forked from OSchip/llvm-project
1459 lines
54 KiB
C++
1459 lines
54 KiB
C++
//===--- CGException.cpp - Emit LLVM Code for C++ exceptions --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This contains code dealing with C++ exception related code generation.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/StmtCXX.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Support/CallSite.h"
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#include "CGObjCRuntime.h"
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#include "CodeGenFunction.h"
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#include "CGException.h"
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#include "CGCleanup.h"
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#include "TargetInfo.h"
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using namespace clang;
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using namespace CodeGen;
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static llvm::Constant *getAllocateExceptionFn(CodeGenFunction &CGF) {
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// void *__cxa_allocate_exception(size_t thrown_size);
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const llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getInt8PtrTy(CGF.getLLVMContext()),
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SizeTy, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_allocate_exception");
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}
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static llvm::Constant *getFreeExceptionFn(CodeGenFunction &CGF) {
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// void __cxa_free_exception(void *thrown_exception);
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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Int8PtrTy, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_free_exception");
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}
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static llvm::Constant *getThrowFn(CodeGenFunction &CGF) {
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// void __cxa_throw(void *thrown_exception, std::type_info *tinfo,
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// void (*dest) (void *));
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::Type *Args[3] = { Int8PtrTy, Int8PtrTy, Int8PtrTy };
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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Args, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_throw");
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}
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static llvm::Constant *getReThrowFn(CodeGenFunction &CGF) {
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// void __cxa_rethrow();
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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/*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_rethrow");
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}
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static llvm::Constant *getGetExceptionPtrFn(CodeGenFunction &CGF) {
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// void *__cxa_get_exception_ptr(void*);
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(Int8PtrTy, Int8PtrTy, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_get_exception_ptr");
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}
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static llvm::Constant *getBeginCatchFn(CodeGenFunction &CGF) {
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// void *__cxa_begin_catch(void*);
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(Int8PtrTy, Int8PtrTy, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch");
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}
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static llvm::Constant *getEndCatchFn(CodeGenFunction &CGF) {
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// void __cxa_end_catch();
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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/*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch");
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}
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static llvm::Constant *getUnexpectedFn(CodeGenFunction &CGF) {
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// void __cxa_call_unexepcted(void *thrown_exception);
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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Int8PtrTy, /*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, "__cxa_call_unexpected");
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}
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llvm::Constant *CodeGenFunction::getUnwindResumeOrRethrowFn() {
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), Int8PtrTy,
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/*IsVarArgs=*/false);
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if (CGM.getLangOptions().SjLjExceptions)
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return CGM.CreateRuntimeFunction(FTy, "_Unwind_SjLj_Resume_or_Rethrow");
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return CGM.CreateRuntimeFunction(FTy, "_Unwind_Resume_or_Rethrow");
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}
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static llvm::Constant *getTerminateFn(CodeGenFunction &CGF) {
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// void __terminate();
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const llvm::FunctionType *FTy =
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llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()),
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/*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy,
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CGF.CGM.getLangOptions().CPlusPlus ? "_ZSt9terminatev" : "abort");
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}
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static llvm::Constant *getCatchallRethrowFn(CodeGenFunction &CGF,
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llvm::StringRef Name) {
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const llvm::Type *Int8PtrTy =
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llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
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const llvm::Type *VoidTy = llvm::Type::getVoidTy(CGF.getLLVMContext());
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const llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, Int8PtrTy,
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/*IsVarArgs=*/false);
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return CGF.CGM.CreateRuntimeFunction(FTy, Name);
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}
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const EHPersonality EHPersonality::GNU_C("__gcc_personality_v0");
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const EHPersonality EHPersonality::GNU_C_SJLJ("__gcc_personality_sj0");
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const EHPersonality EHPersonality::NeXT_ObjC("__objc_personality_v0");
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const EHPersonality EHPersonality::GNU_CPlusPlus("__gxx_personality_v0");
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const EHPersonality EHPersonality::GNU_CPlusPlus_SJLJ("__gxx_personality_sj0");
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const EHPersonality EHPersonality::GNU_ObjC("__gnu_objc_personality_v0",
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"objc_exception_throw");
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const EHPersonality EHPersonality::GNU_ObjCXX("__gnustep_objcxx_personality_v0");
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static const EHPersonality &getCPersonality(const LangOptions &L) {
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if (L.SjLjExceptions)
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return EHPersonality::GNU_C_SJLJ;
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return EHPersonality::GNU_C;
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}
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static const EHPersonality &getObjCPersonality(const LangOptions &L) {
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if (L.NeXTRuntime) {
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if (L.ObjCNonFragileABI) return EHPersonality::NeXT_ObjC;
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else return getCPersonality(L);
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} else {
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return EHPersonality::GNU_ObjC;
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}
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}
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static const EHPersonality &getCXXPersonality(const LangOptions &L) {
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if (L.SjLjExceptions)
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return EHPersonality::GNU_CPlusPlus_SJLJ;
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else
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return EHPersonality::GNU_CPlusPlus;
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}
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/// Determines the personality function to use when both C++
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/// and Objective-C exceptions are being caught.
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static const EHPersonality &getObjCXXPersonality(const LangOptions &L) {
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// The ObjC personality defers to the C++ personality for non-ObjC
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// handlers. Unlike the C++ case, we use the same personality
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// function on targets using (backend-driven) SJLJ EH.
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if (L.NeXTRuntime) {
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if (L.ObjCNonFragileABI)
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return EHPersonality::NeXT_ObjC;
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// In the fragile ABI, just use C++ exception handling and hope
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// they're not doing crazy exception mixing.
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else
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return getCXXPersonality(L);
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}
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// The GNU runtime's personality function inherently doesn't support
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// mixed EH. Use the C++ personality just to avoid returning null.
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return EHPersonality::GNU_ObjCXX;
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}
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const EHPersonality &EHPersonality::get(const LangOptions &L) {
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if (L.CPlusPlus && L.ObjC1)
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return getObjCXXPersonality(L);
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else if (L.CPlusPlus)
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return getCXXPersonality(L);
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else if (L.ObjC1)
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return getObjCPersonality(L);
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else
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return getCPersonality(L);
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}
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static llvm::Constant *getPersonalityFn(CodeGenModule &CGM,
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const EHPersonality &Personality) {
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llvm::Constant *Fn =
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CGM.CreateRuntimeFunction(llvm::FunctionType::get(
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llvm::Type::getInt32Ty(CGM.getLLVMContext()),
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true),
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Personality.getPersonalityFnName());
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return Fn;
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}
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static llvm::Constant *getOpaquePersonalityFn(CodeGenModule &CGM,
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const EHPersonality &Personality) {
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llvm::Constant *Fn = getPersonalityFn(CGM, Personality);
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return llvm::ConstantExpr::getBitCast(Fn, CGM.Int8PtrTy);
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}
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/// Check whether a personality function could reasonably be swapped
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/// for a C++ personality function.
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static bool PersonalityHasOnlyCXXUses(llvm::Constant *Fn) {
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for (llvm::Constant::use_iterator
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I = Fn->use_begin(), E = Fn->use_end(); I != E; ++I) {
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llvm::User *User = *I;
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// Conditionally white-list bitcasts.
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if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(User)) {
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if (CE->getOpcode() != llvm::Instruction::BitCast) return false;
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if (!PersonalityHasOnlyCXXUses(CE))
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return false;
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continue;
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}
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// Otherwise, it has to be a selector call.
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if (!isa<llvm::EHSelectorInst>(User)) return false;
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llvm::EHSelectorInst *Selector = cast<llvm::EHSelectorInst>(User);
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for (unsigned I = 2, E = Selector->getNumArgOperands(); I != E; ++I) {
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// Look for something that would've been returned by the ObjC
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// runtime's GetEHType() method.
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llvm::GlobalVariable *GV
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= dyn_cast<llvm::GlobalVariable>(Selector->getArgOperand(I));
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if (!GV) continue;
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// ObjC EH selector entries are always global variables with
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// names starting like this.
