1 //==- CGObjCRuntime.cpp - Interface to Shared Objective-C Runtime Features ==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
16 #include "CGObjCRuntime.h"
18 #include "CGRecordLayout.h"
19 #include "CodeGenModule.h"
20 #include "CodeGenFunction.h"
21 #include "CGCleanup.h"
23 #include "clang/AST/RecordLayout.h"
24 #include "clang/AST/StmtObjC.h"
26 #include "llvm/Support/CallSite.h"
28 using namespace clang;
29 using namespace CodeGen;
31 static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM,
32 const ObjCInterfaceDecl *OID,
33 const ObjCImplementationDecl *ID,
34 const ObjCIvarDecl *Ivar) {
35 const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
37 // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
38 // in here; it should never be necessary because that should be the lexical
39 // decl context for the ivar.
41 // If we know have an implementation (and the ivar is in it) then
42 // look up in the implementation layout.
43 const ASTRecordLayout *RL;
44 if (ID && declaresSameEntity(ID->getClassInterface(), Container))
45 RL = &CGM.getContext().getASTObjCImplementationLayout(ID);
47 RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
49 // Compute field index.
51 // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
52 // implemented. This should be fixed to get the information from the layout
56 for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
57 IVD; IVD = IVD->getNextIvar()) {
62 assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
64 return RL->getFieldOffset(Index);
67 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
68 const ObjCInterfaceDecl *OID,
69 const ObjCIvarDecl *Ivar) {
70 return LookupFieldBitOffset(CGM, OID, 0, Ivar) /
71 CGM.getContext().getCharWidth();
74 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
75 const ObjCImplementationDecl *OID,
76 const ObjCIvarDecl *Ivar) {
77 return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
78 CGM.getContext().getCharWidth();
81 LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
82 const ObjCInterfaceDecl *OID,
83 llvm::Value *BaseValue,
84 const ObjCIvarDecl *Ivar,
85 unsigned CVRQualifiers,
86 llvm::Value *Offset) {
87 // Compute (type*) ( (char *) BaseValue + Offset)
88 llvm::Type *I8Ptr = CGF.Int8PtrTy;
89 QualType IvarTy = Ivar->getType();
90 llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
91 llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, I8Ptr);
92 V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
93 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
95 if (!Ivar->isBitField()) {
96 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
97 LV.getQuals().addCVRQualifiers(CVRQualifiers);
101 // We need to compute an access strategy for this bit-field. We are given the
102 // offset to the first byte in the bit-field, the sub-byte offset is taken
103 // from the original layout. We reuse the normal bit-field access strategy by
104 // treating this as an access to a struct where the bit-field is in byte 0,
105 // and adjust the containing type size as appropriate.
107 // FIXME: Note that currently we make a very conservative estimate of the
108 // alignment of the bit-field, because (a) it is not clear what guarantees the
109 // runtime makes us, and (b) we don't have a way to specify that the struct is
110 // at an alignment plus offset.
112 // Note, there is a subtle invariant here: we can only call this routine on
113 // non-synthesized ivars but we may be called for synthesized ivars. However,
114 // a synthesized ivar can never be a bit-field, so this is safe.
115 const ASTRecordLayout &RL =
116 CGF.CGM.getContext().getASTObjCInterfaceLayout(OID);
117 uint64_t TypeSizeInBits = CGF.CGM.getContext().toBits(RL.getSize());
118 uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar);
119 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
120 uint64_t ContainingTypeAlign = CGF.CGM.getContext().getTargetInfo().getCharAlign();
121 uint64_t ContainingTypeSize = TypeSizeInBits - (FieldBitOffset - BitOffset);
122 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
123 CharUnits ContainingTypeAlignCharUnits =
124 CGF.CGM.getContext().toCharUnitsFromBits(ContainingTypeAlign);
126 // Allocate a new CGBitFieldInfo object to describe this access.
128 // FIXME: This is incredibly wasteful, these should be uniqued or part of some
129 // layout object. However, this is blocked on other cleanups to the
130 // Objective-C code, so for now we just live with allocating a bunch of these
132 CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
133 CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
134 ContainingTypeSize, ContainingTypeAlign));
136 return LValue::MakeBitfield(V, *Info,
137 IvarTy.withCVRQualifiers(CVRQualifiers),
138 ContainingTypeAlignCharUnits);
142 struct CatchHandler {
143 const VarDecl *Variable;
145 llvm::BasicBlock *Block;
146 llvm::Value *TypeInfo;
149 struct CallObjCEndCatch : EHScopeStack::Cleanup {
150 CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
151 MightThrow(MightThrow), Fn(Fn) {}
155 void Emit(CodeGenFunction &CGF, Flags flags) {
157 CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
161 CGF.EmitCallOrInvoke(Fn);
167 void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
168 const ObjCAtTryStmt &S,
169 llvm::Constant *beginCatchFn,
170 llvm::Constant *endCatchFn,
171 llvm::Constant *exceptionRethrowFn) {
172 // Jump destination for falling out of catch bodies.
