clang  3.7.0
CGObjCRuntime.cpp
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1 //==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
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 // This abstract class defines the interface for Objective-C runtime-specific
11 // code generation. It provides some concrete helper methods for functionality
12 // shared between all (or most) of the Objective-C runtimes supported by clang.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "CGObjCRuntime.h"
17 #include "CGCleanup.h"
18 #include "CGRecordLayout.h"
19 #include "CodeGenFunction.h"
20 #include "CodeGenModule.h"
21 #include "clang/AST/RecordLayout.h"
22 #include "clang/AST/StmtObjC.h"
24 #include "llvm/IR/CallSite.h"
25 
26 using namespace clang;
27 using namespace CodeGen;
28 
30  const ObjCInterfaceDecl *OID,
32  const ObjCIvarDecl *Ivar) {
33  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
34 
35  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
36  // in here; it should never be necessary because that should be the lexical
37  // decl context for the ivar.
38 
39  // If we know have an implementation (and the ivar is in it) then
40  // look up in the implementation layout.
41  const ASTRecordLayout *RL;
42  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
44  else
45  RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
46 
47  // Compute field index.
48  //
49  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
50  // implemented. This should be fixed to get the information from the layout
51  // directly.
52  unsigned Index = 0;
53 
54  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
55  IVD; IVD = IVD->getNextIvar()) {
56  if (Ivar == IVD)
57  break;
58  ++Index;
59  }
60  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
61 
62  return RL->getFieldOffset(Index);
63 }
64 
66  const ObjCInterfaceDecl *OID,
67  const ObjCIvarDecl *Ivar) {
68  return LookupFieldBitOffset(CGM, OID, nullptr, Ivar) /
69  CGM.getContext().getCharWidth();
70 }
71 
73  const ObjCImplementationDecl *OID,
74  const ObjCIvarDecl *Ivar) {
75  return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
76  CGM.getContext().getCharWidth();
77 }
78 
81  const ObjCInterfaceDecl *ID,
82  const ObjCIvarDecl *Ivar) {
83  return LookupFieldBitOffset(CGM, ID, ID->getImplementation(), Ivar);
84 }
85 
87  const ObjCInterfaceDecl *OID,
88  llvm::Value *BaseValue,
89  const ObjCIvarDecl *Ivar,
90  unsigned CVRQualifiers,
92  // Compute (type*) ( (char *) BaseValue + Offset)
93  QualType IvarTy = Ivar->getType();
94  llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
95  llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
96  V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
97 
98  if (!Ivar->isBitField()) {
99  V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
100  LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
101  LV.getQuals().addCVRQualifiers(CVRQualifiers);
102  return LV;
103  }
104 
105  // We need to compute an access strategy for this bit-field. We are given the
106  // offset to the first byte in the bit-field, the sub-byte offset is taken
107  // from the original layout. We reuse the normal bit-field access strategy by
108  // treating this as an access to a struct where the bit-field is in byte 0,
109  // and adjust the containing type size as appropriate.
110  //
111  // FIXME: Note that currently we make a very conservative estimate of the
112  // alignment of the bit-field, because (a) it is not clear what guarantees the
113  // runtime makes us, and (b) we don't have a way to specify that the struct is
114  // at an alignment plus offset.
115  //
116  // Note, there is a subtle invariant here: we can only call this routine on
117  // non-synthesized ivars but we may be called for synthesized ivars. However,
118  // a synthesized ivar can never be a bit-field, so this is safe.
119  uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, nullptr, Ivar);
120  uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
121  uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
122  uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
123  CharUnits StorageSize =
125  llvm::RoundUpToAlignment(BitOffset + BitFieldSize, AlignmentBits));
126  CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
127 
128  // Allocate a new CGBitFieldInfo object to describe this access.
129  //
130  // FIXME: This is incredibly wasteful, these should be uniqued or part of some
131  // layout object. However, this is blocked on other cleanups to the
132  // Objective-C code, so for now we just live with allocating a bunch of these
133  // objects.
