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984 lines
37 KiB
984 lines
37 KiB
//===--- CGVTables.cpp - Emit LLVM Code for C++ vtables -------------------===//
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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++ code generation of virtual tables.
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenFunction.h"
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#include "CGCXXABI.h"
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#include "CodeGenModule.h"
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#include "clang/AST/CXXInheritance.h"
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#include "clang/AST/RecordLayout.h"
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#include "clang/CodeGen/CGFunctionInfo.h"
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#include "clang/Frontend/CodeGenOptions.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include <algorithm>
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#include <cstdio>
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using namespace clang;
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using namespace CodeGen;
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CodeGenVTables::CodeGenVTables(CodeGenModule &CGM)
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: CGM(CGM), VTContext(CGM.getContext().getVTableContext()) {}
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llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD,
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const ThunkInfo &Thunk) {
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const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
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// Compute the mangled name.
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SmallString<256> Name;
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llvm::raw_svector_ostream Out(Name);
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if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD))
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getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(),
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Thunk.This, Out);
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else
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getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out);
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llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD);
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return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true,
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/*DontDefer=*/true, /*IsThunk=*/true);
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}
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static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
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const ThunkInfo &Thunk, llvm::Function *Fn) {
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CGM.setGlobalVisibility(Fn, MD);
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}
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static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk,
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llvm::Function *ThunkFn, bool ForVTable,
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GlobalDecl GD) {
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CGM.setFunctionLinkage(GD, ThunkFn);
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CGM.getCXXABI().setThunkLinkage(ThunkFn, ForVTable, GD,
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!Thunk.Return.isEmpty());
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// Set the right visibility.
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const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
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setThunkVisibility(CGM, MD, Thunk, ThunkFn);
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if (CGM.supportsCOMDAT() && ThunkFn->isWeakForLinker())
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ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName()));
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}
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#ifndef NDEBUG
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static bool similar(const ABIArgInfo &infoL, CanQualType typeL,
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const ABIArgInfo &infoR, CanQualType typeR) {
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return (infoL.getKind() == infoR.getKind() &&
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(typeL == typeR ||
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(isa<PointerType>(typeL) && isa<PointerType>(typeR)) ||
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(isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR))));
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}
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#endif
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static RValue PerformReturnAdjustment(CodeGenFunction &CGF,
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QualType ResultType, RValue RV,
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const ThunkInfo &Thunk) {
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// Emit the return adjustment.
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bool NullCheckValue = !ResultType->isReferenceType();
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llvm::BasicBlock *AdjustNull = nullptr;
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llvm::BasicBlock *AdjustNotNull = nullptr;
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llvm::BasicBlock *AdjustEnd = nullptr;
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llvm::Value *ReturnValue = RV.getScalarVal();
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if (NullCheckValue) {
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AdjustNull = CGF.createBasicBlock("adjust.null");
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AdjustNotNull = CGF.createBasicBlock("adjust.notnull");
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AdjustEnd = CGF.createBasicBlock("adjust.end");
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llvm::Value *IsNull = CGF.Builder.CreateIsNull(ReturnValue);
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CGF.Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull);
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CGF.EmitBlock(AdjustNotNull);
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}
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auto ClassDecl = ResultType->getPointeeType()->getAsCXXRecordDecl();
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auto ClassAlign = CGF.CGM.getClassPointerAlignment(ClassDecl);
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ReturnValue = CGF.CGM.getCXXABI().performReturnAdjustment(CGF,
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Address(ReturnValue, ClassAlign),
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Thunk.Return);
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if (NullCheckValue) {
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CGF.Builder.CreateBr(AdjustEnd);
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CGF.EmitBlock(AdjustNull);
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CGF.Builder.CreateBr(AdjustEnd);
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CGF.EmitBlock(AdjustEnd);
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llvm::PHINode *PHI = CGF.Builder.CreatePHI(ReturnValue->getType(), 2);
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PHI->addIncoming(ReturnValue, AdjustNotNull);
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PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()),
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AdjustNull);
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ReturnValue = PHI;
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}
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return RValue::get(ReturnValue);
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}
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// This function does roughly the same thing as GenerateThunk, but in a
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// very different way, so that va_start and va_end work correctly.
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// FIXME: This function assumes "this" is the first non-sret LLVM argument of
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// a function, and that there is an alloca built in the entry block
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// for all accesses to "this".
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// FIXME: This function assumes there is only one "ret" statement per function.
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// FIXME: Cloning isn't correct in the presence of indirect goto!
