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 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
30 const ObjCInterfaceDecl *OID,
31 const ObjCIvarDecl *Ivar) {
32 return CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar) /
33 CGM.getContext().getCharWidth();
36 uint64_t CGObjCRuntime::ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
37 const ObjCImplementationDecl *OID,
38 const ObjCIvarDecl *Ivar) {
39 return CGM.getContext().lookupFieldBitOffset(OID->getClassInterface(), OID,
41 CGM.getContext().getCharWidth();
44 unsigned CGObjCRuntime::ComputeBitfieldBitOffset(
45 CodeGen::CodeGenModule &CGM,
46 const ObjCInterfaceDecl *ID,
47 const ObjCIvarDecl *Ivar) {
48 return CGM.getContext().lookupFieldBitOffset(ID, ID->getImplementation(),
52 LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
53 const ObjCInterfaceDecl *OID,
54 llvm::Value *BaseValue,
55 const ObjCIvarDecl *Ivar,
56 unsigned CVRQualifiers,
57 llvm::Value *Offset) {
58 // Compute (type*) ( (char *) BaseValue + Offset)
59 QualType InterfaceTy{OID->getTypeForDecl(), 0};
60 QualType ObjectPtrTy =
61 CGF.CGM.getContext().getObjCObjectPointerType(InterfaceTy);
63 Ivar->getUsageType(ObjectPtrTy).withCVRQualifiers(CVRQualifiers);
64 llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
65 llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
66 V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");
68 if (!Ivar->isBitField()) {
69 V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
70 LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
74 // We need to compute an access strategy for this bit-field. We are given the
75 // offset to the first byte in the bit-field, the sub-byte offset is taken
76 // from the original layout. We reuse the normal bit-field access strategy by
77 // treating this as an access to a struct where the bit-field is in byte 0,
78 // and adjust the containing type size as appropriate.
80 // FIXME: Note that currently we make a very conservative estimate of the
81 // alignment of the bit-field, because (a) it is not clear what guarantees the
82 // runtime makes us, and (b) we don't have a way to specify that the struct is
83 // at an alignment plus offset.
85 // Note, there is a subtle invariant here: we can only call this routine on
86 // non-synthesized ivars but we may be called for synthesized ivars. However,
87 // a synthesized ivar can never be a bit-field, so this is safe.
88 uint64_t FieldBitOffset =
89 CGF.CGM.getContext().lookupFieldBitOffset(OID, nullptr, Ivar);
90 uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
91 uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
92 uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
93 CharUnits StorageSize = CGF.CGM.getContext().toCharUnitsFromBits(
94 llvm::alignTo(BitOffset + BitFieldSize, AlignmentBits));
95 CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);
97 // Allocate a new CGBitFieldInfo object to describe this access.
99 // FIXME: This is incredibly wasteful, these should be uniqued or part of some
100 // layout object. However, this is blocked on other cleanups to the
101 // Objective-C code, so for now we just live with allocating a bunch of these
103 CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
104 CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
105 CGF.CGM.getContext().toBits(StorageSize),
106 CharUnits::fromQuantity(0)));
108 Address Addr(V, Alignment);
109 Addr = CGF.Builder.CreateElementBitCast(Addr,
110 llvm::Type::getIntNTy(CGF.getLLVMContext(),
112 return LValue::MakeBitfield(Addr, *Info, IvarTy,
113 LValueBaseInfo(AlignmentSource::Decl),
118 struct CatchHandler {
119 const VarDecl *Variable;
121 llvm::BasicBlock *Block;
122 llvm::Constant *TypeInfo;
125 struct CallObjCEndCatch final : EHScopeStack::Cleanup {
126 CallObjCEndCatch(bool MightThrow, llvm::Value *Fn)
127 : MightThrow(MightThrow), Fn(Fn) {}
131 void Emit(CodeGenFunction &CGF, Flags flags) override {
133 CGF.EmitRuntimeCallOrInvoke(Fn);
135 CGF.EmitNounwindRuntimeCall(Fn);
141 void CGObjCRuntime::EmitTryCatchStmt(CodeGenFunction &CGF,
142 const ObjCAtTryStmt &S,
143 llvm::Constant *beginCatchFn,
144 llvm::Constant *endCatchFn,
145 llvm::Constant *exceptionRethrowFn) {
146 // Jump destination for falling out of catch bodies.