134  CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
135  CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
136  CGF.CGM.getContext().toBits(StorageSize),
138 
139  V = CGF.Builder.CreateBitCast(V,
140  llvm::Type::getIntNPtrTy(CGF.getLLVMContext(),
141  Info->StorageSize));
142  return LValue::MakeBitfield(V, *Info,
143  IvarTy.withCVRQualifiers(CVRQualifiers),
144  Alignment);
145 }
146 
147 namespace {
148  struct CatchHandler {
149  const VarDecl *Variable;
150  const Stmt *Body;
151  llvm::BasicBlock *Block;
152  llvm::Constant *TypeInfo;
153  };
154 
155  struct CallObjCEndCatch : EHScopeStack::Cleanup {
156  CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
157  MightThrow(MightThrow), Fn(Fn) {}
158  bool MightThrow;
159  llvm::Value *Fn;
160 
161  void Emit(CodeGenFunction &CGF, Flags flags) override {
162  if (!MightThrow) {
163  CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
164  return;
165  }
166 
167  CGF.EmitRuntimeCallOrInvoke(Fn);
168  }
169  };
170 }
171 
172 
174  const ObjCAtTryStmt &S,
175  llvm::Constant *beginCatchFn,
176  llvm::Constant *endCatchFn,
177  llvm::Constant *exceptionRethrowFn) {
178  // Jump destination for falling out of catch bodies.
180  if (S.getNumCatchStmts())
181  Cont = CGF.getJumpDestInCurrentScope("eh.cont");
182 
183  CodeGenFunction::FinallyInfo FinallyInfo;
184  if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
185  FinallyInfo.enter(CGF, Finally->getFinallyBody(),
186  beginCatchFn, endCatchFn, exceptionRethrowFn);
187 
189 
190  // Enter the catch, if there is one.
191  if (S.getNumCatchStmts()) {
192  for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
193  const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
194  const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
195 
196  Handlers.push_back(CatchHandler());
197  CatchHandler &Handler = Handlers.back();
198  Handler.Variable = CatchDecl;
199  Handler.Body = CatchStmt->getCatchBody();
200  Handler.Block = CGF.createBasicBlock("catch");
201 
202  // @catch(...) always matches.
203  if (!CatchDecl) {
204  Handler.TypeInfo = nullptr; // catch-all
205  // Don't consider any other catches.
206  break;
207  }
208 
209  Handler.TypeInfo = GetEHType(CatchDecl->getType());
210  }
211 
212  EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
213  for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
214  Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
215  }
216 
217  // Emit the try body.
218  CGF.EmitStmt(S.getTryBody());
219 
220  // Leave the try.
221  if (S.getNumCatchStmts())
222  CGF.popCatchScope();
223 
224  // Remember where we were.
225  CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
226 
227  // Emit the handlers.
228  for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
229  CatchHandler &Handler = Handlers[I];
230 
231  CGF.EmitBlock(Handler.Block);
232  llvm::Value *RawExn = CGF.getExceptionFromSlot();
233 
234  // Enter the catch.
235  llvm::Value *Exn = RawExn;
236  if (beginCatchFn) {
237  Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
238  cast<llvm::CallInst>(Exn)->setDoesNotThrow();
239  }
240 
241  CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
242 
243  if (endCatchFn) {
244  // Add a cleanup to leave the catch.
245  bool EndCatchMightThrow = (Handler.Variable == nullptr);
246 
247  CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
248  EndCatchMightThrow,
249  endCatchFn);
250  }
251 
252  // Bind the catch parameter if it exists.
