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.hasValue())
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") ||
99 fname.find("Create") != StringRef::npos ||
100 fname.find("Copy") != StringRef::npos) {
101 return true;
102 }
103 }
104 }
105 }
106
107 const ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(E);
108 while (implCE && implCE->getCastKind() == CK_BitCast)
109 implCE = dyn_cast<ImplicitCastExpr>(implCE->getSubExpr());
110
111 return implCE && implCE->getCastKind() == CK_ARCConsumeObject;
112 }
113
114 /// 'Loc' is the end of a statement range. This returns the location
115 /// immediately after the semicolon following the statement.
116 /// If no semicolon is found or the location is inside a macro, the returned
117 /// source location will be invalid.
findLocationAfterSemi(SourceLocation loc,ASTContext & Ctx,bool IsDecl)118 SourceLocation trans::findLocationAfterSemi(SourceLocation loc,
119 ASTContext &Ctx, bool IsDecl) {
120 SourceLocation SemiLoc = findSemiAfterLocation(loc, Ctx, IsDecl);
121 if (SemiLoc.isInvalid())
122 return SourceLocation();
123 return SemiLoc.getLocWithOffset(1);
124 }
125
126 /// \arg Loc is the end of a statement range. This returns the location
127 /// of the semicolon following the statement.
128 /// If no semicolon is found or the location is inside a macro, the returned
129 /// source location will be invalid.
findSemiAfterLocation(SourceLocation loc,ASTContext & Ctx,bool IsDecl)130 SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
131 ASTContext &Ctx,
132 bool IsDecl) {
133 SourceManager &SM = Ctx.getSourceManager();
134 if (loc.isMacroID()) {
135 if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOpts(), &loc))
136 return SourceLocation();
137 }
138 loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOpts());
139
140 // Break down the source location.
141 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);
142
143 // Try to load the file buffer.
144 bool invalidTemp = false;
145 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
146 if (invalidTemp)
147 return SourceLocation();
148
149 const char *tokenBegin = file.data() + locInfo.second;
150
151 // Lex from the start of the given location.
152 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
153 Ctx.getLangOpts(),
154 file.begin(), tokenBegin, file.end());
155 Token tok;
156 lexer.LexFromRawLexer(tok);
157 if (tok.isNot(tok::semi)) {
158 if (!IsDecl)
159 return SourceLocation();
160 // Declaration may be followed with other tokens; such as an __attribute,
161 // before ending with a semicolon.
162 return findSemiAfterLocation(tok.getLocation(), Ctx, /*IsDecl*/true);
163 }
164
165 return tok.getLocation();
166 }
167
hasSideEffects(Expr * E,ASTContext & Ctx)168 bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
169 if (!E || !E->HasSideEffects(Ctx))
170 return false;
171
172 E = E->IgnoreParenCasts();
173 ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
174 if (!ME)
175 return true;
176 switch (ME->getMethodFamily()) {
177 case OMF_autorelease:
178 case OMF_dealloc:
179 case OMF_release:
180 case OMF_retain:
181 switch (ME->getReceiverKind()) {
182 case ObjCMessageExpr::SuperInstance:
183 return false;
184 case ObjCMessageExpr::Instance:
185 return hasSideEffects(ME->getInstanceReceiver(), Ctx);
186 default:
187 break;
188 }
189 break;
190 default:
191 break;
192 }
193
194 return true;
195 }
196
isGlobalVar(Expr * E)197 bool trans::isGlobalVar(Expr *E) {
198 E = E->IgnoreParenCasts();
199 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
200 return DRE->getDecl()->getDeclContext()->isFileContext() &&
201 DRE->getDecl()->isExternallyVisible();
202 if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
203 return isGlobalVar(condOp->getTrueExpr()) &&
204 isGlobalVar(condOp->getFalseExpr());
205
206 return false;
207 }
208
getNilString(MigrationPass & Pass)209 StringRef trans::getNilString(MigrationPass &Pass) {
210 return Pass.SemaRef.PP.isMacroDefined("nil") ? "nil" : "0";
211 }
212
213 namespace {
214
215 class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
216 ExprSet &Refs;
217 public:
ReferenceClear(ExprSet & refs)218 ReferenceClear(ExprSet &refs) : Refs(refs) { }
VisitDeclRefExpr(DeclRefExpr * E)219 bool VisitDeclRefExpr(DeclRefExpr *E) { Refs.erase(E); return true; }
220 };
221
222 class ReferenceCollector : public RecursiveASTVisitor<ReferenceCollector> {
223 ValueDecl *Dcl;
224 ExprSet &Refs;
225
226 public:
ReferenceCollector(ValueDecl * D,ExprSet & refs)227 ReferenceCollector(ValueDecl *D, ExprSet &refs)
228 : Dcl(D), Refs(refs) { }
229
VisitDeclRefExpr(DeclRefExpr * E)230 bool VisitDeclRefExpr(DeclRefExpr *E) {
231 if (E->getDecl() == Dcl)