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if (GV->getName().startswith("OBJC_EHTYPE"))
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return false;
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}
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}
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return true;
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}
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/// Try to use the C++ personality function in ObjC++. Not doing this
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/// can cause some incompatibilities with gcc, which is more
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/// aggressive about only using the ObjC++ personality in a function
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/// when it really needs it.
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void CodeGenModule::SimplifyPersonality() {
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// For now, this is really a Darwin-specific operation.
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if (Context.Target.getTriple().isOSDarwin())
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return;
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// If we're not in ObjC++ -fexceptions, there's nothing to do.
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if (!Features.CPlusPlus || !Features.ObjC1 || !Features.Exceptions)
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return;
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const EHPersonality &ObjCXX = EHPersonality::get(Features);
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const EHPersonality &CXX = getCXXPersonality(Features);
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if (&ObjCXX == &CXX ||
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ObjCXX.getPersonalityFnName() == CXX.getPersonalityFnName())
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return;
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llvm::Function *Fn =
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getModule().getFunction(ObjCXX.getPersonalityFnName());
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// Nothing to do if it's unused.
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if (!Fn || Fn->use_empty()) return;
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// Can't do the optimization if it has non-C++ uses.
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if (!PersonalityHasOnlyCXXUses(Fn)) return;
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// Create the C++ personality function and kill off the old
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// function.
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llvm::Constant *CXXFn = getPersonalityFn(*this, CXX);
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// This can happen if the user is screwing with us.
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if (Fn->getType() != CXXFn->getType()) return;
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Fn->replaceAllUsesWith(CXXFn);
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Fn->eraseFromParent();
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}
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/// Returns the value to inject into a selector to indicate the
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/// presence of a catch-all.
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static llvm::Constant *getCatchAllValue(CodeGenFunction &CGF) {
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// Possibly we should use @llvm.eh.catch.all.value here.
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return llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
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}
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/// Returns the value to inject into a selector to indicate the
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/// presence of a cleanup.
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static llvm::Constant *getCleanupValue(CodeGenFunction &CGF) {
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return llvm::ConstantInt::get(CGF.Builder.getInt32Ty(), 0);
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}
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namespace {
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/// A cleanup to free the exception object if its initialization
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/// throws.
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struct FreeException {
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static void Emit(CodeGenFunction &CGF, bool forEH,
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llvm::Value *exn) {
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CGF.Builder.CreateCall(getFreeExceptionFn(CGF), exn)
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->setDoesNotThrow();
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}
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};
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}
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// Emits an exception expression into the given location. This
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// differs from EmitAnyExprToMem only in that, if a final copy-ctor
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// call is required, an exception within that copy ctor causes
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// std::terminate to be invoked.
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static void EmitAnyExprToExn(CodeGenFunction &CGF, const Expr *e,
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llvm::Value *addr) {
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// Make sure the exception object is cleaned up if there's an
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// exception during initialization.
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CGF.pushFullExprCleanup<FreeException>(EHCleanup, addr);
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EHScopeStack::stable_iterator cleanup = CGF.EHStack.stable_begin();
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// __cxa_allocate_exception returns a void*; we need to cast this
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// to the appropriate type for the object.
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const llvm::Type *ty = CGF.ConvertTypeForMem(e->getType())->getPointerTo();
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llvm::Value *typedAddr = CGF.Builder.CreateBitCast(addr, ty);
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// FIXME: this isn't quite right! If there's a final unelided call
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// to a copy constructor, then according to [except.terminate]p1 we
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// must call std::terminate() if that constructor throws, because
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// technically that copy occurs after the exception expression is
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// evaluated but before the exception is caught. But the best way
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// to handle that is to teach EmitAggExpr to do the final copy
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// differently if it can't be elided.
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CGF.EmitAnyExprToMem(e, typedAddr, /*Volatile*/ false, /*IsInit*/ true);
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// Deactivate the cleanup block.
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CGF.DeactivateCleanupBlock(cleanup);
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}
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llvm::Value *CodeGenFunction::getExceptionSlot() {
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if (!ExceptionSlot) {
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const llvm::Type *i8p = llvm::Type::getInt8PtrTy(getLLVMContext());
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ExceptionSlot = CreateTempAlloca(i8p, "exn.slot");
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}
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return ExceptionSlot;
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}
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void CodeGenFunction::EmitCXXThrowExpr(const CXXThrowExpr *E) {
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if (!E->getSubExpr()) {
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if (getInvokeDest()) {
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Builder.CreateInvoke(getReThrowFn(*this),
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getUnreachableBlock(),
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getInvokeDest())
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->setDoesNotReturn();
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} else {
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Builder.CreateCall(getReThrowFn(*this))->setDoesNotReturn();
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Builder.CreateUnreachable();
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}
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// throw is an expression, and the expression emitters expect us
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// to leave ourselves at a valid insertion point.
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EmitBlock(createBasicBlock("throw.cont"));
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return;
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}
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QualType ThrowType = E->getSubExpr()->getType();
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// Now allocate the exception object.
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const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
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uint64_t TypeSize = getContext().getTypeSizeInChars(ThrowType).getQuantity();
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llvm::Constant *AllocExceptionFn = getAllocateExceptionFn(*this);
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llvm::CallInst *ExceptionPtr =
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Builder.CreateCall(AllocExceptionFn,
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llvm::ConstantInt::get(SizeTy, TypeSize),
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"exception");
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ExceptionPtr->setDoesNotThrow();
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EmitAnyExprToExn(*this, E->getSubExpr(), ExceptionPtr);
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// Now throw the exception.
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const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(getLLVMContext());
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llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(ThrowType,
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/*ForEH=*/true);
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// The address of the destructor. If the exception type has a
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// trivial destructor (or isn't a record), we just pass null.
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llvm::Constant *Dtor = 0;
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if (const RecordType *RecordTy = ThrowType->getAs<RecordType>()) {
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CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordTy->getDecl());
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if (!Record->hasTrivialDestructor()) {
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CXXDestructorDecl *DtorD = Record->getDestructor();
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Dtor = CGM.GetAddrOfCXXDestructor(DtorD, Dtor_Complete);
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Dtor = llvm::ConstantExpr::getBitCast(Dtor, Int8PtrTy);
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}
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}
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if (!Dtor) Dtor = llvm::Constant::getNullValue(Int8PtrTy);
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if (getInvokeDest()) {
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llvm::InvokeInst *ThrowCall =
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Builder.CreateInvoke3(getThrowFn(*this),
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getUnreachableBlock(), getInvokeDest(),
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ExceptionPtr, TypeInfo, Dtor);
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ThrowCall->setDoesNotReturn();
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} else {
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llvm::CallInst *ThrowCall =
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Builder.CreateCall3(getThrowFn(*this), ExceptionPtr, TypeInfo, Dtor);
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ThrowCall->setDoesNotReturn();
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Builder.CreateUnreachable();
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}
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// throw is an expression, and the expression emitters expect us
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// to leave ourselves at a valid insertion point.
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EmitBlock(createBasicBlock("throw.cont"));
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}
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void CodeGenFunction::EmitStartEHSpec(const Decl *D) {
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if (!CGM.getLangOptions().CXXExceptions)
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return;
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const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
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if (FD == 0)
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return;
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const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
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if (Proto == 0)
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return;
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ExceptionSpecificationType EST = Proto->getExceptionSpecType();
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if (isNoexceptExceptionSpec(EST)) {
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if (Proto->getNoexceptSpec(getContext()) == FunctionProtoType::NR_Nothrow) {
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// noexcept functions are simple terminate scopes.
