diff options
Diffstat (limited to 'gnu/llvm/tools/clang/lib/CodeGen/CGVTables.cpp')
| -rw-r--r-- | gnu/llvm/tools/clang/lib/CodeGen/CGVTables.cpp | 1068 |
1 files changed, 0 insertions, 1068 deletions
diff --git a/gnu/llvm/tools/clang/lib/CodeGen/CGVTables.cpp b/gnu/llvm/tools/clang/lib/CodeGen/CGVTables.cpp deleted file mode 100644 index bfb089ff908..00000000000 --- a/gnu/llvm/tools/clang/lib/CodeGen/CGVTables.cpp +++ /dev/null @@ -1,1068 +0,0 @@ -//===--- CGVTables.cpp - Emit LLVM Code for C++ vtables -------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// This contains code dealing with C++ code generation of virtual tables. -// -//===----------------------------------------------------------------------===// - -#include "CGCXXABI.h" -#include "CodeGenFunction.h" -#include "CodeGenModule.h" -#include "clang/AST/CXXInheritance.h" -#include "clang/AST/RecordLayout.h" -#include "clang/Basic/CodeGenOptions.h" -#include "clang/CodeGen/CGFunctionInfo.h" -#include "clang/CodeGen/ConstantInitBuilder.h" -#include "llvm/IR/IntrinsicInst.h" -#include "llvm/Support/Format.h" -#include "llvm/Transforms/Utils/Cloning.h" -#include <algorithm> -#include <cstdio> - -using namespace clang; -using namespace CodeGen; - -CodeGenVTables::CodeGenVTables(CodeGenModule &CGM) - : CGM(CGM), VTContext(CGM.getContext().getVTableContext()) {} - -llvm::Constant *CodeGenModule::GetAddrOfThunk(StringRef Name, llvm::Type *FnTy, - GlobalDecl GD) { - return GetOrCreateLLVMFunction(Name, FnTy, GD, /*ForVTable=*/true, - /*DontDefer=*/true, /*IsThunk=*/true); -} - -static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk, - llvm::Function *ThunkFn, bool ForVTable, - GlobalDecl GD) { - CGM.setFunctionLinkage(GD, ThunkFn); - CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD, - !Thunk.Return.isEmpty()); - - // Set the right visibility. - CGM.setGVProperties(ThunkFn, GD); - - if (!CGM.getCXXABI().exportThunk()) { - ThunkFn->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass); - ThunkFn->setDSOLocal(true); - } - - if (CGM.supportsCOMDAT() && ThunkFn->isWeakForLinker()) - ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName())); -} - -#ifndef NDEBUG -static bool similar(const ABIArgInfo &infoL, CanQualType typeL, - const ABIArgInfo &infoR, CanQualType typeR) { - return (infoL.getKind() == infoR.getKind() && - (typeL == typeR || - (isa<PointerType>(typeL) && isa<PointerType>(typeR)) || - (isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR)))); -} -#endif - -static RValue PerformReturnAdjustment(CodeGenFunction &CGF, - QualType ResultType, RValue RV, - const ThunkInfo &Thunk) { - // Emit the return adjustment. - bool NullCheckValue = !ResultType->isReferenceType(); - - llvm::BasicBlock *AdjustNull = nullptr; - llvm::BasicBlock *AdjustNotNull = nullptr; - llvm::BasicBlock *AdjustEnd = nullptr; - - llvm::Value *ReturnValue = RV.getScalarVal(); - - if (NullCheckValue) { - AdjustNull = CGF.createBasicBlock("adjust.null"); - AdjustNotNull = CGF.createBasicBlock("adjust.notnull"); - AdjustEnd = CGF.createBasicBlock("adjust.end"); - - llvm::Value *IsNull = CGF.Builder.CreateIsNull(ReturnValue); - CGF.Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull); - CGF.EmitBlock(AdjustNotNull); - } - - auto ClassDecl = ResultType->getPointeeType()->getAsCXXRecordDecl(); - auto ClassAlign = CGF.CGM.getClassPointerAlignment(ClassDecl); - ReturnValue = CGF.CGM.getCXXABI().performReturnAdjustment(CGF, - Address(ReturnValue, ClassAlign), - Thunk.Return); - - if (NullCheckValue) { - CGF.Builder.CreateBr(AdjustEnd); - CGF.EmitBlock(AdjustNull); - CGF.Builder.CreateBr(AdjustEnd); - CGF.EmitBlock(AdjustEnd); - - llvm::PHINode *PHI = CGF.Builder.CreatePHI(ReturnValue->getType(), 2); - PHI->addIncoming(ReturnValue, AdjustNotNull); - PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), - AdjustNull); - ReturnValue = PHI; - } - - return RValue::get(ReturnValue); -} - -/// This function clones a function's DISubprogram node and enters it into -/// a value map with the intent that the map can be utilized by the cloner -/// to short-circuit Metadata node mapping. -/// Furthermore, the function resolves any DILocalVariable nodes referenced -/// by dbg.value intrinsics so they can be properly mapped during cloning. -static void resolveTopLevelMetadata(llvm::Function *Fn, - llvm::ValueToValueMapTy &VMap) { - // Clone the DISubprogram node and put it into the Value map. - auto *DIS = Fn->getSubprogram(); - if (!DIS) - return; - auto *NewDIS = DIS->replaceWithDistinct(DIS->clone()); - VMap.MD()[DIS].reset(NewDIS); - - // Find all llvm.dbg.declare intrinsics and resolve the DILocalVariable nodes - // they are referencing. - for (auto &BB : Fn->getBasicBlockList()) { - for (auto &I : BB) { - if (auto *DII = dyn_cast<llvm::DbgVariableIntrinsic>(&I)) { - auto *DILocal = DII->getVariable(); - if (!DILocal->isResolved()) - DILocal->resolve(); - } - } - } -} - -// This function does roughly the same thing as GenerateThunk, but in a -// very different way, so that va_start and va_end work correctly. -// FIXME: This function assumes "this" is the first non-sret LLVM argument of -// a function, and that there is an alloca built in the entry block -// for all accesses to "this". -// FIXME: This function assumes there is only one "ret" statement per function. -// FIXME: Cloning isn't correct in the presence of indirect goto! -// FIXME: This implementation of thunks bloats codesize by duplicating the -// function definition. There are alternatives: -// 1. Add some sort of stub support to LLVM for cases where we can -// do a this adjustment, then a sibcall. -// 2. We could transform the definition to take a va_list instead of an -// actual variable argument list, then have the thunks (including a -// no-op thunk for the regular definition) call va_start/va_end. -// There's a bit of per-call overhead for this solution, but it's -// better for codesize if the definition is long. -llvm::Function * -CodeGenFunction::GenerateVarArgsThunk(llvm::Function *Fn, - const CGFunctionInfo &FnInfo, - GlobalDecl GD, const ThunkInfo &Thunk) { - const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); - const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); - QualType ResultType = FPT->getReturnType(); - - // Get the original function - assert(FnInfo.isVariadic()); - llvm::Type *Ty = CGM.getTypes().GetFunctionType(FnInfo); - llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); - llvm::Function *BaseFn = cast<llvm::Function>(Callee); - - // Clone to thunk. - llvm::ValueToValueMapTy VMap; - - // We are cloning a function while some Metadata nodes are still unresolved. - // Ensure that the value mapper does not encounter any of them. - resolveTopLevelMetadata(BaseFn, VMap); - llvm::Function *NewFn = llvm::CloneFunction(BaseFn, VMap); - Fn->replaceAllUsesWith(NewFn); - NewFn->takeName(Fn); - Fn->eraseFromParent(); - Fn = NewFn; - - // "Initialize" CGF (minimally). - CurFn = Fn; - - // Get the "this" value - llvm::Function::arg_iterator AI = Fn->arg_begin(); - if (CGM.ReturnTypeUsesSRet(FnInfo)) - ++AI; - - // Find the first store of "this", which will be to the alloca associated - // with "this". - Address ThisPtr(&*AI, CGM.getClassPointerAlignment(MD->getParent())); - llvm::BasicBlock *EntryBB = &Fn->front(); - llvm::BasicBlock::iterator ThisStore = - std::find_if(EntryBB->begin(), EntryBB->end(), [&](llvm::Instruction &I) { - return isa<llvm::StoreInst>(I) && - I.getOperand(0) == ThisPtr.getPointer(); - }); - assert(ThisStore != EntryBB->end() && - "Store of this should be in entry block?"); - // Adjust "this", if necessary. - Builder.SetInsertPoint(&*ThisStore); - llvm::Value *AdjustedThisPtr = - CGM.getCXXABI().performThisAdjustment(*this, ThisPtr, Thunk.This); - ThisStore->setOperand(0, AdjustedThisPtr); - - if (!Thunk.Return.isEmpty()) { - // Fix up the returned value, if necessary. - for (llvm::BasicBlock &BB : *Fn) { - llvm::Instruction *T = BB.getTerminator(); - if (isa<llvm::ReturnInst>(T)) { - RValue RV = RValue::get(T->getOperand(0)); - T->eraseFromParent(); - Builder.SetInsertPoint(&BB); - RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk); - Builder.CreateRet(RV.getScalarVal()); - break; - } - } - } - - return Fn; -} - -void CodeGenFunction::StartThunk(llvm::Function *Fn, GlobalDecl GD, - const CGFunctionInfo &FnInfo, - bool IsUnprototyped) { - assert(!CurGD.getDecl() && "CurGD was already set!"); - CurGD = GD; - CurFuncIsThunk = true; - - // Build FunctionArgs. - const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); - QualType ThisType = MD->getThisType(); - const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); - QualType ResultType; - if (IsUnprototyped) - ResultType = CGM.getContext().VoidTy; - else if (CGM.getCXXABI().HasThisReturn(GD)) - ResultType = ThisType; - else if (CGM.getCXXABI().hasMostDerivedReturn(GD)) - ResultType = CGM.getContext().VoidPtrTy; - else - ResultType = FPT->getReturnType(); - FunctionArgList FunctionArgs; - - // Create the implicit 'this' parameter declaration. - CGM.getCXXABI().buildThisParam(*this, FunctionArgs); - - // Add the rest of the parameters, if we have a prototype to work with. - if (!IsUnprototyped) { - FunctionArgs.append(MD->param_begin(), MD->param_end()); - - if (isa<CXXDestructorDecl>(MD)) - CGM.getCXXABI().addImplicitStructorParams(*this, ResultType, - FunctionArgs); - } - - // Start defining the function. - auto NL = ApplyDebugLocation::CreateEmpty(*this); - StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs, - MD->getLocation()); - // Create a scope with an artificial location for the body of this function. - auto AL = ApplyDebugLocation::CreateArtificial(*this); - - // Since we didn't pass a GlobalDecl to StartFunction, do