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365 lines
11 KiB
365 lines
11 KiB
//===--- Program.cpp - Bytecode for the constexpr VM ------------*- 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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#include "Program.h"
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#include "ByteCodeStmtGen.h"
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#include "Context.h"
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#include "Function.h"
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#include "Opcode.h"
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#include "PrimType.h"
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#include "clang/AST/Decl.h"
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#include "clang/AST/DeclCXX.h"
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using namespace clang;
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using namespace clang::interp;
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unsigned Program::createGlobalString(const StringLiteral *S) {
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const size_t CharWidth = S->getCharByteWidth();
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const size_t BitWidth = CharWidth * Ctx.getCharBit();
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PrimType CharType;
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switch (CharWidth) {
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case 1:
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CharType = PT_Sint8;
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break;
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case 2:
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CharType = PT_Uint16;
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break;
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case 4:
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CharType = PT_Uint32;
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break;
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default:
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llvm_unreachable("unsupported character width");
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}
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// Create a descriptor for the string.
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Descriptor *Desc = allocateDescriptor(S, CharType, S->getLength() + 1,
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/*isConst=*/true,
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/*isTemporary=*/false,
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/*isMutable=*/false);
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// Allocate storage for the string.
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// The byte length does not include the null terminator.
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unsigned I = Globals.size();
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unsigned Sz = Desc->getAllocSize();
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auto *G = new (Allocator, Sz) Global(Desc, /*isStatic=*/true,
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/*isExtern=*/false);
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Globals.push_back(G);
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// Construct the string in storage.
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const Pointer Ptr(G->block());
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for (unsigned I = 0, N = S->getLength(); I <= N; ++I) {
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Pointer Field = Ptr.atIndex(I).narrow();
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const uint32_t CodePoint = I == N ? 0 : S->getCodeUnit(I);
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switch (CharType) {
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case PT_Sint8: {
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using T = PrimConv<PT_Sint8>::T;
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Field.deref<T>() = T::from(CodePoint, BitWidth);
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break;
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}
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case PT_Uint16: {
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using T = PrimConv<PT_Uint16>::T;
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Field.deref<T>() = T::from(CodePoint, BitWidth);
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break;
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}
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case PT_Uint32: {
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using T = PrimConv<PT_Uint32>::T;
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Field.deref<T>() = T::from(CodePoint, BitWidth);
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break;
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}
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default:
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llvm_unreachable("unsupported character type");
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}
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}
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return I;
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}
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Pointer Program::getPtrGlobal(unsigned Idx) {
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assert(Idx < Globals.size());
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return Pointer(Globals[Idx]->block());
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}
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llvm::Optional<unsigned> Program::getGlobal(const ValueDecl *VD) {
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auto It = GlobalIndices.find(VD);
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if (It != GlobalIndices.end())
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return It->second;
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// Find any previous declarations which were aleady evaluated.
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llvm::Optional<unsigned> Index;
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for (const Decl *P = VD; P; P = P->getPreviousDecl()) {
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auto It = GlobalIndices.find(P);
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if (It != GlobalIndices.end()) {
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Index = It->second;
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break;
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}
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}
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// Map the decl to the existing index.
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if (Index) {
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GlobalIndices[VD] = *Index;
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return {};
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}
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return Index;
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}
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llvm::Optional<unsigned> Program::getOrCreateGlobal(const ValueDecl *VD) {
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if (auto Idx = getGlobal(VD))
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return Idx;
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if (auto Idx = createGlobal(VD)) {
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GlobalIndices[VD] = *Idx;
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return Idx;
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}
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return {};
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}
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llvm::Optional<unsigned> Program::getOrCreateDummy(const ParmVarDecl *PD) {
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auto &ASTCtx = Ctx.getASTContext();
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// Create a pointer to an incomplete array of the specified elements.
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QualType ElemTy = PD->getType()->castAs<PointerType>()->getPointeeType();
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QualType Ty = ASTCtx.getIncompleteArrayType(ElemTy, ArrayType::Normal, 0);
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// Dedup blocks since they are immutable and pointers cannot be compared.
