1348 }
1349 return;
1350 }
1351
1352 FactEntry* LDat = FSet.findLockUniv(Analyzer->FactMan, Cp);
1353 bool NoError = true;
1354 if (!LDat) {
1355 // No exact match found. Look for a partial match.
1356 LDat = FSet.findPartialMatch(Analyzer->FactMan, Cp);
1357 if (LDat) {
1358 // Warn that there's no precise match.
1359 std::string PartMatchStr = LDat->toString();
1360 StringRef PartMatchName(PartMatchStr);
1361 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1362 LK, Loc, &PartMatchName);
1363 } else {
1364 // Warn that there's no match at all.
1365 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1366 LK, Loc);
1367 }
1368 NoError = false;
1369 }
1370 // Make sure the mutex we found is the right kind.
1371 if (NoError && LDat && !LDat->isAtLeast(LK)) {
1372 Analyzer->Handler.handleMutexNotHeld(DiagKind, D, POK, Cp.toString(),
1373 LK, Loc);
1374 }
1375 }
1376
1377 /// \brief Warn if the LSet contains the given lock.
warnIfMutexHeld(const NamedDecl * D,const Expr * Exp,Expr * MutexExp,StringRef DiagKind)1378 void BuildLockset::warnIfMutexHeld(const NamedDecl *D, const Expr *Exp,
1379 Expr *MutexExp, StringRef DiagKind) {
1380 CapabilityExpr Cp = Analyzer->SxBuilder.translateAttrExpr(MutexExp, D, Exp);
1381 if (Cp.isInvalid()) {
1382 warnInvalidLock(Analyzer->Handler, MutexExp, D, Exp, DiagKind);
1383 return;
1384 } else if (Cp.shouldIgnore()) {
1385 return;
1386 }
1387
1388 FactEntry* LDat = FSet.findLock(Analyzer->FactMan, Cp);
1389 if (LDat) {
1390 Analyzer->Handler.handleFunExcludesLock(
1391 DiagKind, D->getNameAsString(), Cp.toString(), Exp->getExprLoc());
1392 }
1393 }
1394
1395 /// \brief Checks guarded_by and pt_guarded_by attributes.
1396 /// Whenever we identify an access (read or write) to a DeclRefExpr that is
1397 /// marked with guarded_by, we must ensure the appropriate mutexes are held.
1398 /// Similarly, we check if the access is to an expression that dereferences
1399 /// a pointer marked with pt_guarded_by.
checkAccess(const Expr * Exp,AccessKind AK,ProtectedOperationKind POK)1400 void BuildLockset::checkAccess(const Expr *Exp, AccessKind AK,
1401 ProtectedOperationKind POK) {
1402 Exp = Exp->IgnoreParenCasts();
1403
1404 SourceLocation Loc = Exp->getExprLoc();
1405
1406 // Local variables of reference type cannot be re-assigned;
1407 // map them to their initializer.
1408 while (const auto *DRE = dyn_cast<DeclRefExpr>(Exp)) {
1409 const auto *VD = dyn_cast<VarDecl>(DRE->getDecl()->getCanonicalDecl());
1410 if (VD && VD->isLocalVarDecl() && VD->getType()->isReferenceType()) {
1411 if (const auto *E = VD->getInit()) {
1412 Exp = E;
1413 continue;
1414 }
1415 }
1416 break;
1417 }
1418
1419 if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(Exp)) {
1420 // For dereferences
1421 if (UO->getOpcode() == clang::UO_Deref)
1422 checkPtAccess(UO->getSubExpr(), AK, POK);
1423 return;
1424 }
1425
1426 if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(Exp)) {
1427 checkPtAccess(AE->getLHS(), AK, POK);
1428 return;
1429 }
1430
1431 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Exp)) {
1432 if (ME->isArrow())
1433 checkPtAccess(ME->getBase(), AK, POK);
1434 else
1435 checkAccess(ME->getBase(), AK, POK);
1436 }
1437
1438 const ValueDecl *D = getValueDecl(Exp);
1439 if (!D || !D->hasAttrs())
1440 return;
1441
1442 if (D->hasAttr<GuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan)) {
1443 Analyzer->Handler.handleNoMutexHeld("mutex", D, POK, AK, Loc);
1444 }
1445
1446 for (const auto *I : D->specific_attrs<GuardedByAttr>())
1447 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), POK,
1448 ClassifyDiagnostic(I), Loc);
1449 }
1450
1451
1452 /// \brief Checks pt_guarded_by and pt_guarded_var attributes.
