1 //===--- Transforms.cpp - Transformations to ARC mode ---------------------===//
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 #include "Transforms.h"
10 #include "Internals.h"
11 #include "clang/ARCMigrate/ARCMT.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/AST/RecursiveASTVisitor.h"
14 #include "clang/Analysis/DomainSpecific/CocoaConventions.h"
15 #include "clang/Basic/SourceManager.h"
16 #include "clang/Basic/TargetInfo.h"
17 #include "clang/Lex/Lexer.h"
18 #include "clang/Lex/Preprocessor.h"
19 #include "clang/Sema/Sema.h"
20
21 using namespace clang;
22 using namespace arcmt;
23 using namespace trans;
24
~ASTTraverser()25 ASTTraverser::~ASTTraverser() { }
26
CFBridgingFunctionsDefined()27 bool MigrationPass::CFBridgingFunctionsDefined() {
28 if (!EnableCFBridgeFns)
29 EnableCFBridgeFns = SemaRef.isKnownName("CFBridgingRetain") &&
30 SemaRef.isKnownName("CFBridgingRelease");
31 return *EnableCFBridgeFns;
32 }
33
34 //===----------------------------------------------------------------------===//
35 // Helpers.
36 //===----------------------------------------------------------------------===//
37
canApplyWeak(ASTContext & Ctx,QualType type,bool AllowOnUnknownClass)38 bool trans::canApplyWeak(ASTContext &Ctx, QualType type,
39 bool AllowOnUnknownClass) {
40 if (!Ctx.getLangOpts().ObjCWeakRuntime)
41 return false;
42
43 QualType T = type;
44 if (T.isNull())
45 return false;
46
47 // iOS is always safe to use 'weak'.
48 if (Ctx.getTargetInfo().getTriple().isiOS() ||
49 Ctx.getTargetInfo().getTriple().isWatchOS())
50 AllowOnUnknownClass = true;
51
52 while (const PointerType *ptr = T->getAs<PointerType>())
53 T = ptr->getPointeeType();
54 if (const ObjCObjectPointerType *ObjT = T->getAs<ObjCObjectPointerType>()) {
55 ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
56 if (!AllowOnUnknownClass && (!Class || Class->getName() == "NSObject"))
57 return false; // id/NSObject is not safe for weak.
58 if (!AllowOnUnknownClass && !Class->hasDefinition())
59 return false; // forward classes are not verifiable, therefore not safe.
60 if (Class && Class->isArcWeakrefUnavailable())
61 return false;
62 }
63
64 return true;
65 }
66
isPlusOneAssign(const BinaryOperator * E)67 bool trans::isPlusOneAssign(const BinaryOperator *E) {
68 if (E->getOpcode() != BO_Assign)
69 return false;
70
71 return isPlusOne(E->getRHS());
72 }
73
isPlusOne(const Expr * E)74 bool trans::isPlusOne(const Expr *E) {
75 if (!E)
76 return false;
77 if (const FullExpr *FE = dyn_cast<FullExpr>(E))
78 E = FE->getSubExpr();
79
80 if (const ObjCMessageExpr *
81 ME = dyn_cast<ObjCMessageExpr>(E->IgnoreParenCasts()))
82 if (ME->getMethodFamily() == OMF_retain)
83 return true;
84
85 if (const CallExpr *
86 callE = dyn_cast<CallExpr>(E->IgnoreParenCasts())) {
87 if (const FunctionDecl *FD = callE->getDirectCallee()) {
88 if (FD->hasAttr<CFReturnsRetainedAttr>())
89 return true;
90
91 if (FD->isGlobal() &&
92 FD->getIdentifier() &&
93 FD->getParent()->isTranslationUnit() &&
94 FD->isExternallyVisible() &&
95 ento::cocoa::isRefType(callE->getType(), "CF",
96 FD->getIdentifier()->getName())) {
97 StringRef fname = FD->getIdentifier()->getName();
98 if (fname.endswith("Retain") || fname.contains("Create") ||
99 fname.contains("Copy"))
100 return true;
101 }
102 }
103 }
104
105 const ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(E);
106 while (implCE && implCE->getCastKind() == CK_BitCast)
107 implCE = dyn_cast<ImplicitCastExpr>(implCE->getSubExpr());
108
109 return implCE && implCE->getCastKind() == CK_ARCConsumeObject;
110 }
111
112 /// 'Loc' is the end of a statement range. This returns the location
113 /// immediately after the semicolon following the statement.