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EHStack.pushTerminate();
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}
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} else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
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unsigned NumExceptions = Proto->getNumExceptions();
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EHFilterScope *Filter = EHStack.pushFilter(NumExceptions);
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for (unsigned I = 0; I != NumExceptions; ++I) {
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QualType Ty = Proto->getExceptionType(I);
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QualType ExceptType = Ty.getNonReferenceType().getUnqualifiedType();
|
|
llvm::Value *EHType = CGM.GetAddrOfRTTIDescriptor(ExceptType,
|
|
/*ForEH=*/true);
|
|
Filter->setFilter(I, EHType);
|
|
}
|
|
}
|
|
}
|
|
|
|
void CodeGenFunction::EmitEndEHSpec(const Decl *D) {
|
|
if (!CGM.getLangOptions().CXXExceptions)
|
|
return;
|
|
|
|
const FunctionDecl* FD = dyn_cast_or_null<FunctionDecl>(D);
|
|
if (FD == 0)
|
|
return;
|
|
const FunctionProtoType *Proto = FD->getType()->getAs<FunctionProtoType>();
|
|
if (Proto == 0)
|
|
return;
|
|
|
|
ExceptionSpecificationType EST = Proto->getExceptionSpecType();
|
|
if (isNoexceptExceptionSpec(EST)) {
|
|
if (Proto->getNoexceptSpec(getContext()) == FunctionProtoType::NR_Nothrow) {
|
|
EHStack.popTerminate();
|
|
}
|
|
} else if (EST == EST_Dynamic || EST == EST_DynamicNone) {
|
|
EHStack.popFilter();
|
|
}
|
|
}
|
|
|
|
void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
|
|
EnterCXXTryStmt(S);
|
|
EmitStmt(S.getTryBlock());
|
|
ExitCXXTryStmt(S);
|
|
}
|
|
|
|
void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
|
|
unsigned NumHandlers = S.getNumHandlers();
|
|
EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
|
|
|
|
for (unsigned I = 0; I != NumHandlers; ++I) {
|
|
const CXXCatchStmt *C = S.getHandler(I);
|
|
|
|
llvm::BasicBlock *Handler = createBasicBlock("catch");
|
|
if (C->getExceptionDecl()) {
|
|
// FIXME: Dropping the reference type on the type into makes it
|
|
// impossible to correctly implement catch-by-reference
|
|
// semantics for pointers. Unfortunately, this is what all
|
|
// existing compilers do, and it's not clear that the standard
|
|
// personality routine is capable of doing this right. See C++ DR 388:
|
|
// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#388
|
|
QualType CaughtType = C->getCaughtType();
|
|
CaughtType = CaughtType.getNonReferenceType().getUnqualifiedType();
|
|
|
|
llvm::Value *TypeInfo = 0;
|
|
if (CaughtType->isObjCObjectPointerType())
|
|
TypeInfo = CGM.getObjCRuntime().GetEHType(CaughtType);
|
|
else
|
|
TypeInfo = CGM.GetAddrOfRTTIDescriptor(CaughtType, /*ForEH=*/true);
|
|
CatchScope->setHandler(I, TypeInfo, Handler);
|
|
} else {
|
|
// No exception decl indicates '...', a catch-all.
|
|
CatchScope->setCatchAllHandler(I, Handler);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Check whether this is a non-EH scope, i.e. a scope which doesn't
|
|
/// affect exception handling. Currently, the only non-EH scopes are
|
|
/// normal-only cleanup scopes.
|
|
static bool isNonEHScope(const EHScope &S) {
|
|
switch (S.getKind()) {
|
|
case EHScope::Cleanup:
|
|
return !cast<EHCleanupScope>(S).isEHCleanup();
|
|
case EHScope::Filter:
|
|
case EHScope::Catch:
|
|
case EHScope::Terminate:
|
|
return false;
|
|
}
|
|
|
|
// Suppress warning.
|
|
return false;
|
|
}
|
|
|
|
llvm::BasicBlock *CodeGenFunction::getInvokeDestImpl() {
|
|
assert(EHStack.requiresLandingPad());
|
|
assert(!EHStack.empty());
|
|
|
|
if (!CGM.getLangOptions().Exceptions)
|
|
return 0;
|
|
|
|
// Check the innermost scope for a cached landing pad. If this is
|
|
// a non-EH cleanup, we'll check enclosing scopes in EmitLandingPad.
|
|
llvm::BasicBlock *LP = EHStack.begin()->getCachedLandingPad();
|
|
if (LP) return LP;
|
|
|
|
// Build the landing pad for this scope.
|
|
LP = EmitLandingPad();
|
|
assert(LP);
|
|
|
|
// Cache the landing pad on the innermost scope. If this is a
|
|
// non-EH scope, cache the landing pad on the enclosing scope, too.
|
|
for (EHScopeStack::iterator ir = EHStack.begin(); true; ++ir) {
|
|
ir->setCachedLandingPad(LP);
|
|
if (!isNonEHScope(*ir)) break;
|
|
}
|
|
|
|
return LP;
|
|
}
|
|
|
|
llvm::BasicBlock *CodeGenFunction::EmitLandingPad() {
|
|
assert(EHStack.requiresLandingPad());
|
|
|
|
// This function contains a hack to work around a design flaw in
|
|
// LLVM's EH IR which breaks semantics after inlining. This same
|
|
// hack is implemented in llvm-gcc.
|
|
//
|
|
// The LLVM EH abstraction is basically a thin veneer over the
|
|
// traditional GCC zero-cost design: for each range of instructions
|
|
// in the function, there is (at most) one "landing pad" with an
|
|
// associated chain of EH actions. A language-specific personality
|
|
// function interprets this chain of actions and (1) decides whether
|
|
// or not to resume execution at the landing pad and (2) if so,
|
|
// provides an integer indicating why it's stopping. In LLVM IR,
|
|
// the association of a landing pad with a range of instructions is
|
|
// achieved via an invoke instruction, the chain of actions becomes
|
|
// the arguments to the @llvm.eh.selector call, and the selector
|
|
// call returns the integer indicator. Other than the required
|
|
// presence of two intrinsic function calls in the landing pad,
|
|
// the IR exactly describes the layout of the output code.
|
|
//
|
|
// A principal advantage of this design is that it is completely
|
|
// language-agnostic; in theory, the LLVM optimizers can treat
|
|
// landing pads neutrally, and targets need only know how to lower
|
|
// the intrinsics to have a functioning exceptions system (assuming
|
|
// that platform exceptions follow something approximately like the
|
|
// GCC design). Unfortunately, landing pads cannot be combined in a
|
|
// language-agnostic way: given selectors A and B, there is no way
|
|
// to make a single landing pad which faithfully represents the
|
|
// semantics of propagating an exception first through A, then
|
|
// through B, without knowing how the personality will interpret the
|
|
// (lowered form of the) selectors. This means that inlining has no
|
|
// choice but to crudely chain invokes (i.e., to ignore invokes in
|
|
// the inlined function, but to turn all unwindable calls into
|
|
// invokes), which is only semantically valid if every unwind stops
|
|
// at every landing pad.
|
|
//
|
|
// Therefore, the invoke-inline hack is to guarantee that every
|
|
// landing pad has a catch-all.
|
|
const bool UseInvokeInlineHack = true;
|
|
|
|
for (EHScopeStack::iterator ir = EHStack.begin(); ; ) {
|
|
assert(ir != EHStack.end() &&
|
|
"stack requiring landing pad is nothing but non-EH scopes?");
|
|
|
|
// If this is a terminate scope, just use the singleton terminate
|
|
// landing pad.
|
|
if (isa<EHTerminateScope>(*ir))
|
|
return getTerminateLandingPad();
|
|
|
|
// If this isn't an EH scope, iterate; otherwise break out.
|
|
if (!isNonEHScope(*ir)) break;
|
|
++ir;
|
|
|
|
// We haven't checked this scope for a cached landing pad yet.
|
|
if (llvm::BasicBlock *LP = ir->getCachedLandingPad())
|
|
return LP;
|
|
}
|
|
|
|
// Save the current IR generation state.