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// FIXME: This implementation of thunks bloats codesize by duplicating the
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// function definition. There are alternatives:
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// 1. Add some sort of stub support to LLVM for cases where we can
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// do a this adjustment, then a sibcall.
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// 2. We could transform the definition to take a va_list instead of an
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// actual variable argument list, then have the thunks (including a
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// no-op thunk for the regular definition) call va_start/va_end.
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// There's a bit of per-call overhead for this solution, but it's
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// better for codesize if the definition is long.
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llvm::Function *
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CodeGenFunction::GenerateVarArgsThunk(llvm::Function *Fn,
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const CGFunctionInfo &FnInfo,
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GlobalDecl GD, const ThunkInfo &Thunk) {
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const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
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const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
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QualType ResultType = FPT->getReturnType();
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// Get the original function
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assert(FnInfo.isVariadic());
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llvm::Type *Ty = CGM.getTypes().GetFunctionType(FnInfo);
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llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
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llvm::Function *BaseFn = cast<llvm::Function>(Callee);
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// Clone to thunk.
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llvm::ValueToValueMapTy VMap;
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llvm::Function *NewFn = llvm::CloneFunction(BaseFn, VMap);
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Fn->replaceAllUsesWith(NewFn);
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NewFn->takeName(Fn);
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Fn->eraseFromParent();
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Fn = NewFn;
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// "Initialize" CGF (minimally).
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CurFn = Fn;
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// Get the "this" value
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llvm::Function::arg_iterator AI = Fn->arg_begin();
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if (CGM.ReturnTypeUsesSRet(FnInfo))
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++AI;
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// Find the first store of "this", which will be to the alloca associated
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// with "this".
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Address ThisPtr(&*AI, CGM.getClassPointerAlignment(MD->getParent()));
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llvm::BasicBlock *EntryBB = &Fn->front();
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llvm::BasicBlock::iterator ThisStore =
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std::find_if(EntryBB->begin(), EntryBB->end(), [&](llvm::Instruction &I) {
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return isa<llvm::StoreInst>(I) &&
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I.getOperand(0) == ThisPtr.getPointer();
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});
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assert(ThisStore != EntryBB->end() &&
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"Store of this should be in entry block?");
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// Adjust "this", if necessary.
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Builder.SetInsertPoint(&*ThisStore);
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llvm::Value *AdjustedThisPtr =
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CGM.getCXXABI().performThisAdjustment(*this, ThisPtr, Thunk.This);
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ThisStore->setOperand(0, AdjustedThisPtr);
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if (!Thunk.Return.isEmpty()) {
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// Fix up the returned value, if necessary.
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for (llvm::BasicBlock &BB : *Fn) {
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llvm::Instruction *T = BB.getTerminator();
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if (isa<llvm::ReturnInst>(T)) {
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RValue RV = RValue::get(T->getOperand(0));
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T->eraseFromParent();
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Builder.SetInsertPoint(&BB);
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RV = PerformReturnAdjustment(*this, ResultType, RV, Thunk);
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Builder.CreateRet(RV.getScalarVal());
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break;
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}
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}
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}
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return Fn;
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}
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void CodeGenFunction::StartThunk(llvm::Function *Fn, GlobalDecl GD,
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const CGFunctionInfo &FnInfo) {
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assert(!CurGD.getDecl() && "CurGD was already set!");
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CurGD = GD;
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CurFuncIsThunk = true;
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// Build FunctionArgs.
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const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
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QualType ThisType = MD->getThisType(getContext());
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const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
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QualType ResultType = CGM.getCXXABI().HasThisReturn(GD)
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? ThisType
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: CGM.getCXXABI().hasMostDerivedReturn(GD)
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? CGM.getContext().VoidPtrTy
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: FPT->getReturnType();
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FunctionArgList FunctionArgs;
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// Create the implicit 'this' parameter declaration.
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CGM.getCXXABI().buildThisParam(*this, FunctionArgs);
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// Add the rest of the parameters.
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FunctionArgs.append(MD->param_begin(), MD->param_end());
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if (isa<CXXDestructorDecl>(MD))
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CGM.getCXXABI().addImplicitStructorParams(*this, ResultType, FunctionArgs);
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// Start defining the function.
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StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs,
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MD->getLocation(), MD->getLocation());
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// Since we didn't pass a GlobalDecl to StartFunction, do this ourselves.