1453 /// POK is the same operationKind that was passed to checkAccess.
checkPtAccess(const Expr * Exp,AccessKind AK,ProtectedOperationKind POK)1454 void BuildLockset::checkPtAccess(const Expr *Exp, AccessKind AK,
1455 ProtectedOperationKind POK) {
1456 while (true) {
1457 if (const ParenExpr *PE = dyn_cast<ParenExpr>(Exp)) {
1458 Exp = PE->getSubExpr();
1459 continue;
1460 }
1461 if (const CastExpr *CE = dyn_cast<CastExpr>(Exp)) {
1462 if (CE->getCastKind() == CK_ArrayToPointerDecay) {
1463 // If it's an actual array, and not a pointer, then it's elements
1464 // are protected by GUARDED_BY, not PT_GUARDED_BY;
1465 checkAccess(CE->getSubExpr(), AK, POK);
1466 return;
1467 }
1468 Exp = CE->getSubExpr();
1469 continue;
1470 }
1471 break;
1472 }
1473
1474 // Pass by reference warnings are under a different flag.
1475 ProtectedOperationKind PtPOK = POK_VarDereference;
1476 if (POK == POK_PassByRef) PtPOK = POK_PtPassByRef;
1477
1478 const ValueDecl *D = getValueDecl(Exp);
1479 if (!D || !D->hasAttrs())
1480 return;
1481
1482 if (D->hasAttr<PtGuardedVarAttr>() && FSet.isEmpty(Analyzer->FactMan))
1483 Analyzer->Handler.handleNoMutexHeld("mutex", D, PtPOK, AK,
1484 Exp->getExprLoc());
1485
1486 for (auto const *I : D->specific_attrs<PtGuardedByAttr>())
1487 warnIfMutexNotHeld(D, Exp, AK, I->getArg(), PtPOK,
1488 ClassifyDiagnostic(I), Exp->getExprLoc());
1489 }
1490
1491 /// \brief Process a function call, method call, constructor call,
1492 /// or destructor call. This involves looking at the attributes on the
1493 /// corresponding function/method/constructor/destructor, issuing warnings,
1494 /// and updating the locksets accordingly.
1495 ///
1496 /// FIXME: For classes annotated with one of the guarded annotations, we need
1497 /// to treat const method calls as reads and non-const method calls as writes,
1498 /// and check that the appropriate locks are held. Non-const method calls with
1499 /// the same signature as const method calls can be also treated as reads.
1500 ///
handleCall(Expr * Exp,const NamedDecl * D,VarDecl * VD)1501 void BuildLockset::handleCall(Expr *Exp, const NamedDecl *D, VarDecl *VD) {
1502 SourceLocation Loc = Exp->getExprLoc();
1503 const AttrVec &ArgAttrs = D->getAttrs();
1504 CapExprSet ExclusiveLocksToAdd, SharedLocksToAdd;
1505 CapExprSet ExclusiveLocksToRemove, SharedLocksToRemove, GenericLocksToRemove;
1506 StringRef CapDiagKind = "mutex";
1507
1508 for(unsigned i = 0; i < ArgAttrs.size(); ++i) {
1509 Attr *At = const_cast<Attr*>(ArgAttrs[i]);
1510 switch (At->getKind()) {
1511 // When we encounter a lock function, we need to add the lock to our
1512 // lockset.
1513 case attr::AcquireCapability: {
1514 auto *A = cast<AcquireCapabilityAttr>(At);
1515 Analyzer->getMutexIDs(A->isShared() ? SharedLocksToAdd
1516 : ExclusiveLocksToAdd,
1517 A, Exp, D, VD);
1518
1519 CapDiagKind = ClassifyDiagnostic(A);
1520 break;
1521 }
1522
1523 // An assert will add a lock to the lockset, but will not generate
1524 // a warning if it is already there, and will not generate a warning
1525 // if it is not removed.
1526 case attr::AssertExclusiveLock: {
1527 AssertExclusiveLockAttr *A = cast<AssertExclusiveLockAttr>(At);
1528
1529 CapExprSet AssertLocks;
1530 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1531 for (const auto &AssertLock : AssertLocks)
1532 Analyzer->addLock(FSet,
1533 llvm::make_unique<LockableFactEntry>(
1534 AssertLock, LK_Exclusive, Loc, false, true),
1535 ClassifyDiagnostic(A));
1536 break;
1537 }
1538 case attr::AssertSharedLock: {
1539 AssertSharedLockAttr *A = cast<AssertSharedLockAttr>(At);
1540
1541 CapExprSet AssertLocks;
1542 Analyzer->getMutexIDs(AssertLocks, A, Exp, D, VD);
1543 for (const auto &AssertLock : AssertLocks)
1544 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1545 AssertLock, LK_Shared, Loc, false, true),
1546 ClassifyDiagnostic(A));
1547 break;
1548 }
1549
1550 // When we encounter an unlock function, we need to remove unlocked
1551 // mutexes from the lockset, and flag a warning if they are not there.