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
|
|
|
|
const EHPersonality &Personality = EHPersonality::get(getLangOptions());
|
|
|
|
// Create and configure the landing pad.
|
|
llvm::BasicBlock *LP = createBasicBlock("lpad");
|
|
EmitBlock(LP);
|
|
|
|
// Save the exception pointer. It's safe to use a single exception
|
|
// pointer per function because EH cleanups can never have nested
|
|
// try/catches.
|
|
llvm::CallInst *Exn =
|
|
Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
|
|
Exn->setDoesNotThrow();
|
|
Builder.CreateStore(Exn, getExceptionSlot());
|
|
|
|
// Build the selector arguments.
|
|
llvm::SmallVector<llvm::Value*, 8> EHSelector;
|
|
EHSelector.push_back(Exn);
|
|
EHSelector.push_back(getOpaquePersonalityFn(CGM, Personality));
|
|
|
|
// Accumulate all the handlers in scope.
|
|
llvm::DenseMap<llvm::Value*, UnwindDest> EHHandlers;
|
|
UnwindDest CatchAll;
|
|
bool HasEHCleanup = false;
|
|
bool HasEHFilter = false;
|
|
llvm::SmallVector<llvm::Value*, 8> EHFilters;
|
|
for (EHScopeStack::iterator I = EHStack.begin(), E = EHStack.end();
|
|
I != E; ++I) {
|
|
|
|
switch (I->getKind()) {
|
|
case EHScope::Cleanup:
|
|
if (!HasEHCleanup)
|
|
HasEHCleanup = cast<EHCleanupScope>(*I).isEHCleanup();
|
|
// We otherwise don't care about cleanups.
|
|
continue;
|
|
|
|
case EHScope::Filter: {
|
|
assert(I.next() == EHStack.end() && "EH filter is not end of EH stack");
|
|
assert(!CatchAll.isValid() && "EH filter reached after catch-all");
|
|
|
|
// Filter scopes get added to the selector in weird ways.
|
|
EHFilterScope &Filter = cast<EHFilterScope>(*I);
|
|
HasEHFilter = true;
|
|
|
|
// Add all the filter values which we aren't already explicitly
|
|
// catching.
|
|
for (unsigned I = 0, E = Filter.getNumFilters(); I != E; ++I) {
|
|
llvm::Value *FV = Filter.getFilter(I);
|
|
if (!EHHandlers.count(FV))
|
|
EHFilters.push_back(FV);
|
|
}
|
|
goto done;
|
|
}
|
|
|
|
case EHScope::Terminate:
|
|
// Terminate scopes are basically catch-alls.
|
|
assert(!CatchAll.isValid());
|
|
CatchAll = UnwindDest(getTerminateHandler(),
|
|
EHStack.getEnclosingEHCleanup(I),
|
|
cast<EHTerminateScope>(*I).getDestIndex());
|
|
goto done;
|
|
|
|
case EHScope::Catch:
|
|
break;
|
|
}
|
|
|
|
EHCatchScope &Catch = cast<EHCatchScope>(*I);
|
|
for (unsigned HI = 0, HE = Catch.getNumHandlers(); HI != HE; ++HI) {
|
|
EHCatchScope::Handler Handler = Catch.getHandler(HI);
|
|
|
|
// Catch-all. We should only have one of these per catch.
|
|
if (!Handler.Type) {
|
|
assert(!CatchAll.isValid());
|
|
CatchAll = UnwindDest(Handler.Block,
|
|
EHStack.getEnclosingEHCleanup(I),
|
|
Handler.Index);
|
|
continue;
|
|
}
|
|
|
|
// Check whether we already have a handler for this type.
|
|
UnwindDest &Dest = EHHandlers[Handler.Type];
|
|
if (Dest.isValid()) continue;
|
|
|
|
EHSelector.push_back(Handler.Type);
|
|
Dest = UnwindDest(Handler.Block,
|
|
EHStack.getEnclosingEHCleanup(I),
|
|
Handler.Index);
|
|
}
|
|
|
|
// Stop if we found a catch-all.
|
|
if (CatchAll.isValid()) break;
|
|
}
|
|
|
|
done:
|
|
unsigned LastToEmitInLoop = EHSelector.size();
|
|
|
|
// If we have a catch-all, add null to the selector.
|
|
if (CatchAll.isValid()) {
|
|
EHSelector.push_back(getCatchAllValue(*this));
|
|
|
|
// If we have an EH filter, we need to add those handlers in the
|
|
// right place in the selector, which is to say, at the end.
|
|
} else if (HasEHFilter) {
|
|
// Create a filter expression: an integer constant saying how many
|
|
// filters there are (+1 to avoid ambiguity with 0 for cleanup),
|
|
// followed by the filter types. The personality routine only
|
|
// lands here if the filter doesn't match.
|
|
EHSelector.push_back(llvm::ConstantInt::get(Builder.getInt32Ty(),
|
|
EHFilters.size() + 1));
|
|
EHSelector.append(EHFilters.begin(), EHFilters.end());
|
|
|
|
// Also check whether we need a cleanup.
|
|
if (UseInvokeInlineHack || HasEHCleanup)
|
|
EHSelector.push_back(UseInvokeInlineHack
|
|
? getCatchAllValue(*this)
|
|
: getCleanupValue(*this));
|
|
|
|
// Otherwise, signal that we at least have cleanups.
|
|
} else if (UseInvokeInlineHack || HasEHCleanup) {
|
|
EHSelector.push_back(UseInvokeInlineHack
|
|
? getCatchAllValue(*this)
|
|
: getCleanupValue(*this));
|
|
} else {
|
|
assert(LastToEmitInLoop > 2);
|
|
LastToEmitInLoop--;
|
|
}
|
|
|
|
assert(EHSelector.size() >= 3 && "selector call has only two arguments!");
|
|
|
|
// Tell the backend how to generate the landing pad.
|
|
llvm::CallInst *Selection =
|
|
Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
|
|
EHSelector.begin(), EHSelector.end(), "eh.selector");
|
|
Selection->setDoesNotThrow();
|
|
|
|
// Select the right handler.
|
|
llvm::Value *llvm_eh_typeid_for =
|
|
CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for);
|
|
|
|
// The results of llvm_eh_typeid_for aren't reliable --- at least
|
|
// not locally --- so we basically have to do this as an 'if' chain.
|
|
// We walk through the first N-1 catch clauses, testing and chaining,
|
|
// and then fall into the final clause (which is either a cleanup, a
|
|
// filter (possibly with a cleanup), a catch-all, or another catch).
|
|
for (unsigned I = 2; I != LastToEmitInLoop; ++I) {
|
|
llvm::Value *Type = EHSelector[I];
|
|
UnwindDest Dest = EHHandlers[Type];
|
|
assert(Dest.isValid() && "no handler entry for value in selector?");
|
|
|
|
// Figure out where to branch on a match. As a debug code-size
|
|
// optimization, if the scope depth matches the innermost cleanup,
|
|
// we branch directly to the catch handler.
|
|
llvm::BasicBlock *Match = Dest.getBlock();
|
|
bool MatchNeedsCleanup =
|
|
Dest.getScopeDepth() != EHStack.getInnermostEHCleanup();
|
|
if (MatchNeedsCleanup)
|
|
Match = createBasicBlock("eh.match");
|
|
|
|
llvm::BasicBlock *Next = createBasicBlock("eh.next");
|
|
|
|
// Check whether the exception matches.
|
|
llvm::CallInst *Id
|
|
= Builder.CreateCall(llvm_eh_typeid_for,
|
|
Builder.CreateBitCast(Type, Int8PtrTy));
|
|
Id->setDoesNotThrow();
|
|
Builder.CreateCondBr(Builder.CreateICmpEQ(Selection, Id),
|
|
Match, Next);
|
|
|
|
// Emit match code if necessary.
|
|
if (MatchNeedsCleanup) {
|
|
EmitBlock(Match);
|
|
EmitBranchThroughEHCleanup(Dest);
|
|
}
|
|
|
|
// Continue to the next match.