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CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
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CXXThisValue = CXXABIThisValue;
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CurCodeDecl = MD;
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CurFuncDecl = MD;
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}
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void CodeGenFunction::FinishThunk() {
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// Clear these to restore the invariants expected by
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// StartFunction/FinishFunction.
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CurCodeDecl = nullptr;
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CurFuncDecl = nullptr;
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FinishFunction();
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}
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void CodeGenFunction::EmitCallAndReturnForThunk(llvm::Value *Callee,
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const ThunkInfo *Thunk) {
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assert(isa<CXXMethodDecl>(CurGD.getDecl()) &&
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"Please use a new CGF for this thunk");
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const CXXMethodDecl *MD = cast<CXXMethodDecl>(CurGD.getDecl());
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// Adjust the 'this' pointer if necessary
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llvm::Value *AdjustedThisPtr =
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Thunk ? CGM.getCXXABI().performThisAdjustment(
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*this, LoadCXXThisAddress(), Thunk->This)
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: LoadCXXThis();
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if (CurFnInfo->usesInAlloca()) {
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// We don't handle return adjusting thunks, because they require us to call
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// the copy constructor. For now, fall through and pretend the return
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// adjustment was empty so we don't crash.
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if (Thunk && !Thunk->Return.isEmpty()) {
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CGM.ErrorUnsupported(
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MD, "non-trivial argument copy for return-adjusting thunk");
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}
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EmitMustTailThunk(MD, AdjustedThisPtr, Callee);
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return;
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}
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// Start building CallArgs.
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CallArgList CallArgs;
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QualType ThisType = MD->getThisType(getContext());
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CallArgs.add(RValue::get(AdjustedThisPtr), ThisType);
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if (isa<CXXDestructorDecl>(MD))
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CGM.getCXXABI().adjustCallArgsForDestructorThunk(*this, CurGD, CallArgs);
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// Add the rest of the arguments.
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for (const ParmVarDecl *PD : MD->parameters())
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EmitDelegateCallArg(CallArgs, PD, PD->getLocStart());
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const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>();
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#ifndef NDEBUG
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const CGFunctionInfo &CallFnInfo = CGM.getTypes().arrangeCXXMethodCall(
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CallArgs, FPT, RequiredArgs::forPrototypePlus(FPT, 1, MD));
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assert(CallFnInfo.getRegParm() == CurFnInfo->getRegParm() &&
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CallFnInfo.isNoReturn() == CurFnInfo->isNoReturn() &&
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CallFnInfo.getCallingConvention() == CurFnInfo->getCallingConvention());
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assert(isa<CXXDestructorDecl>(MD) || // ignore dtor return types
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similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(),
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CurFnInfo->getReturnInfo(), CurFnInfo->getReturnType()));
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assert(CallFnInfo.arg_size() == CurFnInfo->arg_size());
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for (unsigned i = 0, e = CurFnInfo->arg_size(); i != e; ++i)
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assert(similar(CallFnInfo.arg_begin()[i].info,
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CallFnInfo.arg_begin()[i].type,
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CurFnInfo->arg_begin()[i].info,
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CurFnInfo->arg_begin()[i].type));
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#endif
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// Determine whether we have a return value slot to use.
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QualType ResultType = CGM.getCXXABI().HasThisReturn(CurGD)
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? ThisType
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: CGM.getCXXABI().hasMostDerivedReturn(CurGD)
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? CGM.getContext().VoidPtrTy
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: FPT->getReturnType();
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ReturnValueSlot Slot;
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if (!ResultType->isVoidType() &&
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CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
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!hasScalarEvaluationKind(CurFnInfo->getReturnType()))
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Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified());
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// Now emit our call.
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llvm::Instruction *CallOrInvoke;
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RValue RV = EmitCall(*CurFnInfo, Callee, Slot, CallArgs, MD, &CallOrInvoke);
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// Consider return adjustment if we have ThunkInfo.
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if (Thunk && !Thunk->Return.isEmpty())
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RV = PerformReturnAdjustment(*this, ResultType, RV, *Thunk);
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else if (llvm::CallInst* Call = dyn_cast<llvm::CallInst>(CallOrInvoke))
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Call->setTailCallKind(llvm::CallInst::TCK_Tail);
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// Emit return.
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if (!ResultType->isVoidType() && Slot.isNull())
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CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType);
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// Disable the final ARC autorelease.
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AutoreleaseResult = false;
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FinishThunk();
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}
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void CodeGenFunction::EmitMustTailThunk(const CXXMethodDecl *MD,
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llvm::Value *AdjustedThisPtr,
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llvm::Value *Callee) {
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// Emitting a musttail call thunk doesn't use any of the CGCall.cpp machinery
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// to translate AST arguments into LLVM IR arguments. For thunks, we know
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// that the caller prototype more or less matches the callee prototype with
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// the exception of 'this'.
