a14d8b2e36
This implements vtable thunk handling in CIR based on the incubator code, but also compared against the latest Clang LLVM IR codegen. Eventually, we'll want to create CIR abstractions for all of this and move the CXXABI-specific details into the CXXABI lowering pass. For now, we just implement it directly in codegen.
107 lines
4.1 KiB
C++
107 lines
4.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This provides an abstract class for C++ code generation. Concrete subclasses
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// of this implement code generation for specific C++ ABIs.
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//
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//===----------------------------------------------------------------------===//
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#include "CIRGenCXXABI.h"
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#include "CIRGenFunction.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/ExprCXX.h"
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#include "clang/AST/GlobalDecl.h"
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using namespace clang;
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using namespace clang::CIRGen;
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CIRGenCXXABI::~CIRGenCXXABI() {}
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CIRGenCXXABI::AddedStructorArgCounts CIRGenCXXABI::addImplicitConstructorArgs(
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CIRGenFunction &cgf, const CXXConstructorDecl *d, CXXCtorType type,
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bool forVirtualBase, bool delegating, CallArgList &args) {
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AddedStructorArgs addedArgs =
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getImplicitConstructorArgs(cgf, d, type, forVirtualBase, delegating);
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for (auto [idx, prefixArg] : llvm::enumerate(addedArgs.prefix))
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args.insert(args.begin() + 1 + idx,
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CallArg(RValue::get(prefixArg.value), prefixArg.type));
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for (const auto &arg : addedArgs.suffix)
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args.add(RValue::get(arg.value), arg.type);
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return AddedStructorArgCounts(addedArgs.prefix.size(),
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addedArgs.suffix.size());
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}
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CatchTypeInfo CIRGenCXXABI::getCatchAllTypeInfo() {
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return CatchTypeInfo{{}, 0};
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}
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void CIRGenCXXABI::buildThisParam(CIRGenFunction &cgf,
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FunctionArgList ¶ms) {
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const auto *md = cast<CXXMethodDecl>(cgf.curGD.getDecl());
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// FIXME: I'm not entirely sure I like using a fake decl just for code
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// generation. Maybe we can come up with a better way?
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auto *thisDecl =
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ImplicitParamDecl::Create(cgm.getASTContext(), nullptr, md->getLocation(),
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&cgm.getASTContext().Idents.get("this"),
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md->getThisType(), ImplicitParamKind::CXXThis);
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params.push_back(thisDecl);
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cgf.cxxabiThisDecl = thisDecl;
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// Classic codegen computes the alignment of thisDecl and saves it in
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// CodeGenFunction::CXXABIThisAlignment, but it is only used in emitTypeCheck
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// in CodeGenFunction::StartFunction().
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assert(!cir::MissingFeatures::cxxabiThisAlignment());
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}
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cir::GlobalLinkageKind CIRGenCXXABI::getCXXDestructorLinkage(
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GVALinkage linkage, const CXXDestructorDecl *dtor, CXXDtorType dt) const {
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// Delegate back to cgm by default.
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return cgm.getCIRLinkageForDeclarator(dtor, linkage,
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/*isConstantVariable=*/false);
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}
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mlir::Value CIRGenCXXABI::loadIncomingCXXThis(CIRGenFunction &cgf) {
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ImplicitParamDecl *vd = getThisDecl(cgf);
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Address addr = cgf.getAddrOfLocalVar(vd);
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return cir::LoadOp::create(cgf.getBuilder(), cgf.getLoc(vd->getLocation()),
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addr.getElementType(), addr.getPointer());
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}
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void CIRGenCXXABI::setCXXABIThisValue(CIRGenFunction &cgf,
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mlir::Value thisPtr) {
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/// Initialize the 'this' slot.
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assert(getThisDecl(cgf) && "no 'this' variable for function");
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cgf.cxxabiThisValue = thisPtr;
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}
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CharUnits CIRGenCXXABI::getArrayCookieSize(const CXXNewExpr *e) {
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if (!requiresArrayCookie(e))
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return CharUnits::Zero();
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return getArrayCookieSizeImpl(e->getAllocatedType());
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}
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bool CIRGenCXXABI::requiresArrayCookie(const CXXNewExpr *e) {
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// If the class's usual deallocation function takes two arguments,
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// it needs a cookie.
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if (e->doesUsualArrayDeleteWantSize())
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return true;
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return e->getAllocatedType().isDestructedType();
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}
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void CIRGenCXXABI::emitReturnFromThunk(CIRGenFunction &cgf, RValue rv,
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QualType resultType) {
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assert(!cgf.hasAggregateEvaluationKind(resultType) &&
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"cannot handle aggregates");
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mlir::Location loc = cgf.getBuilder().getUnknownLoc();
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cgf.emitReturnOfRValue(loc, rv, resultType);
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}
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