1//===--- TransGCAttrs.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/Basic/SourceManager.h"
14#include "clang/Lex/Lexer.h"
15#include "clang/Sema/SemaDiagnostic.h"
16#include "llvm/ADT/SmallString.h"
17#include "llvm/ADT/TinyPtrVector.h"
18#include "llvm/Support/SaveAndRestore.h"
19
20using namespace clang;
21using namespace arcmt;
22using namespace trans;
23
24namespace {
25
26/// \brief Collects all the places where GC attributes __strong/__weak occur.
27class GCAttrsCollector : public RecursiveASTVisitor<GCAttrsCollector> {
28  MigrationContext &MigrateCtx;
29  bool FullyMigratable;
30  std::vector<ObjCPropertyDecl *> &AllProps;
31
32  typedef RecursiveASTVisitor<GCAttrsCollector> base;
33public:
34  GCAttrsCollector(MigrationContext &ctx,
35                   std::vector<ObjCPropertyDecl *> &AllProps)
36    : MigrateCtx(ctx), FullyMigratable(false),
37      AllProps(AllProps) { }
38
39  bool shouldWalkTypesOfTypeLocs() const { return false; }
40
41  bool VisitAttributedTypeLoc(AttributedTypeLoc TL) {
42    handleAttr(TL);
43    return true;
44  }
45
46  bool TraverseDecl(Decl *D) {
47    if (!D || D->isImplicit())
48      return true;
49
50    SaveAndRestore<bool> Save(FullyMigratable, isMigratable(D));
51
52    if (ObjCPropertyDecl *PropD = dyn_cast<ObjCPropertyDecl>(D)) {
53      lookForAttribute(PropD, PropD->getTypeSourceInfo());
54      AllProps.push_back(PropD);
55    } else if (DeclaratorDecl *DD = dyn_cast<DeclaratorDecl>(D)) {
56      lookForAttribute(DD, DD->getTypeSourceInfo());
57    }
58    return base::TraverseDecl(D);
59  }
60
61  void lookForAttribute(Decl *D, TypeSourceInfo *TInfo) {
62    if (!TInfo)
63      return;
64    TypeLoc TL = TInfo->getTypeLoc();
65    while (TL) {
66      if (QualifiedTypeLoc QL = TL.getAs<QualifiedTypeLoc>()) {
67        TL = QL.getUnqualifiedLoc();
68      } else if (AttributedTypeLoc Attr = TL.getAs<AttributedTypeLoc>()) {
69        if (handleAttr(Attr, D))
70          break;
71        TL = Attr.getModifiedLoc();
72      } else if (ArrayTypeLoc Arr = TL.getAs<ArrayTypeLoc>()) {
73        TL = Arr.getElementLoc();
74      } else if (PointerTypeLoc PT = TL.getAs<PointerTypeLoc>()) {
75        TL = PT.getPointeeLoc();
76      } else if (ReferenceTypeLoc RT = TL.getAs<ReferenceTypeLoc>())
77        TL = RT.getPointeeLoc();
78      else
79        break;
80    }
81  }
82
83  bool handleAttr(AttributedTypeLoc TL, Decl *D = nullptr) {
84    if (TL.getAttrKind() != AttributedType::attr_objc_ownership)
85      return false;
86
87    SourceLocation Loc = TL.getAttrNameLoc();
88    unsigned RawLoc = Loc.getRawEncoding();
89    if (MigrateCtx.AttrSet.count(RawLoc))
90      return true;
91
92    ASTContext &Ctx = MigrateCtx.Pass.Ctx;
93    SourceManager &SM = Ctx.getSourceManager();
94    if (Loc.isMacroID())
95      Loc = SM.getImmediateExpansionRange(Loc).first;
96    SmallString<32> Buf;
97    bool Invalid = false;
98    StringRef Spell = Lexer::getSpelling(
99                                  SM.getSpellingLoc(TL.getAttrEnumOperandLoc()),
100                                  Buf, SM, Ctx.getLangOpts(), &Invalid);
101    if (Invalid)
102      return false;
103    MigrationContext::GCAttrOccurrence::AttrKind Kind;
104    if (Spell == "strong")
105      Kind = MigrationContext::GCAttrOccurrence::Strong;
106    else if (Spell == "weak")
107      Kind = MigrationContext::GCAttrOccurrence::Weak;
108    else
109      return false;
110
111    MigrateCtx.AttrSet.insert(RawLoc);
112    MigrateCtx.GCAttrs.push_back(MigrationContext::GCAttrOccurrence());
113    MigrationContext::GCAttrOccurrence &Attr = MigrateCtx.GCAttrs.back();
114
115    Attr.Kind = Kind;
116    Attr.Loc = Loc;
117    Attr.ModifiedType = TL.getModifiedLoc().getType();
118    Attr.Dcl = D;
119    Attr.FullyMigratable = FullyMigratable;
120    return true;
121  }
122
123  bool isMigratable(Decl *D) {
124    if (isa<TranslationUnitDecl>(D))
125      return false;
126
127    if (isInMainFile(D))
128      return true;
129
130    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
