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"
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"
23 #include "clang/CodeGen/CGFunctionInfo.h"
24 #include "llvm/IR/CallSite.h"
26 using namespace clang;
27 using namespace CodeGen;
29 static uint64_t LookupFieldBitOffset(CodeGen::CodeGenModule &CGM,
30 const ObjCInterfaceDecl *OID,
31 const ObjCImplementationDecl *ID,
32 const ObjCIvarDecl *Ivar) {
33 const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
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.
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))
43 RL = &CGM.getContext().getASTObjCImplementationLayout(ID);
45 RL = &CGM.getContext().getASTObjCInterfaceLayout(Container);
47 // Compute field index.
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
54 for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
55 IVD; IVD = IVD->getNextIvar()) {
60 assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
62 return RL->getFieldOffset(Index);
65 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
66 const ObjCInterfaceDecl *OID,
67 const ObjCIvarDecl *Ivar) {
68 return LookupFieldBitOffset(CGM, OID, nullptr, Ivar) /
69 CGM.getContext().getCharWidth();
72 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
73 const ObjCImplementationDecl *OID,
74 const ObjCIvarDecl *Ivar) {
75 return LookupFieldBitOffset(CGM, OID->getClassInterface(), OID, Ivar) /
76 CGM.getContext().getCharWidth();
79 unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
80 CodeGen::CodeGenModule &CGM,
81 const ObjCInterfaceDecl *ID,
82 const ObjCIvarDecl *Ivar) {
83 return LookupFieldBitOffset(CGM, ID, ID->getImplementation(), Ivar);
86 LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
87 const ObjCInterfaceDecl *OID,
88 llvm::Value *BaseValue,
89 const ObjCIvarDecl *Ivar,
90 unsigned CVRQualifiers,
91 llvm::Value *Offset) {
92 // Compute (type*) ( (char *) BaseValue + Offset)
93 QualType InterfaceTy{OID->getTypeForDecl(), 0};
94 QualType ObjectPtrTy =
95 CGF.CGM.getContext().getObjCObjectPointerType(InterfaceTy);
97 Ivar->getUsageType(ObjectPtrTy).withCVRQualifiers(CVRQualifiers);
98 llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
99 llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
100 V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
102 if (!Ivar->isBitField()) {
103 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
104 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
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 uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, nullptr, Ivar);
123 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
124 uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
125 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
126 CharUnits StorageSize = CGF.CGM.getContext().toCharUnitsFromBits(
127 llvm::alignTo(BitOffset + BitFieldSize, AlignmentBits));
128 CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
130 // Allocate a new CGBitFieldInfo object to describe this access.
132 // FIXME: This is incredibly wasteful, these should be uniqued or part of some
133 // layout object. However, this is blocked on other cleanups to the
134 // Objective-C code, so for now we just live with allocating a bunch of these
136 CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
137 CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
138 CGF.CGM.getContext().toBits(StorageSize),
139 CharUnits::fromQuantity(0)));
141 Address Addr(V, Alignment);
142 Addr = CGF.Builder.CreateElementBitCast(Addr,
143 llvm::Type::getIntNTy(CGF.getLLVMContext(),
145 return LValue::MakeBitfield(Addr, *Info, IvarTy,
146 LValueBaseInfo(AlignmentSource::Decl, false));
150 struct CatchHandler {
151 const VarDecl *Variable;
153 llvm::BasicBlock *Block;
154 llvm::Constant *TypeInfo;
157 struct CallObjCEndCatch final : EHScopeStack::Cleanup {
158 CallObjCEndCatch(bool MightThrow, llvm::Value *Fn)
159 : MightThrow(MightThrow), Fn(Fn) {}
163 void Emit(CodeGenFunction &CGF, Flags flags) override {
165 CGF.EmitRuntimeCallOrInvoke(Fn);
167 CGF.EmitNounwindRuntimeCall(Fn);
173 void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
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.
179 CodeGenFunction::JumpDest Cont;
180 if (S.getNumCatchStmts())
181 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
183 CodeGenFunction::FinallyInfo FinallyInfo;
184 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
185 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
186 beginCatchFn, endCatchFn, exceptionRethrowFn);
188 SmallVector<CatchHandler, 8> Handlers;
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();
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");
202 // @catch(...) always matches.
