Home | History | Annotate | Download | only in ARCMigrate 
      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/AST/StmtVisitor.h"
     15 #include "clang/Analysis/DomainSpecific/CocoaConventions.h"
     16 #include "clang/Basic/SourceManager.h"
     17 #include "clang/Basic/TargetInfo.h"
     18 #include "clang/Lex/Lexer.h"
     19 #include "clang/Sema/Sema.h"
     20 #include "clang/Sema/SemaDiagnostic.h"
     21 #include "llvm/ADT/DenseSet.h"
     22 #include "llvm/ADT/StringSwitch.h"
     23 #include <map>
     24 
     25 using namespace clang;
     26 using namespace arcmt;
     27 using namespace trans;
     28 
     29 ASTTraverser::~ASTTraverser() { }
     30 
     31 bool MigrationPass::CFBridgingFunctionsDefined() {
     32   if (!EnableCFBridgeFns.hasValue())
     33     EnableCFBridgeFns = SemaRef.isKnownName("CFBridgingRetain") &&
     34                         SemaRef.isKnownName("CFBridgingRelease");
     35   return *EnableCFBridgeFns;
     36 }
     37 
     38 //===----------------------------------------------------------------------===//
     39 // Helpers.
     40 //===----------------------------------------------------------------------===//
     41 
     42 bool trans::canApplyWeak(ASTContext &Ctx, QualType type,
     43                          bool AllowOnUnknownClass) {
     44   if (!Ctx.getLangOpts().ObjCARCWeak)
     45     return false;
     46 
     47   QualType T = type;
     48   if (T.isNull())
     49     return false;
     50 
     51   // iOS is always safe to use 'weak'.
     52   if (Ctx.getTargetInfo().getTriple().isiOS())
     53     AllowOnUnknownClass = true;
     54 
     55   while (const PointerType *ptr = T->getAs<PointerType>())
     56     T = ptr->getPointeeType();
     57   if (const ObjCObjectPointerType *ObjT = T->getAs<ObjCObjectPointerType>()) {
     58     ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
     59     if (!AllowOnUnknownClass && (!Class || Class->getName() == "NSObject"))
     60       return false; // id/NSObject is not safe for weak.
     61     if (!AllowOnUnknownClass && !Class->hasDefinition())
     62       return false; // forward classes are not verifiable, therefore not safe.
     63     if (Class && Class->isArcWeakrefUnavailable())
     64       return false;
     65   }
     66 
     67   return true;
     68 }
     69 
     70 bool trans::isPlusOneAssign(const BinaryOperator *E) {
     71   if (E->getOpcode() != BO_Assign)
     72     return false;
     73 
     74   return isPlusOne(E->getRHS());
     75 }
     76 
     77 bool trans::isPlusOne(const Expr *E) {
     78   if (!E)
     79     return false;
     80   if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(E))
     81     E = EWC->getSubExpr();
     82 
     83   if (const ObjCMessageExpr *
     84         ME = dyn_cast<ObjCMessageExpr>(E->IgnoreParenCasts()))
     85     if (ME->getMethodFamily() == OMF_retain)
     86       return true;
     87 
     88   if (const CallExpr *
     89         callE = dyn_cast<CallExpr>(E->IgnoreParenCasts())) {
     90     if (const FunctionDecl *FD = callE->getDirectCallee()) {
     91       if (FD->hasAttr<CFReturnsRetainedAttr>())
     92         return true;
     93 
     94       if (FD->isGlobal() &&
     95           FD->getIdentifier() &&
     96           FD->getParent()->isTranslationUnit() &&
     97           FD->isExternallyVisible() &&
     98           ento::cocoa::isRefType(callE->getType(), "CF",
     99                                  FD->getIdentifier()->getName())) {
    100         StringRef fname = FD->getIdentifier()->getName();
    101         if (fname.endswith("Retain") ||
    102             fname.find("Create") != StringRef::npos ||
    103             fname.find("Copy") != StringRef::npos) {
    104           return true;
    105         }
    106       }
    107     }
    108   }
    109 
    110   const ImplicitCastExpr *implCE = dyn_cast<ImplicitCastExpr>(E);
    111   while (implCE && implCE->getCastKind() ==  CK_BitCast)
    112     implCE = dyn_cast<ImplicitCastExpr>(implCE->getSubExpr());
    113 
    114   if (implCE && implCE->getCastKind() == CK_ARCConsumeObject)
    115     return true;
    116 
    117   return false;
    118 }
    119 
    120 /// \brief 'Loc' is the end of a statement range. This returns the location
    121 /// immediately after the semicolon following the statement.