1552 case attr::ReleaseCapability: {
1553 auto *A = cast<ReleaseCapabilityAttr>(At);
1554 if (A->isGeneric())
1555 Analyzer->getMutexIDs(GenericLocksToRemove, A, Exp, D, VD);
1556 else if (A->isShared())
1557 Analyzer->getMutexIDs(SharedLocksToRemove, A, Exp, D, VD);
1558 else
1559 Analyzer->getMutexIDs(ExclusiveLocksToRemove, A, Exp, D, VD);
1560
1561 CapDiagKind = ClassifyDiagnostic(A);
1562 break;
1563 }
1564
1565 case attr::RequiresCapability: {
1566 RequiresCapabilityAttr *A = cast<RequiresCapabilityAttr>(At);
1567 for (auto *Arg : A->args())
1568 warnIfMutexNotHeld(D, Exp, A->isShared() ? AK_Read : AK_Written, Arg,
1569 POK_FunctionCall, ClassifyDiagnostic(A),
1570 Exp->getExprLoc());
1571 break;
1572 }
1573
1574 case attr::LocksExcluded: {
1575 LocksExcludedAttr *A = cast<LocksExcludedAttr>(At);
1576 for (auto *Arg : A->args())
1577 warnIfMutexHeld(D, Exp, Arg, ClassifyDiagnostic(A));
1578 break;
1579 }
1580
1581 // Ignore attributes unrelated to thread-safety
1582 default:
1583 break;
1584 }
1585 }
1586
1587 // Figure out if we're calling the constructor of scoped lockable class
1588 bool isScopedVar = false;
1589 if (VD) {
1590 if (const CXXConstructorDecl *CD = dyn_cast<const CXXConstructorDecl>(D)) {
1591 const CXXRecordDecl* PD = CD->getParent();
1592 if (PD && PD->hasAttr<ScopedLockableAttr>())
1593 isScopedVar = true;
1594 }
1595 }
1596
1597 // Add locks.
1598 for (const auto &M : ExclusiveLocksToAdd)
1599 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1600 M, LK_Exclusive, Loc, isScopedVar),
1601 CapDiagKind);
1602 for (const auto &M : SharedLocksToAdd)
1603 Analyzer->addLock(FSet, llvm::make_unique<LockableFactEntry>(
1604 M, LK_Shared, Loc, isScopedVar),
1605 CapDiagKind);
1606
1607 if (isScopedVar) {
1608 // Add the managing object as a dummy mutex, mapped to the underlying mutex.
1609 SourceLocation MLoc = VD->getLocation();
1610 DeclRefExpr DRE(VD, false, VD->getType(), VK_LValue, VD->getLocation());
1611 // FIXME: does this store a pointer to DRE?
1612 CapabilityExpr Scp = Analyzer->SxBuilder.translateAttrExpr(&DRE, nullptr);
1613
1614 CapExprSet UnderlyingMutexes(ExclusiveLocksToAdd);
1615 std::copy(SharedLocksToAdd.begin(), SharedLocksToAdd.end(),
1616 std::back_inserter(UnderlyingMutexes));
1617 Analyzer->addLock(FSet,
1618 llvm::make_unique<ScopedLockableFactEntry>(
1619 Scp, MLoc, ExclusiveLocksToAdd, SharedLocksToAdd),
1620 CapDiagKind);
1621 }
1622
1623 // Remove locks.
1624 // FIXME -- should only fully remove if the attribute refers to 'this'.
1625 bool Dtor = isa<CXXDestructorDecl>(D);
1626 for (const auto &M : ExclusiveLocksToRemove)
1627 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Exclusive, CapDiagKind);
1628 for (const auto &M : SharedLocksToRemove)
1629 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Shared, CapDiagKind);
1630 for (const auto &M : GenericLocksToRemove)
1631 Analyzer->removeLock(FSet, M, Loc, Dtor, LK_Generic, CapDiagKind);
1632 }
1633
1634
1635 /// \brief For unary operations which read and write a variable, we need to
1636 /// check whether we hold any required mutexes. Reads are checked in
1637 /// VisitCastExpr.
VisitUnaryOperator(UnaryOperator * UO)1638 void BuildLockset::VisitUnaryOperator(UnaryOperator *UO) {
1639 switch (UO->getOpcode()) {
1640 case clang::UO_PostDec:
1641 case clang::UO_PostInc:
1642 case clang::UO_PreDec:
1643 case clang::UO_PreInc: {
1644 checkAccess(UO->getSubExpr(), AK_Written);
1645 break;
1646 }
1647 default:
1648 break;
1649 }
1650 }
1651
1652 /// For binary operations which assign to a variable (writes), we need to check
1653 /// whether we hold any required mutexes.
1654 /// FIXME: Deal with non-primitive types.
VisitBinaryOperator(BinaryOperator * BO)1655 void BuildLockset::VisitBinaryOperator(BinaryOperator *BO) {
1656 if (!BO->isAssignmentOp())
1657 return;
1658
1659 // adjust the context
1660 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, BO, LVarCtx);
1661
1662 checkAccess(BO->getLHS(), AK_Written);
1663 }
1664
1665
1666 /// Whenever we do an LValue to Rvalue cast, we are reading a variable and
1667 /// need to ensure we hold any required mutexes.
1668 /// FIXME: Deal with non-primitive types.