204 Handler.TypeInfo = nullptr; // catch-all
205 // Don't consider any other catches.
209 Handler.TypeInfo = GetEHType(CatchDecl->getType());
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);
217 // Emit the try body.
218 CGF.EmitStmt(S.getTryBody());
221 if (S.getNumCatchStmts())
224 // Remember where we were.
225 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
227 // Emit the handlers.
228 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
229 CatchHandler &Handler = Handlers[I];
231 CGF.EmitBlock(Handler.Block);
232 llvm::Value *RawExn = CGF.getExceptionFromSlot();
235 llvm::Value *Exn = RawExn;
237 Exn = CGF.EmitNounwindRuntimeCall(beginCatchFn, RawExn, "exn.adjusted");
239 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
242 // Add a cleanup to leave the catch.
243 bool EndCatchMightThrow = (Handler.Variable == nullptr);
245 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
250 // Bind the catch parameter if it exists.
251 if (const VarDecl *CatchParam = Handler.Variable) {
252 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
253 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
255 CGF.EmitAutoVarDecl(*CatchParam);
256 EmitInitOfCatchParam(CGF, CastExn, CatchParam);
259 CGF.ObjCEHValueStack.push_back(Exn);
260 CGF.EmitStmt(Handler.Body);
261 CGF.ObjCEHValueStack.pop_back();
263 // Leave any cleanups associated with the catch.
264 cleanups.ForceCleanup();
266 CGF.EmitBranchThroughCleanup(Cont);
269 // Go back to the try-statement fallthrough.
270 CGF.Builder.restoreIP(SavedIP);
272 // Pop out of the finally.
273 if (S.getFinallyStmt())
274 FinallyInfo.exit(CGF);
277 CGF.EmitBlock(Cont.getBlock());
280 void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
282 const VarDecl *paramDecl) {
284 Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
286 switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
287 case Qualifiers::OCL_Strong:
288 exn = CGF.EmitARCRetainNonBlock(exn);
291 case Qualifiers::OCL_None:
292 case Qualifiers::OCL_ExplicitNone:
293 case Qualifiers::OCL_Autoreleasing:
294 CGF.Builder.CreateStore(exn, paramAddr);
297 case Qualifiers::OCL_Weak:
298 CGF.EmitARCInitWeak(paramAddr, exn);
301 llvm_unreachable("invalid ownership qualifier");
305 struct CallSyncExit final : EHScopeStack::Cleanup {
306 llvm::Value *SyncExitFn;
307 llvm::Value *SyncArg;
308 CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
309 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
311 void Emit(CodeGenFunction &CGF, Flags flags) override {
312 CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
317 void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
318 const ObjCAtSynchronizedStmt &S,
319 llvm::Function *syncEnterFn,
320 llvm::Function *syncExitFn) {
321 CodeGenFunction::RunCleanupsScope cleanups(CGF);
323 // Evaluate the lock operand. This is guaranteed to dominate the
324 // ARC release and lock-release cleanups.
325 const Expr *lockExpr = S.getSynchExpr();
327 if (CGF.getLangOpts().ObjCAutoRefCount) {
328 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
329 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
331 lock = CGF.EmitScalarExpr(lockExpr);
333 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
336 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
338 // Register an all-paths cleanup to release the lock.
339 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
341 // Emit the body of the statement.
342 CGF.EmitStmt(S.getSynchBody());
345 /// Compute the pointer-to-function type to which a message send
346 /// should be casted in order to correctly call the given method
347 /// with the given arguments.
349 /// \param method - may be null
350 /// \param resultType - the result type to use if there's no method
351 /// \param callArgs - the actual arguments, including implicit ones
352 CGObjCRuntime::MessageSendInfo
353 CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
355 CallArgList &callArgs) {
356 // If there's a method, use information from that.
358 const CGFunctionInfo &signature =
359 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
361 llvm::PointerType *signatureType =
362 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
364 const CGFunctionInfo &signatureForCall =
365 CGM.getTypes().arrangeCall(signature, callArgs);
367 return MessageSendInfo(signatureForCall, signatureType);
370 // There's no method; just use a default CC.
371 const CGFunctionInfo &argsInfo =
372 CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
374 // Derive the signature to call from that.
375 llvm::PointerType *signatureType =
376 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
377 return MessageSendInfo(argsInfo, signatureType);