    122 /// If no semicolon is found or the location is inside a macro, the returned
    123 /// source location will be invalid.
    124 SourceLocation trans::findLocationAfterSemi(SourceLocation loc,
    125                                             ASTContext &Ctx, bool IsDecl) {
    126   SourceLocation SemiLoc = findSemiAfterLocation(loc, Ctx, IsDecl);
    127   if (SemiLoc.isInvalid())
    128     return SourceLocation();
    129   return SemiLoc.getLocWithOffset(1);
    130 }
    131 
    132 /// \brief \arg Loc is the end of a statement range. This returns the location
    133 /// of the semicolon following the statement.
    134 /// If no semicolon is found or the location is inside a macro, the returned
    135 /// source location will be invalid.
    136 SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
    137                                             ASTContext &Ctx,
    138                                             bool IsDecl) {
    139   SourceManager &SM = Ctx.getSourceManager();
    140   if (loc.isMacroID()) {
    141     if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOpts(), &loc))
    142       return SourceLocation();
    143   }
    144   loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOpts());
    145 
    146   // Break down the source location.
    147   std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);
    148 
    149   // Try to load the file buffer.
    150   bool invalidTemp = false;
    151   StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
    152   if (invalidTemp)
    153     return SourceLocation();
    154 
    155   const char *tokenBegin = file.data() + locInfo.second;
    156 
    157   // Lex from the start of the given location.
    158   Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
    159               Ctx.getLangOpts(),
    160               file.begin(), tokenBegin, file.end());
    161   Token tok;
    162   lexer.LexFromRawLexer(tok);
    163   if (tok.isNot(tok::semi)) {
    164     if (!IsDecl)
    165       return SourceLocation();
    166     // Declaration may be followed with other tokens; such as an __attribute,
    167     // before ending with a semicolon.
    168     return findSemiAfterLocation(tok.getLocation(), Ctx, /*IsDecl*/true);
    169   }
    170 
    171   return tok.getLocation();
    172 }
    173 
    174 bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
    175   if (!E || !E->HasSideEffects(Ctx))
    176     return false;
    177 
    178   E = E->IgnoreParenCasts();
    179   ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
    180   if (!ME)
    181     return true;
    182   switch (ME->getMethodFamily()) {
    183   case OMF_autorelease:
    184   case OMF_dealloc:
    185   case OMF_release:
    186   case OMF_retain:
    187     switch (ME->getReceiverKind()) {
    188     case ObjCMessageExpr::SuperInstance:
    189       return false;
    190     case ObjCMessageExpr::Instance:
    191       return hasSideEffects(ME->getInstanceReceiver(), Ctx);
    192     default:
    193       break;
    194     }
    195     break;
    196   default:
    197     break;
    198   }
    199 
    200   return true;
    201 }
    202 
    203 bool trans::isGlobalVar(Expr *E) {
    204   E = E->IgnoreParenCasts();
    205   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
    206     return DRE->getDecl()->getDeclContext()->isFileContext() &&
    207            DRE->getDecl()->isExternallyVisible();
    208   if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
    209     return isGlobalVar(condOp->getTrueExpr()) &&
    210            isGlobalVar(condOp->getFalseExpr());
    211 
    212   return false;
    213 }
    214 
    215 StringRef trans::getNilString(ASTContext &Ctx) {
    216   if (Ctx.Idents.get("nil").hasMacroDefinition())
    217     return "nil";
    218   else
    219     return "0";
    220 }
    221 
    222 namespace {
    223 
    224 class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
    225   ExprSet &Refs;
    226 public:
    227   ReferenceClear(ExprSet &refs) : Refs(refs) { }
    228   bool VisitDeclRefExpr(DeclRefExpr *E) { Refs.erase(E); return true; }
    229 };
    230 
    231 class ReferenceCollector : public RecursiveASTVisitor<ReferenceCollector> {
    232   ValueDecl *Dcl;
    233   ExprSet &Refs;
    234 
    235 public:
    236   ReferenceCollector(ValueDecl *D, ExprSet &refs)
    237     : Dcl(D), Refs(refs) { }
    238 
    239   bool VisitDeclRefExpr(DeclRefExpr *E) {
    240     if (E->getDecl() == Dcl)
    241       Refs.insert(E);
    242     return true;
    243   }
    244 };
    245 
    246 class RemovablesCollector : public RecursiveASTVisitor<RemovablesCollector> {
    247   ExprSet &Removables;
    248 
    249 public:
    250   RemovablesCollector(ExprSet &removables)
    251   : Removables(removables) { }