232 Refs.insert(E);
233 return true;
234 }
235 };
236
237 class RemovablesCollector : public RecursiveASTVisitor<RemovablesCollector> {
238 ExprSet &Removables;
239
240 public:
RemovablesCollector(ExprSet & removables)241 RemovablesCollector(ExprSet &removables)
242 : Removables(removables) { }
243
shouldWalkTypesOfTypeLocs() const244 bool shouldWalkTypesOfTypeLocs() const { return false; }
245
TraverseStmtExpr(StmtExpr * E)246 bool TraverseStmtExpr(StmtExpr *E) {
247 CompoundStmt *S = E->getSubStmt();
248 for (CompoundStmt::body_iterator
249 I = S->body_begin(), E = S->body_end(); I != E; ++I) {
250 if (I != E - 1)
251 mark(*I);
252 TraverseStmt(*I);
253 }
254 return true;
255 }
256
VisitCompoundStmt(CompoundStmt * S)257 bool VisitCompoundStmt(CompoundStmt *S) {
258 for (auto *I : S->body())
259 mark(I);
260 return true;
261 }
262
VisitIfStmt(IfStmt * S)263 bool VisitIfStmt(IfStmt *S) {
264 mark(S->getThen());
265 mark(S->getElse());
266 return true;
267 }
268
VisitWhileStmt(WhileStmt * S)269 bool VisitWhileStmt(WhileStmt *S) {
270 mark(S->getBody());
271 return true;
272 }
273
VisitDoStmt(DoStmt * S)274 bool VisitDoStmt(DoStmt *S) {
275 mark(S->getBody());
276 return true;
277 }
278
VisitForStmt(ForStmt * S)279 bool VisitForStmt(ForStmt *S) {
280 mark(S->getInit());
281 mark(S->getInc());
282 mark(S->getBody());
283 return true;
284 }
285
286 private:
mark(Stmt * S)287 void mark(Stmt *S) {
288 if (!S) return;
289
290 while (auto *Label = dyn_cast<LabelStmt>(S))
291 S = Label->getSubStmt();
292 if (auto *E = dyn_cast<Expr>(S))
293 S = E->IgnoreImplicit();
294 if (auto *E = dyn_cast<Expr>(S))
295 Removables.insert(E);
296 }
297 };
298
299 } // end anonymous namespace
300
clearRefsIn(Stmt * S,ExprSet & refs)301 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
302 ReferenceClear(refs).TraverseStmt(S);
303 }
304
collectRefs(ValueDecl * D,Stmt * S,ExprSet & refs)305 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
306 ReferenceCollector(D, refs).TraverseStmt(S);
307 }
308
collectRemovables(Stmt * S,ExprSet & exprs)309 void trans::collectRemovables(Stmt *S, ExprSet &exprs) {
310 RemovablesCollector(exprs).TraverseStmt(S);
311 }
312
313 //===----------------------------------------------------------------------===//
314 // MigrationContext
315 //===----------------------------------------------------------------------===//
316
317 namespace {
318
319 class ASTTransform : public RecursiveASTVisitor<ASTTransform> {
320 MigrationContext &MigrateCtx;
321 typedef RecursiveASTVisitor<ASTTransform> base;
322
323 public:
ASTTransform(MigrationContext & MigrateCtx)324 ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
325
shouldWalkTypesOfTypeLocs() const326 bool shouldWalkTypesOfTypeLocs() const { return false; }
327
TraverseObjCImplementationDecl(ObjCImplementationDecl * D)328 bool TraverseObjCImplementationDecl(ObjCImplementationDecl *D) {
329 ObjCImplementationContext ImplCtx(MigrateCtx, D);
330 for (MigrationContext::traverser_iterator
331 I = MigrateCtx.traversers_begin(),
332 E = MigrateCtx.traversers_end(); I != E; ++I)
333 (*I)->traverseObjCImplementation(ImplCtx);
334
335 return base::TraverseObjCImplementationDecl(D);
336 }
337
TraverseStmt(Stmt * rootS)338 bool TraverseStmt(Stmt *rootS) {
339 if (!rootS)
340 return true;
341
342 BodyContext BodyCtx(MigrateCtx, rootS);
343 for (MigrationContext::traverser_iterator
344 I = MigrateCtx.traversers_begin(),
345 E = MigrateCtx.traversers_end(); I != E; ++I)
346 (*I)->traverseBody(BodyCtx);
347
348 return true;
349 }
350 };
351
352 }
353
~MigrationContext()354 MigrationContext::~MigrationContext() {
355 for (traverser_iterator
356 I = traversers_begin(), E = traversers_end(); I != E; ++I)
357 delete *I;
358 }
359
isGCOwnedNonObjC(QualType T)360 bool MigrationContext::isGCOwnedNonObjC(QualType T) {
361 while (!T.isNull()) {
362 if (const AttributedType *AttrT = T->getAs<AttributedType>()) {
363 if (AttrT->getAttrKind() == attr::ObjCOwnership)
364 return !AttrT->getModifiedType()->isObjCRetainableType();
365 }
366
367 if (T->isArrayType())
368 T = Pass.Ctx.getBaseElementType(T);
369 else if (const PointerType *PT = T->getAs<PointerType>())
370 T = PT->getPointeeType();
371 else if (const ReferenceType *RT = T->getAs<ReferenceType>())
372 T = RT->getPointeeType();
373 else
374 break;
375 }
376
377 return false;
378 }
379
rewritePropertyAttribute(StringRef fromAttr,StringRef toAttr,SourceLocation atLoc)380 bool MigrationContext::rewritePropertyAttribute(StringRef fromAttr,
381 StringRef toAttr,
382 SourceLocation atLoc) {
383 if (atLoc.isMacroID())
384 return false;
385
386 SourceManager &SM = Pass.Ctx.getSourceManager();
387
388 // Break down the source location.
