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
  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.endswith("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 }