253  if (const VarDecl *CatchParam = Handler.Variable) {
254  llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
255  llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
256 
257  CGF.EmitAutoVarDecl(*CatchParam);
258 
259  llvm::Value *CatchParamAddr = CGF.GetAddrOfLocalVar(CatchParam);
260 
261  switch (CatchParam->getType().getQualifiers().getObjCLifetime()) {
263  CastExn = CGF.EmitARCRetainNonBlock(CastExn);
264  // fallthrough
265 
269  CGF.Builder.CreateStore(CastExn, CatchParamAddr);
270  break;
271 
273  CGF.EmitARCInitWeak(CatchParamAddr, CastExn);
274  break;
275  }
276  }
277 
278  CGF.ObjCEHValueStack.push_back(Exn);
279  CGF.EmitStmt(Handler.Body);
280  CGF.ObjCEHValueStack.pop_back();
281 
282  // Leave any cleanups associated with the catch.
283  cleanups.ForceCleanup();
284 
285  CGF.EmitBranchThroughCleanup(Cont);
286  }
287 
288  // Go back to the try-statement fallthrough.
289  CGF.Builder.restoreIP(SavedIP);
290 
291  // Pop out of the finally.
292  if (S.getFinallyStmt())
293  FinallyInfo.exit(CGF);
294 
295  if (Cont.isValid())
296  CGF.EmitBlock(Cont.getBlock());
297 }
298 
299 namespace {
300  struct CallSyncExit : EHScopeStack::Cleanup {
301  llvm::Value *SyncExitFn;
302  llvm::Value *SyncArg;
303  CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
304  : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
305 
306  void Emit(CodeGenFunction &CGF, Flags flags) override {
307  CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
308  }
309  };
310 }
311 
313  const ObjCAtSynchronizedStmt &S,
314  llvm::Function *syncEnterFn,
315  llvm::Function *syncExitFn) {
316  CodeGenFunction::RunCleanupsScope cleanups(CGF);
317 
318  // Evaluate the lock operand. This is guaranteed to dominate the
319  // ARC release and lock-release cleanups.
320  const Expr *lockExpr = S.getSynchExpr();
321  llvm::Value *lock;
322  if (CGF.getLangOpts().ObjCAutoRefCount) {
323  lock = CGF.EmitARCRetainScalarExpr(lockExpr);
324  lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
325  } else {
326  lock = CGF.EmitScalarExpr(lockExpr);
327  }
328  lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
329 
330  // Acquire the lock.
331  CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
332 
333  // Register an all-paths cleanup to release the lock.
334  CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
335 
336  // Emit the body of the statement.
337  CGF.EmitStmt(S.getSynchBody());
338 }
339 
340 /// Compute the pointer-to-function type to which a message send
341 /// should be casted in order to correctly call the given method
342 /// with the given arguments.
343 ///
344 /// \param method - may be null
345 /// \param resultType - the result type to use if there's no method
346 /// \param callArgs - the actual arguments, including implicit ones
349  QualType resultType,
350  CallArgList &callArgs) {
351  // If there's a method, use information from that.
352  if (method) {
353  const CGFunctionInfo &signature =
354  CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
355 
356  llvm::PointerType *signatureType =
357  CGM.getTypes().GetFunctionType(signature)->getPointerTo();
358 
359  // If that's not variadic, there's no need to recompute the ABI
360  // arrangement.
361  if (!signature.isVariadic())
362  return MessageSendInfo(signature, signatureType);
363 
364  // Otherwise, there is.
365  FunctionType::ExtInfo einfo = signature.getExtInfo();
366  const CGFunctionInfo &argsInfo =
367  CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs, einfo,
368  signature.getRequiredArgs());
369 
370  return MessageSendInfo(argsInfo, signatureType);
371  }
372 
373  // There's no method; just use a default CC.
374  const CGFunctionInfo &argsInfo =
375  CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs,
378 
379  // Derive the signature to call from that.
380  llvm::PointerType *signatureType =
381  CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
382  return MessageSendInfo(argsInfo, signatureType);
383 }
const ObjCAtFinallyStmt * getFinallyStmt() const
Retrieve the @finally statement, if any.
Definition: StmtObjC.h:224
bool isBitField() const
Determines whether this field is a bitfield.