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SmallVector<llvm::Value *, 8> Args;
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for (llvm::Argument &A : CurFn->args())
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Args.push_back(&A);
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// Set the adjusted 'this' pointer.
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const ABIArgInfo &ThisAI = CurFnInfo->arg_begin()->info;
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if (ThisAI.isDirect()) {
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const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
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int ThisArgNo = RetAI.isIndirect() && !RetAI.isSRetAfterThis() ? 1 : 0;
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llvm::Type *ThisType = Args[ThisArgNo]->getType();
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if (ThisType != AdjustedThisPtr->getType())
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AdjustedThisPtr = Builder.CreateBitCast(AdjustedThisPtr, ThisType);
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Args[ThisArgNo] = AdjustedThisPtr;
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} else {
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assert(ThisAI.isInAlloca() && "this is passed directly or inalloca");
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Address ThisAddr = GetAddrOfLocalVar(CXXABIThisDecl);
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llvm::Type *ThisType = ThisAddr.getElementType();
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if (ThisType != AdjustedThisPtr->getType())
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AdjustedThisPtr = Builder.CreateBitCast(AdjustedThisPtr, ThisType);
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Builder.CreateStore(AdjustedThisPtr, ThisAddr);
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}
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// Emit the musttail call manually. Even if the prologue pushed cleanups, we
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// don't actually want to run them.
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llvm::CallInst *Call = Builder.CreateCall(Callee, Args);
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Call->setTailCallKind(llvm::CallInst::TCK_MustTail);
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// Apply the standard set of call attributes.
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unsigned CallingConv;
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CodeGen::AttributeListType AttributeList;
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CGM.ConstructAttributeList(Callee->getName(), *CurFnInfo, MD, AttributeList,
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CallingConv, /*AttrOnCallSite=*/true);
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llvm::AttributeSet Attrs =
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llvm::AttributeSet::get(getLLVMContext(), AttributeList);
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Call->setAttributes(Attrs);
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Call->setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
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if (Call->getType()->isVoidTy())
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Builder.CreateRetVoid();
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else
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Builder.CreateRet(Call);
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// Finish the function to maintain CodeGenFunction invariants.
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// FIXME: Don't emit unreachable code.
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EmitBlock(createBasicBlock());
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FinishFunction();
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}
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void CodeGenFunction::generateThunk(llvm::Function *Fn,
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const CGFunctionInfo &FnInfo,
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GlobalDecl GD, const ThunkInfo &Thunk) {
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StartThunk(Fn, GD, FnInfo);
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// Get our callee.
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llvm::Type *Ty =
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CGM.getTypes().GetFunctionType(CGM.getTypes().arrangeGlobalDeclaration(GD));
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llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
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// Make the call and return the result.
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EmitCallAndReturnForThunk(Callee, &Thunk);
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}
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void CodeGenVTables::emitThunk(GlobalDecl GD, const ThunkInfo &Thunk,
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bool ForVTable) {
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const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeGlobalDeclaration(GD);
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// FIXME: re-use FnInfo in this computation.
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llvm::Constant *C = CGM.GetAddrOfThunk(GD, Thunk);
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llvm::GlobalValue *Entry;
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// Strip off a bitcast if we got one back.
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if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(C)) {
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assert(CE->getOpcode() == llvm::Instruction::BitCast);
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Entry = cast<llvm::GlobalValue>(CE->getOperand(0));
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} else {
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Entry = cast<llvm::GlobalValue>(C);
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}
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// There's already a declaration with the same name, check if it has the same
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// type or if we need to replace it.
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if (Entry->getType()->getElementType() !=
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CGM.getTypes().GetFunctionTypeForVTable(GD)) {
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llvm::GlobalValue *OldThunkFn = Entry;
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// If the types mismatch then we have to rewrite the definition.
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assert(OldThunkFn->isDeclaration() &&
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"Shouldn't replace non-declaration");
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// Remove the name from the old thunk function and get a new thunk.
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OldThunkFn->setName(StringRef());
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Entry = cast<llvm::GlobalValue>(CGM.GetAddrOfThunk(GD, Thunk));
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// If needed, replace the old thunk with a bitcast.
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if (!OldThunkFn->use_empty()) {
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llvm::Constant *NewPtrForOldDecl =
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llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType());
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OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl);
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}
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// Remove the old thunk.