114 /// If no semicolon is found or the location is inside a macro, the returned
115 /// source location will be invalid.
findLocationAfterSemi(SourceLocation loc,ASTContext & Ctx,bool IsDecl)116 SourceLocation trans::findLocationAfterSemi(SourceLocation loc,
117 ASTContext &Ctx, bool IsDecl) {
118 SourceLocation SemiLoc = findSemiAfterLocation(loc, Ctx, IsDecl);
119 if (SemiLoc.isInvalid())
120 return SourceLocation();
121 return SemiLoc.getLocWithOffset(1);
122 }
123
124 /// \arg Loc is the end of a statement range. This returns the location
125 /// of the semicolon following the statement.
126 /// If no semicolon is found or the location is inside a macro, the returned
127 /// source location will be invalid.
findSemiAfterLocation(SourceLocation loc,ASTContext & Ctx,bool IsDecl)128 SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
129 ASTContext &Ctx,
130 bool IsDecl) {
131 SourceManager &SM = Ctx.getSourceManager();
132 if (loc.isMacroID()) {
133 if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOpts(), &loc))
134 return SourceLocation();
135 }
136 loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOpts());
137
138 // Break down the source location.
139 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);
140
141 // Try to load the file buffer.
142 bool invalidTemp = false;
143 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
144 if (invalidTemp)
145 return SourceLocation();
146
147 const char *tokenBegin = file.data() + locInfo.second;
148
149 // Lex from the start of the given location.
150 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
151 Ctx.getLangOpts(),
152 file.begin(), tokenBegin, file.end());
153 Token tok;
154 lexer.LexFromRawLexer(tok);
155 if (tok.isNot(tok::semi)) {
156 if (!IsDecl)
157 return SourceLocation();
158 // Declaration may be followed with other tokens; such as an __attribute,
159 // before ending with a semicolon.
160 return findSemiAfterLocation(tok.getLocation(), Ctx, /*IsDecl*/true);
161 }
162
163 return tok.getLocation();
164 }
165
hasSideEffects(Expr * E,ASTContext & Ctx)166 bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
167 if (!E || !E->HasSideEffects(Ctx))
168 return false;
169
170 E = E->IgnoreParenCasts();
171 ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
172 if (!ME)
173 return true;
174 switch (ME->getMethodFamily()) {
175 case OMF_autorelease:
176 case OMF_dealloc:
177 case OMF_release:
178 case OMF_retain:
179 switch (ME->getReceiverKind()) {
180 case ObjCMessageExpr::SuperInstance:
181 return false;
182 case ObjCMessageExpr::Instance:
183 return hasSideEffects(ME->getInstanceReceiver(), Ctx);
184 default:
185 break;
186 }
187 break;
188 default:
189 break;
190 }
191
192 return true;
193 }
194
isGlobalVar(Expr * E)195 bool trans::isGlobalVar(Expr *E) {
196 E = E->IgnoreParenCasts();
197 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
198 return DRE->getDecl()->getDeclContext()->isFileContext() &&
199 DRE->getDecl()->isExternallyVisible();
200 if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
201 return isGlobalVar(condOp->getTrueExpr()) &&
202 isGlobalVar(condOp->getFalseExpr());
203
204 return false;
205 }
206
getNilString(MigrationPass & Pass)207 StringRef trans::getNilString(MigrationPass &Pass) {
208 return Pass.SemaRef.PP.isMacroDefined("nil") ? "nil" : "0";
209 }
210
211 namespace {
212
213 class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
214 ExprSet &Refs;
215 public:
ReferenceClear(ExprSet & refs)216 ReferenceClear(ExprSet &refs) : Refs(refs) { }
VisitDeclRefExpr(DeclRefExpr * E)217 bool VisitDeclRefExpr(DeclRefExpr *E) { Refs.erase(E); return true; }
218 };
219
220 class ReferenceCollector : public RecursiveASTVisitor<ReferenceCollector> {
221 ValueDecl *Dcl;
222 ExprSet &Refs;
223
224 public:
ReferenceCollector(ValueDecl * D,ExprSet & refs)225 ReferenceCollector(ValueDecl *D, ExprSet &refs)
226 : Dcl(D), Refs(refs) { }
227
VisitDeclRefExpr(DeclRefExpr * E)228 bool VisitDeclRefExpr(DeclRefExpr *E) {
229 if (E->getDecl() == Dcl)
230 Refs.insert(E);
231 return true;
232 }
233 };
234
235 class RemovablesCollector : public RecursiveASTVisitor<RemovablesCollector> {
236 ExprSet &Removables;
237
238 public:
RemovablesCollector(ExprSet & removables)239 RemovablesCollector(ExprSet &removables)
240 : Removables(removables) { }
241