|
|
EmitBlock(Next);
|
|
}
|
|
|
|
// Emit the final case in the selector.
|
|
// This might be a catch-all....
|
|
if (CatchAll.isValid()) {
|
|
assert(isa<llvm::ConstantPointerNull>(EHSelector.back()));
|
|
EmitBranchThroughEHCleanup(CatchAll);
|
|
|
|
// ...or an EH filter...
|
|
} else if (HasEHFilter) {
|
|
llvm::Value *SavedSelection = Selection;
|
|
|
|
// First, unwind out to the outermost scope if necessary.
|
|
if (EHStack.hasEHCleanups()) {
|
|
// The end here might not dominate the beginning, so we might need to
|
|
// save the selector if we need it.
|
|
llvm::AllocaInst *SelectorVar = 0;
|
|
if (HasEHCleanup) {
|
|
SelectorVar = CreateTempAlloca(Builder.getInt32Ty(), "selector.var");
|
|
Builder.CreateStore(Selection, SelectorVar);
|
|
}
|
|
|
|
llvm::BasicBlock *CleanupContBB = createBasicBlock("ehspec.cleanup.cont");
|
|
EmitBranchThroughEHCleanup(UnwindDest(CleanupContBB, EHStack.stable_end(),
|
|
EHStack.getNextEHDestIndex()));
|
|
EmitBlock(CleanupContBB);
|
|
|
|
if (HasEHCleanup)
|
|
SavedSelection = Builder.CreateLoad(SelectorVar, "ehspec.saved-selector");
|
|
}
|
|
|
|
// If there was a cleanup, we'll need to actually check whether we
|
|
// landed here because the filter triggered.
|
|
if (UseInvokeInlineHack || HasEHCleanup) {
|
|
llvm::BasicBlock *RethrowBB = createBasicBlock("cleanup");
|
|
llvm::BasicBlock *UnexpectedBB = createBasicBlock("ehspec.unexpected");
|
|
|
|
llvm::Constant *Zero = llvm::ConstantInt::get(Builder.getInt32Ty(), 0);
|
|
llvm::Value *FailsFilter =
|
|
Builder.CreateICmpSLT(SavedSelection, Zero, "ehspec.fails");
|
|
Builder.CreateCondBr(FailsFilter, UnexpectedBB, RethrowBB);
|
|
|
|
// The rethrow block is where we land if this was a cleanup.
|
|
// TODO: can this be _Unwind_Resume if the InvokeInlineHack is off?
|
|
EmitBlock(RethrowBB);
|
|
Builder.CreateCall(getUnwindResumeOrRethrowFn(),
|
|
Builder.CreateLoad(getExceptionSlot()))
|
|
->setDoesNotReturn();
|
|
Builder.CreateUnreachable();
|
|
|
|
EmitBlock(UnexpectedBB);
|
|
}
|
|
|
|
// Call __cxa_call_unexpected. This doesn't need to be an invoke
|
|
// because __cxa_call_unexpected magically filters exceptions
|
|
// according to the last landing pad the exception was thrown
|
|
// into. Seriously.
|
|
Builder.CreateCall(getUnexpectedFn(*this),
|
|
Builder.CreateLoad(getExceptionSlot()))
|
|
->setDoesNotReturn();
|
|
Builder.CreateUnreachable();
|
|
|
|
// ...or a normal catch handler...
|
|
} else if (!UseInvokeInlineHack && !HasEHCleanup) {
|
|
llvm::Value *Type = EHSelector.back();
|
|
EmitBranchThroughEHCleanup(EHHandlers[Type]);
|
|
|
|
// ...or a cleanup.
|
|
} else {
|
|
EmitBranchThroughEHCleanup(getRethrowDest());
|
|
}
|
|
|
|
// Restore the old IR generation state.
|
|
Builder.restoreIP(SavedIP);
|
|
|
|
return LP;
|
|
}
|
|
|
|
namespace {
|
|
/// A cleanup to call __cxa_end_catch. In many cases, the caught
|
|
/// exception type lets us state definitively that the thrown exception
|
|
/// type does not have a destructor. In particular:
|
|
/// - Catch-alls tell us nothing, so we have to conservatively
|
|
/// assume that the thrown exception might have a destructor.
|
|
/// - Catches by reference behave according to their base types.
|
|
/// - Catches of non-record types will only trigger for exceptions
|
|
/// of non-record types, which never have destructors.
|
|
/// - Catches of record types can trigger for arbitrary subclasses
|
|
/// of the caught type, so we have to assume the actual thrown
|
|
/// exception type might have a throwing destructor, even if the
|
|
/// caught type's destructor is trivial or nothrow.
|
|
struct CallEndCatch : EHScopeStack::Cleanup {
|
|
CallEndCatch(bool MightThrow) : MightThrow(MightThrow) {}
|
|
bool MightThrow;
|
|
|
|
void Emit(CodeGenFunction &CGF, bool IsForEH) {
|
|
if (!MightThrow) {
|
|
CGF.Builder.CreateCall(getEndCatchFn(CGF))->setDoesNotThrow();
|
|
return;
|
|
}
|
|
|
|
CGF.EmitCallOrInvoke(getEndCatchFn(CGF), 0, 0);
|
|
}
|
|
};
|
|
}
|
|
|
|
/// Emits a call to __cxa_begin_catch and enters a cleanup to call
|
|
/// __cxa_end_catch.
|
|
///
|
|
/// \param EndMightThrow - true if __cxa_end_catch might throw
|
|
static llvm::Value *CallBeginCatch(CodeGenFunction &CGF,
|
|
llvm::Value *Exn,
|
|
bool EndMightThrow) {
|
|
llvm::CallInst *Call = CGF.Builder.CreateCall(getBeginCatchFn(CGF), Exn);
|
|
Call->setDoesNotThrow();
|
|
|
|
CGF.EHStack.pushCleanup<CallEndCatch>(NormalAndEHCleanup, EndMightThrow);
|
|
|
|
return Call;
|
|
}
|
|
|
|
/// A "special initializer" callback for initializing a catch
|
|
/// parameter during catch initialization.
|
|
static void InitCatchParam(CodeGenFunction &CGF,
|
|
const VarDecl &CatchParam,
|
|
llvm::Value *ParamAddr) {
|
|
// Load the exception from where the landing pad saved it.
|
|
llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot(), "exn");
|
|
|
|
CanQualType CatchType =
|
|
CGF.CGM.getContext().getCanonicalType(CatchParam.getType());
|
|
const llvm::Type *LLVMCatchTy = CGF.ConvertTypeForMem(CatchType);
|
|
|
|
// If we're catching by reference, we can just cast the object
|
|
// pointer to the appropriate pointer.
|
|
if (isa<ReferenceType>(CatchType)) {
|
|
QualType CaughtType = cast<ReferenceType>(CatchType)->getPointeeType();
|
|
bool EndCatchMightThrow = CaughtType->isRecordType();
|
|
|
|
// __cxa_begin_catch returns the adjusted object pointer.
|
|
llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, EndCatchMightThrow);
|
|
|
|
// We have no way to tell the personality function that we're
|
|
// catching by reference, so if we're catching a pointer,
|
|
// __cxa_begin_catch will actually return that pointer by value.
|
|
if (const PointerType *PT = dyn_cast<PointerType>(CaughtType)) {
|
|
QualType PointeeType = PT->getPointeeType();
|
|
|
|
// When catching by reference, generally we should just ignore
|
|
// this by-value pointer and use the exception object instead.
|
|
if (!PointeeType->isRecordType()) {
|
|
|
|
// Exn points to the struct _Unwind_Exception header, which
|
|
// we have to skip past in order to reach the exception data.
|
|
unsigned HeaderSize =
|
|
CGF.CGM.getTargetCodeGenInfo().getSizeOfUnwindException();
|
|
AdjustedExn = CGF.Builder.CreateConstGEP1_32(Exn, HeaderSize);
|
|
|
|
// However, if we're catching a pointer-to-record type that won't
|
|
// work, because the personality function might have adjusted
|
|
// the pointer. There's actually no way for us to fully satisfy
|
|
// the language/ABI contract here: we can't use Exn because it
|
|
// might have the wrong adjustment, but we can't use the by-value
|
|
// pointer because it's off by a level of abstraction.