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OldThunkFn->eraseFromParent();
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}
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llvm::Function *ThunkFn = cast<llvm::Function>(Entry);
|
|
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;
|
|
}
|
|
|
|
setThunkProperties(CGM, Thunk, ThunkFn, ForVTable, GD);
|
|
return;
|
|
}
|
|
|
|
CGM.SetLLVMFunctionAttributesForDefinition(GD.getDecl(), ThunkFn);
|
|
|
|
if (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 =
|
|
CodeGenFunction(CGM).GenerateVarArgsThunk(ThunkFn, FnInfo, GD, Thunk);
|
|
} else {
|
|
// Normal thunk body generation.
|
|
CodeGenFunction(CGM).generateThunk(ThunkFn, FnInfo, GD, Thunk);
|
|
}
|
|
|
|
setThunkProperties(CGM, Thunk, ThunkFn, ForVTable, GD);
|
|
}
|
|
|
|
void CodeGenVTables::maybeEmitThunkForVTable(GlobalDecl GD,
|
|
const ThunkInfo &Thunk) {
|
|
// If the ABI has key functions, only the TU with the key function should emit
|
|
// the thunk. However, we can allow inlining of thunks if we emit them with
|
|
// available_externally linkage together with vtables when optimizations are
|
|
// enabled.
|
|
if (CGM.getTarget().getCXXABI().hasKeyFunctions() &&
|
|
!CGM.getCodeGenOpts().OptimizationLevel)
|
|
return;
|
|
|
|
// We can't emit thunks for member functions with incomplete types.
|
|
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
|
|
if (!CGM.getTypes().isFuncTypeConvertible(
|
|
MD->getType()->castAs<FunctionType>()))
|
|
return;
|
|
|
|
emitThunk(GD, Thunk, /*ForVTable=*/true);
|
|
}
|
|
|
|
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)
|
|
emitThunk(GD, Thunk, /*ForVTable=*/false);
|
|
}
|
|
|
|
llvm::Constant *CodeGenVTables::CreateVTableInitializer(
|
|
const CXXRecordDecl *RD, const VTableComponent *Components,
|
|
unsigned NumComponents, const VTableLayout::VTableThunkTy *VTableThunks,
|
|
unsigned NumVTableThunks, llvm::Constant *RTTI) {
|
|
SmallVector<llvm::Constant *, 64> Inits;
|
|
|
|
llvm::Type *Int8PtrTy = CGM.Int8PtrTy;
|
|
|
|
llvm::Type *PtrDiffTy =
|
|
CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType());
|
|
|
|
unsigned NextVTableThunkIndex = 0;
|
|
|
|
llvm::Constant *PureVirtualFn = nullptr, *DeletedVirtualFn = nullptr;
|
|
|
|
for (unsigned I = 0; I != NumComponents; ++I) {
|
|
VTableComponent Component = Components[I];
|
|
|
|
llvm::Constant *Init = nullptr;
|
|
|
|
switch (Component.getKind()) {
|
|
case VTableComponent::CK_VCallOffset:
|
|
Init = llvm::ConstantInt::get(PtrDiffTy,
|
|
Component.getVCallOffset().getQuantity());
|
|
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
|
|
break;
|
|
case VTableComponent::CK_VBaseOffset:
|
|
Init = llvm::ConstantInt::get(PtrDiffTy,
|
|
Component.getVBaseOffset().getQuantity());
|
|
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
|
|
break;
|
|
case VTableComponent::CK_OffsetToTop:
|
|
Init = llvm::ConstantInt::get(PtrDiffTy,
|
|
Component.getOffsetToTop().getQuantity());
|
|
Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy);
|
|
break;
|
|
case VTableComponent::CK_RTTI:
|
|
Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy);
|
|
break;
|
|
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) {
|
|
Init = llvm::ConstantExpr::getNullValue(Int8PtrTy);
|
|
break;
|
|
}
|
|
// Method is acceptable, continue processing as usual.
|
|
}
|
|
|
|
if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) {
|
|
// We have a pure virtual member function.