VisitCastExpr(CastExpr * CE)1669 void BuildLockset::VisitCastExpr(CastExpr *CE) {
1670 if (CE->getCastKind() != CK_LValueToRValue)
1671 return;
1672 checkAccess(CE->getSubExpr(), AK_Read);
1673 }
1674
1675
VisitCallExpr(CallExpr * Exp)1676 void BuildLockset::VisitCallExpr(CallExpr *Exp) {
1677 bool ExamineArgs = true;
1678 bool OperatorFun = false;
1679
1680 if (CXXMemberCallExpr *CE = dyn_cast<CXXMemberCallExpr>(Exp)) {
1681 MemberExpr *ME = dyn_cast<MemberExpr>(CE->getCallee());
1682 // ME can be null when calling a method pointer
1683 CXXMethodDecl *MD = CE->getMethodDecl();
1684
1685 if (ME && MD) {
1686 if (ME->isArrow()) {
1687 if (MD->isConst()) {
1688 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1689 } else { // FIXME -- should be AK_Written
1690 checkPtAccess(CE->getImplicitObjectArgument(), AK_Read);
1691 }
1692 } else {
1693 if (MD->isConst())
1694 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1695 else // FIXME -- should be AK_Written
1696 checkAccess(CE->getImplicitObjectArgument(), AK_Read);
1697 }
1698 }
1699 } else if (CXXOperatorCallExpr *OE = dyn_cast<CXXOperatorCallExpr>(Exp)) {
1700 OperatorFun = true;
1701
1702 auto OEop = OE->getOperator();
1703 switch (OEop) {
1704 case OO_Equal: {
1705 ExamineArgs = false;
1706 const Expr *Target = OE->getArg(0);
1707 const Expr *Source = OE->getArg(1);
1708 checkAccess(Target, AK_Written);
1709 checkAccess(Source, AK_Read);
1710 break;
1711 }
1712 case OO_Star:
1713 case OO_Arrow:
1714 case OO_Subscript: {
1715 const Expr *Obj = OE->getArg(0);
1716 checkAccess(Obj, AK_Read);
1717 if (!(OEop == OO_Star && OE->getNumArgs() > 1)) {
1718 // Grrr. operator* can be multiplication...
1719 checkPtAccess(Obj, AK_Read);
1720 }
1721 break;
1722 }
1723 default: {
1724 // TODO: get rid of this, and rely on pass-by-ref instead.
1725 const Expr *Obj = OE->getArg(0);
1726 checkAccess(Obj, AK_Read);
1727 break;
1728 }
1729 }
1730 }
1731
1732
1733 if (ExamineArgs) {
1734 if (FunctionDecl *FD = Exp->getDirectCallee()) {
1735 unsigned Fn = FD->getNumParams();
1736 unsigned Cn = Exp->getNumArgs();
1737 unsigned Skip = 0;
1738
1739 unsigned i = 0;
1740 if (OperatorFun) {
1741 if (isa<CXXMethodDecl>(FD)) {
1742 // First arg in operator call is implicit self argument,
1743 // and doesn't appear in the FunctionDecl.
1744 Skip = 1;
1745 Cn--;
1746 } else {
1747 // Ignore the first argument of operators; it's been checked above.
1748 i = 1;
1749 }
1750 }
1751 // Ignore default arguments
1752 unsigned n = (Fn < Cn) ? Fn : Cn;
1753
1754 for (; i < n; ++i) {
1755 ParmVarDecl* Pvd = FD->getParamDecl(i);
1756 Expr* Arg = Exp->getArg(i+Skip);
1757 QualType Qt = Pvd->getType();
1758 if (Qt->isReferenceType())
1759 checkAccess(Arg, AK_Read, POK_PassByRef);
1760 }
1761 }
1762 }
1763
1764 NamedDecl *D = dyn_cast_or_null<NamedDecl>(Exp->getCalleeDecl());
1765 if(!D || !D->hasAttrs())
1766 return;
1767 handleCall(Exp, D);
1768 }
1769
VisitCXXConstructExpr(CXXConstructExpr * Exp)1770 void BuildLockset::VisitCXXConstructExpr(CXXConstructExpr *Exp) {
1771 const CXXConstructorDecl *D = Exp->getConstructor();
1772 if (D && D->isCopyConstructor()) {
1773 const Expr* Source = Exp->getArg(0);
1774 checkAccess(Source, AK_Read);
1775 }
1776 // FIXME -- only handles constructors in DeclStmt below.
1777 }
1778
VisitDeclStmt(DeclStmt * S)1779 void BuildLockset::VisitDeclStmt(DeclStmt *S) {
1780 // adjust the context
1781 LVarCtx = Analyzer->LocalVarMap.getNextContext(CtxIndex, S, LVarCtx);
1782
1783 for (auto *D : S->getDeclGroup()) {
1784 if (VarDecl *VD = dyn_cast_or_null<VarDecl>(D)) {
1785 Expr *E = VD->getInit();
1786 // handle constructors that involve temporaries
1787 if (ExprWithCleanups *EWC = dyn_cast_or_null<ExprWithCleanups>(E))
1788 E = EWC->getSubExpr();
1789
1790 if (CXXConstructExpr *CE = dyn_cast_or_null<CXXConstructExpr>(E)) {
1791 NamedDecl *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());
1792 if (!CtorD || !CtorD->hasAttrs())
1793 return;
1794 handleCall(CE, CtorD, VD);
1795 }
1796 }
1797 }
1798 }
1799
1800
1801
1802 /// \brief Compute the intersection of two locksets and issue warnings for any
1803 /// locks in the symmetric difference.