173 CodeGenFunction::JumpDest Cont;
174 if (S.getNumCatchStmts())
175 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
177 CodeGenFunction::FinallyInfo FinallyInfo;
178 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
179 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
180 beginCatchFn, endCatchFn, exceptionRethrowFn);
182 SmallVector<CatchHandler, 8> Handlers;
184 // Enter the catch, if there is one.
185 if (S.getNumCatchStmts()) {
186 for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
187 const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
188 const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
190 Handlers.push_back(CatchHandler());
191 CatchHandler &Handler = Handlers.back();
192 Handler.Variable = CatchDecl;
193 Handler.Body = CatchStmt->getCatchBody();
194 Handler.Block = CGF.createBasicBlock("catch");
196 // @catch(...) always matches.
198 Handler.TypeInfo = 0; // catch-all
199 // Don't consider any other catches.
203 Handler.TypeInfo = GetEHType(CatchDecl->getType());
206 EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
207 for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
208 Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
211 // Emit the try body.
212 CGF.EmitStmt(S.getTryBody());
215 if (S.getNumCatchStmts())
218 // Remember where we were.
219 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
221 // Emit the handlers.
222 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
223 CatchHandler &Handler = Handlers[I];
225 CGF.EmitBlock(Handler.Block);
226 llvm::Value *RawExn = CGF.getExceptionFromSlot();
229 llvm::Value *Exn = RawExn;
231 Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
232 cast<llvm::CallInst>(Exn)->setDoesNotThrow();
235 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
238 // Add a cleanup to leave the catch.
239 bool EndCatchMightThrow = (Handler.Variable == 0);
241 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
246 // Bind the catch parameter if it exists.
247 if (const VarDecl *CatchParam = Handler.Variable) {
248 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
249 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
251 CGF.EmitAutoVarDecl(*CatchParam);
253 llvm::Value *CatchParamAddr = CGF.GetAddrOfLocalVar(CatchParam);
255 switch (CatchParam->getType().getQualifiers().getObjCLifetime()) {
256 case Qualifiers::OCL_Strong:
257 CastExn = CGF.EmitARCRetainNonBlock(CastExn);
260 case Qualifiers::OCL_None:
261 case Qualifiers::OCL_ExplicitNone:
262 case Qualifiers::OCL_Autoreleasing:
263 CGF.Builder.CreateStore(CastExn, CatchParamAddr);
266 case Qualifiers::OCL_Weak:
267 CGF.EmitARCInitWeak(CatchParamAddr, CastExn);
272 CGF.ObjCEHValueStack.push_back(Exn);
273 CGF.EmitStmt(Handler.Body);
274 CGF.ObjCEHValueStack.pop_back();
276 // Leave any cleanups associated with the catch.
277 cleanups.ForceCleanup();
279 CGF.EmitBranchThroughCleanup(Cont);
282 // Go back to the try-statement fallthrough.
283 CGF.Builder.restoreIP(SavedIP);
285 // Pop out of the finally.
286 if (S.getFinallyStmt())
287 FinallyInfo.exit(CGF);
290 CGF.EmitBlock(Cont.getBlock());
294 struct CallSyncExit : EHScopeStack::Cleanup {
295 llvm::Value *SyncExitFn;
296 llvm::Value *SyncArg;
297 CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
298 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
300 void Emit(CodeGenFunction &CGF, Flags flags) {
301 CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
306 void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
307 const ObjCAtSynchronizedStmt &S,
308 llvm::Function *syncEnterFn,
309 llvm::Function *syncExitFn) {
310 CodeGenFunction::RunCleanupsScope cleanups(CGF);
312 // Evaluate the lock operand. This is guaranteed to dominate the
313 // ARC release and lock-release cleanups.
314 const Expr *lockExpr = S.getSynchExpr();
316 if (CGF.getLangOpts().ObjCAutoRefCount) {
317 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
318 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
320 lock = CGF.EmitScalarExpr(lockExpr);
322 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
325 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
327 // Register an all-paths cleanup to release the lock.
328 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
330 // Emit the body of the statement.
331 CGF.EmitStmt(S.getSynchBody());
334 /// Compute the pointer-to-function type to which a message send
335 /// should be casted in order to correctly call the given method
336 /// with the given arguments.
338 /// \param method - may be null
339 /// \param resultType - the result type to use if there's no method
340 /// \param callArgs - the actual arguments, including implicit ones
341 CGObjCRuntime::MessageSendInfo
342 CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
344 CallArgList &callArgs) {
345 // If there's a method, use information from that.
347 const CGFunctionInfo &signature =
348 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
350 llvm::PointerType *signatureType =
351 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
353 // If that's not variadic, there's no need to recompute the ABI
355 if (!signature.isVariadic())
356 return MessageSendInfo(signature, signatureType);
358 // Otherwise, there is.
359 FunctionType::ExtInfo einfo = signature.getExtInfo();
360 const CGFunctionInfo &argsInfo =
361 CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs, einfo,
362 signature.getRequiredArgs());
364 return MessageSendInfo(argsInfo, signatureType);
367 // There's no method; just use a default CC.
368 const CGFunctionInfo &argsInfo =
369 CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs,
370 FunctionType::ExtInfo(),
373 // Derive the signature to call from that.
374 llvm::PointerType *signatureType =
375 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
376 return MessageSendInfo(argsInfo, signatureType);