389 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
390
391 // Try to load the file buffer.
392 bool invalidTemp = false;
393 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
394 if (invalidTemp)
395 return false;
396
397 const char *tokenBegin = file.data() + locInfo.second;
398
399 // Lex from the start of the given location.
400 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
401 Pass.Ctx.getLangOpts(),
402 file.begin(), tokenBegin, file.end());
403 Token tok;
404 lexer.LexFromRawLexer(tok);
405 if (tok.isNot(tok::at)) return false;
406 lexer.LexFromRawLexer(tok);
407 if (tok.isNot(tok::raw_identifier)) return false;
408 if (tok.getRawIdentifier() != "property")
409 return false;
410 lexer.LexFromRawLexer(tok);
411 if (tok.isNot(tok::l_paren)) return false;
412
413 Token BeforeTok = tok;
414 Token AfterTok;
415 AfterTok.startToken();
416 SourceLocation AttrLoc;
417
418 lexer.LexFromRawLexer(tok);
419 if (tok.is(tok::r_paren))
420 return false;
421
422 while (1) {
423 if (tok.isNot(tok::raw_identifier)) return false;
424 if (tok.getRawIdentifier() == fromAttr) {
425 if (!toAttr.empty()) {
426 Pass.TA.replaceText(tok.getLocation(), fromAttr, toAttr);
427 return true;
428 }
429 // We want to remove the attribute.
430 AttrLoc = tok.getLocation();
431 }
432
433 do {
434 lexer.LexFromRawLexer(tok);
435 if (AttrLoc.isValid() && AfterTok.is(tok::unknown))
436 AfterTok = tok;
437 } while (tok.isNot(tok::comma) && tok.isNot(tok::r_paren));
438 if (tok.is(tok::r_paren))
439 break;
440 if (AttrLoc.isInvalid())
441 BeforeTok = tok;
442 lexer.LexFromRawLexer(tok);
443 }
444
445 if (toAttr.empty() && AttrLoc.isValid() && AfterTok.isNot(tok::unknown)) {
446 // We want to remove the attribute.
447 if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::r_paren)) {
448 Pass.TA.remove(SourceRange(BeforeTok.getLocation(),
449 AfterTok.getLocation()));
450 } else if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::comma)) {
451 Pass.TA.remove(SourceRange(AttrLoc, AfterTok.getLocation()));
452 } else {
453 Pass.TA.remove(SourceRange(BeforeTok.getLocation(), AttrLoc));
454 }
455
456 return true;
457 }
458
459 return false;
460 }
461
addPropertyAttribute(StringRef attr,SourceLocation atLoc)462 bool MigrationContext::addPropertyAttribute(StringRef attr,
463 SourceLocation atLoc) {
464 if (atLoc.isMacroID())
465 return false;
466
467 SourceManager &SM = Pass.Ctx.getSourceManager();
468
469 // Break down the source location.
470 std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
471
472 // Try to load the file buffer.
473 bool invalidTemp = false;
474 StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
475 if (invalidTemp)
476 return false;
477
478 const char *tokenBegin = file.data() + locInfo.second;
479
480 // Lex from the start of the given location.
