149 lines
5.2 KiB
C++
149 lines
5.2 KiB
C++
//===-- WebAssemblyWasmObjectWriter.cpp - WebAssembly Wasm Writer ---------===//
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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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/// \file
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/// This file handles Wasm-specific object emission, converting LLVM's
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/// internal fixups into the appropriate relocations.
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///
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/WebAssemblyFixupKinds.h"
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#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
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#include "llvm/BinaryFormat/Wasm.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCFixupKindInfo.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSectionWasm.h"
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#include "llvm/MC/MCSymbolWasm.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/MC/MCWasmObjectWriter.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/ErrorHandling.h"
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using namespace llvm;
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namespace {
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class WebAssemblyWasmObjectWriter final : public MCWasmObjectTargetWriter {
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public:
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explicit WebAssemblyWasmObjectWriter(bool Is64Bit, bool IsEmscripten);
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private:
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unsigned getRelocType(const MCValue &Target,
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const MCFixup &Fixup) const override;
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};
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} // end anonymous namespace
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WebAssemblyWasmObjectWriter::WebAssemblyWasmObjectWriter(bool Is64Bit,
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bool IsEmscripten)
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: MCWasmObjectTargetWriter(Is64Bit, IsEmscripten) {}
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static const MCSection *getFixupSection(const MCExpr *Expr) {
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if (auto SyExp = dyn_cast<MCSymbolRefExpr>(Expr)) {
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if (SyExp->getSymbol().isInSection())
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return &SyExp->getSymbol().getSection();
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return nullptr;
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}
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if (auto BinOp = dyn_cast<MCBinaryExpr>(Expr)) {
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auto SectionLHS = getFixupSection(BinOp->getLHS());
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auto SectionRHS = getFixupSection(BinOp->getRHS());
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return SectionLHS == SectionRHS ? nullptr : SectionLHS;
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}
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if (auto UnOp = dyn_cast<MCUnaryExpr>(Expr))
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return getFixupSection(UnOp->getSubExpr());
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return nullptr;
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}
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unsigned WebAssemblyWasmObjectWriter::getRelocType(const MCValue &Target,
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const MCFixup &Fixup) const {
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const MCSymbolRefExpr *RefA = Target.getSymA();
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assert(RefA);
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auto& SymA = cast<MCSymbolWasm>(RefA->getSymbol());
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MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
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switch (Modifier) {
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case MCSymbolRefExpr::VK_GOT:
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return wasm::R_WASM_GLOBAL_INDEX_LEB;
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case MCSymbolRefExpr::VK_WASM_TBREL:
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assert(SymA.isFunction());
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return wasm::R_WASM_TABLE_INDEX_REL_SLEB;
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case MCSymbolRefExpr::VK_WASM_TLSREL:
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return wasm::R_WASM_MEMORY_ADDR_TLS_SLEB;
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case MCSymbolRefExpr::VK_WASM_MBREL:
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assert(SymA.isData());
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return is64Bit() ? wasm::R_WASM_MEMORY_ADDR_REL_SLEB64
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: wasm::R_WASM_MEMORY_ADDR_REL_SLEB;
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case MCSymbolRefExpr::VK_WASM_TYPEINDEX:
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return wasm::R_WASM_TYPE_INDEX_LEB;
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default:
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break;
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}
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switch (unsigned(Fixup.getKind())) {
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case WebAssembly::fixup_sleb128_i32:
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if (SymA.isFunction())
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return wasm::R_WASM_TABLE_INDEX_SLEB;
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return wasm::R_WASM_MEMORY_ADDR_SLEB;
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case WebAssembly::fixup_sleb128_i64:
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if (SymA.isFunction())
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return wasm::R_WASM_TABLE_INDEX_SLEB64;
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return wasm::R_WASM_MEMORY_ADDR_SLEB64;
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case WebAssembly::fixup_uleb128_i32:
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if (SymA.isGlobal())
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return wasm::R_WASM_GLOBAL_INDEX_LEB;
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if (SymA.isFunction())
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return wasm::R_WASM_FUNCTION_INDEX_LEB;
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if (SymA.isEvent())
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return wasm::R_WASM_EVENT_INDEX_LEB;
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if (SymA.isTable())
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return wasm::R_WASM_TABLE_NUMBER_LEB;
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return wasm::R_WASM_MEMORY_ADDR_LEB;
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case WebAssembly::fixup_uleb128_i64:
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assert(SymA.isData());
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return wasm::R_WASM_MEMORY_ADDR_LEB64;
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case FK_Data_4:
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if (SymA.isFunction())
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return wasm::R_WASM_TABLE_INDEX_I32;
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if (SymA.isGlobal())
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return wasm::R_WASM_GLOBAL_INDEX_I32;
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if (auto Section = static_cast<const MCSectionWasm *>(
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getFixupSection(Fixup.getValue()))) {
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if (Section->getKind().isText())
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return wasm::R_WASM_FUNCTION_OFFSET_I32;
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else if (!Section->isWasmData())
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return wasm::R_WASM_SECTION_OFFSET_I32;
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}
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return wasm::R_WASM_MEMORY_ADDR_I32;
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case FK_Data_8:
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if (SymA.isFunction())
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return wasm::R_WASM_TABLE_INDEX_I64;
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if (SymA.isGlobal())
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llvm_unreachable("unimplemented R_WASM_GLOBAL_INDEX_I64");
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if (auto Section = static_cast<const MCSectionWasm *>(
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getFixupSection(Fixup.getValue()))) {
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if (Section->getKind().isText())
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return wasm::R_WASM_FUNCTION_OFFSET_I64;
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else if (!Section->isWasmData())
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llvm_unreachable("unimplemented R_WASM_SECTION_OFFSET_I64");
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}
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assert(SymA.isData());
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return wasm::R_WASM_MEMORY_ADDR_I64;
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default:
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llvm_unreachable("unimplemented fixup kind");
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}
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}
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std::unique_ptr<MCObjectTargetWriter>
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llvm::createWebAssemblyWasmObjectWriter(bool Is64Bit, bool IsEmscripten) {
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return std::make_unique<WebAssemblyWasmObjectWriter>(Is64Bit, IsEmscripten);
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}
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