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 #include "clang/Sema/SemaObjC.h"
21
22 using namespace clang;
23 using namespace arcmt;
24 using namespace trans;
25
~ASTTraverser()26 ASTTraverser::~ASTTraverser() { }
27
CFBridgingFunctionsDefined()28 bool MigrationPass::CFBridgingFunctionsDefined() {
29 if (!EnableCFBridgeFns)
30 EnableCFBridgeFns = SemaRef.ObjC().isKnownName("CFBridgingRetain") &&
31 SemaRef.ObjC().isKnownName("CFBridgingRelease");
32 return *EnableCFBridgeFns;
33 }
34
35 //===----------------------------------------------------------------------===//
36 // Helpers.
37 //===----------------------------------------------------------------------===//
38
canApplyWeak(ASTContext & Ctx,QualType type,bool AllowOnUnknownClass)39 bool trans::canApplyWeak(ASTContext &Ctx, QualType type,
40 bool AllowOnUnknownClass) {
41 if (!Ctx.getLangOpts().ObjCWeakRuntime)
42 return false;
43
44 QualType T = type;
45 if (T.isNull())
46 return false;
47
48 // iOS is always safe to use 'weak'.
49 if (Ctx.getTargetInfo().getTriple().isiOS() ||
50 Ctx.getTargetInfo().getTriple().isWatchOS())
51 AllowOnUnknownClass = true;
52
53 while (const PointerType *ptr = T->getAs<PointerType>())
54 T = ptr->getPointeeType();
55 if (const ObjCObjectPointerType *ObjT = T->getAs<ObjCObjectPointerType>()) {
56 ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
57 if (!AllowOnUnknownClass && (!Class || Class->getName() == "NSObject"))
58 return false; // id/NSObject is not safe for weak.
59 if (!AllowOnUnknownClass && !Class->hasDefinition())
60 return false; // forward classes are not verifiable, therefore not safe.
61 if (Class && Class->isArcWeakrefUnavailable())
62 return false;
63 }
64
65 return true;
66 }
67
isPlusOneAssign(const BinaryOperator * E)68 bool trans::isPlusOneAssign(const BinaryOperator *E) {
69 if (E->getOpcode() != BO_Assign)
70 return false;
71
72 return isPlusOne(E->getRHS());
73 }
74
isPlusOne(const Expr * E)75 bool trans::isPlusOne(const Expr *E) {
76 if (!E)
77 return false;
78 if (const FullExpr *FE = dyn_cast<FullExpr>(E))
79 E = FE->getSubExpr();
80
81 if (const ObjCMessageExpr *
82 ME = dyn_cast<ObjCMessageExpr>(E->IgnoreParenCasts()))
83 if (ME->getMethodFamily() == OMF_retain)
84 return true;
85
86 if (const CallExpr *
87 callE = dyn_cast<CallExpr>(E->IgnoreParenCasts())) {
88 if (const FunctionDecl *FD = callE->getDirectCallee()) {
89 if (FD->hasAttr<CFReturnsRetainedAttr>())
90 return true;
91
92 if (FD->isGlobal() &&
93 FD->getIdentifier() &&
94 FD->getParent()->isTranslationUnit() &&
95 FD->isExternallyVisible() &&
96 ento::cocoa::isRefType(callE->getType(), "CF",
97 FD->getIdentifier()->getName())) {
98 StringRef fname = FD->getIdentifier()->getName();
99 if (fname.ends_with("Retain") || fname.contains("Create") ||
100 fname.contains("Copy"))
101 return true;
102 }
103 }
104 }
105
106 const ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(E);
107 while (implCE && implCE->getCastKind() == CK_BitCast)
108 implCE = dyn_cast<ImplicitCastExpr>(implCE->getSubExpr());
109
110 return implCE && implCE->getCastKind() == CK_ARCConsumeObject;
111 }
112
113 /// 'Loc' is the end of a statement range. This returns the location
114 /// immediately after the semicolon following the statement.
115 /// If no semicolon is found or the location is inside a macro, the returned
116 /// source location will be invalid.
findLocationAfterSemi(SourceLocation loc,ASTContext & Ctx,bool IsDecl)117 SourceLocation trans::findLocationAfterSemi(SourceLocation loc,
118 ASTContext &Ctx, bool IsDecl) {
119 SourceLocation SemiLoc = findSemiAfterLocation(loc, Ctx, IsDecl);
120 if (SemiLoc.isInvalid())
121 return SourceLocation();
122 return SemiLoc.getLocWithOffset(1);
123 }
124
125 /// \arg Loc is the end of a statement range. This returns the location
126 /// of the semicolon following the statement.
