xref: /freebsd/contrib/llvm-project/clang/lib/ARCMigrate/Transforms.cpp (revision a90b9d0159070121c221b966469c3e36d912bf82) 
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 
25 ASTTraverser::~ASTTraverser() { }
26 
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 
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 
67 bool trans::isPlusOneAssign(const BinaryOperator *E) {
68   if (E->getOpcode() != BO_Assign)
69     return false;
70 
71   return isPlusOne(E->getRHS());
72 }
73 
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.ends_with("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.
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.
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 
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 
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 
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:
216   ReferenceClear(ExprSet &refs) : Refs(refs) { }
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:
225   ReferenceCollector(ValueDecl *D, ExprSet &refs)
226     : Dcl(D), Refs(refs) { }
227 
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:
239   RemovablesCollector(ExprSet &removables)
240   : Removables(removables) { }
241 
242   bool shouldWalkTypesOfTypeLocs() const { return false; }
243 
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 
255   bool VisitCompoundStmt(CompoundStmt *S) {
256     for (auto *I : S->body())
257       mark(I);
258     return true;
259   }
260 
261   bool VisitIfStmt(IfStmt *S) {
262     mark(S->getThen());
263     mark(S->getElse());
264     return true;
265   }
266 
267   bool VisitWhileStmt(WhileStmt *S) {
268     mark(S->getBody());
269     return true;
270   }
271 
272   bool VisitDoStmt(DoStmt *S) {
273     mark(S->getBody());
274     return true;
275   }
276 
277   bool VisitForStmt(ForStmt *S) {
278     mark(S->getInit());
279     mark(S->getInc());
280     mark(S->getBody());
281     return true;
282   }
283 
284 private:
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 
299 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
300   ReferenceClear(refs).TraverseStmt(S);
301 }
302 
303 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
304   ReferenceCollector(D, refs).TraverseStmt(S);
305 }
306 
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:
322   ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
323 
324   bool shouldWalkTypesOfTypeLocs() const { return false; }
325 
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 
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 
352 MigrationContext::~MigrationContext() {
353   for (traverser_iterator
354          I = traversers_begin(), E = traversers_end(); I != E; ++I)
355     delete *I;
356 }
357 
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 
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 
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 
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 
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 
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 
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 
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