xref: /freebsd/contrib/llvm-project/clang/lib/ARCMigrate/Transforms.cpp (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a) 
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 
26 ASTTraverser::~ASTTraverser() { }
27 
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 
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 
68 bool trans::isPlusOneAssign(const BinaryOperator *E) {
69   if (E->getOpcode() != BO_Assign)
70     return false;
71 
72   return isPlusOne(E->getRHS());
73 }
74 
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.
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.
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 
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 
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 
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:
217   ReferenceClear(ExprSet &refs) : Refs(refs) { }
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:
226   ReferenceCollector(ValueDecl *D, ExprSet &refs)
227     : Dcl(D), Refs(refs) { }
228 
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:
240   RemovablesCollector(ExprSet &removables)
241   : Removables(removables) { }
242 
243   bool shouldWalkTypesOfTypeLocs() const { return false; }
244 
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 
256   bool VisitCompoundStmt(CompoundStmt *S) {
257     for (auto *I : S->body())
258       mark(I);
259     return true;
260   }
261 
262   bool VisitIfStmt(IfStmt *S) {
263     mark(S->getThen());
264     mark(S->getElse());
265     return true;
266   }
267 
268   bool VisitWhileStmt(WhileStmt *S) {
269     mark(S->getBody());
270     return true;
271   }
272 
273   bool VisitDoStmt(DoStmt *S) {
274     mark(S->getBody());
275     return true;
276   }
277 
278   bool VisitForStmt(ForStmt *S) {
279     mark(S->getInit());
280     mark(S->getInc());
281     mark(S->getBody());
282     return true;
283   }
284 
285 private:
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 
300 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
301   ReferenceClear(refs).TraverseStmt(S);
302 }
303 
304 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
305   ReferenceCollector(D, refs).TraverseStmt(S);
306 }
307 
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:
323   ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
324 
325   bool shouldWalkTypesOfTypeLocs() const { return false; }
326 
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 
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 
353 MigrationContext::~MigrationContext() {
354   for (traverser_iterator
355          I = traversers_begin(), E = traversers_end(); I != E; ++I)
356     delete *I;
357 }
358 
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 
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 
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 
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 
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 
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 
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 
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