127 /// If no semicolon is found or the location is inside a macro, the returned
128 /// source location will be invalid.
findSemiAfterLocation(SourceLocation loc,ASTContext & Ctx,bool IsDecl)129 SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
130 ASTContext &Ctx,
131 bool IsDecl) {
132 SourceManager &SM = Ctx.getSourceManager();
133 if (loc.isMacroID()) {
134 if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOpts(), &loc))
135 return SourceLocation();
136 }
137 loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOpts());
138
139 // Break down the source location.
140 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);
141
142 // Try to load the file buffer.
143 bool invalidTemp = false;
144 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
145 if (invalidTemp)
146 return SourceLocation();
147
148 const char *tokenBegin = file.data() + locInfo.second;
149
150 // Lex from the start of the given location.
151 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
152 Ctx.getLangOpts(),
153 file.begin(), tokenBegin, file.end());
154 Token tok;
155 lexer.LexFromRawLexer(tok);
156 if (tok.isNot(tok::semi)) {
157 if (!IsDecl)
158 return SourceLocation();
159 // Declaration may be followed with other tokens; such as an __attribute,
160 // before ending with a semicolon.
161 return findSemiAfterLocation(tok.getLocation(), Ctx, /*IsDecl*/true);
162 }
163
164 return tok.getLocation();
165 }
166
hasSideEffects(Expr * E,ASTContext & Ctx)167 bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
168 if (!E || !E->HasSideEffects(Ctx))
169 return false;
170
171 E = E->IgnoreParenCasts();
172 ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
173 if (!ME)
174 return true;
175 switch (ME->getMethodFamily()) {
176 case OMF_autorelease:
177 case OMF_dealloc:
178 case OMF_release:
179 case OMF_retain:
180 switch (ME->getReceiverKind()) {
181 case ObjCMessageExpr::SuperInstance:
182 return false;
183 case ObjCMessageExpr::Instance:
184 return hasSideEffects(ME->getInstanceReceiver(), Ctx);
185 default:
186 break;
187 }
188 break;
189 default:
190 break;
191 }
192
193 return true;
194 }
195
isGlobalVar(Expr * E)196 bool trans::isGlobalVar(Expr *E) {
197 E = E->IgnoreParenCasts();
198 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
199 return DRE->getDecl()->getDeclContext()->isFileContext() &&
200 DRE->getDecl()->isExternallyVisible();
201 if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
202 return isGlobalVar(condOp->getTrueExpr()) &&
203 isGlobalVar(condOp->getFalseExpr());
204
205 return false;
206 }
207
getNilString(MigrationPass & Pass)208 StringRef trans::getNilString(MigrationPass &Pass) {
209 return Pass.SemaRef.PP.isMacroDefined("nil") ? "nil" : "0";
210 }
211
212 namespace {
213
214 class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
215 ExprSet &Refs;
216 public:
ReferenceClear(ExprSet & refs)217 ReferenceClear(ExprSet &refs) : Refs(refs) { }
VisitDeclRefExpr(DeclRefExpr * E)218 bool VisitDeclRefExpr(DeclRefExpr *E) { Refs.erase(E); return true; }
219 };
220
221 class ReferenceCollector : public RecursiveASTVisitor<ReferenceCollector> {
222 ValueDecl *Dcl;
223 ExprSet &Refs;
224
225 public:
ReferenceCollector(ValueDecl * D,ExprSet & refs)226 ReferenceCollector(ValueDecl *D, ExprSet &refs)
227 : Dcl(D), Refs(refs) { }
228
VisitDeclRefExpr(DeclRefExpr * E)229 bool VisitDeclRefExpr(DeclRefExpr *E) {
230 if (E->getDecl() == Dcl)
231 Refs.insert(E);
232 return true;
233 }
234 };
235
236 class RemovablesCollector : public RecursiveASTVisitor<RemovablesCollector> {
237 ExprSet &Removables;
238
239 public:
RemovablesCollector(ExprSet & removables)240 RemovablesCollector(ExprSet &removables)
241 : Removables(removables) { }
242
shouldWalkTypesOfTypeLocs() const243 bool shouldWalkTypesOfTypeLocs() const { return false; }
244
TraverseStmtExpr(StmtExpr * E)245 bool TraverseStmtExpr(StmtExpr *E) {
246 CompoundStmt *S = E->getSubStmt();
247 for (CompoundStmt::body_iterator
248 I = S->body_begin(), E = S->body_end(); I != E; ++I) {
249 if (I != E - 1)
250 mark(*I);