131      return FD->hasBody();
132
133    if (ObjCContainerDecl *ContD = dyn_cast<ObjCContainerDecl>(D))
134      return hasObjCImpl(ContD);
135
136    if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
137      for (const auto *MI : RD->methods()) {
138        if (MI->isOutOfLine())
139          return true;
140      }
141      return false;
142    }
143
144    return isMigratable(cast<Decl>(D->getDeclContext()));
145  }
146
147  static bool hasObjCImpl(Decl *D) {
148    if (!D)
149      return false;
150    if (ObjCContainerDecl *ContD = dyn_cast<ObjCContainerDecl>(D)) {
151      if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(ContD))
152        return ID->getImplementation() != nullptr;
153      if (ObjCCategoryDecl *CD = dyn_cast<ObjCCategoryDecl>(ContD))
154        return CD->getImplementation() != nullptr;
155      return isa<ObjCImplDecl>(ContD);
156    }
157    return false;
158  }
159
160  bool isInMainFile(Decl *D) {
161    if (!D)
162      return false;
163
164    for (auto I : D->redecls())
165      if (!isInMainFile(I->getLocation()))
166        return false;
167
168    return true;
169  }
170
171  bool isInMainFile(SourceLocation Loc) {
172    if (Loc.isInvalid())
173      return false;
174
175    SourceManager &SM = MigrateCtx.Pass.Ctx.getSourceManager();
176    return SM.isInFileID(SM.getExpansionLoc(Loc), SM.getMainFileID());
177  }
178};
179
180} // anonymous namespace
181
182static void errorForGCAttrsOnNonObjC(MigrationContext &MigrateCtx) {
183  TransformActions &TA = MigrateCtx.Pass.TA;
184
185  for (unsigned i = 0, e = MigrateCtx.GCAttrs.size(); i != e; ++i) {
186    MigrationContext::GCAttrOccurrence &Attr = MigrateCtx.GCAttrs[i];
187    if (Attr.FullyMigratable && Attr.Dcl) {
188      if (Attr.ModifiedType.isNull())
189        continue;
190      if (!Attr.ModifiedType->isObjCRetainableType()) {
191        TA.reportError("GC managed memory will become unmanaged in ARC",
192                       Attr.Loc);
193      }
194    }
195  }
196}
197
198static void checkWeakGCAttrs(MigrationContext &MigrateCtx) {
199  TransformActions &TA = MigrateCtx.Pass.TA;
200
201  for (unsigned i = 0, e = MigrateCtx.GCAttrs.size(); i != e; ++i) {
202    MigrationContext::GCAttrOccurrence &Attr = MigrateCtx.GCAttrs[i];
203    if (Attr.Kind == MigrationContext::GCAttrOccurrence::Weak) {
204      if (Attr.ModifiedType.isNull() ||
205          !Attr.ModifiedType->isObjCRetainableType())
206        continue;
207      if (!canApplyWeak(MigrateCtx.Pass.Ctx, Attr.ModifiedType,
208                        /*AllowOnUnknownClass=*/true)) {
209        Transaction Trans(TA);
210        if (!MigrateCtx.RemovedAttrSet.count(Attr.Loc.getRawEncoding()))
211          TA.replaceText(Attr.Loc, "__weak", "__unsafe_unretained");
212        TA.clearDiagnostic(diag::err_arc_weak_no_runtime,
213                           diag::err_arc_unsupported_weak_class,
214                           Attr.Loc);
215      }
216    }
217  }
218}
219
220typedef llvm::TinyPtrVector<ObjCPropertyDecl *> IndivPropsTy;
221
222static void checkAllAtProps(MigrationContext &MigrateCtx,
223                            SourceLocation AtLoc,
224                            IndivPropsTy &IndProps) {
225  if (IndProps.empty())
226    return;
227
228  for (IndivPropsTy::iterator
229         PI = IndProps.begin(), PE = IndProps.end(); PI != PE; ++PI) {
230    QualType T = (*PI)->getType();
231    if (T.isNull() || !T->isObjCRetainableType())
232      return;
233  }
234
235  SmallVector<std::pair<AttributedTypeLoc, ObjCPropertyDecl *>, 4> ATLs;
236  bool hasWeak = false, hasStrong = false;
237  ObjCPropertyDecl::PropertyAttributeKind
238    Attrs = ObjCPropertyDecl::OBJC_PR_noattr;
239  for (IndivPropsTy::iterator
240         PI = IndProps.begin(), PE = IndProps.end(); PI != PE; ++PI) {
241    ObjCPropertyDecl *PD = *PI;
242    Attrs = PD->getPropertyAttributesAsWritten();
243    TypeSourceInfo *TInfo = PD->getTypeSourceInfo();
244    if (!TInfo)
245      return;
246    TypeLoc TL = TInfo->getTypeLoc();
247    if (AttributedTypeLoc ATL =