1804 ///
1805 /// This function is used at a merge point in the CFG when comparing the lockset
1806 /// of each branch being merged. For example, given the following sequence:
1807 /// A; if () then B; else C; D; we need to check that the lockset after B and C
1808 /// are the same. In the event of a difference, we use the intersection of these
1809 /// two locksets at the start of D.
1810 ///
1811 /// \param FSet1 The first lockset.
1812 /// \param FSet2 The second lockset.
1813 /// \param JoinLoc The location of the join point for error reporting
1814 /// \param LEK1 The error message to report if a mutex is missing from LSet1
1815 /// \param LEK2 The error message to report if a mutex is missing from Lset2
intersectAndWarn(FactSet & FSet1,const FactSet & FSet2,SourceLocation JoinLoc,LockErrorKind LEK1,LockErrorKind LEK2,bool Modify)1816 void ThreadSafetyAnalyzer::intersectAndWarn(FactSet &FSet1,
1817 const FactSet &FSet2,
1818 SourceLocation JoinLoc,
1819 LockErrorKind LEK1,
1820 LockErrorKind LEK2,
1821 bool Modify) {
1822 FactSet FSet1Orig = FSet1;
1823
1824 // Find locks in FSet2 that conflict or are not in FSet1, and warn.
1825 for (const auto &Fact : FSet2) {
1826 const FactEntry *LDat1 = nullptr;
1827 const FactEntry *LDat2 = &FactMan[Fact];
1828 FactSet::iterator Iter1 = FSet1.findLockIter(FactMan, *LDat2);
1829 if (Iter1 != FSet1.end()) LDat1 = &FactMan[*Iter1];
1830
1831 if (LDat1) {
1832 if (LDat1->kind() != LDat2->kind()) {
1833 Handler.handleExclusiveAndShared("mutex", LDat2->toString(),
1834 LDat2->loc(), LDat1->loc());
1835 if (Modify && LDat1->kind() != LK_Exclusive) {
1836 // Take the exclusive lock, which is the one in FSet2.
1837 *Iter1 = Fact;
1838 }
1839 }
1840 else if (Modify && LDat1->asserted() && !LDat2->asserted()) {
1841 // The non-asserted lock in FSet2 is the one we want to track.
1842 *Iter1 = Fact;
1843 }
1844 } else {
1845 LDat2->handleRemovalFromIntersection(FSet2, FactMan, JoinLoc, LEK1,
1846 Handler);
1847 }
1848 }
1849
1850 // Find locks in FSet1 that are not in FSet2, and remove them.
1851 for (const auto &Fact : FSet1Orig) {
1852 const FactEntry *LDat1 = &FactMan[Fact];
1853 const FactEntry *LDat2 = FSet2.findLock(FactMan, *LDat1);
1854
1855 if (!LDat2) {
1856 LDat1->handleRemovalFromIntersection(FSet1Orig, FactMan, JoinLoc, LEK2,
1857 Handler);
1858 if (Modify)
1859 FSet1.removeLock(FactMan, *LDat1);
1860 }
1861 }
1862 }
1863
1864
1865 // Return true if block B never continues to its successors.
neverReturns(const CFGBlock * B)1866 inline bool neverReturns(const CFGBlock* B) {
1867 if (B->hasNoReturnElement())
1868 return true;
1869 if (B->empty())
1870 return false;
1871
1872 CFGElement Last = B->back();
1873 if (Optional<CFGStmt> S = Last.getAs<CFGStmt>()) {
1874 if (isa<CXXThrowExpr>(S->getStmt()))
1875 return true;
1876 }
1877 return false;
1878 }
1879
1880
1881 /// \brief Check a function's CFG for thread-safety violations.
1882 ///
1883 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
1884 /// at the end of each block, and issue warnings for thread safety violations.
1885 /// Each block in the CFG is traversed exactly once.
runAnalysis(AnalysisDeclContext & AC)1886 void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
1887 // TODO: this whole function needs be rewritten as a visitor for CFGWalker.
1888 // For now, we just use the walker to set things up.