251 TraverseStmt(*I);
252 }
253 return true;
254 }
255
VisitCompoundStmt(CompoundStmt * S)256 bool VisitCompoundStmt(CompoundStmt *S) {
257 for (auto *I : S->body())
258 mark(I);
259 return true;
260 }
261
VisitIfStmt(IfStmt * S)262 bool VisitIfStmt(IfStmt *S) {
263 mark(S->getThen());
264 mark(S->getElse());
265 return true;
266 }
267
VisitWhileStmt(WhileStmt * S)268 bool VisitWhileStmt(WhileStmt *S) {
269 mark(S->getBody());
270 return true;
271 }
272
VisitDoStmt(DoStmt * S)273 bool VisitDoStmt(DoStmt *S) {
274 mark(S->getBody());
275 return true;
276 }
277
VisitForStmt(ForStmt * S)278 bool VisitForStmt(ForStmt *S) {
279 mark(S->getInit());
280 mark(S->getInc());
281 mark(S->getBody());
282 return true;
283 }
284
285 private:
mark(Stmt * S)286 void mark(Stmt *S) {
287 if (!S) return;
288
289 while (auto *Label = dyn_cast<LabelStmt>(S))
290 S = Label->getSubStmt();
291 if (auto *E = dyn_cast<Expr>(S))
292 S = E->IgnoreImplicit();
293 if (auto *E = dyn_cast<Expr>(S))
294 Removables.insert(E);
295 }
296 };
297
298 } // end anonymous namespace
299
clearRefsIn(Stmt * S,ExprSet & refs)300 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
301 ReferenceClear(refs).TraverseStmt(S);
302 }
303
collectRefs(ValueDecl * D,Stmt * S,ExprSet & refs)304 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
305 ReferenceCollector(D, refs).TraverseStmt(S);
306 }
307
collectRemovables(Stmt * S,ExprSet & exprs)308 void trans::collectRemovables(Stmt *S, ExprSet &exprs) {
309 RemovablesCollector(exprs).TraverseStmt(S);
310 }
311
312 //===----------------------------------------------------------------------===//
313 // MigrationContext
314 //===----------------------------------------------------------------------===//
315
316 namespace {
317
318 class ASTTransform : public RecursiveASTVisitor<ASTTransform> {
319 MigrationContext &MigrateCtx;
320 typedef RecursiveASTVisitor<ASTTransform> base;
321
322 public:
ASTTransform(MigrationContext & MigrateCtx)323 ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
324
shouldWalkTypesOfTypeLocs() const325 bool shouldWalkTypesOfTypeLocs() const { return false; }
326
TraverseObjCImplementationDecl(ObjCImplementationDecl * D)327 bool TraverseObjCImplementationDecl(ObjCImplementationDecl *D) {
328 ObjCImplementationContext ImplCtx(MigrateCtx, D);
329 for (MigrationContext::traverser_iterator
330 I = MigrateCtx.traversers_begin(),
331 E = MigrateCtx.traversers_end(); I != E; ++I)
332 (*I)->traverseObjCImplementation(ImplCtx);
333
334 return base::TraverseObjCImplementationDecl(D);
335 }
336
TraverseStmt(Stmt * rootS)337 bool TraverseStmt(Stmt *rootS) {
338 if (!rootS)
339 return true;
340
341 BodyContext BodyCtx(MigrateCtx, rootS);
342 for (MigrationContext::traverser_iterator
343 I = MigrateCtx.traversers_begin(),
344 E = MigrateCtx.traversers_end(); I != E; ++I)
345 (*I)->traverseBody(BodyCtx);
346
347 return true;
348 }
349 };
350
351 }
352
~MigrationContext()353 MigrationContext::~MigrationContext() {
354 for (traverser_iterator
355 I = traversers_begin(), E = traversers_end(); I != E; ++I)
356 delete *I;
357 }
358
isGCOwnedNonObjC(QualType T)359 bool MigrationContext::isGCOwnedNonObjC(QualType T) {
360 while (!T.isNull()) {
361 if (const AttributedType *AttrT = T->getAs<AttributedType>()) {
362 if (AttrT->getAttrKind() == attr::ObjCOwnership)
363 return !AttrT->getModifiedType()->isObjCRetainableType();
364 }
365
366 if (T->isArrayType())
367 T = Pass.Ctx.getBaseElementType(T);
368 else if (const PointerType *PT = T->getAs<PointerType>())
369 T = PT->getPointeeType();
370 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
371 T = RT->getPointeeType();
372 else
373 break;
374 }
375
376 return false;
377 }
378
rewritePropertyAttribute(StringRef fromAttr,StringRef toAttr,SourceLocation atLoc)379 bool MigrationContext::rewritePropertyAttribute(StringRef fromAttr,
380 StringRef toAttr,
381 SourceLocation atLoc) {
382 if (atLoc.isMacroID())
383 return false;
384
385 SourceManager &SM = Pass.Ctx.getSourceManager();
386
387 // Break down the source location.