Definition: Decl.h:2330
void EmitAutoVarDecl(const VarDecl &D)
Definition: CGDecl.cpp:847
const LangOptions & getLangOpts() const
llvm::Value * EmitARCRetainNonBlock(llvm::Value *value)
Definition: CGObjC.cpp:1933
const ASTRecordLayout & getASTObjCImplementationLayout(const ObjCImplementationDecl *D) const
Get or compute information about the layout of the specified Objective-C implementation.
uint64_t ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM, const ObjCInterfaceDecl *OID, const ObjCIvarDecl *Ivar)
Defines the Objective-C statement AST node classes.
llvm::Type * ConvertTypeForMem(QualType T)
const ObjCInterfaceDecl * getContainingInterface() const
Return the class interface that this ivar is logically contained in; this is either the interface whe...
Definition: DeclObjC.cpp:1631
void EmitARCInitWeak(llvm::Value *value, llvm::Value *addr)
Definition: CGObjC.cpp:2214
const VarDecl * getCatchParamDecl() const
Definition: StmtObjC.h:94
class EHCatchScope * pushCatch(unsigned NumHandlers)
Definition: CGCleanup.cpp:232
Represents Objective-C's @catch statement.
Definition: StmtObjC.h:74
const CompoundStmt * getSynchBody() const
Definition: StmtObjC.h:282
A class controlling the emission of a finally block.
MessageSendInfo getMessageSendInfo(const ObjCMethodDecl *method, QualType resultType, CallArgList &callArgs)
const Qualifiers & getQuals() const
Definition: CGValue.h:256
uint32_t Offset
Definition: CacheTokens.cpp:43
static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM, const ObjCInterfaceDecl *OID, const ObjCImplementationDecl *ID, const ObjCIvarDecl *Ivar)
void addCVRQualifiers(unsigned mask)
Definition: Type.h:260
CodeGen::CodeGenModule & CGM
Definition: CGObjCRuntime.h:65
const CGFunctionInfo & arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD, QualType receiverType)
Definition: CGCall.cpp:295
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1006
const Stmt * getCatchBody() const
Definition: StmtObjC.h:90
void EmitStmt(const Stmt *S)
Definition: CGStmt.cpp:45
llvm::BasicBlock * createBasicBlock(const Twine &name="", llvm::Function *parent=nullptr, llvm::BasicBlock *before=nullptr)
createBasicBlock - Create an LLVM basic block.
uint64_t getFieldOffset(unsigned FieldNo) const
Definition: RecordLayout.h:181
llvm::Value * EmitARCRetainScalarExpr(const Expr *expr)
Definition: CGObjC.cpp:2731
const ObjCAtCatchStmt * getCatchStmt(unsigned I) const
Retrieve a @catch statement.
Definition: StmtObjC.h:206
Represents an ObjC class declaration.
Definition: DeclObjC.h:851
QualType getType() const
Definition: Decl.h:538
llvm::CallSite EmitRuntimeCallOrInvoke(llvm::Value *callee, ArrayRef< llvm::Value * > args, const Twine &name="")
Emits a call or invoke instruction to the given runtime function.
Definition: CGCall.cpp:3052
static CGBitFieldInfo MakeInfo(class CodeGenTypes &Types, const FieldDecl *FD, uint64_t Offset, uint64_t Size, uint64_t StorageSize, CharUnits StorageOffset)
Given a bit-field decl, build an appropriate helper object for accessing that field (which is expecte...
const TargetInfo & getTarget() const
ID
Defines the set of possible language-specific address spaces.
Definition: AddressSpaces.h:27
void enter(CodeGenFunction &CGF, const Stmt *Finally, llvm::Constant *beginCatchFn, llvm::Constant *endCatchFn, llvm::Constant *rethrowFn)
Enters a new scope for capturing cleanups, all of which will be executed once the scope is exited...
llvm::Value * GetAddrOfLocalVar(const VarDecl *VD)
GetAddrOfLocalVar - Return the address of a local variable.