1889 threadSafety::CFGWalker walker;
1890 if (!walker.init(AC))
1891 return;
1892
1893 // AC.dumpCFG(true);
1894 // threadSafety::printSCFG(walker);
1895
1896 CFG *CFGraph = walker.getGraph();
1897 const NamedDecl *D = walker.getDecl();
1898 const FunctionDecl *CurrentFunction = dyn_cast<FunctionDecl>(D);
1899 CurrentMethod = dyn_cast<CXXMethodDecl>(D);
1900
1901 if (D->hasAttr<NoThreadSafetyAnalysisAttr>())
1902 return;
1903
1904 // FIXME: Do something a bit more intelligent inside constructor and
1905 // destructor code. Constructors and destructors must assume unique access
1906 // to 'this', so checks on member variable access is disabled, but we should
1907 // still enable checks on other objects.
1908 if (isa<CXXConstructorDecl>(D))
1909 return; // Don't check inside constructors.
1910 if (isa<CXXDestructorDecl>(D))
1911 return; // Don't check inside destructors.
1912
1913 Handler.enterFunction(CurrentFunction);
1914
1915 BlockInfo.resize(CFGraph->getNumBlockIDs(),
1916 CFGBlockInfo::getEmptyBlockInfo(LocalVarMap));
1917
1918 // We need to explore the CFG via a "topological" ordering.
1919 // That way, we will be guaranteed to have information about required
1920 // predecessor locksets when exploring a new block.
1921 const PostOrderCFGView *SortedGraph = walker.getSortedGraph();
1922 PostOrderCFGView::CFGBlockSet VisitedBlocks(CFGraph);
1923
1924 // Mark entry block as reachable
1925 BlockInfo[CFGraph->getEntry().getBlockID()].Reachable = true;
1926
1927 // Compute SSA names for local variables
1928 LocalVarMap.traverseCFG(CFGraph, SortedGraph, BlockInfo);
1929
1930 // Fill in source locations for all CFGBlocks.
1931 findBlockLocations(CFGraph, SortedGraph, BlockInfo);
1932
1933 CapExprSet ExclusiveLocksAcquired;
1934 CapExprSet SharedLocksAcquired;
1935 CapExprSet LocksReleased;
1936
1937 // Add locks from exclusive_locks_required and shared_locks_required
1938 // to initial lockset. Also turn off checking for lock and unlock functions.
1939 // FIXME: is there a more intelligent way to check lock/unlock functions?
1940 if (!SortedGraph->empty() && D->hasAttrs()) {
1941 const CFGBlock *FirstBlock = *SortedGraph->begin();
1942 FactSet &InitialLockset = BlockInfo[FirstBlock->getBlockID()].EntrySet;
1943 const AttrVec &ArgAttrs = D->getAttrs();
1944
1945 CapExprSet ExclusiveLocksToAdd;
1946 CapExprSet SharedLocksToAdd;
1947 StringRef CapDiagKind = "mutex";
1948
1949 SourceLocation Loc = D->getLocation();
1950 for (const auto *Attr : ArgAttrs) {
1951 Loc = Attr->getLocation();
1952 if (const auto *A = dyn_cast<RequiresCapabilityAttr>(Attr)) {
1953 getMutexIDs(A->isShared() ? SharedLocksToAdd : ExclusiveLocksToAdd, A,
1954 nullptr, D);
1955 CapDiagKind = ClassifyDiagnostic(A);
1956 } else if (const auto *A = dyn_cast<ReleaseCapabilityAttr>(Attr)) {
1957 // UNLOCK_FUNCTION() is used to hide the underlying lock implementation.
1958 // We must ignore such methods.
1959 if (A->args_size() == 0)
1960 return;
1961 // FIXME -- deal with exclusive vs. shared unlock functions?
1962 getMutexIDs(ExclusiveLocksToAdd, A, nullptr, D);
1963 getMutexIDs(LocksReleased, A, nullptr, D);
1964 CapDiagKind = ClassifyDiagnostic(A);
1965 } else if (const auto *A = dyn_cast<AcquireCapabilityAttr>(Attr)) {
1966 if (A->args_size() == 0)
1967 return;
1968 getMutexIDs(A->isShared() ? SharedLocksAcquired
1969 : ExclusiveLocksAcquired,
1970 A, nullptr, D);
1971 CapDiagKind = ClassifyDiagnostic(A);
1972 } else if (isa<ExclusiveTrylockFunctionAttr>(Attr)) {
1973 // Don't try to check trylock functions for now
1974 return;
1975 } else if (isa<SharedTrylockFunctionAttr>(Attr)) {
1976 // Don't try to check trylock functions for now
1977 return;
1978 }
1979 }
1980
1981 // FIXME -- Loc can be wrong here.
1982 for (const auto &Mu : ExclusiveLocksToAdd)
1983 addLock(InitialLockset,
1984 llvm::make_unique<LockableFactEntry>(Mu, LK_Exclusive, Loc),
1985 CapDiagKind, true);
1986 for (const auto &Mu : SharedLocksToAdd)
1987 addLock(InitialLockset,
1988 llvm::make_unique<LockableFactEntry>(Mu, LK_Shared, Loc),
1989 CapDiagKind, true);
1990 }
1991
1992 for (const auto *CurrBlock : *SortedGraph) {
1993 int CurrBlockID = CurrBlock->getBlockID();
1994 CFGBlockInfo *CurrBlockInfo = &BlockInfo[CurrBlockID];
1995
1996 // Use the default initial lockset in case there are no predecessors.