shouldWalkTypesOfTypeLocs() const242 bool shouldWalkTypesOfTypeLocs() const { return false; }
243
TraverseStmtExpr(StmtExpr * E)244 bool TraverseStmtExpr(StmtExpr *E) {
245 CompoundStmt *S = E->getSubStmt();
246 for (CompoundStmt::body_iterator
247 I = S->body_begin(), E = S->body_end(); I != E; ++I) {
248 if (I != E - 1)
249 mark(*I);
250 TraverseStmt(*I);
251 }
252 return true;
253 }
254
VisitCompoundStmt(CompoundStmt * S)255 bool VisitCompoundStmt(CompoundStmt *S) {
256 for (auto *I : S->body())
257 mark(I);
258 return true;
259 }
260
VisitIfStmt(IfStmt * S)261 bool VisitIfStmt(IfStmt *S) {
262 mark(S->getThen());
263 mark(S->getElse());
264 return true;
265 }
266
VisitWhileStmt(WhileStmt * S)267 bool VisitWhileStmt(WhileStmt *S) {
268 mark(S->getBody());
269 return true;
270 }
271
VisitDoStmt(DoStmt * S)272 bool VisitDoStmt(DoStmt *S) {
273 mark(S->getBody());
274 return true;
275 }
276
VisitForStmt(ForStmt * S)277 bool VisitForStmt(ForStmt *S) {
278 mark(S->getInit());
279 mark(S->getInc());
280 mark(S->getBody());
281 return true;
282 }
283
284 private:
mark(Stmt * S)285 void mark(Stmt *S) {
286 if (!S) return;
287
288 while (auto *Label = dyn_cast<LabelStmt>(S))
289 S = Label->getSubStmt();
290 if (auto *E = dyn_cast<Expr>(S))
291 S = E->IgnoreImplicit();
292 if (auto *E = dyn_cast<Expr>(S))
293 Removables.insert(E);
294 }
295 };
296
297 } // end anonymous namespace
298
clearRefsIn(Stmt * S,ExprSet & refs)299 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
300 ReferenceClear(refs).TraverseStmt(S);
301 }
302
collectRefs(ValueDecl * D,Stmt * S,ExprSet & refs)303 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
304 ReferenceCollector(D, refs).TraverseStmt(S);
305 }
306
collectRemovables(Stmt * S,ExprSet & exprs)307 void trans::collectRemovables(Stmt *S, ExprSet &exprs) {
308 RemovablesCollector(exprs).TraverseStmt(S);
309 }
310
311 //===----------------------------------------------------------------------===//
312 // MigrationContext
313 //===----------------------------------------------------------------------===//
314
315 namespace {
316
317 class ASTTransform : public RecursiveASTVisitor<ASTTransform> {
318 MigrationContext &MigrateCtx;
319 typedef RecursiveASTVisitor<ASTTransform> base;
320
321 public:
ASTTransform(MigrationContext & MigrateCtx)322 ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
323
shouldWalkTypesOfTypeLocs() const324 bool shouldWalkTypesOfTypeLocs() const { return false; }
325
TraverseObjCImplementationDecl(ObjCImplementationDecl * D)326 bool TraverseObjCImplementationDecl(ObjCImplementationDecl *D) {
327 ObjCImplementationContext ImplCtx(MigrateCtx, D);
328 for (MigrationContext::traverser_iterator
329 I = MigrateCtx.traversers_begin(),
330 E = MigrateCtx.traversers_end(); I != E; ++I)
331 (*I)->traverseObjCImplementation(ImplCtx);
332
333 return base::TraverseObjCImplementationDecl(D);
334 }
335
TraverseStmt(Stmt * rootS)336 bool TraverseStmt(Stmt *rootS) {
337 if (!rootS)
338 return true;
339
340 BodyContext BodyCtx(MigrateCtx, rootS);
341 for (MigrationContext::traverser_iterator
342 I = MigrateCtx.traversers_begin(),
343 E = MigrateCtx.traversers_end(); I != E; ++I)
344 (*I)->traverseBody(BodyCtx);
345
346 return true;
347 }
348 };
349
350 }
351
~MigrationContext()352 MigrationContext::~MigrationContext() {
353 for (traverser_iterator
354 I = traversers_begin(), E = traversers_end(); I != E; ++I)
355 delete *I;
356 }
357
isGCOwnedNonObjC(QualType T)358 bool MigrationContext::isGCOwnedNonObjC(QualType T) {
359 while (!T.isNull()) {
360 if (const AttributedType *AttrT = T->getAs<AttributedType>()) {
361 if (AttrT->getAttrKind() == attr::ObjCOwnership)
362 return !AttrT->getModifiedType()->isObjCRetainableType();
363 }
364
365 if (T->isArrayType())
366 T = Pass.Ctx.getBaseElementType(T);
367 else if (const PointerType *PT = T->getAs<PointerType>())
368 T = PT->getPointeeType();
369 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
370 T = RT->getPointeeType();
371 else
372 break;
373 }
374
375 return false;
376 }
377
rewritePropertyAttribute(StringRef fromAttr,StringRef toAttr,SourceLocation atLoc)378 bool MigrationContext::rewritePropertyAttribute(StringRef fromAttr,
379 StringRef toAttr,
380 SourceLocation atLoc) {
381 if (atLoc.isMacroID())
382 return false;
383
384 SourceManager &SM = Pass.Ctx.getSourceManager();
385
386 // Break down the source location.