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auto It = DummyParams.find(PD);
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if (It != DummyParams.end())
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return It->second;
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if (auto Idx = createGlobal(PD, Ty, /*isStatic=*/true, /*isExtern=*/true)) {
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DummyParams[PD] = *Idx;
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return Idx;
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}
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return {};
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}
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llvm::Optional<unsigned> Program::createGlobal(const ValueDecl *VD) {
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bool IsStatic, IsExtern;
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if (auto *Var = dyn_cast<VarDecl>(VD)) {
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IsStatic = !Var->hasLocalStorage();
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IsExtern = !Var->getAnyInitializer();
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} else {
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IsStatic = false;
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IsExtern = true;
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}
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if (auto Idx = createGlobal(VD, VD->getType(), IsStatic, IsExtern)) {
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for (const Decl *P = VD; P; P = P->getPreviousDecl())
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GlobalIndices[P] = *Idx;
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return *Idx;
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}
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return {};
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}
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llvm::Optional<unsigned> Program::createGlobal(const Expr *E) {
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return createGlobal(E, E->getType(), /*isStatic=*/true, /*isExtern=*/false);
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}
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llvm::Optional<unsigned> Program::createGlobal(const DeclTy &D, QualType Ty,
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bool IsStatic, bool IsExtern) {
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// Create a descriptor for the global.
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Descriptor *Desc;
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const bool IsConst = Ty.isConstQualified();
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const bool IsTemporary = D.dyn_cast<const Expr *>();
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if (auto T = Ctx.classify(Ty)) {
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Desc = createDescriptor(D, *T, IsConst, IsTemporary);
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} else {
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Desc = createDescriptor(D, Ty.getTypePtr(), IsConst, IsTemporary);
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}
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if (!Desc)
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return {};
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// Allocate a block for storage.
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unsigned I = Globals.size();
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auto *G = new (Allocator, Desc->getAllocSize())
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Global(getCurrentDecl(), Desc, IsStatic, IsExtern);
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G->block()->invokeCtor();
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Globals.push_back(G);
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return I;
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}
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Function *Program::getFunction(const FunctionDecl *F) {
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F = F->getDefinition();
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auto It = Funcs.find(F);
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return It == Funcs.end() ? nullptr : It->second.get();
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}
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llvm::Expected<Function *> Program::getOrCreateFunction(const FunctionDecl *F) {
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if (Function *Func = getFunction(F)) {
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return Func;
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}
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// Try to compile the function if it wasn't compiled yet.
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if (const FunctionDecl *FD = F->getDefinition())
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return ByteCodeStmtGen<ByteCodeEmitter>(Ctx, *this).compileFunc(FD);
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// A relocation which traps if not resolved.
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return nullptr;
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}
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Record *Program::getOrCreateRecord(const RecordDecl *RD) {
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// Use the actual definition as a key.
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RD = RD->getDefinition();
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if (!RD)
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return nullptr;
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// Deduplicate records.
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auto It = Records.find(RD);
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if (It != Records.end()) {
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return It->second;
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}
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// Number of bytes required by fields and base classes.
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unsigned Size = 0;
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// Number of bytes required by virtual base.
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unsigned VirtSize = 0;
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// Helper to get a base descriptor.
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auto GetBaseDesc = [this](const RecordDecl *BD, Record *BR) -> Descriptor * {
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if (!BR)
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return nullptr;
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return allocateDescriptor(BD, BR, /*isConst=*/false,
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/*isTemporary=*/false,
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/*isMutable=*/false);
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};
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// Reserve space for base classes.
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Record::BaseList Bases;
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Record::VirtualBaseList VirtBases;
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if (auto *CD = dyn_cast<CXXRecordDecl>(RD)) {
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for (const CXXBaseSpecifier &Spec : CD->bases()) {
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if (Spec.isVirtual())
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continue;
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const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
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Record *BR = getOrCreateRecord(BD);
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if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
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Size += align(sizeof(InlineDescriptor));
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Bases.push_back({BD, Size, Desc, BR});
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Size += align(BR->getSize());
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continue;
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}
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return nullptr;
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}
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for (const CXXBaseSpecifier &Spec : CD->vbases()) {
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const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
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Record *BR = getOrCreateRecord(BD);
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if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
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VirtSize += align(sizeof(InlineDescriptor));
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VirtBases.push_back({BD, VirtSize, Desc, BR});
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VirtSize += align(BR->getSize());
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continue;
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}
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return nullptr;
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}
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}
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// Reserve space for fields.