ASTContext & getContext() const
llvm::BasicBlock * getBlock() const
Represents Objective-C's @synchronized statement.
Definition: StmtObjC.h:262
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
llvm::Value * getExceptionFromSlot()
void EmitAtSynchronizedStmt(CodeGenFunction &CGF, const ObjCAtSynchronizedStmt &S, llvm::Function *syncEnterFn, llvm::Function *syncExitFn)
llvm::LLVMContext & getLLVMContext()
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
LValue MakeNaturalAlignAddrLValue(llvm::Value *V, QualType T)
unsigned ComputeBitfieldBitOffset(CodeGen::CodeGenModule &CGM, const ObjCInterfaceDecl *ID, const ObjCIvarDecl *Ivar)
There is no lifetime qualification on this type.
Definition: Type.h:130
FunctionType::ExtInfo getExtInfo() const
ASTContext & getContext() const
RequiredArgs getRequiredArgs() const
QualType withCVRQualifiers(unsigned CVR) const
Definition: Type.h:756
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3344
SmallVector< llvm::Value *, 8 > ObjCEHValueStack
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2093
JumpDest getJumpDestInCurrentScope(llvm::BasicBlock *Target)
Assigning into this object requires a lifetime extension.
Definition: Type.h:147
llvm::Value * EmitScalarExpr(const Expr *E, bool IgnoreResultAssign=false)
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1645
QualType getType() const
Definition: Expr.h:125
static LValue MakeBitfield(llvm::Value *Addr, const CGBitFieldInfo &Info, QualType type, CharUnits Alignment)
Create a new object to represent a bit-field access.
Definition: CGValue.h:335
const Expr * getSynchExpr() const
Definition: StmtObjC.h:290
Represents Objective-C's @finally statement.
Definition: StmtObjC.h:120
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:1705
ObjCImplementationDecl * getImplementation() const
Definition: DeclObjC.cpp:1393
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
Definition: CGStmt.cpp:348
unsigned getNumCatchStmts() const
Retrieve the number of @catch statements in this try-catch-finally block.
Definition: StmtObjC.h:203
Reading or writing from this object requires a barrier call.
Definition: Type.h:144
llvm::Type * ConvertType(QualType T)
Represents Objective-C's @try ... @catch ... @finally statement.
Definition: StmtObjC.h:154
const Stmt * getTryBody() const
Retrieve the @try body.
Definition: StmtObjC.h:197
void EmitTryCatchStmt(CodeGenFunction &CGF, const ObjCAtTryStmt &S, llvm::Constant *beginCatchFn, llvm::Constant *endCatchFn, llvm::Constant *exceptionRethrowFn)
LValue EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF, const ObjCInterfaceDecl *OID, llvm::Value *BaseValue, const ObjCIvarDecl *Ivar, unsigned CVRQualifiers, llvm::Value *Offset)
const CGFunctionInfo & arrangeFreeFunctionCall(const CallArgList &Args, const FunctionType *Ty, bool ChainCall)
Definition: CGCall.cpp:414
void EmitBranchThroughCleanup(JumpDest Dest)
Definition: CGCleanup.cpp:940
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
ObjCIvarDecl * all_declared_ivar_begin()
Definition: DeclObjC.cpp:1433
llvm::Value * EmitObjCConsumeObject(QualType T, llvm::Value *Ptr)
Definition: CGObjC.cpp:1759
const ASTRecordLayout & getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D) const
Get or compute information about the layout of the specified Objective-C interface.
virtual llvm::Constant * GetEHType(QualType T)=0
void setHandler(unsigned I, llvm::Constant *Type, llvm::BasicBlock *Block)
Definition: CGCleanup.h:189
Structure with information about how a bitfield should be accessed.
llvm::FunctionType * GetFunctionType(const CGFunctionInfo &Info)
GetFunctionType - Get the LLVM function type for.
Definition: CGCall.cpp:1253