clang  14.0.0git
TransProperties.cpp
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1 //===--- TransProperties.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 // rewriteProperties:
10 //
11 // - Adds strong/weak/unsafe_unretained ownership specifier to properties that
12 // are missing one.
13 // - Migrates properties from (retain) to (strong) and (assign) to
14 // (unsafe_unretained/weak).
15 // - If a property is synthesized, adds the ownership specifier in the ivar
16 // backing the property.
17 //
18 // @interface Foo : NSObject {
19 // NSObject *x;
20 // }
21 // @property (assign) id x;
22 // @end
23 // ---->
24 // @interface Foo : NSObject {
25 // NSObject *__weak x;
26 // }
27 // @property (weak) id x;
28 // @end
29 //
30 //===----------------------------------------------------------------------===//
31 
32 #include "Transforms.h"
33 #include "Internals.h"
35 #include "clang/Lex/Lexer.h"
37 #include <map>
38 
39 using namespace clang;
40 using namespace arcmt;
41 using namespace trans;
42 
43 namespace {
44 
45 class PropertiesRewriter {
46  MigrationContext &MigrateCtx;
47  MigrationPass &Pass;
48  ObjCImplementationDecl *CurImplD;
49 
50  enum PropActionKind {
51  PropAction_None,
52  PropAction_RetainReplacedWithStrong,
53  PropAction_AssignRemoved,
54  PropAction_AssignRewritten,
55  PropAction_MaybeAddWeakOrUnsafe
56  };
57 
58  struct PropData {
59  ObjCPropertyDecl *PropD;
60  ObjCIvarDecl *IvarD;
61  ObjCPropertyImplDecl *ImplD;
62 
63  PropData(ObjCPropertyDecl *propD)
64  : PropD(propD), IvarD(nullptr), ImplD(nullptr) {}
65  };
66 
67  typedef SmallVector<PropData, 2> PropsTy;
68  typedef std::map<SourceLocation, PropsTy> AtPropDeclsTy;
69  AtPropDeclsTy AtProps;
70  llvm::DenseMap<IdentifierInfo *, PropActionKind> ActionOnProp;
71 
72 public:
73  explicit PropertiesRewriter(MigrationContext &MigrateCtx)
74  : MigrateCtx(MigrateCtx), Pass(MigrateCtx.Pass) { }
75 
76  static void collectProperties(ObjCContainerDecl *D, AtPropDeclsTy &AtProps,
77  AtPropDeclsTy *PrevAtProps = nullptr) {
78  for (auto *Prop : D->instance_properties()) {
79  SourceLocation Loc = Prop->getAtLoc();
80  if (Loc.isInvalid())
81  continue;
82  if (PrevAtProps)
83  if (PrevAtProps->find(Loc) != PrevAtProps->end())
84  continue;
85  PropsTy &props = AtProps[Loc];
86  props.push_back(Prop);
87  }
88  }
89 
90  void doTransform(ObjCImplementationDecl *D) {
91  CurImplD = D;
93  if (!iface)
94  return;
95 
96  collectProperties(iface, AtProps);
97 
98  // Look through extensions.