388 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
389
390 // Try to load the file buffer.
391 bool invalidTemp = false;
392 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
393 if (invalidTemp)
394 return false;
395
396 const char *tokenBegin = file.data() + locInfo.second;
397
398 // Lex from the start of the given location.
399 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
400 Pass.Ctx.getLangOpts(),
401 file.begin(), tokenBegin, file.end());
402 Token tok;
403 lexer.LexFromRawLexer(tok);
404 if (tok.isNot(tok::at)) return false;
405 lexer.LexFromRawLexer(tok);
406 if (tok.isNot(tok::raw_identifier)) return false;
407 if (tok.getRawIdentifier() != "property")
408 return false;
409 lexer.LexFromRawLexer(tok);
410 if (tok.isNot(tok::l_paren)) return false;
411
412 Token BeforeTok = tok;
413 Token AfterTok;
414 AfterTok.startToken();
415 SourceLocation AttrLoc;
416
417 lexer.LexFromRawLexer(tok);
418 if (tok.is(tok::r_paren))
419 return false;
420
421 while (true) {
422 if (tok.isNot(tok::raw_identifier)) return false;
423 if (tok.getRawIdentifier() == fromAttr) {
424 if (!toAttr.empty()) {
425 Pass.TA.replaceText(tok.getLocation(), fromAttr, toAttr);
426 return true;
427 }
428 // We want to remove the attribute.
429 AttrLoc = tok.getLocation();
430 }
431
432 do {
433 lexer.LexFromRawLexer(tok);
434 if (AttrLoc.isValid() && AfterTok.is(tok::unknown))
435 AfterTok = tok;
436 } while (tok.isNot(tok::comma) && tok.isNot(tok::r_paren));
437 if (tok.is(tok::r_paren))
438 break;
439 if (AttrLoc.isInvalid())
440 BeforeTok = tok;
441 lexer.LexFromRawLexer(tok);
442 }
443
444 if (toAttr.empty() && AttrLoc.isValid() && AfterTok.isNot(tok::unknown)) {
445 // We want to remove the attribute.
446 if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::r_paren)) {
447 Pass.TA.remove(SourceRange(BeforeTok.getLocation(),
448 AfterTok.getLocation()));
449 } else if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::comma)) {
450 Pass.TA.remove(SourceRange(AttrLoc, AfterTok.getLocation()));
451 } else {
452 Pass.TA.remove(SourceRange(BeforeTok.getLocation(), AttrLoc));
453 }
454
455 return true;
456 }
457
458 return false;
459 }
460
addPropertyAttribute(StringRef attr,SourceLocation atLoc)461 bool MigrationContext::addPropertyAttribute(StringRef attr,
462 SourceLocation atLoc) {
463 if (atLoc.isMacroID())
464 return false;
465
466 SourceManager &SM = Pass.Ctx.getSourceManager();
467
468 // Break down the source location.
469 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
470
471 // Try to load the file buffer.
472 bool invalidTemp = false;
473 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
474 if (invalidTemp)
475 return false;
476
477 const char *tokenBegin = file.data() + locInfo.second;
478
479 // Lex from the start of the given location.
