1 //===--- Transforms.cpp - Transformations to ARC mode ---------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "Transforms.h"
11 #include "Internals.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 (LabelStmt *Label = dyn_cast<LabelStmt>(S))
291       S = Label->getSubStmt();
292     S = S->IgnoreImplicit();
293     if (Expr *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 (1) {
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