|
|
//
|
|
// The current solution is to dump the adjusted pointer into an
|
|
// alloca, which breaks language semantics (because changing the
|
|
// pointer doesn't change the exception) but at least works.
|
|
// The better solution would be to filter out non-exact matches
|
|
// and rethrow them, but this is tricky because the rethrow
|
|
// really needs to be catchable by other sites at this landing
|
|
// pad. The best solution is to fix the personality function.
|
|
} else {
|
|
// Pull the pointer for the reference type off.
|
|
const llvm::Type *PtrTy =
|
|
cast<llvm::PointerType>(LLVMCatchTy)->getElementType();
|
|
|
|
// Create the temporary and write the adjusted pointer into it.
|
|
llvm::Value *ExnPtrTmp = CGF.CreateTempAlloca(PtrTy, "exn.byref.tmp");
|
|
llvm::Value *Casted = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
|
|
CGF.Builder.CreateStore(Casted, ExnPtrTmp);
|
|
|
|
// Bind the reference to the temporary.
|
|
AdjustedExn = ExnPtrTmp;
|
|
}
|
|
}
|
|
|
|
llvm::Value *ExnCast =
|
|
CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.byref");
|
|
CGF.Builder.CreateStore(ExnCast, ParamAddr);
|
|
return;
|
|
}
|
|
|
|
// Non-aggregates (plus complexes).
|
|
bool IsComplex = false;
|
|
if (!CGF.hasAggregateLLVMType(CatchType) ||
|
|
(IsComplex = CatchType->isAnyComplexType())) {
|
|
llvm::Value *AdjustedExn = CallBeginCatch(CGF, Exn, false);
|
|
|
|
// If the catch type is a pointer type, __cxa_begin_catch returns
|
|
// the pointer by value.
|
|
if (CatchType->hasPointerRepresentation()) {
|
|
llvm::Value *CastExn =
|
|
CGF.Builder.CreateBitCast(AdjustedExn, LLVMCatchTy, "exn.casted");
|
|
CGF.Builder.CreateStore(CastExn, ParamAddr);
|
|
return;
|
|
}
|
|
|
|
// Otherwise, it returns a pointer into the exception object.
|
|
|
|
const llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok
|
|
llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy);
|
|
|
|
if (IsComplex) {
|
|
CGF.StoreComplexToAddr(CGF.LoadComplexFromAddr(Cast, /*volatile*/ false),
|
|
ParamAddr, /*volatile*/ false);
|
|
} else {
|
|
unsigned Alignment =
|
|
CGF.getContext().getDeclAlign(&CatchParam).getQuantity();
|
|
llvm::Value *ExnLoad = CGF.Builder.CreateLoad(Cast, "exn.scalar");
|
|
CGF.EmitStoreOfScalar(ExnLoad, ParamAddr, /*volatile*/ false, Alignment,
|
|
CatchType);
|
|
}
|
|
return;
|
|
}
|
|
|
|
assert(isa<RecordType>(CatchType) && "unexpected catch type!");
|
|
|
|
const llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok
|
|
|
|
// Check for a copy expression. If we don't have a copy expression,
|
|
// that means a trivial copy is okay.
|
|
const Expr *copyExpr = CatchParam.getInit();
|
|
if (!copyExpr) {
|
|
llvm::Value *rawAdjustedExn = CallBeginCatch(CGF, Exn, true);
|
|
llvm::Value *adjustedExn = CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy);
|
|
CGF.EmitAggregateCopy(ParamAddr, adjustedExn, CatchType);
|
|
return;
|
|
}
|
|
|
|
// We have to call __cxa_get_exception_ptr to get the adjusted
|
|
// pointer before copying.
|
|
llvm::CallInst *rawAdjustedExn =
|
|
CGF.Builder.CreateCall(getGetExceptionPtrFn(CGF), Exn);
|
|
rawAdjustedExn->setDoesNotThrow();
|
|
|
|
// Cast that to the appropriate type.
|
|
llvm::Value *adjustedExn = CGF.Builder.CreateBitCast(rawAdjustedExn, PtrTy);
|
|
|
|
// The copy expression is defined in terms of an OpaqueValueExpr.
|
|
// Find it and map it to the adjusted expression.
|
|
CodeGenFunction::OpaqueValueMapping
|
|
opaque(CGF, OpaqueValueExpr::findInCopyConstruct(copyExpr),
|
|
CGF.MakeAddrLValue(adjustedExn, CatchParam.getType()));
|
|
|
|
// Call the copy ctor in a terminate scope.
|
|
CGF.EHStack.pushTerminate();
|
|
|
|
// Perform the copy construction.
|
|
CGF.EmitAggExpr(copyExpr, AggValueSlot::forAddr(ParamAddr, false, false));
|
|
|
|
// Leave the terminate scope.
|
|
CGF.EHStack.popTerminate();
|
|
|
|
// Undo the opaque value mapping.
|
|
opaque.pop();
|
|
|
|
// Finally we can call __cxa_begin_catch.
|
|
CallBeginCatch(CGF, Exn, true);
|
|
}
|
|
|
|
/// Begins a catch statement by initializing the catch variable and
|
|
/// calling __cxa_begin_catch.
|
|
static void BeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *S) {
|
|
// We have to be very careful with the ordering of cleanups here:
|
|
// C++ [except.throw]p4:
|
|
// The destruction [of the exception temporary] occurs
|
|
// immediately after the destruction of the object declared in
|
|
// the exception-declaration in the handler.
|
|
//
|
|
// So the precise ordering is:
|
|
// 1. Construct catch variable.
|
|
// 2. __cxa_begin_catch
|
|
// 3. Enter __cxa_end_catch cleanup
|
|
// 4. Enter dtor cleanup
|
|
//
|
|
// We do this by using a slightly abnormal initialization process.
|
|
// Delegation sequence:
|
|
// - ExitCXXTryStmt opens a RunCleanupsScope
|
|
// - EmitAutoVarAlloca creates the variable and debug info
|
|
// - InitCatchParam initializes the variable from the exception
|
|
// - CallBeginCatch calls __cxa_begin_catch
|
|
// - CallBeginCatch enters the __cxa_end_catch cleanup
|
|
// - EmitAutoVarCleanups enters the variable destructor cleanup
|
|
// - EmitCXXTryStmt emits the code for the catch body
|
|
// - EmitCXXTryStmt close the RunCleanupsScope
|
|
|
|
VarDecl *CatchParam = S->getExceptionDecl();
|
|
if (!CatchParam) {
|
|
llvm::Value *Exn = CGF.Builder.CreateLoad(CGF.getExceptionSlot(), "exn");
|
|
CallBeginCatch(CGF, Exn, true);
|
|
return;
|
|
}
|
|
|
|
// Emit the local.
|
|
CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
|
|
InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF));
|
|
CGF.EmitAutoVarCleanups(var);
|
|
}
|
|
|
|
namespace {
|
|
struct CallRethrow : EHScopeStack::Cleanup {
|
|
void Emit(CodeGenFunction &CGF, bool IsForEH) {
|
|
CGF.EmitCallOrInvoke(getReThrowFn(CGF), 0, 0);
|
|
}
|
|
};
|
|
}
|
|
|
|
void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
|
|
unsigned NumHandlers = S.getNumHandlers();
|
|
EHCatchScope &CatchScope = cast<EHCatchScope>(*EHStack.begin());
|
|
assert(CatchScope.getNumHandlers() == NumHandlers);
|
|
|
|
// Copy the handler blocks off before we pop the EH stack. Emitting
|
|
// the handlers might scribble on this memory.