147 CodeGenFunction::JumpDest Cont;
148 if (S.getNumCatchStmts())
149 Cont = CGF.getJumpDestInCurrentScope("eh.cont");
151 CodeGenFunction::FinallyInfo FinallyInfo;
152 if (const ObjCAtFinallyStmt *Finally = S.getFinallyStmt())
153 FinallyInfo.enter(CGF, Finally->getFinallyBody(),
154 beginCatchFn, endCatchFn, exceptionRethrowFn);
156 SmallVector<CatchHandler, 8> Handlers;
158 // Enter the catch, if there is one.
159 if (S.getNumCatchStmts()) {
160 for (unsigned I = 0, N = S.getNumCatchStmts(); I != N; ++I) {
161 const ObjCAtCatchStmt *CatchStmt = S.getCatchStmt(I);
162 const VarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
164 Handlers.push_back(CatchHandler());
165 CatchHandler &Handler = Handlers.back();
166 Handler.Variable = CatchDecl;
167 Handler.Body = CatchStmt->getCatchBody();
168 Handler.Block = CGF.createBasicBlock("catch");
170 // @catch(...) always matches.
172 Handler.TypeInfo = nullptr; // catch-all
173 // Don't consider any other catches.
177 Handler.TypeInfo = GetEHType(CatchDecl->getType());
180 EHCatchScope *Catch = CGF.EHStack.pushCatch(Handlers.size());
181 for (unsigned I = 0, E = Handlers.size(); I != E; ++I)
182 Catch->setHandler(I, Handlers[I].TypeInfo, Handlers[I].Block);
185 // Emit the try body.
186 CGF.EmitStmt(S.getTryBody());
189 if (S.getNumCatchStmts())
192 // Remember where we were.
193 CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
195 // Emit the handlers.
196 for (unsigned I = 0, E = Handlers.size(); I != E; ++I) {
197 CatchHandler &Handler = Handlers[I];
199 CGF.EmitBlock(Handler.Block);
200 llvm::Value *RawExn = CGF.getExceptionFromSlot();
203 llvm::Value *Exn = RawExn;
205 Exn = CGF.EmitNounwindRuntimeCall(beginCatchFn, RawExn, "exn.adjusted");
207 CodeGenFunction::LexicalScope cleanups(CGF, Handler.Body->getSourceRange());
210 // Add a cleanup to leave the catch.
211 bool EndCatchMightThrow = (Handler.Variable == nullptr);
213 CGF.EHStack.pushCleanup<CallObjCEndCatch>(NormalAndEHCleanup,
218 // Bind the catch parameter if it exists.
219 if (const VarDecl *CatchParam = Handler.Variable) {
220 llvm::Type *CatchType = CGF.ConvertType(CatchParam->getType());
221 llvm::Value *CastExn = CGF.Builder.CreateBitCast(Exn, CatchType);
223 CGF.EmitAutoVarDecl(*CatchParam);
224 EmitInitOfCatchParam(CGF, CastExn, CatchParam);
227 CGF.ObjCEHValueStack.push_back(Exn);
228 CGF.EmitStmt(Handler.Body);
229 CGF.ObjCEHValueStack.pop_back();
231 // Leave any cleanups associated with the catch.
232 cleanups.ForceCleanup();
234 CGF.EmitBranchThroughCleanup(Cont);
237 // Go back to the try-statement fallthrough.
238 CGF.Builder.restoreIP(SavedIP);
240 // Pop out of the finally.