    252 
    253   bool shouldWalkTypesOfTypeLocs() const { return false; }
    254 
    255   bool TraverseStmtExpr(StmtExpr *E) {
    256     CompoundStmt *S = E->getSubStmt();
    257     for (CompoundStmt::body_iterator
    258         I = S->body_begin(), E = S->body_end(); I != E; ++I) {
    259       if (I != E - 1)
    260         mark(*I);
    261       TraverseStmt(*I);
    262     }
    263     return true;
    264   }
    265 
    266   bool VisitCompoundStmt(CompoundStmt *S) {
    267     for (auto *I : S->body())
    268       mark(I);
    269     return true;
    270   }
    271 
    272   bool VisitIfStmt(IfStmt *S) {
    273     mark(S->getThen());
    274     mark(S->getElse());
    275     return true;
    276   }
    277 
    278   bool VisitWhileStmt(WhileStmt *S) {
    279     mark(S->getBody());
    280     return true;
    281   }
    282 
    283   bool VisitDoStmt(DoStmt *S) {
    284     mark(S->getBody());
    285     return true;
    286   }
    287 
    288   bool VisitForStmt(ForStmt *S) {
    289     mark(S->getInit());
    290     mark(S->getInc());
    291     mark(S->getBody());
    292     return true;
    293   }
    294 
    295 private:
    296   void mark(Stmt *S) {
    297     if (!S) return;
    298 
    299     while (LabelStmt *Label = dyn_cast<LabelStmt>(S))
    300       S = Label->getSubStmt();
    301     S = S->IgnoreImplicit();
    302     if (Expr *E = dyn_cast<Expr>(S))
    303       Removables.insert(E);
    304   }
    305 };
    306 
    307 } // end anonymous namespace
    308 
    309 void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
    310   ReferenceClear(refs).TraverseStmt(S);
    311 }
    312 
    313 void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
    314   ReferenceCollector(D, refs).TraverseStmt(S);
    315 }
    316 
    317 void trans::collectRemovables(Stmt *S, ExprSet &exprs) {
    318   RemovablesCollector(exprs).TraverseStmt(S);
    319 }
    320 
    321 //===----------------------------------------------------------------------===//
    322 // MigrationContext
    323 //===----------------------------------------------------------------------===//
    324 
    325 namespace {
    326 
    327 class ASTTransform : public RecursiveASTVisitor<ASTTransform> {
    328   MigrationContext &MigrateCtx;
    329   typedef RecursiveASTVisitor<ASTTransform> base;
    330 
    331 public:
    332   ASTTransform(MigrationContext &MigrateCtx) : MigrateCtx(MigrateCtx) { }
    333 
    334   bool shouldWalkTypesOfTypeLocs() const { return false; }
    335 
    336   bool TraverseObjCImplementationDecl(ObjCImplementationDecl *D) {
    337     ObjCImplementationContext ImplCtx(MigrateCtx, D);
    338     for (MigrationContext::traverser_iterator
    339            I = MigrateCtx.traversers_begin(),
    340            E = MigrateCtx.traversers_end(); I != E; ++I)
    341       (*I)->traverseObjCImplementation(ImplCtx);
    342 
    343     return base::TraverseObjCImplementationDecl(D);
    344   }
    345 
    346   bool TraverseStmt(Stmt *rootS) {
    347     if (!rootS)
    348       return true;
    349 
    350     BodyContext BodyCtx(MigrateCtx, rootS);
    351     for (MigrationContext::traverser_iterator
    352            I = MigrateCtx.traversers_begin(),
    353            E = MigrateCtx.traversers_end(); I != E; ++I)
    354       (*I)->traverseBody(BodyCtx);
    355 
    356     return true;
    357   }
    358 };
    359 
    360 }
    361 
    362 MigrationContext::~MigrationContext() {
    363   for (traverser_iterator
    364          I = traversers_begin(), E = traversers_end(); I != E; ++I)
    365     delete *I;
    366 }
    367 
    368 bool MigrationContext::isGCOwnedNonObjC(QualType T) {
    369   while (!T.isNull()) {
    370     if (const AttributedType *AttrT = T->getAs<AttributedType>()) {
    371       if (AttrT->getAttrKind() == AttributedType::attr_objc_ownership)
    372         return !AttrT->getModifiedType()->isObjCRetainableType();
    373     }
    374 
    375     if (T->isArrayType())
    376       T = Pass.Ctx.getBaseElementType(T);
    377     else if (const PointerType *PT = T->getAs<PointerType>())
    378       T = PT->getPointeeType();
    379     else if (const ReferenceType *RT = T->getAs<ReferenceType>())
    380       T = RT->getPointeeType();
    381     else
    382       break;
    383   }
    384 
    385   return false;
    386 }
    387 
    388 bool MigrationContext::rewritePropertyAttribute(StringRef fromAttr,
    389                                                 StringRef toAttr,
    390                                                 SourceLocation atLoc) {
    391   if (atLoc.isMacroID())
    392     return false;
    393 
    394   SourceManager &SM = Pass.Ctx.getSourceManager();
    395 
    396   // Break down the source location.