this ourselves. - CGM.getCXXABI().EmitInstanceFunctionProlog(*this); - CXXThisValue = CXXABIThisValue; - CurCodeDecl = MD; - CurFuncDecl = MD; -} - -void CodeGenFunction::FinishThunk() { - // Clear these to restore the invariants expected by - // StartFunction/FinishFunction. - CurCodeDecl = nullptr; - CurFuncDecl = nullptr; - - FinishFunction(); -} - -void CodeGenFunction::EmitCallAndReturnForThunk(llvm::Constant *CalleePtr, - const ThunkInfo *Thunk, - bool IsUnprototyped) { - assert(isa<CXXMethodDecl>(CurGD.getDecl()) && - "Please use a new CGF for this thunk"); - const CXXMethodDecl *MD = cast<CXXMethodDecl>(CurGD.getDecl()); - - // Adjust the 'this' pointer if necessary - llvm::Value *AdjustedThisPtr = - Thunk ? CGM.getCXXABI().performThisAdjustment( - *this, LoadCXXThisAddress(), Thunk->This) - : LoadCXXThis(); - - if (CurFnInfo->usesInAlloca() || IsUnprototyped) { - // We don't handle return adjusting thunks, because they require us to call - // the copy constructor. For now, fall through and pretend the return - // adjustment was empty so we don't crash. - if (Thunk && !Thunk->Return.isEmpty()) { - if (IsUnprototyped) - CGM.ErrorUnsupported( - MD, "return-adjusting thunk with incomplete parameter type"); - else - CGM.ErrorUnsupported( - MD, "non-trivial argument copy for return-adjusting thunk"); - } - EmitMustTailThunk(CurGD, AdjustedThisPtr, CalleePtr); - return; - } - - // Start building CallArgs. - CallArgList CallArgs; - QualType ThisType = MD->getThisType(); - CallArgs.add(RValue::get(AdjustedThisPtr), ThisType); - - if (isa<CXXDestructorDecl>(MD)) - CGM.getCXXABI().adjustCallArgsForDestructorThunk(*this, CurGD, CallArgs); - -#ifndef NDEBUG - unsigned PrefixArgs = CallArgs.size() - 1; -#endif - // Add the rest of the arguments. - for (const ParmVarDecl *PD : MD->parameters()) - EmitDelegateCallArg(CallArgs, PD, SourceLocation()); - - const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); - -#ifndef NDEBUG - const CGFunctionInfo &CallFnInfo = CGM.getTypes().arrangeCXXMethodCall( - CallArgs, FPT, RequiredArgs::forPrototypePlus(FPT, 1, MD), PrefixArgs); - assert(CallFnInfo.getRegParm() == CurFnInfo->getRegParm() && - CallFnInfo.isNoReturn() == CurFnInfo->isNoReturn() && - CallFnInfo.getCallingConvention() == CurFnInfo->getCallingConvention()); - assert(isa<CXXDestructorDecl>(MD) || // ignore dtor return types - similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(), - CurFnInfo->getReturnInfo(), CurFnInfo->getReturnType())); - assert(CallFnInfo.arg_size() == CurFnInfo->arg_size()); - for (unsigned i = 0, e = CurFnInfo->arg_size(); i != e; ++i) - assert(similar(CallFnInfo.arg_begin()[i].info, - CallFnInfo.arg_begin()[i].type, - CurFnInfo->arg_begin()[i].info, - CurFnInfo->arg_begin()[i].type)); -#endif - - // Determine whether we have a return value slot to use. - QualType ResultType = CGM.getCXXABI().HasThisReturn(CurGD) - ? ThisType - : CGM.getCXXABI().hasMostDerivedReturn(CurGD) - ? CGM.getContext().VoidPtrTy - : FPT->getReturnType(); - ReturnValueSlot Slot; - if (!ResultType->isVoidType() && - CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect) - Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified()); - - // Now emit our call. - llvm::Instruction *CallOrInvoke; - CGCallee Callee = CGCallee::forDirect(CalleePtr, CurGD); - RValue RV = EmitCall(*CurFnInfo, Callee, Slot, CallArgs, &CallOrInvoke); - - // Consider return adjustment if we have ThunkInfo. - if (Thunk && !Thunk->Return.isEmpty()) - RV = PerformReturnAdjustment(*this, ResultType, RV, *Thunk); - else if (llvm::CallInst* Call = dyn_cast<llvm::CallInst>(CallOrInvoke)) - Call->setTailCallKind(llvm::CallInst::TCK_Tail); - - // Emit return. - if (!ResultType->isVoidType() && Slot.isNull()) - CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType); - - // Disable the final ARC autorelease. - AutoreleaseResult = false; - - FinishThunk(); -} - -void CodeGenFunction::EmitMustTailThunk(GlobalDecl GD, - llvm::Value *AdjustedThisPtr, - llvm::Value *CalleePtr) { - // Emitting a musttail call thunk doesn't use any of the CGCall.cpp machinery - // to translate AST arguments into LLVM IR arguments. For thunks, we know - // that the caller prototype more or less matches the callee prototype with - // the exception of 'this'. - SmallVector<llvm::Value *, 8> Args; - for (llvm::Argument &A : CurFn->args()) - Args.push_back(&A); - - // Set the adjusted 'this' pointer. - const ABIArgInfo &ThisAI = CurFnInfo->arg_begin()->info; - if (ThisAI.isDirect()) { - const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo(); - int ThisArgNo = RetAI.isIndirect() && !RetAI.isSRetAfterThis() ? 