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 IvarTy = Ivar->getType().withCVRQualifiers(CVRQualifiers);
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");
98 if (!Ivar->isBitField()) {
99 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
100 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
104 // We need to compute an access strategy for this bit-field. We are given the
105 // offset to the first byte in the bit-field, the sub-byte offset is taken
106 // from the original layout. We reuse the normal bit-field access strategy by
107 // treating this as an access to a struct where the bit-field is in byte 0,
108 // and adjust the containing type size as appropriate.
110 // FIXME: Note that currently we make a very conservative estimate of the
111 // alignment of the bit-field, because (a) it is not clear what guarantees the
112 // runtime makes us, and (b) we don't have a way to specify that the struct is
113 // at an alignment plus offset.
115 // Note, there is a subtle invariant here: we can only call this routine on
116 // non-synthesized ivars but we may be called for synthesized ivars. However,
117 // a synthesized ivar can never be a bit-field, so this is safe.
118 uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, nullptr, Ivar);
119 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
120 uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
121 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
122 CharUnits StorageSize = CGF.CGM.getContext().toCharUnitsFromBits(
123 llvm::alignTo(BitOffset + BitFieldSize, AlignmentBits));
124 CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
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 CGF.CGM.getContext().toBits(StorageSize),
135 CharUnits::fromQuantity(0)));
137 Address Addr(V, Alignment);
138 Addr = CGF.Builder.CreateElementBitCast(Addr,
139 llvm::Type::getIntNTy(CGF.getLLVMContext(),
141 return LValue::MakeBitfield(Addr, *Info, IvarTy, AlignmentSource::Decl);
145 struct CatchHandler {
146 const VarDecl *Variable;
148 llvm::BasicBlock *Block;
149 llvm::Constant *TypeInfo;
152 struct CallObjCEndCatch final : EHScopeStack::Cleanup {
153 CallObjCEndCatch(bool MightThrow, llvm::Value *Fn)
154 : MightThrow(MightThrow), Fn(Fn) {}
158 void Emit(CodeGenFunction &CGF, Flags flags) override {
160 CGF.EmitRuntimeCallOrInvoke(Fn);
162 CGF.EmitNounwindRuntimeCall(Fn);
168 void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
169 const ObjCAtTryStmt &S,
170 llvm::Constant *beginCatchFn,
171 llvm::Constant *endCatchFn,
172 llvm::Constant *exceptionRethrowFn) {
173 // Jump destination for falling out of catch bodies.
174 CodeGenFunction::JumpDest Cont;
175 if (S.getNumCatchStmts())
176 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
178 CodeGenFunction::FinallyInfo FinallyInfo;
179 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
180 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
181 beginCatchFn, endCatchFn, exceptionRethrowFn);
183 SmallVector<CatchHandler, 8> Handlers;
185 // Enter the catch, if there is one.
186 if (S.getNumCatchStmts()) {
187 for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
188 const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
189 const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
191 Handlers.push_back(CatchHandler());
192 CatchHandler &Handler = Handlers.back();
193 Handler.Variable = CatchDecl;
194 Handler.Body = CatchStmt->getCatchBody();
195 Handler.Block = CGF.createBasicBlock("catch");
197 // @catch(...) always matches.
199 Handler.TypeInfo = nullptr; // catch-all
200 // Don't consider any other catches.
204 Handler.TypeInfo = GetEHType(CatchDecl->getType());
207 EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
208 for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
209 Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
212 // Emit the try body.
213 CGF.EmitStmt(S.getTryBody());
216 if (S.getNumCatchStmts())
219 // Remember where we were.
220 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
222 // Emit the handlers.
223 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
224 CatchHandler &Handler = Handlers[I];
226 CGF.EmitBlock(Handler.Block);
227 llvm::Value *RawExn = CGF.getExceptionFromSlot();
230 llvm::Value *Exn = RawExn;
232 Exn = CGF.EmitNounwindRuntimeCall(beginCatchFn, RawExn, "exn.adjusted");
234 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
237 // Add a cleanup to leave the catch.
238 bool EndCatchMightThrow = (Handler.Variable == nullptr);
240 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
245 // Bind the catch parameter if it exists.
246 if (const VarDecl *CatchParam = Handler.Variable) {
247 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
248 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
250 CGF.EmitAutoVarDecl(*CatchParam);
251 EmitInitOfCatchParam(CGF, CastExn, CatchParam);
254 CGF.ObjCEHValueStack.push_back(Exn);
255 CGF.EmitStmt(Handler.Body);
256 CGF.ObjCEHValueStack.pop_back();
258 // Leave any cleanups associated with the catch.
259 cleanups.ForceCleanup();
261 CGF.EmitBranchThroughCleanup(Cont);
264 // Go back to the try-statement fallthrough.
265 CGF.Builder.restoreIP(SavedIP);
267 // Pop out of the finally.
268 if (S.getFinallyStmt())
269 FinallyInfo.exit(CGF);
272 CGF.EmitBlock(Cont.getBlock());
275 void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
277 const VarDecl *paramDecl) {
279 Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
281 switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
282 case Qualifiers::OCL_Strong:
283 exn = CGF.EmitARCRetainNonBlock(exn);
286 case Qualifiers::OCL_None:
287 case Qualifiers::OCL_ExplicitNone:
288 case Qualifiers::OCL_Autoreleasing:
289 CGF.Builder.CreateStore(exn, paramAddr);
292 case Qualifiers::OCL_Weak:
293 CGF.EmitARCInitWeak(paramAddr, exn);
296 llvm_unreachable("invalid ownership qualifier");
300 struct CallSyncExit final : EHScopeStack::Cleanup {
301 llvm::Value *SyncExitFn;
302 llvm::Value *SyncArg;
303 CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
304 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
306 void Emit(CodeGenFunction &CGF, Flags flags) override {
307 CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
312 void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
313 const ObjCAtSynchronizedStmt &S,
314 llvm::Function *syncEnterFn,
315 llvm::Function *syncExitFn) {
316 CodeGenFunction::RunCleanupsScope cleanups(CGF);
318 // Evaluate the lock operand. This is guaranteed to dominate the
319 // ARC release and lock-release cleanups.
320 const Expr *lockExpr = S.getSynchExpr();
322 if (CGF.getLangOpts().ObjCAutoRefCount) {
323 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
324 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
326 lock = CGF.EmitScalarExpr(lockExpr);
328 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
331 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
333 // Register an all-paths cleanup to release the lock.
334 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
336 // Emit the body of the statement.
337 CGF.EmitStmt(S.getSynchBody());
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.
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
347 CGObjCRuntime::MessageSendInfo
348 CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
350 CallArgList &callArgs) {
351 // If there's a method, use information from that.
353 const CGFunctionInfo &signature =
354 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
356 llvm::PointerType *signatureType =
357 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
359 const CGFunctionInfo &signatureForCall =
360 CGM.getTypes().arrangeCall(signature, callArgs);
362 return MessageSendInfo(signatureForCall, signatureType);
365 // There's no method; just use a default CC.
366 const CGFunctionInfo &argsInfo =
367 CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
369 // Derive the signature to call from that.
370 llvm::PointerType *signatureType =
371 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
372 return MessageSendInfo(argsInfo, signatureType);