481 Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
482 Pass.Ctx.getLangOpts(),
483 file.begin(), tokenBegin, file.end());
484 Token tok;
485 lexer.LexFromRawLexer(tok);
486 if (tok.isNot(tok::at)) return false;
487 lexer.LexFromRawLexer(tok);
488 if (tok.isNot(tok::raw_identifier)) return false;
489 if (tok.getRawIdentifier() != "property")
490 return false;
491 lexer.LexFromRawLexer(tok);
492
493 if (tok.isNot(tok::l_paren)) {
494 Pass.TA.insert(tok.getLocation(), std::string("(") + attr.str() + ") ");
495 return true;
496 }
497
498 lexer.LexFromRawLexer(tok);
499 if (tok.is(tok::r_paren)) {
500 Pass.TA.insert(tok.getLocation(), attr);
501 return true;
502 }
503
504 if (tok.isNot(tok::raw_identifier)) return false;
505
506 Pass.TA.insert(tok.getLocation(), std::string(attr) + ", ");
507 return true;
508 }
509
traverse(TranslationUnitDecl * TU)510 void MigrationContext::traverse(TranslationUnitDecl *TU) {
511 for (traverser_iterator
512 I = traversers_begin(), E = traversers_end(); I != E; ++I)
513 (*I)->traverseTU(*this);
514
515 ASTTransform(*this).TraverseDecl(TU);
516 }
517
GCRewriteFinalize(MigrationPass & pass)518 static void GCRewriteFinalize(MigrationPass &pass) {
519 ASTContext &Ctx = pass.Ctx;
520 TransformActions &TA = pass.TA;
521 DeclContext *DC = Ctx.getTranslationUnitDecl();
522 Selector FinalizeSel =
523 Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize"));
524
525 typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl>
526 impl_iterator;
527 for (impl_iterator I = impl_iterator(DC->decls_begin()),
528 E = impl_iterator(DC->decls_end()); I != E; ++I) {
529 for (const auto *MD : I->instance_methods()) {
530 if (!MD->hasBody())
531 continue;
532
533 if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) {
534 const ObjCMethodDecl *FinalizeM = MD;
535 Transaction Trans(TA);
536 TA.insert(FinalizeM->getSourceRange().getBegin(),
537 "#if !__has_feature(objc_arc)\n");
538 CharSourceRange::getTokenRange(FinalizeM->getSourceRange());
539 const SourceManager &SM = pass.Ctx.getSourceManager();
540 const LangOptions &LangOpts = pass.Ctx.getLangOpts();
541 bool Invalid;
542 std::string str = "\n#endif\n";
543 str += Lexer::getSourceText(
544 CharSourceRange::getTokenRange(FinalizeM->getSourceRange()),
545 SM, LangOpts, &Invalid);
546 TA.insertAfterToken(FinalizeM->getSourceRange().getEnd(), str);
547
548 break;
549 }
550 }
551 }
552 }
553
554 //===----------------------------------------------------------------------===//
555 // getAllTransformations.
556 //===----------------------------------------------------------------------===//
557
traverseAST(MigrationPass & pass)558 static void traverseAST(MigrationPass &pass) {
559 MigrationContext MigrateCtx(pass);
560
561 if (pass.isGCMigration()) {
562 MigrateCtx.addTraverser(new GCCollectableCallsTraverser);
563 MigrateCtx.addTraverser(new GCAttrsTraverser());
564 }
565 MigrateCtx.addTraverser(new PropertyRewriteTraverser());
566 MigrateCtx.addTraverser(new BlockObjCVariableTraverser());
567 MigrateCtx.addTraverser(new ProtectedScopeTraverser());
568
569 MigrateCtx.traverse(pass.Ctx.getTranslationUnitDecl());
570 }
571
independentTransforms(MigrationPass & pass)572 static void independentTransforms(MigrationPass &pass) {
573 rewriteAutoreleasePool(pass);
574 removeRetainReleaseDeallocFinalize(pass);
575 rewriteUnusedInitDelegate(pass);
576 removeZeroOutPropsInDeallocFinalize(pass);
577 makeAssignARCSafe(pass);
578 rewriteUnbridgedCasts(pass);
579 checkAPIUses(pass);
580 traverseAST(pass);
581 }
582
getAllTransformations(LangOptions::GCMode OrigGCMode,bool NoFinalizeRemoval)583 std::vector<TransformFn> arcmt::getAllTransformations(
584 LangOptions::GCMode OrigGCMode,
585 bool NoFinalizeRemoval) {
586 std::vector<TransformFn> transforms;
587
588 if (OrigGCMode == LangOptions::GCOnly && NoFinalizeRemoval)
589 transforms.push_back(GCRewriteFinalize);
590 transforms.push_back(independentTransforms);
591 // This depends on previous transformations removing various expressions.
592 transforms.push_back(removeEmptyStatementsAndDeallocFinalize);
593
594 return transforms;
595 }
596