clang/lib/ARCMigrate/Transforms.cpp

   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 }