xref: /freebsd/contrib/llvm-project/clang/lib/ARCMigrate/Transforms.cpp (revision c66ec88fed842fbaad62c30d510644ceb7bd2d71) 
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.hasValue())
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.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.
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.
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 
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 
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 
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:
218   ReferenceClear(ExprSet &refs) : Refs(refs) { }
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:
227   ReferenceCollector(ValueDecl *D, ExprSet &refs)
228     : Dcl(D), Refs(refs) { }
229 
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:
241   RemovablesCollector(ExprSet &removables)
242   : Removables(removables) { }
243 
244   bool shouldWalkTypesOfTypeLocs() const { return false; }
245 
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 
257   bool VisitCompoundStmt(CompoundStmt *S) {
258     for (auto *I : S->body())
259       mark(I);
260     return true;
261   }
262 
263   bool VisitIfStmt(IfStmt *S) {
264     mark(S->getThen());
265     mark(S->getElse());
266     return true;
267   }
268 
269   bool VisitWhileStmt(WhileStmt *S) {
270     mark(S->getBody());
271     return true;
272   }
273 
274   bool VisitDoStmt(DoStmt *S) {
275     mark(S->getBody());
276     return true;
277   }
278 
279   bool VisitForStmt(ForStmt *S) {
280     mark(S->getInit());
281     mark(S->getInc());
282     mark(S->getBody());
283     return true;
284   }
285 
286 private:
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 
301 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
302   ReferenceClear(refs).TraverseStmt(S);
303 }
304 
305 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
306   ReferenceCollector(D, refs).TraverseStmt(S);
307 }
308 
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:
324   ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
325 
326   bool shouldWalkTypesOfTypeLocs() const { return false; }
327 
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 
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 
354 MigrationContext::~MigrationContext() {
355   for (traverser_iterator
356          I = traversers_begin(), E = traversers_end(); I != E; ++I)
357     delete *I;
358 }
359 
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 
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 
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 
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 
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 
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 
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 
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