fffbfe7c0c
WebAssemblyUtils depends on CodeGen which depends on all middle end optimization libraries. This component is used by WebAssembly's AsmParser, Disassembler, and MCTargetDesc libraries. Because of this, any MC layer tool built with WebAssembly support includes a larger portion of LLVM than it should. To fix this I've created an MC only version of WebAssemblyTypeUtilities.cpp in MCTargetDesc to be used by the MC components. This shrinks llvm-objdump and llvm-mc on my local release+asserts build by 5-6 MB. Reviewed By: MaskRay, aheejin Differential Revision: https://reviews.llvm.org/D144354
302 lines
10 KiB
C++
302 lines
10 KiB
C++
//==- WebAssemblyDisassembler.cpp - Disassembler for WebAssembly -*- 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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/// \file
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/// This file is part of the WebAssembly Disassembler.
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///
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/// It contains code to translate the data produced by the decoder into
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/// MCInsts.
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///
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/WebAssemblyMCTypeUtilities.h"
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#include "TargetInfo/WebAssemblyTargetInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCDecoderOps.h"
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#include "llvm/MC/MCDisassembler/MCDisassembler.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCInstrInfo.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCSymbolWasm.h"
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#include "llvm/MC/TargetRegistry.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/LEB128.h"
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using namespace llvm;
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#define DEBUG_TYPE "wasm-disassembler"
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using DecodeStatus = MCDisassembler::DecodeStatus;
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#include "WebAssemblyGenDisassemblerTables.inc"
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namespace {
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static constexpr int WebAssemblyInstructionTableSize = 256;
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class WebAssemblyDisassembler final : public MCDisassembler {
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std::unique_ptr<const MCInstrInfo> MCII;
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DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
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ArrayRef<uint8_t> Bytes, uint64_t Address,
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raw_ostream &CStream) const override;
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std::optional<DecodeStatus>
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onSymbolStart(SymbolInfoTy &Symbol, uint64_t &Size, ArrayRef<uint8_t> Bytes,
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uint64_t Address, raw_ostream &CStream) const override;
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public:
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WebAssemblyDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
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std::unique_ptr<const MCInstrInfo> MCII)
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: MCDisassembler(STI, Ctx), MCII(std::move(MCII)) {}
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};
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} // end anonymous namespace
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static MCDisassembler *createWebAssemblyDisassembler(const Target &T,
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const MCSubtargetInfo &STI,
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MCContext &Ctx) {
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std::unique_ptr<const MCInstrInfo> MCII(T.createMCInstrInfo());
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return new WebAssemblyDisassembler(STI, Ctx, std::move(MCII));
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}
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extern "C" LLVM_EXTERNAL_VISIBILITY void
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LLVMInitializeWebAssemblyDisassembler() {
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// Register the disassembler for each target.