|
|
llvm::SmallVector<EHCatchScope::Handler, 8> Handlers(NumHandlers);
|
|
memcpy(Handlers.data(), CatchScope.begin(),
|
|
NumHandlers * sizeof(EHCatchScope::Handler));
|
|
EHStack.popCatch();
|
|
|
|
// The fall-through block.
|
|
llvm::BasicBlock *ContBB = createBasicBlock("try.cont");
|
|
|
|
// We just emitted the body of the try; jump to the continue block.
|
|
if (HaveInsertPoint())
|
|
Builder.CreateBr(ContBB);
|
|
|
|
// Determine if we need an implicit rethrow for all these catch handlers.
|
|
bool ImplicitRethrow = false;
|
|
if (IsFnTryBlock)
|
|
ImplicitRethrow = isa<CXXDestructorDecl>(CurCodeDecl) ||
|
|
isa<CXXConstructorDecl>(CurCodeDecl);
|
|
|
|
for (unsigned I = 0; I != NumHandlers; ++I) {
|
|
llvm::BasicBlock *CatchBlock = Handlers[I].Block;
|
|
EmitBlock(CatchBlock);
|
|
|
|
// Catch the exception if this isn't a catch-all.
|
|
const CXXCatchStmt *C = S.getHandler(I);
|
|
|
|
// Enter a cleanup scope, including the catch variable and the
|
|
// end-catch.
|
|
RunCleanupsScope CatchScope(*this);
|
|
|
|
// Initialize the catch variable and set up the cleanups.
|
|
BeginCatch(*this, C);
|
|
|
|
// If there's an implicit rethrow, push a normal "cleanup" to call
|
|
// _cxa_rethrow. This needs to happen before __cxa_end_catch is
|
|
// called, and so it is pushed after BeginCatch.
|
|
if (ImplicitRethrow)
|
|
EHStack.pushCleanup<CallRethrow>(NormalCleanup);
|
|
|
|
// Perform the body of the catch.
|
|
EmitStmt(C->getHandlerBlock());
|
|
|
|
// Fall out through the catch cleanups.
|
|
CatchScope.ForceCleanup();
|
|
|
|
// Branch out of the try.
|
|
if (HaveInsertPoint())
|
|
Builder.CreateBr(ContBB);
|
|
}
|
|
|
|
EmitBlock(ContBB);
|
|
}
|
|
|
|
namespace {
|
|
struct CallEndCatchForFinally : EHScopeStack::Cleanup {
|
|
llvm::Value *ForEHVar;
|
|
llvm::Value *EndCatchFn;
|
|
CallEndCatchForFinally(llvm::Value *ForEHVar, llvm::Value *EndCatchFn)
|
|
: ForEHVar(ForEHVar), EndCatchFn(EndCatchFn) {}
|
|
|
|
void Emit(CodeGenFunction &CGF, bool IsForEH) {
|
|
llvm::BasicBlock *EndCatchBB = CGF.createBasicBlock("finally.endcatch");
|
|
llvm::BasicBlock *CleanupContBB =
|
|
CGF.createBasicBlock("finally.cleanup.cont");
|
|
|
|
llvm::Value *ShouldEndCatch =
|
|
CGF.Builder.CreateLoad(ForEHVar, "finally.endcatch");
|
|
CGF.Builder.CreateCondBr(ShouldEndCatch, EndCatchBB, CleanupContBB);
|
|
CGF.EmitBlock(EndCatchBB);
|
|
CGF.EmitCallOrInvoke(EndCatchFn, 0, 0); // catch-all, so might throw
|
|
CGF.EmitBlock(CleanupContBB);
|
|
}
|
|
};
|
|
|
|
struct PerformFinally : EHScopeStack::Cleanup {
|
|
const Stmt *Body;
|
|
llvm::Value *ForEHVar;
|
|
llvm::Value *EndCatchFn;
|
|
llvm::Value *RethrowFn;
|
|
llvm::Value *SavedExnVar;
|
|
|
|
PerformFinally(const Stmt *Body, llvm::Value *ForEHVar,
|
|
llvm::Value *EndCatchFn,
|
|
llvm::Value *RethrowFn, llvm::Value *SavedExnVar)
|
|
: Body(Body), ForEHVar(ForEHVar), EndCatchFn(EndCatchFn),
|
|
RethrowFn(RethrowFn), SavedExnVar(SavedExnVar) {}
|
|
|
|
void Emit(CodeGenFunction &CGF, bool IsForEH) {
|
|
// Enter a cleanup to call the end-catch function if one was provided.
|
|
if (EndCatchFn)
|
|
CGF.EHStack.pushCleanup<CallEndCatchForFinally>(NormalAndEHCleanup,
|
|
ForEHVar, EndCatchFn);
|
|
|
|
// Save the current cleanup destination in case there are
|
|
// cleanups in the finally block.
|
|
llvm::Value *SavedCleanupDest =
|
|
CGF.Builder.CreateLoad(CGF.getNormalCleanupDestSlot(),
|
|
"cleanup.dest.saved");
|
|
|
|
// Emit the finally block.
|
|
CGF.EmitStmt(Body);
|
|
|
|
// If the end of the finally is reachable, check whether this was
|
|
// for EH. If so, rethrow.
|
|
if (CGF.HaveInsertPoint()) {
|
|
llvm::BasicBlock *RethrowBB = CGF.createBasicBlock("finally.rethrow");
|
|
llvm::BasicBlock *ContBB = CGF.createBasicBlock("finally.cont");
|
|
|
|
llvm::Value *ShouldRethrow =
|
|
CGF.Builder.CreateLoad(ForEHVar, "finally.shouldthrow");
|
|
CGF.Builder.CreateCondBr(ShouldRethrow, RethrowBB, ContBB);
|
|
|
|
CGF.EmitBlock(RethrowBB);
|
|
if (SavedExnVar) {
|
|
llvm::Value *Args[] = { CGF.Builder.CreateLoad(SavedExnVar) };
|
|
CGF.EmitCallOrInvoke(RethrowFn, Args, Args+1);
|
|
} else {
|
|
CGF.EmitCallOrInvoke(RethrowFn, 0, 0);
|
|
}
|
|
CGF.Builder.CreateUnreachable();
|
|
|
|
CGF.EmitBlock(ContBB);
|
|
|
|
// Restore the cleanup destination.
|
|
CGF.Builder.CreateStore(SavedCleanupDest,
|
|
CGF.getNormalCleanupDestSlot());
|
|
}
|
|
|
|
// Leave the end-catch cleanup. As an optimization, pretend that
|
|
// the fallthrough path was inaccessible; we've dynamically proven
|
|
// that we're not in the EH case along that path.
|
|
if (EndCatchFn) {
|
|
CGBuilderTy::InsertPoint SavedIP = CGF.Builder.saveAndClearIP();
|
|
CGF.PopCleanupBlock();
|
|
CGF.Builder.restoreIP(SavedIP);
|
|
}
|
|
|
|
// Now make sure we actually have an insertion point or the
|
|
// cleanup gods will hate us.
|
|
CGF.EnsureInsertPoint();
|
|
}
|
|
};
|
|
}
|
|
|
|
/// Enters a finally block for an implementation using zero-cost
|
|
/// exceptions. This is mostly general, but hard-codes some
|
|
/// language/ABI-specific behavior in the catch-all sections.
|
|
CodeGenFunction::FinallyInfo
|
|
CodeGenFunction::EnterFinallyBlock(const Stmt *Body,
|
|
llvm::Constant *BeginCatchFn,
|
|
llvm::Constant *EndCatchFn,
|
|
llvm::Constant *RethrowFn) {
|
|
assert((BeginCatchFn != 0) == (EndCatchFn != 0) &&
|
|
"begin/end catch functions not paired");
|
|
assert(RethrowFn && "rethrow function is required");
|
|
|
|
// The rethrow function has one of the following two types:
|
|
// void (*)()
|
|
// void (*)(void*)
|
|
// In the latter case we need to pass it the exception object.