1 : 0; - llvm::Type *ThisType = Args[ThisArgNo]->getType(); - if (ThisType != AdjustedThisPtr->getType()) - AdjustedThisPtr = Builder.CreateBitCast(AdjustedThisPtr, ThisType); - Args[ThisArgNo] = AdjustedThisPtr; - } else { - assert(ThisAI.isInAlloca() && "this is passed directly or inalloca"); - Address ThisAddr = GetAddrOfLocalVar(CXXABIThisDecl); - llvm::Type *ThisType = ThisAddr.getElementType(); - if (ThisType != AdjustedThisPtr->getType()) - AdjustedThisPtr = Builder.CreateBitCast(AdjustedThisPtr, ThisType); - Builder.CreateStore(AdjustedThisPtr, ThisAddr); - } - - // Emit the musttail call manually. Even if the prologue pushed cleanups, we - // don't actually want to run them. - llvm::CallInst *Call = Builder.CreateCall(CalleePtr, Args); - Call->setTailCallKind(llvm::CallInst::TCK_MustTail); - - // Apply the standard set of call attributes. - unsigned CallingConv; - llvm::AttributeList Attrs; - CGM.ConstructAttributeList(CalleePtr->getName(), *CurFnInfo, GD, Attrs, - CallingConv, /*AttrOnCallSite=*/true); - Call->setAttributes(Attrs); - Call->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv)); - - if (Call->getType()->isVoidTy()) - Builder.CreateRetVoid(); - else - Builder.CreateRet(Call); - - // Finish the function to maintain CodeGenFunction invariants. - // FIXME: Don't emit unreachable code. - EmitBlock(createBasicBlock()); - FinishFunction(); -} - -void CodeGenFunction::generateThunk(llvm::Function *Fn, - const CGFunctionInfo &FnInfo, GlobalDecl GD, - const ThunkInfo &Thunk, - bool IsUnprototyped) { - StartThunk(Fn, GD, FnInfo, IsUnprototyped); - // Create a scope with an artificial location for the body of this function. - auto AL = ApplyDebugLocation::CreateArtificial(*this); - - // Get our callee. Use a placeholder type if this method is unprototyped so - // that CodeGenModule doesn't try to set attributes. - llvm::Type *Ty; - if (IsUnprototyped) - Ty = llvm::StructType::get(getLLVMContext()); - else - Ty = CGM.getTypes().GetFunctionType(FnInfo); - - llvm::Constant *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); - - // Fix up the function type for an unprototyped musttail call. - if (IsUnprototyped) - Callee = llvm::ConstantExpr::getBitCast(Callee, Fn->getType()); - - // Make the call and return the result. - EmitCallAndReturnForThunk(Callee, &Thunk, IsUnprototyped); -} - -static bool shouldEmitVTableThunk(CodeGenModule &CGM, const CXXMethodDecl *MD, - bool IsUnprototyped, bool ForVTable) { - // Always emit thunks in the MS C++ ABI. We cannot rely on other TUs to - // provide thunks for us. - if (CGM.getTarget().getCXXABI().isMicrosoft()) - return true; - - // In the Itanium C++ ABI, vtable thunks are provided by TUs that provide - // definitions of the main method. Therefore, emitting thunks with the vtable - // is purely an optimization. Emit the thunk if optimizations are enabled and - // all of the parameter types are complete. - if (ForVTable) - return CGM.getCodeGenOpts().OptimizationLevel && !IsUnprototyped; - - // Always emit thunks along with the method definition. - return true; -} - -llvm::Constant *CodeGenVTables::maybeEmitThunk(GlobalDecl GD, - const ThunkInfo &TI, - bool ForVTable) { - const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); - - // First, get a declaration. Compute the mangled name. Don't worry about - // getting the function prototype right, since we may only need this - // declaration to fill in a vtable slot. - SmallString<256> Name; - MangleContext &MCtx = CGM.getCXXABI().getMangleContext(); - llvm::raw_svector_ostream Out(Name); - if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) - MCtx.mangleCXXDtorThunk(DD, GD.getDtorType(), TI.This, Out); - else - MCtx.mangleThunk(MD, TI, Out); - llvm::Type *ThunkVTableTy = CGM.getTypes().GetFunctionTypeForVTable(GD); - llvm::Constant *Thunk = CGM.GetAddrOfThunk(Name, ThunkVTableTy, GD); - - // If we don't need to emit a definition, return this declaration as is. - bool IsUnprototyped = !CGM.getTypes().isFuncTypeConvertible( - MD->getType()->castAs<FunctionType>()); - if (!shouldEmitVTableThunk(CGM, MD, IsUnprototyped, ForVTable)) - return Thunk; - - // Arrange a function prototype appropriate for a function definition. In some - // cases in the MS ABI, we may need to build an unprototyped musttail thunk. - const CGFunctionInfo &FnInfo = - IsUnprototyped ? CGM.getTypes().arrangeUnprototypedMustTailThunk(MD) - : CGM.getTypes().arrangeGlobalDeclaration(GD); - llvm::FunctionType *ThunkFnTy = CGM.getTypes().GetFunctionType(FnInfo); - - // If the type of the underlying GlobalValue is wrong, we'll have to replace - // it. It should be a declaration. - llvm::Function *ThunkFn = cast<llvm::Function>(Thunk->stripPointerCasts()); - if (ThunkFn->getFunctionType() != ThunkFnTy) { - llvm::GlobalValue *OldThunkFn = ThunkFn; - - assert(OldThunkFn->isDeclaration() && "Shouldn't replace non-declaration"); - - // Remove the name from the old thunk function and get a new thunk. - OldThunkFn->setName(StringRef()); - ThunkFn = llvm::Function::Create(ThunkFnTy, llvm::Function::ExternalLinkage, - Name.str(), &CGM.getModule()); - CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn); - - // If needed, replace the old thunk with a bitcast. - if (!OldThunkFn->use_empty()) { - llvm::Constant *NewPtrForOldDecl = - llvm::ConstantExpr::getBitCast(ThunkFn, OldThunkFn->getType()); - OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl); - } - - // Remove the old thunk. - OldThunkFn->eraseFromParent(); - } - - bool ABIHasKeyFunctions = CGM.getTarget().getCXXABI().hasKeyFunctions(); - bool UseAvailableExternallyLinkage = ForVTable && ABIHasKeyFunctions; - - if (!ThunkFn->isDeclaration()) { - if (!ABIHasKeyFunctions || UseAvailableExternallyLinkage) { - // There is already a thunk emitted for this function, do nothing. - return ThunkFn; - } - - setThunkProperties(CGM, TI, ThunkFn, ForVTable, GD); - return ThunkFn; - } - - // If this will be unprototyped, add the "thunk" attribute so that LLVM knows - // that the return type is meaningless. These thunks can be used to call - // functions with differing return types, and the caller is required to cast - // the prototype appropriately to extract the correct value. - if (IsUnprototyped) - ThunkFn->addFnAttr("thunk"); - - CGM.SetLLVMFunctionAttributesForDefinition(GD.getDecl(), ThunkFn); - - if (!IsUnprototyped && ThunkFn->isVarArg()) { - // Varargs thunks are special; we can't just generate a call because - // we can't copy the varargs. Our implementation is rather - // expensive/sucky at the moment, so don't generate the thunk unless - // we have to. - // FIXME: Do something better here; GenerateVarArgsThunk is extremely ugly. - if (UseAvailableExternallyLinkage) - return ThunkFn; - ThunkFn = CodeGenFunction(CGM).GenerateVarArgsThunk(ThunkFn, FnInfo, GD, - TI); - } else { - // Normal thunk body generation. - CodeGenFunction(CGM).generateThunk(ThunkFn, FnInfo, GD, TI, IsUnprototyped); - } - - setThunkProperties(CGM, TI, ThunkFn, ForVTable, GD); - return ThunkFn; -} - -void CodeGenVTables::EmitThunks(GlobalDecl GD) { - const CXXMethodDecl *MD = - cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl(); - - // We don't need to generate thunks for the base destructor. - if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) - return; - - const VTableContextBase::ThunkInfoVectorTy *ThunkInfoVector = - VTContext->getThunkInfo(GD); - - if (!ThunkInfoVector) - return; - - for (const ThunkInfo& Thunk : *ThunkInfoVector) - maybeEmitThunk(GD, Thunk, /*ForVTable=*/false); -} - -void CodeGenVTables::addVTableComponent( - ConstantArrayBuilder &builder, const VTableLayout &layout, - unsigned idx, llvm::Constant *rtti, unsigned &nextVTableThunkIndex) { - auto &component = layout.vtable_components()[idx]; - - auto addOffsetConstant = [&](CharUnits offset) { - builder.add(llvm::ConstantExpr::getIntToPtr( - llvm::ConstantInt::get(CGM.PtrDiffTy, offset.getQuantity()), - CGM.Int8PtrTy)); - }; - - switch (component.getKind()) { - case VTableComponent::CK_VCallOffset: - return addOffsetConstant(component.getVCallOffset()); - - case VTableComponent::CK_VBaseOffset: - return addOffsetConstant(component.getVBaseOffset()); - - case VTableComponent::CK_OffsetToTop: - return addOffsetConstant(component.getOffsetToTop()); - - case VTableComponent::CK_RTTI: - return builder.add(llvm::ConstantExpr::getBitCast(rtti, CGM.Int8PtrTy)); - - case VTableComponent::CK_FunctionPointer: - case VTableComponent::CK_CompleteDtorPointer: - case VTableComponent::CK_DeletingDtorPointer: { - GlobalDecl GD; - - // Get the right global decl. - switch (component.getKind()) { - default: - llvm_unreachable("Unexpected vtable component kind"); - case VTableComponent::CK_FunctionPointer: - GD = component.getFunctionDecl(); - break; - case VTableComponent::CK_CompleteDtorPointer: - GD = GlobalDecl(component.getDestructorDecl(), Dtor_Complete); - break; - case VTableComponent::CK_DeletingDtorPointer: - GD = GlobalDecl(component.getDestructorDecl(), Dtor_Deleting); - break; - } - - if (CGM.getLangOpts().CUDA) { - // Emit NULL for methods we can't codegen on this - // side. Otherwise we'd end up with vtable with unresolved - // references. - const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); - // OK on device side: functions w/ __device__ attribute - // OK on host side: anything except __device__-only functions. - bool CanEmitMethod = - CGM.getLangOpts().CUDAIsDevice - ? MD->hasAttr<CUDADeviceAttr>() - : (MD->hasAttr<CUDAHostAttr>() || !MD->hasAttr<CUDADeviceAttr>()); - if (!CanEmitMethod) - return builder.addNullPointer(CGM.Int8PtrTy); - // Method is acceptable, continue processing as usual. - } - - auto getSpecialVirtualFn = [&](StringRef name) { - llvm::FunctionType *fnTy = - llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false); - llvm::Constant *fn = CGM.CreateRuntimeFunction(fnTy, name); - if (auto f = dyn_cast<llvm::Function>(fn)) - f->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); - return