|
|
if (!PureVirtualFn) {
|
|
llvm::FunctionType *Ty =
|
|
llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
|
|
StringRef PureCallName = CGM.getCXXABI().GetPureVirtualCallName();
|
|
PureVirtualFn = CGM.CreateRuntimeFunction(Ty, PureCallName);
|
|
if (auto *F = dyn_cast<llvm::Function>(PureVirtualFn))
|
|
F->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
|
|
PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn,
|
|
CGM.Int8PtrTy);
|
|
}
|
|
Init = PureVirtualFn;
|
|
} else if (cast<CXXMethodDecl>(GD.getDecl())->isDeleted()) {
|
|
if (!DeletedVirtualFn) {
|
|
llvm::FunctionType *Ty =
|
|
llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
|
|
StringRef DeletedCallName =
|
|
CGM.getCXXABI().GetDeletedVirtualCallName();
|
|
DeletedVirtualFn = CGM.CreateRuntimeFunction(Ty, DeletedCallName);
|
|
if (auto *F = dyn_cast<llvm::Function>(DeletedVirtualFn))
|
|
F->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
|
|
DeletedVirtualFn = llvm::ConstantExpr::getBitCast(DeletedVirtualFn,
|
|
CGM.Int8PtrTy);
|
|
}
|
|
Init = DeletedVirtualFn;
|
|
} else {
|
|
// Check if we should use a thunk.
|
|
if (NextVTableThunkIndex < NumVTableThunks &&
|
|
VTableThunks[NextVTableThunkIndex].first == I) {
|
|
const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second;
|
|
|
|
maybeEmitThunkForVTable(GD, Thunk);
|
|
Init = CGM.GetAddrOfThunk(GD, Thunk);
|
|
|
|
NextVTableThunkIndex++;
|
|
} else {
|
|
llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD);
|
|
|
|
Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true);
|
|
}
|
|
|
|
Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case VTableComponent::CK_UnusedFunctionPointer:
|
|
Init = llvm::ConstantExpr::getNullValue(Int8PtrTy);
|
|
break;
|
|
};
|
|
|
|
Inits.push_back(Init);
|
|
}
|
|
|
|
llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents);
|
|
return llvm::ConstantArray::get(ArrayType, Inits);
|
|
}
|
|
|
|
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::ArrayType *ArrayType =
|
|
llvm::ArrayType::get(CGM.Int8PtrTy, VTLayout->getNumVTableComponents());
|
|
|
|
// 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;
|
|
|
|
// Create the variable that will hold the construction vtable.
|
|
llvm::GlobalVariable *VTable =
|
|
CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage);
|
|
CGM.setGlobalVisibility(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.
|
|
llvm::Constant *Init = CreateVTableInitializer(
|
|
Base.getBase(), VTLayout->vtable_component_begin(),
|
|
VTLayout->getNumVTableComponents(), VTLayout->vtable_thunk_begin(),
|
|
VTLayout->getNumVTableThunks(), RTTI);
|
|
VTable->setInitializer(Init);
|
|
|
|
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) &&
|
|
"Shouldn't query vtable linkage without key function or "
|
|
"optimizations");
|
|
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 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);
|
|
|
|
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().PrepareForLTO)
|
|
return;
|
|
|
|
CharUnits PointerWidth =
|
|
Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
|
|
|
|
typedef std::pair<const CXXRecordDecl *, unsigned> BSEntry;
|
|
std::vector<BSEntry> BitsetEntries;
|
|
// Create a bit set entry for each address point.
|
|
for (auto &&AP : VTLayout.getAddressPoints())
|
|
BitsetEntries.push_back(std::make_pair(AP.first.getBase(), AP.second));
|
|
|
|
// Sort the bit set entries for determinism.
|
|
std::sort(BitsetEntries.begin(), BitsetEntries.end(),
|
|
[this](const BSEntry &E1, const BSEntry &E2) {
|
|
if (&E1 == &E2)
|
|
return false;
|
|
|
|
std::string S1;
|
|
llvm::raw_string_ostream O1(S1);
|
|
getCXXABI().getMangleContext().mangleTypeName(
|
|
QualType(E1.first->getTypeForDecl(), 0), O1);
|
|
O1.flush();
|
|
|
|
std::string S2;
|
|
llvm::raw_string_ostream O2(S2);
|
|
getCXXABI().getMangleContext().mangleTypeName(
|
|
QualType(E2.first->getTypeForDecl(), 0), O2);
|
|
O2.flush();
|
|
|
|
if (S1 < S2)
|
|
return true;
|
|
if (S1 != S2)
|
|
return false;
|
|
|
|
return E1.second < E2.second;
|
|
});
|
|
|
|
for (auto BitsetEntry : BitsetEntries)
|
|
AddVTableTypeMetadata(VTable, PointerWidth * BitsetEntry.second,
|
|
BitsetEntry.first);
|
|
}
|