|
|
// But we can't use the exception slot because the @finally might
|
|
// have a landing pad (which would overwrite the exception slot).
|
|
const llvm::FunctionType *RethrowFnTy =
|
|
cast<llvm::FunctionType>(
|
|
cast<llvm::PointerType>(RethrowFn->getType())
|
|
->getElementType());
|
|
llvm::Value *SavedExnVar = 0;
|
|
if (RethrowFnTy->getNumParams())
|
|
SavedExnVar = CreateTempAlloca(Builder.getInt8PtrTy(), "finally.exn");
|
|
|
|
// A finally block is a statement which must be executed on any edge
|
|
// out of a given scope. Unlike a cleanup, the finally block may
|
|
// contain arbitrary control flow leading out of itself. In
|
|
// addition, finally blocks should always be executed, even if there
|
|
// are no catch handlers higher on the stack. Therefore, we
|
|
// surround the protected scope with a combination of a normal
|
|
// cleanup (to catch attempts to break out of the block via normal
|
|
// control flow) and an EH catch-all (semantically "outside" any try
|
|
// statement to which the finally block might have been attached).
|
|
// The finally block itself is generated in the context of a cleanup
|
|
// which conditionally leaves the catch-all.
|
|
|
|
FinallyInfo Info;
|
|
|
|
// Jump destination for performing the finally block on an exception
|
|
// edge. We'll never actually reach this block, so unreachable is
|
|
// fine.
|
|
JumpDest RethrowDest = getJumpDestInCurrentScope(getUnreachableBlock());
|
|
|
|
// Whether the finally block is being executed for EH purposes.
|
|
llvm::AllocaInst *ForEHVar = CreateTempAlloca(Builder.getInt1Ty(),
|
|
"finally.for-eh");
|
|
InitTempAlloca(ForEHVar, llvm::ConstantInt::getFalse(getLLVMContext()));
|
|
|
|
// Enter a normal cleanup which will perform the @finally block.
|
|
EHStack.pushCleanup<PerformFinally>(NormalCleanup, Body,
|
|
ForEHVar, EndCatchFn,
|
|
RethrowFn, SavedExnVar);
|
|
|
|
// Enter a catch-all scope.
|
|
llvm::BasicBlock *CatchAllBB = createBasicBlock("finally.catchall");
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
|
|
Builder.SetInsertPoint(CatchAllBB);
|
|
|
|
// If there's a begin-catch function, call it.
|
|
if (BeginCatchFn) {
|
|
Builder.CreateCall(BeginCatchFn, Builder.CreateLoad(getExceptionSlot()))
|
|
->setDoesNotThrow();
|
|
}
|
|
|
|
// If we need to remember the exception pointer to rethrow later, do so.
|
|
if (SavedExnVar) {
|
|
llvm::Value *SavedExn = Builder.CreateLoad(getExceptionSlot());
|
|
Builder.CreateStore(SavedExn, SavedExnVar);
|
|
}
|
|
|
|
// Tell the finally block that we're in EH.
|
|
Builder.CreateStore(llvm::ConstantInt::getTrue(getLLVMContext()), ForEHVar);
|
|
|
|
// Thread a jump through the finally cleanup.
|
|
EmitBranchThroughCleanup(RethrowDest);
|
|
|
|
Builder.restoreIP(SavedIP);
|
|
|
|
EHCatchScope *CatchScope = EHStack.pushCatch(1);
|
|
CatchScope->setCatchAllHandler(0, CatchAllBB);
|
|
|
|
return Info;
|
|
}
|
|
|
|
void CodeGenFunction::ExitFinallyBlock(FinallyInfo &Info) {
|
|
// Leave the finally catch-all.
|
|
EHCatchScope &Catch = cast<EHCatchScope>(*EHStack.begin());
|
|
llvm::BasicBlock *CatchAllBB = Catch.getHandler(0).Block;
|
|
EHStack.popCatch();
|
|
|
|
// And leave the normal cleanup.
|
|
PopCleanupBlock();
|
|
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
|
|
EmitBlock(CatchAllBB, true);
|
|
|
|
Builder.restoreIP(SavedIP);
|
|
}
|
|
|
|
llvm::BasicBlock *CodeGenFunction::getTerminateLandingPad() {
|
|
if (TerminateLandingPad)
|
|
return TerminateLandingPad;
|
|
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
|
|
|
|
// This will get inserted at the end of the function.
|
|
TerminateLandingPad = createBasicBlock("terminate.lpad");
|
|
Builder.SetInsertPoint(TerminateLandingPad);
|
|
|
|
// Tell the backend that this is a landing pad.
|
|
llvm::CallInst *Exn =
|
|
Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_exception), "exn");
|
|
Exn->setDoesNotThrow();
|
|
|
|
const EHPersonality &Personality = EHPersonality::get(CGM.getLangOptions());
|
|
|
|
// Tell the backend what the exception table should be:
|
|
// nothing but a catch-all.
|
|
llvm::Value *Args[3] = { Exn, getOpaquePersonalityFn(CGM, Personality),
|
|
getCatchAllValue(*this) };
|
|
Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::eh_selector),
|
|
Args, Args+3, "eh.selector")
|
|
->setDoesNotThrow();
|
|
|
|
llvm::CallInst *TerminateCall = Builder.CreateCall(getTerminateFn(*this));
|
|
TerminateCall->setDoesNotReturn();
|
|
TerminateCall->setDoesNotThrow();
|
|
Builder.CreateUnreachable();
|
|
|
|
// Restore the saved insertion state.
|
|
Builder.restoreIP(SavedIP);
|
|
|
|
return TerminateLandingPad;
|
|
}
|
|
|
|
llvm::BasicBlock *CodeGenFunction::getTerminateHandler() {
|
|
if (TerminateHandler)
|
|
return TerminateHandler;
|
|
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
|
|
|
|
// Set up the terminate handler. This block is inserted at the very
|
|
// end of the function by FinishFunction.
|
|
TerminateHandler = createBasicBlock("terminate.handler");
|
|
Builder.SetInsertPoint(TerminateHandler);
|
|
llvm::CallInst *TerminateCall = Builder.CreateCall(getTerminateFn(*this));
|
|
TerminateCall->setDoesNotReturn();
|
|
TerminateCall->setDoesNotThrow();
|
|
Builder.CreateUnreachable();
|
|
|
|
// Restore the saved insertion state.
|
|
Builder.restoreIP(SavedIP);
|
|
|
|
return TerminateHandler;
|
|
}
|
|
|
|
CodeGenFunction::UnwindDest CodeGenFunction::getRethrowDest() {
|
|
if (RethrowBlock.isValid()) return RethrowBlock;
|
|
|
|
CGBuilderTy::InsertPoint SavedIP = Builder.saveIP();
|
|
|
|
// We emit a jump to a notional label at the outermost unwind state.
|
|
llvm::BasicBlock *Unwind = createBasicBlock("eh.resume");
|
|
Builder.SetInsertPoint(Unwind);
|
|
|
|
const EHPersonality &Personality = EHPersonality::get(CGM.getLangOptions());
|
|
|
|
// This can always be a call because we necessarily didn't find
|
|
// anything on the EH stack which needs our help.
|
|
llvm::StringRef RethrowName = Personality.getCatchallRethrowFnName();
|
|
llvm::Constant *RethrowFn;
|
|
if (!RethrowName.empty())
|
|
RethrowFn = getCatchallRethrowFn(*this, RethrowName);
|
|
else
|
|
RethrowFn = getUnwindResumeOrRethrowFn();
|
|
|
|
Builder.CreateCall(RethrowFn, Builder.CreateLoad(getExceptionSlot()))
|
|
->setDoesNotReturn();
|
|
Builder.CreateUnreachable();
|
|
|
|
Builder.restoreIP(SavedIP);
|
|
|
|
RethrowBlock = UnwindDest(Unwind, EHStack.stable_end(), 0);
|
|
return RethrowBlock;
|
|
}
|
|
|