1997 VisitedBlocks.insert(CurrBlock);
1998
1999 // Iterate through the predecessor blocks and warn if the lockset for all
2000 // predecessors is not the same. We take the entry lockset of the current
2001 // block to be the intersection of all previous locksets.
2002 // FIXME: By keeping the intersection, we may output more errors in future
2003 // for a lock which is not in the intersection, but was in the union. We
2004 // may want to also keep the union in future. As an example, let's say
2005 // the intersection contains Mutex L, and the union contains L and M.
2006 // Later we unlock M. At this point, we would output an error because we
2007 // never locked M; although the real error is probably that we forgot to
2008 // lock M on all code paths. Conversely, let's say that later we lock M.
2009 // In this case, we should compare against the intersection instead of the
2010 // union because the real error is probably that we forgot to unlock M on
2011 // all code paths.
2012 bool LocksetInitialized = false;
2013 SmallVector<CFGBlock *, 8> SpecialBlocks;
2014 for (CFGBlock::const_pred_iterator PI = CurrBlock->pred_begin(),
2015 PE = CurrBlock->pred_end(); PI != PE; ++PI) {
2016
2017 // if *PI -> CurrBlock is a back edge
2018 if (*PI == nullptr || !VisitedBlocks.alreadySet(*PI))
2019 continue;
2020
2021 int PrevBlockID = (*PI)->getBlockID();
2022 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2023
2024 // Ignore edges from blocks that can't return.
2025 if (neverReturns(*PI) || !PrevBlockInfo->Reachable)
2026 continue;
2027
2028 // Okay, we can reach this block from the entry.
2029 CurrBlockInfo->Reachable = true;
2030
2031 // If the previous block ended in a 'continue' or 'break' statement, then
2032 // a difference in locksets is probably due to a bug in that block, rather
2033 // than in some other predecessor. In that case, keep the other
2034 // predecessor's lockset.
2035 if (const Stmt *Terminator = (*PI)->getTerminator()) {
2036 if (isa<ContinueStmt>(Terminator) || isa<BreakStmt>(Terminator)) {
2037 SpecialBlocks.push_back(*PI);
2038 continue;
2039 }
2040 }
2041
2042 FactSet PrevLockset;
2043 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet, *PI, CurrBlock);
2044
2045 if (!LocksetInitialized) {
2046 CurrBlockInfo->EntrySet = PrevLockset;
2047 LocksetInitialized = true;
2048 } else {
2049 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2050 CurrBlockInfo->EntryLoc,
2051 LEK_LockedSomePredecessors);
2052 }
2053 }
2054
2055 // Skip rest of block if it's not reachable.
2056 if (!CurrBlockInfo->Reachable)
2057 continue;
2058
2059 // Process continue and break blocks. Assume that the lockset for the
2060 // resulting block is unaffected by any discrepancies in them.
2061 for (const auto *PrevBlock : SpecialBlocks) {
2062 int PrevBlockID = PrevBlock->getBlockID();
2063 CFGBlockInfo *PrevBlockInfo = &BlockInfo[PrevBlockID];
2064
2065 if (!LocksetInitialized) {
2066 CurrBlockInfo->EntrySet = PrevBlockInfo->ExitSet;
2067 LocksetInitialized = true;
2068 } else {
2069 // Determine whether this edge is a loop terminator for diagnostic
2070 // purposes. FIXME: A 'break' statement might be a loop terminator, but
2071 // it might also be part of a switch. Also, a subsequent destructor
2072 // might add to the lockset, in which case the real issue might be a
2073 // double lock on the other path.
2074 const Stmt *Terminator = PrevBlock->getTerminator();
2075 bool IsLoop = Terminator && isa<ContinueStmt>(Terminator);
2076
2077 FactSet PrevLockset;
2078 getEdgeLockset(PrevLockset, PrevBlockInfo->ExitSet,
2079 PrevBlock, CurrBlock);
2080
2081 // Do not update EntrySet.
2082 intersectAndWarn(CurrBlockInfo->EntrySet, PrevLockset,
2083 PrevBlockInfo->ExitLoc,
2084 IsLoop ? LEK_LockedSomeLoopIterations
2085 : LEK_LockedSomePredecessors,
2086 false);
2087 }
2088 }
2089
2090 BuildLockset LocksetBuilder(this, *CurrBlockInfo);
2091
2092 // Visit all the statements in the basic block.
2093 for (CFGBlock::const_iterator BI = CurrBlock->begin(),
2094 BE = CurrBlock->end(); BI != BE; ++BI) {
2095 switch (BI->getKind()) {
2096 case CFGElement::Statement: {
2097 CFGStmt CS = BI->castAs<CFGStmt>();
2098 LocksetBuilder.Visit(const_cast<Stmt*>(CS.getStmt()));
2099 break;
2100 }
2101 // Ignore BaseDtor, MemberDtor, and TemporaryDtor for now.
