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