    397   std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
    398 
    399   // Try to load the file buffer.
    400   bool invalidTemp = false;
    401   StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
    402   if (invalidTemp)
    403     return false;
    404 
    405   const char *tokenBegin = file.data() + locInfo.second;
    406 
    407   // Lex from the start of the given location.
    408   Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
    409               Pass.Ctx.getLangOpts(),
    410               file.begin(), tokenBegin, file.end());
    411   Token tok;
    412   lexer.LexFromRawLexer(tok);
    413   if (tok.isNot(tok::at)) return false;
    414   lexer.LexFromRawLexer(tok);
    415   if (tok.isNot(tok::raw_identifier)) return false;
    416   if (tok.getRawIdentifier() != "property")
    417     return false;
    418   lexer.LexFromRawLexer(tok);
    419   if (tok.isNot(tok::l_paren)) return false;
    420 
    421   Token BeforeTok = tok;
    422   Token AfterTok;
    423   AfterTok.startToken();
    424   SourceLocation AttrLoc;
    425 
    426   lexer.LexFromRawLexer(tok);
    427   if (tok.is(tok::r_paren))
    428     return false;
    429 
    430   while (1) {
    431     if (tok.isNot(tok::raw_identifier)) return false;
    432     if (tok.getRawIdentifier() == fromAttr) {
    433       if (!toAttr.empty()) {
    434         Pass.TA.replaceText(tok.getLocation(), fromAttr, toAttr);
    435         return true;
    436       }
    437       // We want to remove the attribute.
    438       AttrLoc = tok.getLocation();
    439     }
    440 
    441     do {
    442       lexer.LexFromRawLexer(tok);
    443       if (AttrLoc.isValid() && AfterTok.is(tok::unknown))
    444         AfterTok = tok;
    445     } while (tok.isNot(tok::comma) && tok.isNot(tok::r_paren));
    446     if (tok.is(tok::r_paren))
    447       break;
    448     if (AttrLoc.isInvalid())
    449       BeforeTok = tok;
    450     lexer.LexFromRawLexer(tok);
    451   }
    452 
    453   if (toAttr.empty() && AttrLoc.isValid() && AfterTok.isNot(tok::unknown)) {
    454     // We want to remove the attribute.
    455     if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::r_paren)) {
    456       Pass.TA.remove(SourceRange(BeforeTok.getLocation(),
    457                                  AfterTok.getLocation()));
    458     } else if (BeforeTok.is(tok::l_paren) && AfterTok.is(tok::comma)) {
    459       Pass.TA.remove(SourceRange(AttrLoc, AfterTok.getLocation()));
    460     } else {
    461       Pass.TA.remove(SourceRange(BeforeTok.getLocation(), AttrLoc));
    462     }
    463 
    464     return true;
    465   }
    466 
    467   return false;
    468 }
    469 
    470 bool MigrationContext::addPropertyAttribute(StringRef attr,
    471                                             SourceLocation atLoc) {
    472   if (atLoc.isMacroID())
    473     return false;
    474 
    475   SourceManager &SM = Pass.Ctx.getSourceManager();
    476 
    477   // Break down the source location.
    478   std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(atLoc);
    479 
    480   // Try to load the file buffer.
    481   bool invalidTemp = false;
    482   StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
    483   if (invalidTemp)
    484     return false;
    485 
    486   const char *tokenBegin = file.data() + locInfo.second;
    487 
    488   // Lex from the start of the given location.