2102 case CFGElement::AutomaticObjectDtor: {
2103 CFGAutomaticObjDtor AD = BI->castAs<CFGAutomaticObjDtor>();
2104 CXXDestructorDecl *DD = const_cast<CXXDestructorDecl *>(
2105 AD.getDestructorDecl(AC.getASTContext()));
2106 if (!DD->hasAttrs())
2107 break;
2108
2109 // Create a dummy expression,
2110 VarDecl *VD = const_cast<VarDecl*>(AD.getVarDecl());
2111 DeclRefExpr DRE(VD, false, VD->getType().getNonReferenceType(),
2112 VK_LValue, AD.getTriggerStmt()->getLocEnd());
2113 LocksetBuilder.handleCall(&DRE, DD);
2114 break;
2115 }
2116 default:
2117 break;
2118 }
2119 }
2120 CurrBlockInfo->ExitSet = LocksetBuilder.FSet;
2121
2122 // For every back edge from CurrBlock (the end of the loop) to another block
2123 // (FirstLoopBlock) we need to check that the Lockset of Block is equal to
2124 // the one held at the beginning of FirstLoopBlock. We can look up the
2125 // Lockset held at the beginning of FirstLoopBlock in the EntryLockSets map.
2126 for (CFGBlock::const_succ_iterator SI = CurrBlock->succ_begin(),
2127 SE = CurrBlock->succ_end(); SI != SE; ++SI) {
2128
2129 // if CurrBlock -> *SI is *not* a back edge
2130 if (*SI == nullptr || !VisitedBlocks.alreadySet(*SI))
2131 continue;
2132
2133 CFGBlock *FirstLoopBlock = *SI;
2134 CFGBlockInfo *PreLoop = &BlockInfo[FirstLoopBlock->getBlockID()];
2135 CFGBlockInfo *LoopEnd = &BlockInfo[CurrBlockID];
2136 intersectAndWarn(LoopEnd->ExitSet, PreLoop->EntrySet,
2137 PreLoop->EntryLoc,
2138 LEK_LockedSomeLoopIterations,
2139 false);
2140 }
2141 }
2142
2143 CFGBlockInfo *Initial = &BlockInfo[CFGraph->getEntry().getBlockID()];
2144 CFGBlockInfo *Final = &BlockInfo[CFGraph->getExit().getBlockID()];
2145
2146 // Skip the final check if the exit block is unreachable.
2147 if (!Final->Reachable)
2148 return;
2149
2150 // By default, we expect all locks held on entry to be held on exit.
2151 FactSet ExpectedExitSet = Initial->EntrySet;
2152
2153 // Adjust the expected exit set by adding or removing locks, as declared
2154 // by *-LOCK_FUNCTION and UNLOCK_FUNCTION. The intersect below will then
2155 // issue the appropriate warning.
2156 // FIXME: the location here is not quite right.
2157 for (const auto &Lock : ExclusiveLocksAcquired)
2158 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2159 Lock, LK_Exclusive, D->getLocation()));
2160 for (const auto &Lock : SharedLocksAcquired)
2161 ExpectedExitSet.addLock(FactMan, llvm::make_unique<LockableFactEntry>(
2162 Lock, LK_Shared, D->getLocation()));
2163 for (const auto &Lock : LocksReleased)
2164 ExpectedExitSet.removeLock(FactMan, Lock);
2165
2166 // FIXME: Should we call this function for all blocks which exit the function?
2167 intersectAndWarn(ExpectedExitSet, Final->ExitSet,
2168 Final->ExitLoc,
2169 LEK_LockedAtEndOfFunction,
2170 LEK_NotLockedAtEndOfFunction,
2171 false);
2172
2173 Handler.leaveFunction(CurrentFunction);
2174 }
2175
2176
2177 /// \brief Check a function's CFG for thread-safety violations.
2178 ///
2179 /// We traverse the blocks in the CFG, compute the set of mutexes that are held
2180 /// at the end of each block, and issue warnings for thread safety violations.
2181 /// Each block in the CFG is traversed exactly once.
runThreadSafetyAnalysis(AnalysisDeclContext & AC,ThreadSafetyHandler & Handler)2182 void runThreadSafetyAnalysis(AnalysisDeclContext &AC,
2183 ThreadSafetyHandler &Handler) {
2184 ThreadSafetyAnalyzer Analyzer(Handler);
2185 Analyzer.runAnalysis(AC);
2186 }
2187
2188 /// \brief Helper function that returns a LockKind required for the given level
2189 /// of access.
getLockKindFromAccessKind(AccessKind AK)2190 LockKind getLockKindFromAccessKind(AccessKind AK) {
2191 switch (AK) {
2192 case AK_Read :
2193 return LK_Shared;
2194 case AK_Written :
2195 return LK_Exclusive;
2196 }
2197 llvm_unreachable("Unknown AccessKind");
2198 }
2199
2200 }} // end namespace clang::threadSafety
2201