241 if (S.getFinallyStmt())
242 FinallyInfo.exit(CGF);
245 CGF.EmitBlock(Cont.getBlock());
248 void CGObjCRuntime::EmitInitOfCatchParam(CodeGenFunction &CGF,
250 const VarDecl *paramDecl) {
252 Address paramAddr = CGF.GetAddrOfLocalVar(paramDecl);
254 switch (paramDecl->getType().getQualifiers().getObjCLifetime()) {
255 case Qualifiers::OCL_Strong:
256 exn = CGF.EmitARCRetainNonBlock(exn);
259 case Qualifiers::OCL_None:
260 case Qualifiers::OCL_ExplicitNone:
261 case Qualifiers::OCL_Autoreleasing:
262 CGF.Builder.CreateStore(exn, paramAddr);
265 case Qualifiers::OCL_Weak:
266 CGF.EmitARCInitWeak(paramAddr, exn);
269 llvm_unreachable("invalid ownership qualifier");
273 struct CallSyncExit final : EHScopeStack::Cleanup {
274 llvm::Value *SyncExitFn;
275 llvm::Value *SyncArg;
276 CallSyncExit(llvm::Value *SyncExitFn, llvm::Value *SyncArg)
277 : SyncExitFn(SyncExitFn), SyncArg(SyncArg) {}
279 void Emit(CodeGenFunction &CGF, Flags flags) override {
280 CGF.Builder.CreateCall(SyncExitFn, SyncArg)->setDoesNotThrow();
285 void CGObjCRuntime::EmitAtSynchronizedStmt(CodeGenFunction &CGF,
286 const ObjCAtSynchronizedStmt &S,
287 llvm::Function *syncEnterFn,
288 llvm::Function *syncExitFn) {
289 CodeGenFunction::RunCleanupsScope cleanups(CGF);
291 // Evaluate the lock operand. This is guaranteed to dominate the
292 // ARC release and lock-release cleanups.
293 const Expr *lockExpr = S.getSynchExpr();
295 if (CGF.getLangOpts().ObjCAutoRefCount) {
296 lock = CGF.EmitARCRetainScalarExpr(lockExpr);
297 lock = CGF.EmitObjCConsumeObject(lockExpr->getType(), lock);
299 lock = CGF.EmitScalarExpr(lockExpr);
301 lock = CGF.Builder.CreateBitCast(lock, CGF.VoidPtrTy);
304 CGF.Builder.CreateCall(syncEnterFn, lock)->setDoesNotThrow();
306 // Register an all-paths cleanup to release the lock.
307 CGF.EHStack.pushCleanup<CallSyncExit>(NormalAndEHCleanup, syncExitFn, lock);
309 // Emit the body of the statement.
310 CGF.EmitStmt(S.getSynchBody());
313 /// Compute the pointer-to-function type to which a message send
314 /// should be casted in order to correctly call the given method
315 /// with the given arguments.
317 /// \param method - may be null
318 /// \param resultType - the result type to use if there's no method
319 /// \param callArgs - the actual arguments, including implicit ones
320 CGObjCRuntime::MessageSendInfo
321 CGObjCRuntime::getMessageSendInfo(const ObjCMethodDecl *method,
323 CallArgList &callArgs) {
324 // If there's a method, use information from that.
326 const CGFunctionInfo &signature =
327 CGM.getTypes().arrangeObjCMessageSendSignature(method, callArgs[0].Ty);
329 llvm::PointerType *signatureType =
330 CGM.getTypes().GetFunctionType(signature)->getPointerTo();
332 const CGFunctionInfo &signatureForCall =
333 CGM.getTypes().arrangeCall(signature, callArgs);
335 return MessageSendInfo(signatureForCall, signatureType);
338 // There's no method; just use a default CC.
339 const CGFunctionInfo &argsInfo =
340 CGM.getTypes().arrangeUnprototypedObjCMessageSend(resultType, callArgs);
342 // Derive the signature to call from that.
343 llvm::PointerType *signatureType =
344 CGM.getTypes().GetFunctionType(argsInfo)->getPointerTo();
345 return MessageSendInfo(argsInfo, signatureType);