llvm::ConstantExpr::getBitCast(fn, CGM.Int8PtrTy); - }; - - llvm::Constant *fnPtr; - - // Pure virtual member functions. - if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) { - if (!PureVirtualFn) - PureVirtualFn = - getSpecialVirtualFn(CGM.getCXXABI().GetPureVirtualCallName()); - fnPtr = PureVirtualFn; - - // Deleted virtual member functions. - } else if (cast<CXXMethodDecl>(GD.getDecl())->isDeleted()) { - if (!DeletedVirtualFn) - DeletedVirtualFn = - getSpecialVirtualFn(CGM.getCXXABI().GetDeletedVirtualCallName()); - fnPtr = DeletedVirtualFn; - - // Thunks. - } else if (nextVTableThunkIndex < layout.vtable_thunks().size() && - layout.vtable_thunks()[nextVTableThunkIndex].first == idx) { - auto &thunkInfo = layout.vtable_thunks()[nextVTableThunkIndex].second; - - nextVTableThunkIndex++; - fnPtr = maybeEmitThunk(GD, thunkInfo, /*ForVTable=*/true); - - // Otherwise we can use the method definition directly. - } else { - llvm::Type *fnTy = CGM.getTypes().GetFunctionTypeForVTable(GD); - fnPtr = CGM.GetAddrOfFunction(GD, fnTy, /*ForVTable=*/true); - } - - fnPtr = llvm::ConstantExpr::getBitCast(fnPtr, CGM.Int8PtrTy); - builder.add(fnPtr); - return; - } - - case VTableComponent::CK_UnusedFunctionPointer: - return builder.addNullPointer(CGM.Int8PtrTy); - } - - llvm_unreachable("Unexpected vtable component kind"); -} - -llvm::Type *CodeGenVTables::getVTableType(const VTableLayout &layout) { - SmallVector<llvm::Type *, 4> tys; - for (unsigned i = 0, e = layout.getNumVTables(); i != e; ++i) { - tys.push_back(llvm::ArrayType::get(CGM.Int8PtrTy, layout.getVTableSize(i))); - } - - return llvm::StructType::get(CGM.getLLVMContext(), tys); -} - -void CodeGenVTables::createVTableInitializer(ConstantStructBuilder &builder, - const VTableLayout &layout, - llvm::Constant *rtti) { - unsigned nextVTableThunkIndex = 0; - for (unsigned i = 0, e = layout.getNumVTables(); i != e; ++i) { - auto vtableElem = builder.beginArray(CGM.Int8PtrTy); - size_t thisIndex = layout.getVTableOffset(i); - size_t nextIndex = thisIndex + layout.getVTableSize(i); - for (unsigned i = thisIndex; i != nextIndex; ++i) { - addVTableComponent(vtableElem, layout, i, rtti, nextVTableThunkIndex); - } - vtableElem.finishAndAddTo(builder); - } -} - -llvm::GlobalVariable * -CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, - const BaseSubobject &Base, - bool BaseIsVirtual, - llvm::GlobalVariable::LinkageTypes Linkage, - VTableAddressPointsMapTy& AddressPoints) { - if (CGDebugInfo *DI = CGM.getModuleDebugInfo()) - DI->completeClassData(Base.getBase()); - - std::unique_ptr<VTableLayout> VTLayout( - getItaniumVTableContext().createConstructionVTableLayout( - Base.getBase(), Base.getBaseOffset(), BaseIsVirtual, RD)); - - // Add the address points. - AddressPoints = VTLayout->getAddressPoints(); - - // Get the mangled construction vtable name. - SmallString<256> OutName; - llvm::raw_svector_ostream Out(OutName); - cast<ItaniumMangleContext>(CGM.getCXXABI().getMangleContext()) - .mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), - Base.getBase(), Out); - StringRef Name = OutName.str(); - - llvm::Type *VTType = getVTableType(*VTLayout); - - // Construction vtable symbols are not part of the Itanium ABI, so we cannot - // guarantee that they actually will be available externally. Instead, when - // emitting an available_externally VTT, we provide references to an internal - // linkage construction vtable. The ABI only requires complete-object vtables - // to be the same for all instances of a type, not construction vtables. - if (Linkage == llvm::GlobalVariable::AvailableExternallyLinkage) - Linkage = llvm::GlobalVariable::InternalLinkage; - - unsigned Align = CGM.getDataLayout().getABITypeAlignment(VTType); - - // Create the variable that will hold the construction vtable. - llvm::GlobalVariable *VTable = - CGM.CreateOrReplaceCXXRuntimeVariable(Name, VTType, Linkage, Align); - CGM.setGVProperties(VTable, RD); - - // V-tables are always unnamed_addr. - VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); - - llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor( - CGM.getContext().getTagDeclType(Base.getBase())); - - // Create and set the initializer. - ConstantInitBuilder builder(CGM); - auto components = builder.beginStruct(); - createVTableInitializer(components, *VTLayout, RTTI); - components.finishAndSetAsInitializer(VTable); - - CGM.EmitVTableTypeMetadata(VTable, *VTLayout.get()); - - return VTable; -} - -static bool shouldEmitAvailableExternallyVTable(const CodeGenModule &CGM, - const CXXRecordDecl *RD) { - return CGM.getCodeGenOpts().OptimizationLevel > 0 && - CGM.getCXXABI().canSpeculativelyEmitVTable(RD); -} - -/// Compute the required linkage of the vtable for the given class. -/// -/// Note that we only call this at the end of the translation