99  for (auto *Ext : iface->visible_extensions())
100  collectProperties(Ext, AtProps);
101 
103  prop_impl_iterator;
104  for (prop_impl_iterator
105  I = prop_impl_iterator(D->decls_begin()),
106  E = prop_impl_iterator(D->decls_end()); I != E; ++I) {
107  ObjCPropertyImplDecl *implD = *I;
109  continue;
110  ObjCPropertyDecl *propD = implD->getPropertyDecl();
111  if (!propD || propD->isInvalidDecl())
112  continue;
113  ObjCIvarDecl *ivarD = implD->getPropertyIvarDecl();
114  if (!ivarD || ivarD->isInvalidDecl())
115  continue;
116  AtPropDeclsTy::iterator findAtLoc = AtProps.find(propD->getAtLoc());
117  if (findAtLoc == AtProps.end())
118  continue;
119 
120  PropsTy &props = findAtLoc->second;
121  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
122  if (I->PropD == propD) {
123  I->IvarD = ivarD;
124  I->ImplD = implD;
125  break;
126  }
127  }
128  }
129 
130  for (AtPropDeclsTy::iterator
131  I = AtProps.begin(), E = AtProps.end(); I != E; ++I) {
132  SourceLocation atLoc = I->first;
133  PropsTy &props = I->second;
134  if (!getPropertyType(props)->isObjCRetainableType())
135  continue;
136  if (hasIvarWithExplicitARCOwnership(props))
137  continue;
138 
139  Transaction Trans(Pass.TA);
140  rewriteProperty(props, atLoc);
141  }
142  }
143 
144 private:
145  void doPropAction(PropActionKind kind,
146  PropsTy &props, SourceLocation atLoc,
147  bool markAction = true) {
148  if (markAction)
149  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I)
150  ActionOnProp[I->PropD->getIdentifier()] = kind;
151 
152  switch (kind) {
153  case PropAction_None:
154  return;
155  case PropAction_RetainReplacedWithStrong: {
156  StringRef toAttr = "strong";
157  MigrateCtx.rewritePropertyAttribute("retain", toAttr, atLoc);
158  return;
159  }
160  case PropAction_AssignRemoved:
161  return removeAssignForDefaultStrong(props, atLoc);
162  case PropAction_AssignRewritten:
163  return rewriteAssign(props, atLoc);
164  case PropAction_MaybeAddWeakOrUnsafe:
165  return maybeAddWeakOrUnsafeUnretainedAttr(props, atLoc);
166  }
167  }
168 
169  void rewriteProperty(PropsTy &props, SourceLocation atLoc) {
170  ObjCPropertyAttribute::Kind propAttrs = getPropertyAttrs(props);
171 
172  if (propAttrs &
176  return;
177 
178  if (propAttrs & ObjCPropertyAttribute::kind_retain) {
179  // strong is the default.
180  return doPropAction(PropAction_RetainReplacedWithStrong, props, atLoc);
181  }
182 
183  bool HasIvarAssignedAPlusOneObject = hasIvarAssignedAPlusOneObject(props);
184 
185  if (propAttrs & ObjCPropertyAttribute::kind_assign) {
186  if (HasIvarAssignedAPlusOneObject)
187  return doPropAction(PropAction_AssignRemoved, props, atLoc);
188  return doPropAction(PropAction_AssignRewritten, props, atLoc);
189  }
190 
191  if (HasIvarAssignedAPlusOneObject ||
192  (Pass.isGCMigration() && !hasGCWeak(props, atLoc)))
193  return; // 'strong' by default.
194 
195  return doPropAction(PropAction_MaybeAddWeakOrUnsafe, props, atLoc);
196  }
197 
198  void removeAssignForDefaultStrong(PropsTy &props,
199  SourceLocation atLoc) const {
200  removeAttribute("retain", atLoc);
201  if (!removeAttribute("assign", atLoc))
202  return;
203 
204  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
205  if (I->ImplD)
206  Pass.TA.clearDiagnostic(diag::err_arc_strong_property_ownership,
207  diag::err_arc_assign_property_ownership,
208  diag::err_arc_inconsistent_property_ownership,
209  I->IvarD->getLocation());
210  }
211  }
212 
213  void rewriteAssign(PropsTy &props, SourceLocation atLoc) const {
214  bool canUseWeak = canApplyWeak(Pass.Ctx, getPropertyType(props),
215  /*AllowOnUnknownClass=*/Pass.isGCMigration());
216  const char *toWhich =