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TargetRegistry::RegisterMCDisassembler(getTheWebAssemblyTarget32(),
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createWebAssemblyDisassembler);
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TargetRegistry::RegisterMCDisassembler(getTheWebAssemblyTarget64(),
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createWebAssemblyDisassembler);
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}
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static int nextByte(ArrayRef<uint8_t> Bytes, uint64_t &Size) {
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if (Size >= Bytes.size())
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return -1;
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auto V = Bytes[Size];
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Size++;
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return V;
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}
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static bool nextLEB(int64_t &Val, ArrayRef<uint8_t> Bytes, uint64_t &Size,
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bool Signed) {
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unsigned N = 0;
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const char *Error = nullptr;
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Val = Signed ? decodeSLEB128(Bytes.data() + Size, &N,
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Bytes.data() + Bytes.size(), &Error)
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: static_cast<int64_t>(decodeULEB128(Bytes.data() + Size, &N,
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Bytes.data() + Bytes.size(),
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&Error));
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if (Error)
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return false;
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Size += N;
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return true;
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}
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static bool parseLEBImmediate(MCInst &MI, uint64_t &Size,
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ArrayRef<uint8_t> Bytes, bool Signed) {
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int64_t Val;
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if (!nextLEB(Val, Bytes, Size, Signed))
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return false;
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MI.addOperand(MCOperand::createImm(Val));
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return true;
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}
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template <typename T>
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bool parseImmediate(MCInst &MI, uint64_t &Size, ArrayRef<uint8_t> Bytes) {
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if (Size + sizeof(T) > Bytes.size())
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return false;
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T Val = support::endian::read<T, support::endianness::little, 1>(
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Bytes.data() + Size);
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Size += sizeof(T);
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if (std::is_floating_point<T>::value) {
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MI.addOperand(
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MCOperand::createDFPImm(bit_cast<uint64_t>(static_cast<double>(Val))));
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} else {
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MI.addOperand(MCOperand::createImm(static_cast<int64_t>(Val)));
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}
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return true;
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}
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std::optional<MCDisassembler::DecodeStatus>
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WebAssemblyDisassembler::onSymbolStart(SymbolInfoTy &Symbol, uint64_t &Size,
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ArrayRef<uint8_t> Bytes,
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uint64_t Address,
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raw_ostream &CStream) const {
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Size = 0;
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if (Address == 0) {
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// Start of a code section: we're parsing only the function count.
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int64_t FunctionCount;
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if (!nextLEB(FunctionCount, Bytes, Size, false))
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return std::nullopt;
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outs() << " # " << FunctionCount << " functions in section.";
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} else {
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// Parse the start of a single function.
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int64_t BodySize, LocalEntryCount;
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if (!nextLEB(BodySize, Bytes, Size, false) ||
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!nextLEB(LocalEntryCount, Bytes, Size, false))
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return std::nullopt;
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if (LocalEntryCount) {
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outs() << " .local ";
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for (int64_t I = 0; I < LocalEntryCount; I++) {
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int64_t Count, Type;
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if (!nextLEB(Count, Bytes, Size, false) ||
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!nextLEB(Type, Bytes, Size, false))
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return std::nullopt;
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for (int64_t J = 0; J < Count; J++) {
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if (I || J)
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outs() << ", ";
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outs() << WebAssembly::anyTypeToString(Type);
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}
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}
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}
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}
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outs() << "\n";
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return MCDisassembler::Success;
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}
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MCDisassembler::DecodeStatus WebAssemblyDisassembler::getInstruction(
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MCInst &MI, uint64_t &Size, ArrayRef<uint8_t> Bytes, uint64_t /*Address*/,
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raw_ostream &CS) const {
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CommentStream = &CS;
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Size = 0;
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int Opc = nextByte(Bytes, Size);
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if (Opc < 0)
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return MCDisassembler::Fail;
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const auto *WasmInst = &InstructionTable0[Opc];
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// If this is a prefix byte, indirect to another table.
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if (WasmInst->ET == ET_Prefix) {
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WasmInst = nullptr;
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// Linear search, so far only 2 entries.
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for (auto PT = PrefixTable; PT->Table; PT++) {
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if (PT->Prefix == Opc) {
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WasmInst = PT->Table;
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break;
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}
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}
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if (!WasmInst)
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return MCDisassembler::Fail;
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int64_t PrefixedOpc;
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if (!nextLEB(PrefixedOpc, Bytes, Size, false))
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return MCDisassembler::Fail;
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if (PrefixedOpc < 0 || PrefixedOpc >= WebAssemblyInstructionTableSize)
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return MCDisassembler::Fail;
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WasmInst += PrefixedOpc;
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}
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if (WasmInst->ET == ET_Unused)
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return MCDisassembler::Fail;
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// At this point we must have a valid instruction to decode.
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assert(WasmInst->ET == ET_Instruction);
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MI.setOpcode(WasmInst->Opcode);
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// Parse any operands.
