From: Daniel Dunbar Date: Mon, 2 Mar 2009 06:08:11 +0000 (+0000) Subject: First cut at zero-cost EH support. X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4ff36847f44b35c2677330c39e87dff1d745944a;p=clang First cut at zero-cost EH support. - Still manually generates the EH code; the parts related to cleanup need to be integrated into the cleanup stack (for proper interaction with VLAs, etc.). - Some differences vs gcc in corner cases; I believe our behavior is correct but need to verify/file bugs vs gcc. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65809 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp index eee9d438c6..0f38eb94bc 100644 --- a/lib/CodeGen/CGObjCMac.cpp +++ b/lib/CodeGen/CGObjCMac.cpp @@ -614,12 +614,13 @@ private: ObjCNonFragileABITypesHelper ObjCTypes; llvm::GlobalVariable* ObjCEmptyCacheVar; llvm::GlobalVariable* ObjCEmptyVtableVar; + /// MetaClassReferences - uniqued meta class references. llvm::DenseMap MetaClassReferences; /// EHTypeReferences - uniqued class ehtype references. llvm::DenseMap EHTypeReferences; - + /// FinishNonFragileABIModule - Write out global data structures at the end of /// processing a translation unit. void FinishNonFragileABIModule(); @@ -708,7 +709,7 @@ private: /// GetInterfaceEHType - Get the ehtype for the given Objective-C /// interface. The return value has type EHTypePtrTy. llvm::Value *GetInterfaceEHType(const ObjCInterfaceType *IT); - + public: CGObjCNonFragileABIMac(CodeGen::CodeGenModule &cgm); // FIXME. All stubs for now! @@ -3383,7 +3384,6 @@ ObjCNonFragileABITypesHelper::ObjCNonFragileABITypesHelper(CodeGen::CodeGenModul "__objc_personality_v0"); EHPersonalityPtr = llvm::ConstantExpr::getBitCast(Personality, Int8PtrTy); - Params.clear(); Params.push_back(Int8PtrTy); UnwindResumeOrRethrowFn = @@ -3413,7 +3413,7 @@ ObjCNonFragileABITypesHelper::ObjCNonFragileABITypesHelper(CodeGen::CodeGenModul Int8PtrTy, ClassnfABIPtrTy, NULL); - CGM.getModule().addTypeName("struct._objc_typeinfo", CategorynfABITy); + CGM.getModule().addTypeName("struct._objc_typeinfo", EHTypeTy); EHTypePtrTy = llvm::PointerType::getUnqual(EHTypeTy); } @@ -4729,16 +4729,12 @@ void CGObjCNonFragileABIMac::EmitObjCGlobalAssign(CodeGen::CodeGenFunction &CGF, void CGObjCNonFragileABIMac::EmitTryOrSynchronizedStmt(CodeGen::CodeGenFunction &CGF, const Stmt &S) { - // We don't handle anything interesting yet. - if (const ObjCAtTryStmt *TS = dyn_cast(&S)) - if (TS->getCatchStmts()) - return CGF.ErrorUnsupported(&S, "try (with catch) statement"); - bool isTry = isa(S); llvm::BasicBlock *TryBlock = CGF.createBasicBlock("try"); llvm::BasicBlock *PrevLandingPad = CGF.getInvokeDest(); - llvm::BasicBlock *LandingPad = CGF.createBasicBlock("try.pad"); + llvm::BasicBlock *TryHandler = CGF.createBasicBlock("try.handler"); llvm::BasicBlock *FinallyBlock = CGF.createBasicBlock("finally"); + llvm::BasicBlock *FinallyRethrow = CGF.createBasicBlock("finally.throw"); llvm::BasicBlock *FinallyEnd = CGF.createBasicBlock("finally.end"); // For @synchronized, call objc_sync_enter(sync.expr). The @@ -4757,13 +4753,193 @@ CGObjCNonFragileABIMac::EmitTryOrSynchronizedStmt(CodeGen::CodeGenFunction &CGF, // through finally. CGF.PushCleanupBlock(FinallyBlock); - CGF.setInvokeDest(LandingPad); + CGF.setInvokeDest(TryHandler); CGF.EmitBlock(TryBlock); CGF.EmitStmt(isTry ? cast(S).getTryBody() : cast(S).getSynchBody()); CGF.EmitBranchThroughCleanup(FinallyEnd); + // Emit the exception handler. + + CGF.EmitBlock(TryHandler); + + llvm::Value *llvm_eh_exception = + CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_exception); + llvm::Value *llvm_eh_selector_i64 = + CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_selector_i64); + llvm::Value *llvm_eh_typeid_for_i64 = + CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for_i64); + llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc"); + llvm::Value *RethrowPtr = CGF.CreateTempAlloca(Exc->getType(), "_rethrow"); + + llvm::SmallVector SelectorArgs; + SelectorArgs.push_back(Exc); + SelectorArgs.push_back(ObjCTypes.EHPersonalityPtr); + + // Construct the lists of (type, catch body) to handle. + llvm::SmallVector, 8> Handlers; + bool HasCatchAll = false; + if (isTry) { + if (const ObjCAtCatchStmt* CatchStmt = + cast(S).getCatchStmts()) { + for (; CatchStmt; CatchStmt = CatchStmt->getNextCatchStmt()) { + const DeclStmt *DS = CatchStmt->getCatchParamStmt(); + Handlers.push_back(std::make_pair(DS, CatchStmt->getCatchBody())); + + // catch(...) always matches. + if (!DS) { + // Use i8* null here to signal this is a catch all, not a cleanup. + llvm::Value *Null = llvm::Constant::getNullValue(ObjCTypes.Int8PtrTy); + SelectorArgs.push_back(Null); + HasCatchAll = true; + break; + } + + const VarDecl *VD = cast(DS->getSolitaryDecl()); + if (CGF.getContext().isObjCIdType(VD->getType()) || + VD->getType()->isObjCQualifiedIdType()) { + llvm::Value *IDEHType = + CGM.getModule().getGlobalVariable("OBJC_EHTYPE_id"); + if (!IDEHType) + IDEHType = + new llvm::GlobalVariable(ObjCTypes.EHTypeTy, false, + llvm::GlobalValue::ExternalLinkage, + 0, "OBJC_EHTYPE_id", &CGM.getModule()); + SelectorArgs.push_back(IDEHType); + HasCatchAll = true; + break; + } + + // All other types should be Objective-C interface pointer types. + const PointerType *PT = VD->getType()->getAsPointerType(); + assert(PT && "Invalid @catch type."); + const ObjCInterfaceType *IT = + PT->getPointeeType()->getAsObjCInterfaceType(); + assert(IT && "Invalid @catch type."); + llvm::Value *EHType = GetInterfaceEHType(IT); + SelectorArgs.push_back(EHType); + } + } + } + + // We use a cleanup unless there was already a catch all. + if (!HasCatchAll) { + SelectorArgs.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0)); + Handlers.push_back(std::make_pair((const DeclStmt*) 0, (const Stmt*) 0)); + } + + llvm::Value *Selector = + CGF.Builder.CreateCall(llvm_eh_selector_i64, + SelectorArgs.begin(), SelectorArgs.end(), + "selector"); + for (unsigned i = 0, e = Handlers.size(); i != e; ++i) { + const DeclStmt *CatchParam = Handlers[i].first; + const Stmt *CatchBody = Handlers[i].second; + + llvm::BasicBlock *Next = 0; + + // The last handler always matches. + if (i + 1 != e) { + assert(CatchParam && "Only last handler can be a catch all."); + + llvm::BasicBlock *Match = CGF.createBasicBlock("match"); + Next = CGF.createBasicBlock("catch.next"); + llvm::Value *Id = + CGF.Builder.CreateCall(llvm_eh_typeid_for_i64, + CGF.Builder.CreateBitCast(SelectorArgs[i+2], + ObjCTypes.Int8PtrTy)); + CGF.Builder.CreateCondBr(CGF.Builder.CreateICmpEQ(Selector, Id), + Match, Next); + + CGF.EmitBlock(Match); + } + + if (CatchBody) { + llvm::BasicBlock *MatchEnd = CGF.createBasicBlock("match.end"); + llvm::BasicBlock *MatchHandler = CGF.createBasicBlock("match.handler"); + + // Cleanups must call objc_end_catch. + // + // FIXME: It seems incorrect for objc_begin_catch to be inside + // this context, but this matches gcc. + CGF.PushCleanupBlock(MatchEnd); + CGF.setInvokeDest(MatchHandler); + + llvm::Value *ExcObject = + CGF.Builder.CreateCall(ObjCTypes.ObjCBeginCatchFn, Exc); + + // Bind the catch parameter if it exists. + if (CatchParam) { + const VarDecl *VD = cast(CatchParam->getSolitaryDecl()); + ExcObject = CGF.Builder.CreateBitCast(ExcObject, + CGF.ConvertType(VD->getType())); + CGF.EmitStmt(CatchParam); + CGF.Builder.CreateStore(ExcObject, CGF.GetAddrOfLocalVar(VD)); + } + + CGF.ObjCEHValueStack.push_back(ExcObject); + CGF.EmitStmt(CatchBody); + CGF.ObjCEHValueStack.pop_back(); + + CGF.EmitBranchThroughCleanup(FinallyEnd); + + CGF.EmitBlock(MatchHandler); + + llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc"); + // We are required to emit this call to satisfy LLVM, even + // though we don't use the result. + llvm::SmallVector Args; + Args.push_back(Exc); + Args.push_back(ObjCTypes.EHPersonalityPtr); + Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, + 0)); + CGF.Builder.CreateCall(llvm_eh_selector_i64, Args.begin(), Args.end()); + CGF.Builder.CreateStore(Exc, RethrowPtr); + CGF.EmitBranchThroughCleanup(FinallyRethrow); + + CodeGenFunction::CleanupBlockInfo Info = CGF.PopCleanupBlock(); + + CGF.EmitBlock(MatchEnd); + + // Unfortunately, we also have to generate another EH frame here + // in case this throws. + llvm::BasicBlock *MatchEndHandler = + CGF.createBasicBlock("match.end.handler"); + llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont"); + CGF.Builder.CreateInvoke(ObjCTypes.ObjCEndCatchFn, + Cont, MatchEndHandler, + Args.begin(), Args.begin()); + + CGF.EmitBlock(Cont); + if (Info.SwitchBlock) + CGF.EmitBlock(Info.SwitchBlock); + if (Info.EndBlock) + CGF.EmitBlock(Info.EndBlock); + + CGF.EmitBlock(MatchEndHandler); + Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc"); + // We are required to emit this call to satisfy LLVM, even + // though we don't use the result. + Args.clear(); + Args.push_back(Exc); + Args.push_back(ObjCTypes.EHPersonalityPtr); + Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, + 0)); + CGF.Builder.CreateCall(llvm_eh_selector_i64, Args.begin(), Args.end()); + CGF.Builder.CreateStore(Exc, RethrowPtr); + CGF.EmitBranchThroughCleanup(FinallyRethrow); + + if (Next) + CGF.EmitBlock(Next); + } else { + assert(!Next && "catchup should be last handler."); + + CGF.Builder.CreateStore(Exc, RethrowPtr); + CGF.EmitBranchThroughCleanup(FinallyRethrow); + } + } + // Pop the cleanup entry, the @finally is outside this cleanup // scope. CodeGenFunction::CleanupBlockInfo Info = CGF.PopCleanupBlock(); @@ -4779,57 +4955,19 @@ CGObjCNonFragileABIMac::EmitTryOrSynchronizedStmt(CodeGen::CodeGenFunction &CGF, // Emit 'objc_sync_exit(expr)' as finally's sole statement for // @synchronized. CGF.Builder.CreateCall(ObjCTypes.SyncExitFn, SyncArg); - } + } if (Info.SwitchBlock) CGF.EmitBlock(Info.SwitchBlock); if (Info.EndBlock) CGF.EmitBlock(Info.EndBlock); - // Branch around the landing pad if necessary. + // Branch around the rethrow code. CGF.EmitBranch(FinallyEnd); - // Emit the landing pad. - - // Clear insertion point to avoid