217  (Pass.isGCMigration() && !hasGCWeak(props, atLoc)) ? "strong" :
218  (canUseWeak ? "weak" : "unsafe_unretained");
219 
220  bool rewroteAttr = rewriteAttribute("assign", toWhich, atLoc);
221  if (!rewroteAttr)
222  canUseWeak = false;
223 
224  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
225  if (isUserDeclared(I->IvarD)) {
226  if (I->IvarD &&
227  I->IvarD->getType().getObjCLifetime() != Qualifiers::OCL_Weak) {
228  const char *toWhich =
229  (Pass.isGCMigration() && !hasGCWeak(props, atLoc)) ? "__strong " :
230  (canUseWeak ? "__weak " : "__unsafe_unretained ");
231  Pass.TA.insert(I->IvarD->getLocation(), toWhich);
232  }
233  }
234  if (I->ImplD)
235  Pass.TA.clearDiagnostic(diag::err_arc_strong_property_ownership,
236  diag::err_arc_assign_property_ownership,
237  diag::err_arc_inconsistent_property_ownership,
238  I->IvarD->getLocation());
239  }
240  }
241 
242  void maybeAddWeakOrUnsafeUnretainedAttr(PropsTy &props,
243  SourceLocation atLoc) const {
244  bool canUseWeak = canApplyWeak(Pass.Ctx, getPropertyType(props),
245  /*AllowOnUnknownClass=*/Pass.isGCMigration());
246 
247  bool addedAttr = addAttribute(canUseWeak ? "weak" : "unsafe_unretained",
248  atLoc);
249  if (!addedAttr)
250  canUseWeak = false;
251 
252  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
253  if (isUserDeclared(I->IvarD)) {
254  if (I->IvarD &&
255  I->IvarD->getType().getObjCLifetime() != Qualifiers::OCL_Weak)
256  Pass.TA.insert(I->IvarD->getLocation(),
257  canUseWeak ? "__weak " : "__unsafe_unretained ");
258  }
259  if (I->ImplD) {
260  Pass.TA.clearDiagnostic(diag::err_arc_strong_property_ownership,
261  diag::err_arc_assign_property_ownership,
262  diag::err_arc_inconsistent_property_ownership,
263  I->IvarD->getLocation());
264  Pass.TA.clearDiagnostic(
265  diag::err_arc_objc_property_default_assign_on_object,
266  I->ImplD->getLocation());
267  }
268  }
269  }
270 
271  bool removeAttribute(StringRef fromAttr, SourceLocation atLoc) const {
272  return MigrateCtx.removePropertyAttribute(fromAttr, atLoc);
273  }
274 
275  bool rewriteAttribute(StringRef fromAttr, StringRef toAttr,
276  SourceLocation atLoc) const {
277  return MigrateCtx.rewritePropertyAttribute(fromAttr, toAttr, atLoc);
278  }
279 
280  bool addAttribute(StringRef attr, SourceLocation atLoc) const {
281  return MigrateCtx.addPropertyAttribute(attr, atLoc);
282  }
283 
284  class PlusOneAssign : public RecursiveASTVisitor<PlusOneAssign> {
285  ObjCIvarDecl *Ivar;
286  public:
287  PlusOneAssign(ObjCIvarDecl *D) : Ivar(D) {}
288 
289  bool VisitBinaryOperator(BinaryOperator *E) {
290  if (E->getOpcode() != BO_Assign)
291  return true;
292 
293  Expr *lhs = E->getLHS()->IgnoreParenImpCasts();
294  if (ObjCIvarRefExpr *RE = dyn_cast<ObjCIvarRefExpr>(lhs)) {
295  if (RE->getDecl() != Ivar)
296  return true;
297 
298  if (isPlusOneAssign(E))
299  return false;
300  }
301 
302  return true;
303  }
304  };
305 
306  bool hasIvarAssignedAPlusOneObject(PropsTy &props) const {
307  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
308  PlusOneAssign oneAssign(I->IvarD);
309  bool notFound = oneAssign.TraverseDecl(CurImplD);
310  if (!notFound)
311  return true;
312  }
313 
314  return false;
315  }
316 
317  bool hasIvarWithExplicitARCOwnership(PropsTy &props) const {
318  if (Pass.isGCMigration())
319  return false;
320 
321  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I) {
322  if (isUserDeclared(I->IvarD)) {
323  if (isa<AttributedType>(I->IvarD->getType()))
324  return true;
325  if (I->IvarD->getType().getLocalQualifiers().getObjCLifetime()
327  return true;
328  }
329  }
330 
331  return false;
332  }
333 
334  // Returns true if all declarations in the @property have GC __weak.