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for (uint8_t OPI = 0; OPI < WasmInst->NumOperands; OPI++) {
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auto OT = OperandTable[WasmInst->OperandStart + OPI];
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switch (OT) {
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// ULEB operands:
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case WebAssembly::OPERAND_BASIC_BLOCK:
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case WebAssembly::OPERAND_LOCAL:
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case WebAssembly::OPERAND_GLOBAL:
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case WebAssembly::OPERAND_FUNCTION32:
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case WebAssembly::OPERAND_TABLE:
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case WebAssembly::OPERAND_OFFSET32:
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case WebAssembly::OPERAND_OFFSET64:
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case WebAssembly::OPERAND_P2ALIGN:
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case WebAssembly::OPERAND_TYPEINDEX:
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case WebAssembly::OPERAND_TAG:
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case MCOI::OPERAND_IMMEDIATE: {
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if (!parseLEBImmediate(MI, Size, Bytes, false))
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return MCDisassembler::Fail;
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break;
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}
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// SLEB operands:
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case WebAssembly::OPERAND_I32IMM:
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case WebAssembly::OPERAND_I64IMM: {
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if (!parseLEBImmediate(MI, Size, Bytes, true))
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return MCDisassembler::Fail;
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break;
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}
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// block_type operands:
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case WebAssembly::OPERAND_SIGNATURE: {
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int64_t Val;
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uint64_t PrevSize = Size;
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if (!nextLEB(Val, Bytes, Size, true))
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return MCDisassembler::Fail;
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if (Val < 0) {
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// Negative values are single septet value types or empty types
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if (Size != PrevSize + 1) {
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MI.addOperand(
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MCOperand::createImm(int64_t(WebAssembly::BlockType::Invalid)));
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} else {
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MI.addOperand(MCOperand::createImm(Val & 0x7f));
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}
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} else {
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// We don't have access to the signature, so create a symbol without one
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MCSymbol *Sym = getContext().createTempSymbol("typeindex", true);
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auto *WasmSym = cast<MCSymbolWasm>(Sym);
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WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
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const MCExpr *Expr = MCSymbolRefExpr::create(
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WasmSym, MCSymbolRefExpr::VK_WASM_TYPEINDEX, getContext());
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MI.addOperand(MCOperand::createExpr(Expr));
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}
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break;
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}
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// FP operands.
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case WebAssembly::OPERAND_F32IMM: {
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if (!parseImmediate<float>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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case WebAssembly::OPERAND_F64IMM: {
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if (!parseImmediate<double>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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// Vector lane operands (not LEB encoded).
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case WebAssembly::OPERAND_VEC_I8IMM: {
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if (!parseImmediate<uint8_t>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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case WebAssembly::OPERAND_VEC_I16IMM: {
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if (!parseImmediate<uint16_t>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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case WebAssembly::OPERAND_VEC_I32IMM: {
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if (!parseImmediate<uint32_t>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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case WebAssembly::OPERAND_VEC_I64IMM: {
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if (!parseImmediate<uint64_t>(MI, Size, Bytes))
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return MCDisassembler::Fail;
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break;
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}
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case WebAssembly::OPERAND_BRLIST: {
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int64_t TargetTableLen;
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if (!nextLEB(TargetTableLen, Bytes, Size, false))
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return MCDisassembler::Fail;
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for (int64_t I = 0; I < TargetTableLen; I++) {
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if (!parseLEBImmediate(MI, Size, Bytes, false))
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return MCDisassembler::Fail;
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}
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// Default case.
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if (!parseLEBImmediate(MI, Size, Bytes, false))
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return MCDisassembler::Fail;
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break;
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}
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case MCOI::OPERAND_REGISTER:
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// The tablegen header currently does not have any register operands since
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// we use only the stack (_S) instructions.
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// If you hit this that probably means a bad instruction definition in
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// tablegen.
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llvm_unreachable("Register operand in WebAssemblyDisassembler");
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default:
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llvm_unreachable("Unknown operand type in WebAssemblyDisassembler");
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}
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}
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return MCDisassembler::Success;
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}
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