480 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
481 Pass.Ctx.getLangOpts(),
482 file.begin(), tokenBegin, file.end());
483 Token tok;
484 lexer.LexFromRawLexer(tok);
485 if (tok.isNot(tok::at)) return false;
486 lexer.LexFromRawLexer(tok);
487 if (tok.isNot(tok::raw_identifier)) return false;
488 if (tok.getRawIdentifier() != "property")
489 return false;
490 lexer.LexFromRawLexer(tok);
491
492 if (tok.isNot(tok::l_paren)) {
493 Pass.TA.insert(tok.getLocation(), std::string("(") + attr.str() + ") ");
494 return true;
495 }
496
497 lexer.LexFromRawLexer(tok);
498 if (tok.is(tok::r_paren)) {
499 Pass.TA.insert(tok.getLocation(), attr);
500 return true;
501 }
502
503 if (tok.isNot(tok::raw_identifier)) return false;
504
505 Pass.TA.insert(tok.getLocation(), std::string(attr) + ", ");
506 return true;
507 }
508
traverse(TranslationUnitDecl * TU)509 void MigrationContext::traverse(TranslationUnitDecl *TU) {
510 for (traverser_iterator
511 I = traversers_begin(), E = traversers_end(); I != E; ++I)
512 (*I)->traverseTU(*this);
513
514 ASTTransform(*this).TraverseDecl(TU);
515 }
516
GCRewriteFinalize(MigrationPass & pass)517 static void GCRewriteFinalize(MigrationPass &pass) {
518 ASTContext &Ctx = pass.Ctx;
519 TransformActions &TA = pass.TA;
520 DeclContext *DC = Ctx.getTranslationUnitDecl();
521 Selector FinalizeSel =
522 Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize"));
523
524 typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl>
525 impl_iterator;
526 for (impl_iterator I = impl_iterator(DC->decls_begin()),
527 E = impl_iterator(DC->decls_end()); I != E; ++I) {
528 for (const auto *MD : I->instance_methods()) {
529 if (!MD->hasBody())
530 continue;
531
532 if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) {
533 const ObjCMethodDecl *FinalizeM = MD;
534 Transaction Trans(TA);
535 TA.insert(FinalizeM->getSourceRange().getBegin(),
536 "#if !__has_feature(objc_arc)\n");
537 CharSourceRange::getTokenRange(FinalizeM->getSourceRange());
538 const SourceManager &SM = pass.Ctx.getSourceManager();
539 const LangOptions &LangOpts = pass.Ctx.getLangOpts();
540 bool Invalid;
541 std::string str = "\n#endif\n";
542 str += Lexer::getSourceText(
543 CharSourceRange::getTokenRange(FinalizeM->getSourceRange()),
544 SM, LangOpts, &Invalid);
545 TA.insertAfterToken(FinalizeM->getSourceRange().getEnd(), str);
546
547 break;
548 }
549 }
550 }
551 }
552
553 //===----------------------------------------------------------------------===//
554 // getAllTransformations.
555 //===----------------------------------------------------------------------===//
556
traverseAST(MigrationPass & pass)557 static void traverseAST(MigrationPass &pass) {
558 MigrationContext MigrateCtx(pass);
559
560 if (pass.isGCMigration()) {
561 MigrateCtx.addTraverser(new GCCollectableCallsTraverser);
562 MigrateCtx.addTraverser(new GCAttrsTraverser());
563 }
564 MigrateCtx.addTraverser(new PropertyRewriteTraverser());
565 MigrateCtx.addTraverser(new BlockObjCVariableTraverser());
566 MigrateCtx.addTraverser(new ProtectedScopeTraverser());
567
568 MigrateCtx.traverse(pass.Ctx.getTranslationUnitDecl());
569 }
570
independentTransforms(MigrationPass & pass)571 static void independentTransforms(MigrationPass &pass) {
572 rewriteAutoreleasePool(pass);
573 removeRetainReleaseDeallocFinalize(pass);
574 rewriteUnusedInitDelegate(pass);
575 removeZeroOutPropsInDeallocFinalize(pass);
576 makeAssignARCSafe(pass);
577 rewriteUnbridgedCasts(pass);
578 checkAPIUses(pass);
579 traverseAST(pass);
580 }
581
getAllTransformations(LangOptions::GCMode OrigGCMode,bool NoFinalizeRemoval)582 std::vector<TransformFn> arcmt::getAllTransformations(
583 LangOptions::GCMode OrigGCMode,
584 bool NoFinalizeRemoval) {
585 std::vector<TransformFn> transforms;
586
587 if (OrigGCMode == LangOptions::GCOnly && NoFinalizeRemoval)
588 transforms.push_back(GCRewriteFinalize);
589 transforms.push_back(independentTransforms);
590 // This depends on previous transformations removing various expressions.
591 transforms.push_back(removeEmptyStatementsAndDeallocFinalize);
592
593 return transforms;
594 }
595