335  bool hasGCWeak(PropsTy &props, SourceLocation atLoc) const {
336  if (!Pass.isGCMigration())
337  return false;
338  if (props.empty())
339  return false;
340  return MigrateCtx.AtPropsWeak.count(atLoc);
341  }
342 
343  bool isUserDeclared(ObjCIvarDecl *ivarD) const {
344  return ivarD && !ivarD->getSynthesize();
345  }
346 
347  QualType getPropertyType(PropsTy &props) const {
348  assert(!props.empty());
349  QualType ty = props[0].PropD->getType().getUnqualifiedType();
350 
351 #ifndef NDEBUG
352  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I)
353  assert(ty == I->PropD->getType().getUnqualifiedType());
354 #endif
355 
356  return ty;
357  }
358 
359  ObjCPropertyAttribute::Kind getPropertyAttrs(PropsTy &props) const {
360  assert(!props.empty());
362  props[0].PropD->getPropertyAttributesAsWritten();
363 
364 #ifndef NDEBUG
365  for (PropsTy::iterator I = props.begin(), E = props.end(); I != E; ++I)
366  assert(attrs == I->PropD->getPropertyAttributesAsWritten());
367 #endif
368 
369  return attrs;
370  }
371 };
372 
373 } // anonymous namespace
374 
376  ObjCImplementationContext &ImplCtx) {
377  PropertiesRewriter(ImplCtx.getMigrationContext())
378  .doTransform(ImplCtx.getImplementationDecl());
379 }
clang::ObjCInterfaceDecl
Represents an ObjC class declaration.
Definition: DeclObjC.h:1151
clang::ObjCPropertyImplDecl::getPropertyIvarDecl
ObjCIvarDecl * getPropertyIvarDecl() const
Definition: DeclObjC.h:2824
clang::DeclContext::decls_end
decl_iterator decls_end() const
Definition: DeclBase.h:2117
clang::DeclContext::specific_decl_iterator
specific_decl_iterator - Iterates over a subrange of declarations stored in a DeclContext,...
Definition: DeclBase.h:2135
clang::arcmt::trans::isPlusOneAssign
bool isPlusOneAssign(const BinaryOperator *E)
Definition: Transforms.cpp:67
clang::arcmt::MigrationPass
Definition: Internals.h:146
clang::ObjCImplementationDecl
ObjCImplementationDecl - Represents a class definition - this is where method definitions are specifi...
Definition: DeclObjC.h:2546
Transforms.h
clang::Qualifiers::OCL_Weak
@ OCL_Weak
Reading or writing from this object requires a barrier call.
Definition: Type.h:176
llvm::SmallVector
Definition: LLVM.h:38
clang::SourceLocation
Encodes a location in the source.
Definition: SourceLocation.h:88
clang::arcmt::trans::MigrationContext::removePropertyAttribute
bool removePropertyAttribute(StringRef fromAttr, SourceLocation atLoc)
Definition: Transforms.h:115
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:673
clang::ObjCPropertyImplDecl
ObjCPropertyImplDecl - Represents implementation declaration of a property in a class or category imp...
Definition: DeclObjC.h:2751
Internals.h
SourceManager.h
clang::ObjCInterfaceDecl::visible_extensions
visible_extensions_range visible_extensions() const
Definition: DeclObjC.h:1702
clang::BinaryOperator::getOpcode
Opcode getOpcode() const
Definition: Expr.h:3847
clang::arcmt::MigrationPass::TA
TransformActions & TA
Definition: Internals.h:152
clang::ObjCPropertyAttribute::kind_strong
@ kind_strong
Definition: DeclObjCCommon.h:34
clang::ObjCImplDecl::getClassInterface
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2434
clang::arcmt::MigrationPass::isGCMigration
bool isGCMigration() const
Definition: Internals.h:167
clang::ObjCPropertyAttribute::kind_copy
@ kind_copy
Definition: DeclObjCCommon.h:29
clang::ast_matchers::attr
const internal::VariadicAllOfMatcher< Attr > attr
Matches attributes.
Definition: ASTMatchersInternal.cpp:1029
clang::BinaryOperator
A builtin binary operation expression such as "x + y" or "x <= y".
Definition: Expr.h:3803
clang::arcmt::Transaction
Definition: Internals.h:124
clang::Qualifiers::OCL_Strong
@ OCL_Strong
Assigning into this object requires the old value to be released and the new value to be retained.
Definition: Type.h:173
clang::ObjCPropertyImplDecl::Synthesize
@ Synthesize
Definition: DeclObjC.h:2754
clang::ObjCPropertyAttribute::kind_weak
@ kind_weak
Definition: DeclObjCCommon.h:33
clang::ObjCPropertyAttribute::kind_unsafe_unretained
@ kind_unsafe_unretained
Definition: DeclObjCCommon.h:35
clang::arcmt::trans::MigrationContext
Definition: Transforms.h:80
clang::arcmt::trans::ObjCImplementationContext::getMigrationContext
MigrationContext & getMigrationContext()
Definition: Transforms.h:68
clang::RecursiveASTVisitor
A class that does preorder or postorder depth-first traversal on the entire Clang AST and visits each...