unit. -llvm::GlobalVariable::LinkageTypes -CodeGenModule::getVTableLinkage(const CXXRecordDecl *RD) { - if (!RD->isExternallyVisible()) - return llvm::GlobalVariable::InternalLinkage; - - // We're at the end of the translation unit, so the current key - // function is fully correct. - const CXXMethodDecl *keyFunction = Context.getCurrentKeyFunction(RD); - if (keyFunction && !RD->hasAttr<DLLImportAttr>()) { - // If this class has a key function, use that to determine the - // linkage of the vtable. - const FunctionDecl *def = nullptr; - if (keyFunction->hasBody(def)) - keyFunction = cast<CXXMethodDecl>(def); - - switch (keyFunction->getTemplateSpecializationKind()) { - case TSK_Undeclared: - case TSK_ExplicitSpecialization: - assert((def || CodeGenOpts.OptimizationLevel > 0 || - CodeGenOpts.getDebugInfo() != codegenoptions::NoDebugInfo) && - "Shouldn't query vtable linkage without key function, " - "optimizations, or debug info"); - if (!def && CodeGenOpts.OptimizationLevel > 0) - return llvm::GlobalVariable::AvailableExternallyLinkage; - - if (keyFunction->isInlined()) - return !Context.getLangOpts().AppleKext ? - llvm::GlobalVariable::LinkOnceODRLinkage : - llvm::Function::InternalLinkage; - - return llvm::GlobalVariable::ExternalLinkage; - - case TSK_ImplicitInstantiation: - return !Context.getLangOpts().AppleKext ? - llvm::GlobalVariable::LinkOnceODRLinkage : - llvm::Function::InternalLinkage; - - case TSK_ExplicitInstantiationDefinition: - return !Context.getLangOpts().AppleKext ? - llvm::GlobalVariable::WeakODRLinkage : - llvm::Function::InternalLinkage; - - case TSK_ExplicitInstantiationDeclaration: - llvm_unreachable("Should not have been asked to emit this"); - } - } - - // -fapple-kext mode does not support weak linkage, so we must use - // internal linkage. - if (Context.getLangOpts().AppleKext) - return llvm::Function::InternalLinkage; - - llvm::GlobalVariable::LinkageTypes DiscardableODRLinkage = - llvm::GlobalValue::LinkOnceODRLinkage; - llvm::GlobalVariable::LinkageTypes NonDiscardableODRLinkage = - llvm::GlobalValue::WeakODRLinkage; - if (RD->hasAttr<DLLExportAttr>()) { - // Cannot discard exported vtables. - DiscardableODRLinkage = NonDiscardableODRLinkage; - } else if (RD->hasAttr<DLLImportAttr>()) { - // Imported vtables are available externally. - DiscardableODRLinkage = llvm::GlobalVariable::AvailableExternallyLinkage; - NonDiscardableODRLinkage = llvm::GlobalVariable::AvailableExternallyLinkage; - } - - switch (RD->getTemplateSpecializationKind()) { - case TSK_Undeclared: - case TSK_ExplicitSpecialization: - case TSK_ImplicitInstantiation: - return DiscardableODRLinkage; - - case TSK_ExplicitInstantiationDeclaration: - // Explicit instantiations in MSVC do not provide vtables, so we must emit - // our own. - if (getTarget().getCXXABI().isMicrosoft()) - return DiscardableODRLinkage; - return shouldEmitAvailableExternallyVTable(*this, RD) - ? llvm::GlobalVariable::AvailableExternallyLinkage - : llvm::GlobalVariable::ExternalLinkage; - - case TSK_ExplicitInstantiationDefinition: - return NonDiscardableODRLinkage; - } - - llvm_unreachable("Invalid TemplateSpecializationKind!"); -} - -/// This is a callback from Sema to tell us that a particular vtable is -/// required to be emitted in this translation unit. -/// -/// This is only called for vtables that _must_ be emitted (mainly due to key -/// functions). For weak vtables, CodeGen tracks when they are needed and -/// emits them as-needed. -void CodeGenModule::EmitVTable(CXXRecordDecl *theClass) { - VTables.GenerateClassData(theClass); -} - -void -CodeGenVTables::GenerateClassData(const CXXRecordDecl *RD) { - if (CGDebugInfo *DI = CGM.getModuleDebugInfo()) - DI->completeClassData(RD); - - if (RD->getNumVBases()) - CGM.getCXXABI().emitVirtualInheritanceTables(RD); - - CGM.getCXXABI().emitVTableDefinitions(*this, RD); -} - -/// At this point in the translation unit, does it appear that can we -/// rely on the vtable being defined elsewhere in the program? -/// -/// The response is really only definitive when called at the end of -/// the translation unit. -/// -/// The only semantic restriction here is that the object file should -/// not contain a vtable definition when that vtable is defined -/// strongly elsewhere. Otherwise, we'd just like to avoid emitting -/// vtables when unnecessary. -bool CodeGenVTables::isVTableExternal(const CXXRecordDecl *RD) { - assert(RD->isDynamicClass() && "Non-dynamic classes have no VTable."); - - // We always synthesize vtables if they are needed in the MS ABI. MSVC doesn't - // emit them even if there is an explicit template instantiation. - if (CGM.getTarget().getCXXABI().isMicrosoft()) - return false; - - // If we have an explicit instantiation declaration (and not a - // definition), the vtable is defined elsewhere. - TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind(); - if (TSK == TSK_ExplicitInstantiationDeclaration) - return true; - - // Otherwise, if the class is an instantiated template, the - // vtable must be defined here. - if (TSK == TSK_ImplicitInstantiation || - TSK == TSK_ExplicitInstantiationDefinition) - return false; - - // Otherwise, if the class doesn't have a key function (possibly - // anymore), the vtable must be defined here. - const CXXMethodDecl *keyFunction = CGM.getContext().getCurrentKeyFunction(RD); - if (!keyFunction) - return false; - - // Otherwise, if we don't have a definition of the key function, the - // vtable must be defined somewhere else. - return !keyFunction->hasBody(); -} - -/// Given that we're currently at the end of the translation unit, and -/// we've emitted a reference to the vtable for this class, should -/// we define that vtable? -static bool shouldEmitVTableAtEndOfTranslationUnit(CodeGenModule &CGM, - const CXXRecordDecl *RD) { - // If vtable is internal then it has to be done. - if (!CGM.getVTables().isVTableExternal(RD)) - return true; - - // If it's external then maybe we will need it as available_externally. - return shouldEmitAvailableExternallyVTable(CGM, RD); -} - -/// Given that at some point we emitted a reference to one or more -/// vtables, and that we are now at the end of the translation unit, -/// decide whether we should emit them. -void CodeGenModule::EmitDeferredVTables() { -#ifndef NDEBUG - // Remember the size of DeferredVTables, because we're going to assume - // that this entire operation doesn't modify it. - size_t savedSize = DeferredVTables.size(); -#endif - - for (const CXXRecordDecl *RD : DeferredVTables) - if (shouldEmitVTableAtEndOfTranslationUnit(*this, RD)) - VTables.GenerateClassData(RD); - else if (shouldOpportunisticallyEmitVTables()) - OpportunisticVTables.push_back(RD); - - assert(savedSize == DeferredVTables.size() && - "deferred extra vtables during vtable emission?"); - DeferredVTables.clear(); -} - -bool CodeGenModule::HasHiddenLTOVisibility(const CXXRecordDecl *RD) { - LinkageInfo LV = RD->getLinkageAndVisibility(); - if (!isExternallyVisible(LV.getLinkage())) - return true; - - if (RD->hasAttr<LTOVisibilityPublicAttr>() || RD->hasAttr<UuidAttr>()) - return false; - - if (getTriple().isOSBinFormatCOFF()) { - if (RD->hasAttr<DLLExportAttr>() || RD->hasAttr<DLLImportAttr>()) - return false; - } else { - if (LV.getVisibility() != HiddenVisibility) - return false; - } - - if (getCodeGenOpts().LTOVisibilityPublicStd) { - const DeclContext *DC = RD; - while (1) { - auto *D = cast<Decl>(DC); - DC = DC->getParent(); - if (isa<TranslationUnitDecl>(DC->getRedeclContext())) { - if (auto *ND = dyn_cast<NamespaceDecl>(D)) - if (const IdentifierInfo *II = ND->getIdentifier()) - if (II->isStr("std") || II->isStr("stdext")) - return false; - break; - } - } - } - - return true; -} - -void CodeGenModule::EmitVTableTypeMetadata(llvm::GlobalVariable *VTable, - const VTableLayout &VTLayout) { - if (!getCodeGenOpts().LTOUnit) - return; - - CharUnits PointerWidth = - Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0)); - - typedef std::pair<const CXXRecordDecl *, unsigned> AddressPoint; - std::vector<AddressPoint> AddressPoints; - for (auto &&AP : VTLayout.getAddressPoints()) - AddressPoints.push_back(std::make_pair( - AP.first.getBase(), VTLayout.getVTableOffset(AP.second.VTableIndex) + - AP.second.AddressPointIndex)); - - // Sort the address points for determinism. - llvm::sort(AddressPoints, [this](const AddressPoint &AP1, - const AddressPoint &AP2) { - if (&AP1 == &AP2) - return false; - - std::string S1; - llvm::raw_string_ostream O1(S1); - getCXXABI().getMangleContext().mangleTypeName( - QualType(AP1.first->getTypeForDecl(), 0), O1); - O1.flush(); - - std::string S2; - llvm::raw_string_ostream O2(S2); - getCXXABI().getMangleContext().mangleTypeName( - QualType(AP2.first->getTypeForDecl(), 0), O2); - O2.flush(); - - if (S1 < S2) - return true; - if (S1 != S2) - return false; - - return AP1.second < AP2.second; - }); - - ArrayRef<VTableComponent> Comps = VTLayout.vtable_components(); - for (auto AP : AddressPoints) { - // Create type metadata for the address point. - AddVTableTypeMetadata(VTable, PointerWidth * AP.second, AP.first); - - // The class associated with each address point could also potentially be - // used for indirect calls via a member function pointer, so we need to - // annotate the address of each function pointer with the appropriate member - // function pointer type. - for (unsigned I = 0; I != Comps.size(); ++I) { - if (Comps[I].getKind() != VTableComponent::CK_FunctionPointer) - continue; - llvm::Metadata *MD = CreateMetadataIdentifierForVirtualMemPtrType( - Context.getMemberPointerType( - Comps[I].getFunctionDecl()->getType(), - Context.getRecordType(AP.first).getTypePtr())); - VTable->addTypeMetadata((PointerWidth * I).getQuantity(), MD); - } - } -} |