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Record::FieldList Fields;
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for (const FieldDecl *FD : RD->fields()) {
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// Reserve space for the field's descriptor and the offset.
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Size += align(sizeof(InlineDescriptor));
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// Classify the field and add its metadata.
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QualType FT = FD->getType();
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const bool IsConst = FT.isConstQualified();
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const bool IsMutable = FD->isMutable();
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Descriptor *Desc;
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if (llvm::Optional<PrimType> T = Ctx.classify(FT)) {
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Desc = createDescriptor(FD, *T, IsConst, /*isTemporary=*/false,
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IsMutable);
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} else {
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Desc = createDescriptor(FD, FT.getTypePtr(), IsConst,
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/*isTemporary=*/false, IsMutable);
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}
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if (!Desc)
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return nullptr;
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Fields.push_back({FD, Size, Desc});
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Size += align(Desc->getAllocSize());
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}
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Record *R = new (Allocator) Record(RD, std::move(Bases), std::move(Fields),
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std::move(VirtBases), VirtSize, Size);
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Records.insert({RD, R});
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return R;
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}
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Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
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bool IsConst, bool IsTemporary,
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bool IsMutable) {
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// Classes and structures.
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if (auto *RT = Ty->getAs<RecordType>()) {
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if (auto *Record = getOrCreateRecord(RT->getDecl()))
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return allocateDescriptor(D, Record, IsConst, IsTemporary, IsMutable);
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}
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// Arrays.
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if (auto ArrayType = Ty->getAsArrayTypeUnsafe()) {
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QualType ElemTy = ArrayType->getElementType();
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// Array of well-known bounds.
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if (auto CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
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size_t NumElems = CAT->getSize().getZExtValue();
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if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
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// Arrays of primitives.
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unsigned ElemSize = primSize(*T);
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if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems) {
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return {};
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}
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return allocateDescriptor(D, *T, NumElems, IsConst, IsTemporary,
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IsMutable);
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} else {
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// Arrays of composites. In this case, the array is a list of pointers,
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// followed by the actual elements.
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Descriptor *Desc =
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createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
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if (!Desc)
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return nullptr;
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InterpSize ElemSize = Desc->getAllocSize() + sizeof(InlineDescriptor);
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if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems)
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return {};
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return allocateDescriptor(D, Desc, NumElems, IsConst, IsTemporary,
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IsMutable);
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}
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}
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// Array of unknown bounds - cannot be accessed and pointer arithmetic
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// is forbidden on pointers to such objects.
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if (isa<IncompleteArrayType>(ArrayType)) {
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if (llvm::Optional<PrimType> T = Ctx.classify(ElemTy)) {
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return allocateDescriptor(D, *T, IsTemporary,
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Descriptor::UnknownSize{});
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} else {
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Descriptor *Desc =
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createDescriptor(D, ElemTy.getTypePtr(), IsConst, IsTemporary);
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if (!Desc)
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return nullptr;
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return allocateDescriptor(D, Desc, IsTemporary,
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Descriptor::UnknownSize{});
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}
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}
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}
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// Atomic types.
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if (auto *AT = Ty->getAs<AtomicType>()) {
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const Type *InnerTy = AT->getValueType().getTypePtr();
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return createDescriptor(D, InnerTy, IsConst, IsTemporary, IsMutable);
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}
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// Complex types - represented as arrays of elements.
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if (auto *CT = Ty->getAs<ComplexType>()) {
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PrimType ElemTy = *Ctx.classify(CT->getElementType());
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return allocateDescriptor(D, ElemTy, 2, IsConst, IsTemporary, IsMutable);
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}
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return nullptr;
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}
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