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 unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
82 CodeGen::CodeGenModule &CGM,
83 const ObjCInterfaceDecl *ID,
84 const ObjCIvarDecl *Ivar) {
85 return LookupFieldBitOffset(CGM, ID, ID->getImplementation(), Ivar);
88 LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
89 const ObjCInterfaceDecl *OID,
90 llvm::Value *BaseValue,
91 const ObjCIvarDecl *Ivar,
92 unsigned CVRQualifiers,
93 llvm::Value *Offset) {
94 // Compute (type*) ( (char *) BaseValue + Offset)
95 llvm::Type *I8Ptr = CGF.Int8PtrTy;
96 QualType IvarTy = Ivar->getType();
97 llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
98 llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, I8Ptr);
99 V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
100 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
102 if (!Ivar->isBitField()) {
103 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
104 LV.getQuals().addCVRQualifiers(CVRQualifiers);
108 // We need to compute an access strategy for this bit-field. We are given the
109 // offset to the first byte in the bit-field, the sub-byte offset is taken
110 // from the original layout. We reuse the normal bit-field access strategy by
111 // treating this as an access to a struct where the bit-field is in byte 0,
112 // and adjust the containing type size as appropriate.
114 // FIXME: Note that currently we make a very conservative estimate of the
115 // alignment of the bit-field, because (a) it is not clear what guarantees the
116 // runtime makes us, and (b) we don't have a way to specify that the struct is
117 // at an alignment plus offset.
119 // Note, there is a subtle invariant here: we can only call this routine on
120 // non-synthesized ivars but we may be called for synthesized ivars. However,
121 // a synthesized ivar can never be a bit-field, so this is safe.
122 const ASTRecordLayout &RL =
123 CGF.CGM.getContext().getASTObjCInterfaceLayout(OID);
124 uint64_t TypeSizeInBits = CGF.CGM.getContext().toBits(RL.getSize());
125 uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar);
126 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
127 uint64_t ContainingTypeAlign = CGF.CGM.getContext().getTargetInfo().getCharAlign();
128 uint64_t ContainingTypeSize = TypeSizeInBits - (FieldBitOffset - BitOffset);
129 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
130 CharUnits ContainingTypeAlignCharUnits =
131 CGF.CGM.getContext().toCharUnitsFromBits(ContainingTypeAlign);
133 // Allocate a new CGBitFieldInfo object to describe this access.
135 // FIXME: This is incredibly wasteful, these should be uniqued or part of some
136 // layout object. However, this is blocked on other cleanups to the
137 // Objective-C code, so for now we just live with allocating a bunch of these
139 CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
140 CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
141 ContainingTypeSize, ContainingTypeAlign));
143 return LValue::MakeBitfield(V, *Info,
144 IvarTy.withCVRQualifiers(CVRQualifiers),
145 ContainingTypeAlignCharUnits);
149 struct CatchHandler {
150 const VarDecl *Variable;
152 llvm::BasicBlock *Block;
153 llvm::Value *TypeInfo;
156 struct CallObjCEndCatch : EHScopeStack::Cleanup {
157 CallObjCEndCatch(bool MightThrow, llvm::Value *Fn) :
158 MightThrow(MightThrow), Fn(Fn) {}
162 void Emit(CodeGenFunction &CGF, Flags flags) {
164 CGF.Builder.CreateCall(Fn)->setDoesNotThrow();
168 CGF.EmitCallOrInvoke(Fn);
174 void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
175 const ObjCAtTryStmt &S,
176 llvm::Constant *beginCatchFn,
177 llvm::Constant *endCatchFn,
178 llvm::Constant *exceptionRethrowFn) {
179 // Jump destination for falling out of catch bodies.
180 CodeGenFunction::JumpDest Cont;
181 if (S.getNumCatchStmts())
182 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
184 CodeGenFunction::FinallyInfo FinallyInfo;
185 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
186 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
187 beginCatchFn, endCatchFn, exceptionRethrowFn);
189 SmallVector<CatchHandler, 8> Handlers;
191 // Enter the catch, if there is one.
192 if (S.getNumCatchStmts()) {
193 for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
194 const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
195 const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
197 Handlers.push_back(CatchHandler());
198 CatchHandler &Handler = Handlers.back();
199 Handler.Variable = CatchDecl;
200 Handler.Body = CatchStmt->getCatchBody();
201 Handler.Block = CGF.createBasicBlock("catch");
203 // @catch(...) always matches.
205 Handler.TypeInfo = 0; // catch-all
206 // Don't consider any other catches.
210 Handler.TypeInfo = GetEHType(CatchDecl->getType());
213 EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
214 for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
215 Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
218 // Emit the try body.