387 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
388
389 // Try to load the file buffer.
390 bool invalidTemp = false;
391 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
392 if (invalidTemp)
393 return false;
394
395 const char *tokenBegin = file.data() + locInfo.second;
396
397 // Lex from the start of the given location.
398 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
399 Pass.Ctx.getLangOpts(),
400 file.begin(), tokenBegin, file.end());
401 Token tok;
402 lexer.LexFromRawLexer(tok);
403 if (tok.isNot(tok::at)) return false;
404 lexer.LexFromRawLexer(tok);
405 if (tok.isNot(tok::raw_identifier)) return false;
406 if (tok.getRawIdentifier() != "property")
407 return false;
408 lexer.LexFromRawLexer(tok);
409 if (tok.isNot(tok::l_paren)) return false;
410
411 Token BeforeTok = tok;
412 Token AfterTok;
413 AfterTok.startToken();
414 SourceLocation AttrLoc;
415
416 lexer.LexFromRawLexer(tok);
417 if (tok.is(tok::r_paren))
418 return false;
419
420 while (true) {
421 if (tok.isNot(tok::raw_identifier)) return false;
422 if (tok.getRawIdentifier() == fromAttr) {
423 if (!toAttr.empty()) {
424 Pass.TA.replaceText(tok.getLocation(), fromAttr, toAttr);
425 return true;
426 }
427 // We want to remove the attribute.
428 AttrLoc = tok.getLocation();
429 }
430
431 do {
432 lexer.LexFromRawLexer(tok);
433 if (AttrLoc.isValid() && AfterTok.is(tok::unknown))
434 AfterTok = tok;
435 } while (tok.isNot(tok::comma) && tok.isNot(tok::r_paren));
436 if (tok.is(tok::r_paren))
437 break;
438 if (AttrLoc.isInvalid())
439 BeforeTok = tok;
440 lexer.LexFromRawLexer(tok);
441 }
442
443 if (toAttr.empty() && AttrLoc.isValid() && AfterTok.isNot(tok::unknown)) {
444 // We want to remove the attribute.
445 if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::r_paren)) {
446 Pass.TA.remove(SourceRange(BeforeTok.getLocation(),
447 AfterTok.getLocation()));
448 } else if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::comma)) {
449 Pass.TA.remove(SourceRange(AttrLoc, AfterTok.getLocation()));
450 } else {
451 Pass.TA.remove(SourceRange(BeforeTok.getLocation(), AttrLoc));
452 }
453
454 return true;
455 }
456
457 return false;
458 }
459
addPropertyAttribute(StringRef attr,SourceLocation atLoc)460 bool MigrationContext::addPropertyAttribute(StringRef attr,
461 SourceLocation atLoc) {
462 if (atLoc.isMacroID())
463 return false;
464
465 SourceManager &SM = Pass.Ctx.getSourceManager();
466
467 // Break down the source location.
468 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
469
470 // Try to load the file buffer.
471 bool invalidTemp = false;
472 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
473 if (invalidTemp)
474 return false;
475
476 const char *tokenBegin = file.data() + locInfo.second;
477
478 // Lex from the start of the given location.