chaining. - CGF.Builder.ClearInsertionPoint(); - CGF.EmitBlock(LandingPad); - - llvm::Value *llvm_eh_exception = - CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_exception); - llvm::Value *llvm_eh_selector_i64 = - CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_selector_i64); - llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc"); - - llvm::SmallVector Args; - Args.push_back(Exc); - Args.push_back(ObjCTypes.EHPersonalityPtr); - Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0)); - - llvm::Value *Selector = - CGF.Builder.CreateCall(llvm_eh_selector_i64, Args.begin(), Args.end()); - - // The only valid result for the limited case we are considering is - // the cleanup. - (void) Selector; - - // Re-emit cleanup code for exceptional case. - if (isTry) { - // FIXME: This is horrible, in many ways: (a) it is broken because - // we are messing with some global data structures (like where - // labels point at), (b) it is exponential in the size of code - // generated, (c) seriously, its just gross. - if (const ObjCAtFinallyStmt* FinallyStmt = - cast(S).getFinallyStmt()) - CGF.EmitStmt(FinallyStmt->getFinallyBody()); - } else { - // Emit 'objc_sync_exit(expr)' as finally's sole statement for - // @synchronized. - CGF.Builder.CreateCall(ObjCTypes.SyncExitFn, SyncArg); - } - - CGF.EnsureInsertPoint(); - CGF.Builder.CreateCall(ObjCTypes.UnwindResumeOrRethrowFn, Exc); + CGF.EmitBlock(FinallyRethrow); + CGF.Builder.CreateCall(ObjCTypes.UnwindResumeOrRethrowFn, + CGF.Builder.CreateLoad(RethrowPtr)); CGF.Builder.CreateUnreachable(); CGF.EmitBlock(FinallyEnd); @@ -4838,28 +4976,28 @@ CGObjCNonFragileABIMac::EmitTryOrSynchronizedStmt(CodeGen::CodeGenFunction &CGF, /// EmitThrowStmt - Generate code for a throw statement. void CGObjCNonFragileABIMac::EmitThrowStmt(CodeGen::CodeGenFunction &CGF, const ObjCAtThrowStmt &S) { - llvm::Value *ExceptionAsObject; - + llvm::Value *Exception; if (const Expr *ThrowExpr = S.getThrowExpr()) { - llvm::Value *Exception = CGF.EmitScalarExpr(ThrowExpr); - ExceptionAsObject = - CGF.Builder.CreateBitCast(Exception, ObjCTypes.ObjectPtrTy, "tmp"); - - llvm::BasicBlock *InvokeDest = CGF.getInvokeDest(); - if (InvokeDest) { - llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont"); - CGF.Builder.CreateInvoke(ObjCTypes.ExceptionThrowFn, - Cont, InvokeDest, - &ExceptionAsObject, &ExceptionAsObject + 1); - CGF.EmitBlock(Cont); - } else - CGF.Builder.CreateCall(ObjCTypes.ExceptionThrowFn, ExceptionAsObject); - - CGF.Builder.CreateUnreachable(); + Exception = CGF.EmitScalarExpr(ThrowExpr); } else { - CGF.ErrorUnsupported(&S, "rethrow statement"); + assert((!CGF.ObjCEHValueStack.empty() && CGF.ObjCEHValueStack.back()) && + "Unexpected rethrow outside @catch block."); + Exception = CGF.ObjCEHValueStack.back(); } + llvm::Value *ExceptionAsObject = + CGF.Builder.CreateBitCast(Exception, ObjCTypes.ObjectPtrTy, "tmp"); + llvm::BasicBlock *InvokeDest = CGF.getInvokeDest(); + if (InvokeDest) { + llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont"); + CGF.Builder.CreateInvoke(ObjCTypes.ExceptionThrowFn, + Cont, InvokeDest, + &ExceptionAsObject, &ExceptionAsObject + 1); + CGF.EmitBlock(Cont); + } else + CGF.Builder.CreateCall(ObjCTypes.ExceptionThrowFn, ExceptionAsObject); + CGF.Builder.CreateUnreachable(); + // Clear the insertion point to indicate we are in unreachable code. CGF.Builder.ClearInsertionPoint(); }