248            TL.getAs<AttributedTypeLoc>()) {
249      ATLs.push_back(std::make_pair(ATL, PD));
250      if (TInfo->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
251        hasWeak = true;
252      } else if (TInfo->getType().getObjCLifetime() == Qualifiers::OCL_Strong)
253        hasStrong = true;
254      else
255        return;
256    }
257  }
258  if (ATLs.empty())
259    return;
260  if (hasWeak && hasStrong)
261    return;
262
263  TransformActions &TA = MigrateCtx.Pass.TA;
264  Transaction Trans(TA);
265
266  if (GCAttrsCollector::hasObjCImpl(
267                              cast<Decl>(IndProps.front()->getDeclContext()))) {
268    if (hasWeak)
269      MigrateCtx.AtPropsWeak.insert(AtLoc.getRawEncoding());
270
271  } else {
272    StringRef toAttr = "strong";
273    if (hasWeak) {
274      if (canApplyWeak(MigrateCtx.Pass.Ctx, IndProps.front()->getType(),
275                       /*AllowOnUnkwownClass=*/true))
276        toAttr = "weak";
277      else
278        toAttr = "unsafe_unretained";
279    }
280    if (Attrs & ObjCPropertyDecl::OBJC_PR_assign)
281      MigrateCtx.rewritePropertyAttribute("assign", toAttr, AtLoc);
282    else
283      MigrateCtx.addPropertyAttribute(toAttr, AtLoc);
284  }
285
286  for (unsigned i = 0, e = ATLs.size(); i != e; ++i) {
287    SourceLocation Loc = ATLs[i].first.getAttrNameLoc();
288    if (Loc.isMacroID())
289      Loc = MigrateCtx.Pass.Ctx.getSourceManager()
290                                         .getImmediateExpansionRange(Loc).first;
291    TA.remove(Loc);
292    TA.clearDiagnostic(diag::err_objc_property_attr_mutually_exclusive, AtLoc);
293    TA.clearDiagnostic(diag::err_arc_inconsistent_property_ownership,
294                       ATLs[i].second->getLocation());
295    MigrateCtx.RemovedAttrSet.insert(Loc.getRawEncoding());
296  }
297}
298
299static void checkAllProps(MigrationContext &MigrateCtx,
300                          std::vector<ObjCPropertyDecl *> &AllProps) {
301  typedef llvm::TinyPtrVector<ObjCPropertyDecl *> IndivPropsTy;
302  llvm::DenseMap<unsigned, IndivPropsTy> AtProps;
303
304  for (unsigned i = 0, e = AllProps.size(); i != e; ++i) {
305    ObjCPropertyDecl *PD = AllProps[i];
306    if (PD->getPropertyAttributesAsWritten() &
307          (ObjCPropertyDecl::OBJC_PR_assign |
308           ObjCPropertyDecl::OBJC_PR_readonly)) {
309      SourceLocation AtLoc = PD->getAtLoc();
310      if (AtLoc.isInvalid())
311        continue;
312      unsigned RawAt = AtLoc.getRawEncoding();
313      AtProps[RawAt].push_back(PD);
314    }
315  }
316
317  for (llvm::DenseMap<unsigned, IndivPropsTy>::iterator
318         I = AtProps.begin(), E = AtProps.end(); I != E; ++I) {
319    SourceLocation AtLoc = SourceLocation::getFromRawEncoding(I->first);
320    IndivPropsTy &IndProps = I->second;
321    checkAllAtProps(MigrateCtx, AtLoc, IndProps);
322  }
323}
324
325void GCAttrsTraverser::traverseTU(MigrationContext &MigrateCtx) {
326  std::vector<ObjCPropertyDecl *> AllProps;
327  GCAttrsCollector(MigrateCtx, AllProps).TraverseDecl(
328                                  MigrateCtx.Pass.Ctx.getTranslationUnitDecl());
329
330  errorForGCAttrsOnNonObjC(MigrateCtx);
331  checkAllProps(MigrateCtx, AllProps);
332  checkWeakGCAttrs(MigrateCtx);
333}
334
335void MigrationContext::dumpGCAttrs() {
336  llvm::errs() << "\n################\n";
337  for (unsigned i = 0, e = GCAttrs.size(); i != e; ++i) {
338    GCAttrOccurrence &Attr = GCAttrs[i];
339    llvm::errs() << "KIND: "
340        << (Attr.Kind == GCAttrOccurrence::Strong ? "strong" : "weak");
341    llvm::errs() << "\nLOC: ";
342    Attr.Loc.dump(Pass.Ctx.getSourceManager());
343    llvm::errs() << "\nTYPE: ";
344    Attr.ModifiedType.dump();
345    if (Attr.Dcl) {
346      llvm::errs() << "DECL:\n";
347      Attr.Dcl->dump();
348    } else {
349      llvm::errs() << "DECL: NONE";
350    }
351    llvm::errs() << "\nMIGRATABLE: " << Attr.FullyMigratable;
352    llvm::errs() << "\n----------------\n";
353  }
354  llvm::errs() << "\n################\n";
355}
356