Definition: RecursiveASTVisitor.h:164
clang::arcmt::trans::MigrationContext::addPropertyAttribute
bool addPropertyAttribute(StringRef attr, SourceLocation atLoc)
Definition: Transforms.cpp:460
clang::Decl::isInvalidDecl
bool isInvalidDecl() const
Definition: DeclBase.h:558
clang::arcmt::TransformActions::insert
void insert(SourceLocation loc, StringRef text)
Definition: TransformActions.cpp:629
clang::ObjCIvarDecl::getSynthesize
bool getSynthesize() const
Definition: DeclObjC.h:1977
clang::arcmt::MigrationPass::Ctx
ASTContext & Ctx
Definition: Internals.h:148
SemaDiagnostic.h
clang::BinaryOperator::getLHS
Expr * getLHS() const
Definition: Expr.h:3852
Lexer.h
clang::Expr::IgnoreParenImpCasts
Expr * IgnoreParenImpCasts() LLVM_READONLY
Skip past any parentheses and implicit casts which might surround this expression until reaching a fi...
Definition: Expr.cpp:2919
clang::ObjCPropertyDecl
Represents one property declaration in an Objective-C interface.
Definition: DeclObjC.h:732
clang::arcmt::trans::ObjCImplementationContext::getImplementationDecl
ObjCImplementationDecl * getImplementationDecl()
Definition: Transforms.h:69
clang::ObjCPropertyAttribute::kind_assign
@ kind_assign
Definition: DeclObjCCommon.h:26
clang::ObjCPropertyImplDecl::getPropertyImplementation
Kind getPropertyImplementation() const
Definition: DeclObjC.h:2820
clang::ObjCPropertyImplDecl::getPropertyDecl
ObjCPropertyDecl * getPropertyDecl() const
Definition: DeclObjC.h:2815
clang::ObjCPropertyAttribute::Kind
Kind
Definition: DeclObjCCommon.h:22
clang::SourceLocation::isInvalid
bool isInvalid() const
Definition: SourceLocation.h:113
clang
Definition: CalledOnceCheck.h:17
clang::ObjCIvarDecl
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1924
clang::arcmt::trans::canApplyWeak
bool canApplyWeak(ASTContext &Ctx, QualType type, bool AllowOnUnknownClass=false)
Determine whether we can add weak to the given type.
Definition: Transforms.cpp:38
clang::arcmt::trans::MigrationContext::AtPropsWeak
llvm::DenseSet< SourceLocation > AtPropsWeak
Set of raw '@' locations for 'assign' properties group that contain GC __weak.
Definition: Transforms.h:101
clang::ObjCContainerDecl
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:948
clang::ObjCContainerDecl::instance_properties
instprop_range instance_properties() const
Definition: DeclObjC.h:982
clang::arcmt::trans::ObjCImplementationContext
Definition: Transforms.h:59
clang::ObjCPropertyDecl::getAtLoc
SourceLocation getAtLoc() const
Definition: DeclObjC.h:796
clang::arcmt::TransformActions::clearDiagnostic
bool clearDiagnostic(ArrayRef< unsigned > IDs, SourceRange range)
Definition: TransformActions.cpp:671
clang::arcmt::trans::MigrationContext::rewritePropertyAttribute
bool rewritePropertyAttribute(StringRef fromAttr, StringRef toAttr, SourceLocation atLoc)
Definition: Transforms.cpp:378
clang::Expr
This represents one expression.
Definition: Expr.h:109
clang::arcmt::trans::PropertyRewriteTraverser::traverseObjCImplementation
void traverseObjCImplementation(ObjCImplementationContext &ImplCtx) override
Definition: TransProperties.cpp:375
clang::diag::kind
unsigned kind
All of the diagnostics that can be emitted by the frontend.
Definition: DiagnosticIDs.h:62
clang::ObjCPropertyAttribute::kind_retain
@ kind_retain
Definition: DeclObjCCommon.h:28
clang::ObjCIvarRefExpr
ObjCIvarRefExpr - A reference to an ObjC instance variable.
Definition: ExprObjC.h:548
clang::DeclContext::decls_begin
decl_iterator decls_begin() const
Definition: DeclBase.cpp:1419