d9e0bbd17b
Context: https://github.com/WebAssembly/memory64/blob/master/proposals/memory64/Overview.md This is just a first step, adding the new instruction variants while keeping the existing 32-bit functionality working. Some of the basic load/store tests have new wasm64 versions that show that the basics of the target are working. Further features need implementation, but these will be added in followups to keep things reviewable. Differential Revision: https://reviews.llvm.org/D80769
134 lines
4.5 KiB
C++
134 lines
4.5 KiB
C++
//===-- WebAssemblyAsmBackend.cpp - WebAssembly Assembler Backend ---------===//
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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 implements the WebAssemblyAsmBackend class.
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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/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCDirectives.h"
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#include "llvm/MC/MCExpr.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/MCSubtargetInfo.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCWasmObjectWriter.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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class WebAssemblyAsmBackend final : public MCAsmBackend {
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bool Is64Bit;
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bool IsEmscripten;
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public:
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explicit WebAssemblyAsmBackend(bool Is64Bit, bool IsEmscripten)
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: MCAsmBackend(support::little), Is64Bit(Is64Bit),
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IsEmscripten(IsEmscripten) {}
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unsigned getNumFixupKinds() const override {
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return WebAssembly::NumTargetFixupKinds;
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}
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const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
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void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target, MutableArrayRef<char> Data,
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uint64_t Value, bool IsPCRel,
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const MCSubtargetInfo *STI) const override;
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std::unique_ptr<MCObjectTargetWriter>
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createObjectTargetWriter() const override;
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// No instruction requires relaxation
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bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
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const MCRelaxableFragment *DF,
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const MCAsmLayout &Layout) const override {
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return false;
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}
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bool mayNeedRelaxation(const MCInst &Inst,
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const MCSubtargetInfo &STI) const override {
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return false;
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}
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bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
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};
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const MCFixupKindInfo &
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WebAssemblyAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
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const static MCFixupKindInfo Infos[WebAssembly::NumTargetFixupKinds] = {
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// This table *must* be in the order that the fixup_* kinds are defined in
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// WebAssemblyFixupKinds.h.
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//
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// Name Offset (bits) Size (bits) Flags
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{"fixup_sleb128_i32", 0, 5 * 8, 0},
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{"fixup_sleb128_i64", 0, 10 * 8, 0},
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{"fixup_uleb128_i32", 0, 5 * 8, 0},
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{"fixup_uleb128_i64", 0, 10 * 8, 0},
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};
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if (Kind < FirstTargetFixupKind)
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return MCAsmBackend::getFixupKindInfo(Kind);
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assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
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"Invalid kind!");
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return Infos[Kind - FirstTargetFixupKind];
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}
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bool WebAssemblyAsmBackend::writeNopData(raw_ostream &OS,
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uint64_t Count) const {
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for (uint64_t I = 0; I < Count; ++I)
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OS << char(WebAssembly::Nop);
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return true;
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}
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void WebAssemblyAsmBackend::applyFixup(const MCAssembler &Asm,
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const MCFixup &Fixup,
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const MCValue &Target,
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MutableArrayRef<char> Data,
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uint64_t Value, bool IsPCRel,
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const MCSubtargetInfo *STI) const {
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const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
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assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
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unsigned NumBytes = alignTo(Info.TargetSize, 8) / 8;
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if (Value == 0)
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return; // Doesn't change encoding.
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// Shift the value into position.
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Value <<= Info.TargetOffset;
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unsigned Offset = Fixup.getOffset();
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assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
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// For each byte of the fragment that the fixup touches, mask in the
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// bits from the fixup value.
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for (unsigned I = 0; I != NumBytes; ++I)
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Data[Offset + I] |= uint8_t((Value >> (I * 8)) & 0xff);
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}
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std::unique_ptr<MCObjectTargetWriter>
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WebAssemblyAsmBackend::createObjectTargetWriter() const {
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return createWebAssemblyWasmObjectWriter(Is64Bit, IsEmscripten);
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}
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} // end anonymous namespace
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MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Triple &TT) {
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return new WebAssemblyAsmBackend(TT.isArch64Bit(), TT.isOSEmscripten());
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}
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