    489   Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
    490               Pass.Ctx.getLangOpts(),
    491               file.begin(), tokenBegin, file.end());
    492   Token tok;
    493   lexer.LexFromRawLexer(tok);
    494   if (tok.isNot(tok::at)) return false;
    495   lexer.LexFromRawLexer(tok);
    496   if (tok.isNot(tok::raw_identifier)) return false;
    497   if (tok.getRawIdentifier() != "property")
    498     return false;
    499   lexer.LexFromRawLexer(tok);
    500 
    501   if (tok.isNot(tok::l_paren)) {
    502     Pass.TA.insert(tok.getLocation(), std::string("(") + attr.str() + ") ");
    503     return true;
    504   }
    505 
    506   lexer.LexFromRawLexer(tok);
    507   if (tok.is(tok::r_paren)) {
    508     Pass.TA.insert(tok.getLocation(), attr);
    509     return true;
    510   }
    511 
    512   if (tok.isNot(tok::raw_identifier)) return false;
    513 
    514   Pass.TA.insert(tok.getLocation(), std::string(attr) + ", ");
    515   return true;
    516 }
    517 
    518 void MigrationContext::traverse(TranslationUnitDecl *TU) {
    519   for (traverser_iterator
    520          I = traversers_begin(), E = traversers_end(); I != E; ++I)
    521     (*I)->traverseTU(*this);
    522 
    523   ASTTransform(*this).TraverseDecl(TU);
    524 }
    525 
    526 static void GCRewriteFinalize(MigrationPass &pass) {
    527   ASTContext &Ctx = pass.Ctx;
    528   TransformActions &TA = pass.TA;
    529   DeclContext *DC = Ctx.getTranslationUnitDecl();
    530   Selector FinalizeSel =
    531    Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize"));
    532 
    533   typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl>
    534   impl_iterator;
    535   for (impl_iterator I = impl_iterator(DC->decls_begin()),
    536        E = impl_iterator(DC->decls_end()); I != E; ++I) {
    537     for (const auto *MD : I->instance_methods()) {
    538       if (!MD->hasBody())
    539         continue;
    540 
    541       if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) {
    542         const ObjCMethodDecl *FinalizeM = MD;
    543         Transaction Trans(TA);
    544         TA.insert(FinalizeM->getSourceRange().getBegin(),
    545                   "#if !__has_feature(objc_arc)\n");
    546         CharSourceRange::getTokenRange(FinalizeM->getSourceRange());
    547         const SourceManager &SM = pass.Ctx.getSourceManager();
    548         const LangOptions &LangOpts = pass.Ctx.getLangOpts();
    549         bool Invalid;
    550         std::string str = "\n#endif\n";
    551         str += Lexer::getSourceText(
    552                   CharSourceRange::getTokenRange(FinalizeM->getSourceRange()),
    553                                     SM, LangOpts, &Invalid);
    554         TA.insertAfterToken(FinalizeM->getSourceRange().getEnd(), str);
    555 
    556         break;
    557       }
    558     }
    559   }
    560 }
    561 
    562 //===----------------------------------------------------------------------===//
    563 // getAllTransformations.
    564 //===----------------------------------------------------------------------===//
    565 
    566 static void traverseAST(MigrationPass &pass) {
    567   MigrationContext MigrateCtx(pass);
    568 
    569   if (pass.isGCMigration()) {
    570     MigrateCtx.addTraverser(new GCCollectableCallsTraverser);
    571     MigrateCtx.addTraverser(new GCAttrsTraverser());
    572   }
    573   MigrateCtx.addTraverser(new PropertyRewriteTraverser());
    574   MigrateCtx.addTraverser(new BlockObjCVariableTraverser());
    575   MigrateCtx.addTraverser(new ProtectedScopeTraverser());
    576 
    577   MigrateCtx.traverse(pass.Ctx.getTranslationUnitDecl());
    578 }
    579 
    580 static void independentTransforms(MigrationPass &pass) {
    581   rewriteAutoreleasePool(pass);
    582   removeRetainReleaseDeallocFinalize(pass);
    583   rewriteUnusedInitDelegate(pass);
    584   removeZeroOutPropsInDeallocFinalize(pass);
    585   makeAssignARCSafe(pass);
    586   rewriteUnbridgedCasts(pass);
    587   checkAPIUses(pass);
    588   traverseAST(pass);
    589 }
    590 
    591 std::vector<TransformFn> arcmt::getAllTransformations(
    592                                                LangOptions::GCMode OrigGCMode,
    593                                                bool NoFinalizeRemoval) {
    594   std::vector<TransformFn> transforms;
    595 
    596   if (OrigGCMode ==  LangOptions::GCOnly && NoFinalizeRemoval)
    597     transforms.push_back(GCRewriteFinalize);
    598   transforms.push_back(independentTransforms);
    599   // This depends on previous transformations removing various expressions.
    600   transforms.push_back(removeEmptyStatementsAndDeallocFinalize);
    601 
    602   return transforms;
    603 }
    604