479 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
480 Pass.Ctx.getLangOpts(),
481 file.begin(), tokenBegin, file.end());
482 Token tok;
483 lexer.LexFromRawLexer(tok);
484 if (tok.isNot(tok::at)) return false;
485 lexer.LexFromRawLexer(tok);
486 if (tok.isNot(tok::raw_identifier)) return false;
487 if (tok.getRawIdentifier() != "property")
488 return false;
489 lexer.LexFromRawLexer(tok);
490
491 if (tok.isNot(tok::l_paren)) {
492 Pass.TA.insert(tok.getLocation(), std::string("(") + attr.str() + ") ");
493 return true;
494 }
495
496 lexer.LexFromRawLexer(tok);
497 if (tok.is(tok::r_paren)) {
498 Pass.TA.insert(tok.getLocation(), attr);
499 return true;
500 }
501
502 if (tok.isNot(tok::raw_identifier)) return false;
503
504 Pass.TA.insert(tok.getLocation(), std::string(attr) + ", ");
505 return true;
506 }
507
traverse(TranslationUnitDecl * TU)508 void MigrationContext::traverse(TranslationUnitDecl *TU) {
509 for (traverser_iterator
510 I = traversers_begin(), E = traversers_end(); I != E; ++I)
511 (*I)->traverseTU(*this);
512
513 ASTTransform(*this).TraverseDecl(TU);
514 }
515
GCRewriteFinalize(MigrationPass & pass)516 static void GCRewriteFinalize(MigrationPass &pass) {
517 ASTContext &Ctx = pass.Ctx;
518 TransformActions &TA = pass.TA;
519 DeclContext *DC = Ctx.getTranslationUnitDecl();
520 Selector FinalizeSel =
521 Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize"));
522
523 typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl>
524 impl_iterator;
525 for (impl_iterator I = impl_iterator(DC->decls_begin()),
526 E = impl_iterator(DC->decls_end()); I != E; ++I) {
527 for (const auto *MD : I->instance_methods()) {
528 if (!MD->hasBody())
529 continue;
530
531 if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) {
532 const ObjCMethodDecl *FinalizeM = MD;
533 Transaction Trans(TA);
534 TA.insert(FinalizeM->getSourceRange().getBegin(),
535 "#if !__has_feature(objc_arc)\n");
536 CharSourceRange::getTokenRange(FinalizeM->getSourceRange());
537 const SourceManager &SM = pass.Ctx.getSourceManager();
538 const LangOptions &LangOpts = pass.Ctx.getLangOpts();
539 bool Invalid;
540 std::string str = "\n#endif\n";
541 str += Lexer::getSourceText(
542 CharSourceRange::getTokenRange(FinalizeM->getSourceRange()),
543 SM, LangOpts, &Invalid);
544 TA.insertAfterToken(FinalizeM->getSourceRange().getEnd(), str);
545
546 break;
547 }
548 }
549 }
550 }
551
552 //===----------------------------------------------------------------------===//
553 // getAllTransformations.
554 //===----------------------------------------------------------------------===//
555
traverseAST(MigrationPass & pass)556 static void traverseAST(MigrationPass &pass) {
557 MigrationContext MigrateCtx(pass);
558
559 if (pass.isGCMigration()) {
560 MigrateCtx.addTraverser(new GCCollectableCallsTraverser);
561 MigrateCtx.addTraverser(new GCAttrsTraverser());
562 }
563 MigrateCtx.addTraverser(new PropertyRewriteTraverser());
564 MigrateCtx.addTraverser(new BlockObjCVariableTraverser());
565 MigrateCtx.addTraverser(new ProtectedScopeTraverser());
566
567 MigrateCtx.traverse(pass.Ctx.getTranslationUnitDecl());
568 }
569
independentTransforms(MigrationPass & pass)570 static void independentTransforms(MigrationPass &pass) {
571 rewriteAutoreleasePool(pass);
572 removeRetainReleaseDeallocFinalize(pass);
573 rewriteUnusedInitDelegate(pass);
574 removeZeroOutPropsInDeallocFinalize(pass);
575 makeAssignARCSafe(pass);
576 rewriteUnbridgedCasts(pass);
577 checkAPIUses(pass);
578 traverseAST(pass);
579 }
580
getAllTransformations(LangOptions::GCMode OrigGCMode,bool NoFinalizeRemoval)581 std::vector<TransformFn> arcmt::getAllTransformations(
582 LangOptions::GCMode OrigGCMode,
583 bool NoFinalizeRemoval) {
584 std::vector<TransformFn> transforms;
585
586 if (OrigGCMode == LangOptions::GCOnly && NoFinalizeRemoval)
587 transforms.push_back(GCRewriteFinalize);
588 transforms.push_back(independentTransforms);
589 // This depends on previous transformations removing various expressions.
590 transforms.push_back(removeEmptyStatementsAndDeallocFinalize);
591
592 return transforms;
593 }
594