diff options
Diffstat (limited to 'contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp | 461 |
1 files changed, 446 insertions, 15 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp b/contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp index 9e88b1e..0a1a4ce 100644 --- a/contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp +++ b/contrib/llvm/tools/clang/lib/CodeGen/ItaniumCXXABI.cpp @@ -19,14 +19,18 @@ //===----------------------------------------------------------------------===// #include "CGCXXABI.h" +#include "CGCleanup.h" #include "CGRecordLayout.h" #include "CGVTables.h" #include "CodeGenFunction.h" #include "CodeGenModule.h" +#include "TargetInfo.h" #include "clang/AST/Mangle.h" #include "clang/AST/Type.h" +#include "clang/AST/StmtCXX.h" #include "llvm/IR/CallSite.h" #include "llvm/IR/DataLayout.h" +#include "llvm/IR/Instructions.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/Value.h" @@ -111,10 +115,22 @@ public: const CXXDestructorDecl *Dtor) override; void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override; + void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override; + + void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override; + + llvm::CallInst * + emitTerminateForUnexpectedException(CodeGenFunction &CGF, + llvm::Value *Exn) override; void EmitFundamentalRTTIDescriptor(QualType Type); void EmitFundamentalRTTIDescriptors(); llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override; + llvm::Constant * + getAddrOfCXXCatchHandlerType(QualType Ty, + QualType CatchHandlerType) override { + return getAddrOfRTTIDescriptor(Ty); + } bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override; void EmitBadTypeidCall(CodeGenFunction &CGF) override; @@ -849,7 +865,7 @@ bool ItaniumCXXABI::classifyReturnType(CGFunctionInfo &FI) const { /// The Itanium ABI requires non-zero initialization only for data /// member pointers, for which '0' is a valid offset. bool ItaniumCXXABI::isZeroInitializable(const MemberPointerType *MPT) { - return MPT->getPointeeType()->isFunctionType(); + return MPT->isMemberFunctionPointer(); } /// The Itanium ABI always places an offset to the complete object @@ -906,6 +922,59 @@ void ItaniumCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) { CGF.EmitRuntimeCallOrInvoke(Fn); } +static llvm::Constant *getAllocateExceptionFn(CodeGenModule &CGM) { + // void *__cxa_allocate_exception(size_t thrown_size); + + llvm::FunctionType *FTy = + llvm::FunctionType::get(CGM.Int8PtrTy, CGM.SizeTy, /*IsVarArgs=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_allocate_exception"); +} + +static llvm::Constant *getThrowFn(CodeGenModule &CGM) { + // void __cxa_throw(void *thrown_exception, std::type_info *tinfo, + // void (*dest) (void *)); + + llvm::Type *Args[3] = { CGM.Int8PtrTy, CGM.Int8PtrTy, CGM.Int8PtrTy }; + llvm::FunctionType *FTy = + llvm::FunctionType::get(CGM.VoidTy, Args, /*IsVarArgs=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_throw"); +} + +void ItaniumCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) { + QualType ThrowType = E->getSubExpr()->getType(); + // Now allocate the exception object. + llvm::Type *SizeTy = CGF.ConvertType(getContext().getSizeType()); + uint64_t TypeSize = getContext().getTypeSizeInChars(ThrowType).getQuantity(); + + llvm::Constant *AllocExceptionFn = getAllocateExceptionFn(CGM); + llvm::CallInst *ExceptionPtr = CGF.EmitNounwindRuntimeCall( + AllocExceptionFn, llvm::ConstantInt::get(SizeTy, TypeSize), "exception"); + + CGF.EmitAnyExprToExn(E->getSubExpr(), ExceptionPtr); + + // Now throw the exception. + llvm::Constant *TypeInfo = CGM.GetAddrOfRTTIDescriptor(ThrowType, + /*ForEH=*/true); + + // The address of the destructor. If the exception type has a + // trivial destructor (or isn't a record), we just pass null. + llvm::Constant *Dtor = nullptr; + if (const RecordType *RecordTy = ThrowType->getAs<RecordType>()) { + CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordTy->getDecl()); + if (!Record->hasTrivialDestructor()) { + CXXDestructorDecl *DtorD = Record->getDestructor(); + Dtor = CGM.getAddrOfCXXStructor(DtorD, StructorType::Complete); + Dtor = llvm::ConstantExpr::getBitCast(Dtor, CGM.Int8PtrTy); + } + } + if (!Dtor) Dtor = llvm::Constant::getNullValue(CGM.Int8PtrTy); + + llvm::Value *args[] = { ExceptionPtr, TypeInfo, Dtor }; + CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(CGM), args); +} + static llvm::Constant *getItaniumDynamicCastFn(CodeGenFunction &CGF) { // void *__dynamic_cast(const void *sub, // const abi::__class_type_info *src, @@ -1259,6 +1328,9 @@ void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT, // Set the correct linkage. VTable->setLinkage(Linkage); + if (CGM.supportsCOMDAT() && VTable->isWeakForLinker()) + VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName())); + // Set the right visibility. CGM.setGlobalVisibility(VTable, RD); @@ -1278,6 +1350,8 @@ void ItaniumCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT, cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && DC->getParent()->isTranslationUnit()) EmitFundamentalRTTIDescriptors(); + + CGM.EmitVTableBitSetEntries(VTable, VTLayout); } llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor( @@ -1314,7 +1388,7 @@ llvm::Value *ItaniumCXXABI::getVTableAddressPointInStructor( llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr( BaseSubobject Base, const CXXRecordDecl *VTableClass) { - llvm::Constant *VTable = getAddrOfVTable(VTableClass, CharUnits()); + auto *VTable = getAddrOfVTable(VTableClass, CharUnits()); // Find the appropriate vtable within the vtable group. uint64_t AddressPoint = CGM.getItaniumVTableContext() @@ -1325,7 +1399,8 @@ llvm::Constant *ItaniumCXXABI::getVTableAddressPointForConstExpr( llvm::ConstantInt::get(CGM.Int64Ty, AddressPoint) }; - return llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Indices); + return llvm::ConstantExpr::getInBoundsGetElementPtr(VTable->getValueType(), + VTable, Indices); } llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, @@ -1369,6 +1444,9 @@ llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF, Ty = Ty->getPointerTo()->getPointerTo(); llvm::Value *VTable = CGF.GetVTablePtr(This, Ty); + if (CGF.SanOpts.has(SanitizerKind::CFIVCall)) + CGF.EmitVTablePtrCheckForCall(cast<CXXMethodDecl>(GD.getDecl()), VTable); + uint64_t VTableIndex = CGM.getItaniumVTableContext().getMethodVTableIndex(GD); llvm::Value *VFuncPtr = CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn"); @@ -1591,7 +1669,7 @@ llvm::Value *ARMCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, CGF.Builder.CreateStore(elementSize, cookie); // The second element is the element count. - cookie = CGF.Builder.CreateConstInBoundsGEP1_32(cookie, 1); + cookie = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.SizeTy, cookie, 1); CGF.Builder.CreateStore(numElements, cookie); // Finally, compute a pointer to the actual data buffer by skipping @@ -1714,11 +1792,12 @@ void ItaniumCXXABI::EmitGuardedInit(CodeGenFunction &CGF, // The ABI says: It is suggested that it be emitted in the same COMDAT group // as the associated data object - if (!D.isLocalVarDecl() && var->isWeakForLinker() && CGM.supportsCOMDAT()) { - llvm::Comdat *C = CGM.getModule().getOrInsertComdat(var->getName()); + llvm::Comdat *C = var->getComdat(); + if (!D.isLocalVarDecl() && C) { guard->setComdat(C); - var->setComdat(C); CGF.CurFn->setComdat(C); + } else if (CGM.supportsCOMDAT() && guard->isWeakForLinker()) { + guard->setComdat(CGM.getModule().getOrInsertComdat(guard->getName())); } CGM.setStaticLocalDeclGuardAddress(&D, guard); @@ -2011,7 +2090,7 @@ void ItaniumCXXABI::EmitThreadLocalInitFuncs( CGBuilderTy Builder(Entry); if (InitIsInitFunc) { if (Init) - Builder.CreateCall(Init); + Builder.CreateCall(Init, {}); } else { // Don't know whether we have an init function. Call it if it exists. llvm::Value *Have = Builder.CreateIsNotNull(Init); @@ -2020,7 +2099,7 @@ void ItaniumCXXABI::EmitThreadLocalInitFuncs( Builder.CreateCondBr(Have, InitBB, ExitBB); Builder.SetInsertPoint(InitBB); - Builder.CreateCall(Init); + Builder.CreateCall(Init, {}); Builder.CreateBr(ExitBB); Builder.SetInsertPoint(ExitBB); @@ -2049,7 +2128,7 @@ LValue ItaniumCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, llvm::Value *Val = CGF.CGM.GetAddrOfGlobalVar(VD, Ty); llvm::Function *Wrapper = getOrCreateThreadLocalWrapper(VD, Val); - Val = CGF.Builder.CreateCall(Wrapper); + Val = CGF.Builder.CreateCall(Wrapper, {}); LValue LV; if (VD->getType()->isReferenceType()) @@ -2528,7 +2607,8 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty) { // The vtable address point is 2. llvm::Constant *Two = llvm::ConstantInt::get(PtrDiffTy, 2); - VTable = llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, Two); + VTable = + llvm::ConstantExpr::getInBoundsGetElementPtr(CGM.Int8PtrTy, VTable, Two); VTable = llvm::ConstantExpr::getBitCast(VTable, CGM.Int8PtrTy); Fields.push_back(VTable); @@ -2718,9 +2798,13 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(QualType Ty, bool Force) { llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields); + llvm::Module &M = CGM.getModule(); llvm::GlobalVariable *GV = - new llvm::GlobalVariable(CGM.getModule(), Init->getType(), - /*Constant=*/true, Linkage, Init, Name); + new llvm::GlobalVariable(M, Init->getType(), + /*Constant=*/true, Linkage, Init, Name); + + if (CGM.supportsCOMDAT() && GV->isWeakForLinker()) + GV->setComdat(M.getOrInsertComdat(GV->getName())); // If there's already an old global variable, replace it with the new one. if (OldGV) { @@ -3136,8 +3220,8 @@ static void emitConstructorDestructorAlias(CodeGenModule &CGM, llvm::PointerType *AliasType = Aliasee->getType(); // Create the alias with no name. - auto *Alias = llvm::GlobalAlias::create( - AliasType->getElementType(), 0, Linkage, "", Aliasee, &CGM.getModule()); + auto *Alias = llvm::GlobalAlias::create(AliasType, Linkage, "", Aliasee, + &CGM.getModule()); // Switch any previous uses to the alias. if (Entry) { @@ -3204,5 +3288,352 @@ void ItaniumCXXABI::emitCXXStructor(const CXXMethodDecl *MD, getMangleContext().mangleCXXCtorComdat(CD, Out); llvm::Comdat *C = CGM.getModule().getOrInsertComdat(Out.str()); Fn->setComdat(C); + } else { + CGM.maybeSetTrivialComdat(*MD, *Fn); + } +} + +static llvm::Constant *getBeginCatchFn(CodeGenModule &CGM) { + // void *__cxa_begin_catch(void*); + llvm::FunctionType *FTy = llvm::FunctionType::get( + CGM.Int8PtrTy, CGM.Int8PtrTy, /*IsVarArgs=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_begin_catch"); +} + +static llvm::Constant *getEndCatchFn(CodeGenModule &CGM) { + // void __cxa_end_catch(); + llvm::FunctionType *FTy = + llvm::FunctionType::get(CGM.VoidTy, /*IsVarArgs=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_end_catch"); +} + +static llvm::Constant *getGetExceptionPtrFn(CodeGenModule &CGM) { + // void *__cxa_get_exception_ptr(void*); + llvm::FunctionType *FTy = llvm::FunctionType::get( + CGM.Int8PtrTy, CGM.Int8PtrTy, /*IsVarArgs=*/false); + + return CGM.CreateRuntimeFunction(FTy, "__cxa_get_exception_ptr"); +} + +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, Flags flags) override { + if (!MightThrow) { + CGF.EmitNounwindRuntimeCall(getEndCatchFn(CGF.CGM)); + return; + } + + CGF.EmitRuntimeCallOrInvoke(getEndCatchFn(CGF.CGM)); + } + }; +} + +/// 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.EmitNounwindRuntimeCall(getBeginCatchFn(CGF.CGM), Exn); + + 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, + SourceLocation Loc) { + // Load the exception from where the landing pad saved it. + llvm::Value *Exn = CGF.getExceptionFromSlot(); + + CanQualType CatchType = + CGF.CGM.getContext().getCanonicalType(CatchParam.getType()); + 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. + 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; + } + + // Scalars and complexes. + TypeEvaluationKind TEK = CGF.getEvaluationKind(CatchType); + if (TEK != TEK_Aggregate) { + 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"); + + switch (CatchType.getQualifiers().getObjCLifetime()) { + case Qualifiers::OCL_Strong: + CastExn = CGF.EmitARCRetainNonBlock(CastExn); + // fallthrough + + case Qualifiers::OCL_None: + case Qualifiers::OCL_ExplicitNone: + case Qualifiers::OCL_Autoreleasing: + CGF.Builder.CreateStore(CastExn, ParamAddr); + return; + + case Qualifiers::OCL_Weak: + CGF.EmitARCInitWeak(ParamAddr, CastExn); + return; + } + llvm_unreachable("bad ownership qualifier!"); + } + + // Otherwise, it returns a pointer into the exception object. + + llvm::Type *PtrTy = LLVMCatchTy->getPointerTo(0); // addrspace 0 ok + llvm::Value *Cast = CGF.Builder.CreateBitCast(AdjustedExn, PtrTy); + + LValue srcLV = CGF.MakeNaturalAlignAddrLValue(Cast, CatchType); + LValue destLV = CGF.MakeAddrLValue(ParamAddr, CatchType, + CGF.getContext().getDeclAlign(&CatchParam)); + switch (TEK) { + case TEK_Complex: + CGF.EmitStoreOfComplex(CGF.EmitLoadOfComplex(srcLV, Loc), destLV, + /*init*/ true); + return; + case TEK_Scalar: { + llvm::Value *ExnLoad = CGF.EmitLoadOfScalar(srcLV, Loc); + CGF.EmitStoreOfScalar(ExnLoad, destLV, /*init*/ true); + return; + } + case TEK_Aggregate: + llvm_unreachable("evaluation kind filtered out!"); + } + llvm_unreachable("bad evaluation kind"); + } + + assert(isa<RecordType>(CatchType) && "unexpected catch type!"); + + 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.EmitNounwindRuntimeCall(getGetExceptionPtrFn(CGF.CGM), Exn); + + // 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. + CharUnits Alignment = CGF.getContext().getDeclAlign(&CatchParam); + CGF.EmitAggExpr(copyExpr, + AggValueSlot::forAddr(ParamAddr, Alignment, Qualifiers(), + AggValueSlot::IsNotDestructed, + AggValueSlot::DoesNotNeedGCBarriers, + AggValueSlot::IsNotAliased)); + + // 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. +void ItaniumCXXABI::emitBeginCatch(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.getExceptionFromSlot(); + CallBeginCatch(CGF, Exn, true); + return; + } + + // Emit the local. + CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam); + InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF), S->getLocStart()); + CGF.EmitAutoVarCleanups(var); +} + +/// Get or define the following function: +/// void @__clang_call_terminate(i8* %exn) nounwind noreturn +/// This code is used only in C++. +static llvm::Constant *getClangCallTerminateFn(CodeGenModule &CGM) { + llvm::FunctionType *fnTy = + llvm::FunctionType::get(CGM.VoidTy, CGM.Int8PtrTy, /*IsVarArgs=*/false); + llvm::Constant *fnRef = + CGM.CreateRuntimeFunction(fnTy, "__clang_call_terminate"); + + llvm::Function *fn = dyn_cast<llvm::Function>(fnRef); + if (fn && fn->empty()) { + fn->setDoesNotThrow(); + fn->setDoesNotReturn(); + + // What we really want is to massively penalize inlining without + // forbidding it completely. The difference between that and + // 'noinline' is negligible. + fn->addFnAttr(llvm::Attribute::NoInline); + + // Allow this function to be shared across translation units, but + // we don't want it to turn into an exported symbol. + fn->setLinkage(llvm::Function::LinkOnceODRLinkage); + fn->setVisibility(llvm::Function::HiddenVisibility); + if (CGM.supportsCOMDAT()) + fn->setComdat(CGM.getModule().getOrInsertComdat(fn->getName())); + + // Set up the function. + llvm::BasicBlock *entry = + llvm::BasicBlock::Create(CGM.getLLVMContext(), "", fn); + CGBuilderTy builder(entry); + + // Pull the exception pointer out of the parameter list. + llvm::Value *exn = &*fn->arg_begin(); + + // Call __cxa_begin_catch(exn). + llvm::CallInst *catchCall = builder.CreateCall(getBeginCatchFn(CGM), exn); + catchCall->setDoesNotThrow(); + catchCall->setCallingConv(CGM.getRuntimeCC()); + + // Call std::terminate(). + llvm::CallInst *termCall = builder.CreateCall(CGM.getTerminateFn(), {}); + termCall->setDoesNotThrow(); + termCall->setDoesNotReturn(); + termCall->setCallingConv(CGM.getRuntimeCC()); + + // std::terminate cannot return. + builder.CreateUnreachable(); + } + + return fnRef; +} + +llvm::CallInst * +ItaniumCXXABI::emitTerminateForUnexpectedException(CodeGenFunction &CGF, + llvm::Value *Exn) { + // In C++, we want to call __cxa_begin_catch() before terminating. + if (Exn) { + assert(CGF.CGM.getLangOpts().CPlusPlus); + return CGF.EmitNounwindRuntimeCall(getClangCallTerminateFn(CGF.CGM), Exn); } + return CGF.EmitNounwindRuntimeCall(CGF.CGM.getTerminateFn()); } |