219 CGF.EmitStmt(S.getTryBody());
222 if (S.getNumCatchStmts())
225 // Remember where we were.
226 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
228 // Emit the handlers.
229 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
230 CatchHandler &Handler = Handlers[I];
232 CGF.EmitBlock(Handler.Block);
233 llvm::Value *RawExn = CGF.getExceptionFromSlot();
236 llvm::Value *Exn = RawExn;
238 Exn = CGF.Builder.CreateCall(beginCatchFn, RawExn, "exn.adjusted");
239 cast<llvm::CallInst>(Exn)->setDoesNotThrow();
242 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
245 // Add a cleanup to leave the catch.
246 bool EndCatchMightThrow = (Handler.Variable == 0);
248 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
253 // Bind the catch parameter if it exists.
254 if (const VarDecl *CatchParam = Handler.Variable) {
255 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
256 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
258 CGF.EmitAutoVarDecl(*CatchParam);
260 llvm::Value *CatchParamAddr = CGF.GetAddrOfLocalVar(CatchParam);
262 switch (CatchParam->getType().getQualifiers().getObjCLifetime()) {
263 case Qualifiers::OCL_Strong:
264 CastExn = CGF.EmitARCRetainNonBlock(CastExn);
267 case Qualifiers::OCL_None:
268 case Qualifiers::OCL_ExplicitNone:
269 case Qualifiers::OCL_Autoreleasing:
270 CGF.Builder.CreateStore(CastExn, CatchParamAddr);
273 case Qualifiers::OCL_Weak:
274 CGF.EmitARCInitWeak(CatchParamAddr, CastExn);
279 CGF.ObjCEHValueStack.push_back(Exn);
280 CGF.EmitStmt(Handler.Body);
281 CGF.ObjCEHValueStack.pop_back();
283 // Leave any cleanups associated with the catch.
284 cleanups.ForceCleanup();
286 CGF.EmitBranchThroughCleanup(Cont);
289 // Go back to the try-statement fallthrough.
290 CGF.Builder.restoreIP(SavedIP);
292 // Pop out of the finally.
293 if (S.getFinallyStmt())
294 FinallyInfo.exit(CGF);
297 CGF.EmitBlock(Cont.getBlock());
301 struct CallSyncExit : EHScopeStack::Cleanup {
302 llvm::Value *SyncExitFn;
303 llvm::Value *SyncArg;
304 CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
305 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
307 void Emit(CodeGenFunction &CGF, Flags flags) {
308 CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
313 void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
314 const ObjCAtSynchronizedStmt &S,
315 llvm::Function *syncEnterFn,
316 llvm::Function *syncExitFn) {
317 CodeGenFunction::RunCleanupsScope cleanups(CGF);
319 // Evaluate the lock operand. This is guaranteed to dominate the
320 // ARC release and lock-release cleanups.
321 const Expr *lockExpr = S.getSynchExpr();
323 if (CGF.getLangOpts().ObjCAutoRefCount) {
324 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
325 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
327 lock = CGF.EmitScalarExpr(lockExpr);
329 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
332 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
334 // Register an all-paths cleanup to release the lock.
335 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
337 // Emit the body of the statement.
338 CGF.EmitStmt(S.getSynchBody());
341 /// Compute the pointer-to-function type to which a message send
342 /// should be casted in order to correctly call the given method
343 /// with the given arguments.
345 /// \param method - may be null
346 /// \param resultType - the result type to use if there's no method
347 /// \param callArgs - the actual arguments, including implicit ones
348 CGObjCRuntime::MessageSendInfo
349 CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
351 CallArgList &callArgs) {
352 // If there's a method, use information from that.
354 const CGFunctionInfo &signature =
355 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
357 llvm::PointerType *signatureType =
358 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
360 // If that's not variadic, there's no need to recompute the ABI
362 if (!signature.isVariadic())
363 return MessageSendInfo(signature, signatureType);
365 // Otherwise, there is.
366 FunctionType::ExtInfo einfo = signature.getExtInfo();
367 const CGFunctionInfo &argsInfo =
368 CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs, einfo,
369 signature.getRequiredArgs());
371 return MessageSendInfo(argsInfo, signatureType);
374 // There's no method; just use a default CC.
375 const CGFunctionInfo &argsInfo =
376 CGM.getTypes().arrangeFreeFunctionCall(resultType, callArgs,
377 FunctionType::ExtInfo(),
380 // Derive the signature to call from that.
381 llvm::PointerType *signatureType =
382 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
383 return MessageSendInfo(argsInfo, signatureType);