c239acb5b6
We will increase the use of raw relocation types and eliminate fixup kinds that correspond to relocation types. The getFixupKindInfo functions will return an rvalue instead. Let's update the return type from a const reference to a value type.
118 lines
4.1 KiB
C++
118 lines
4.1 KiB
C++
//===-- WebAssemblyAsmBackend.cpp - WebAssembly Assembler Backend ---------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
///
|
|
/// \file
|
|
/// This file implements the WebAssemblyAsmBackend class.
|
|
///
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "MCTargetDesc/WebAssemblyFixupKinds.h"
|
|
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
|
|
#include "llvm/MC/MCAsmBackend.h"
|
|
#include "llvm/MC/MCAssembler.h"
|
|
#include "llvm/MC/MCExpr.h"
|
|
#include "llvm/MC/MCFixupKindInfo.h"
|
|
#include "llvm/MC/MCObjectWriter.h"
|
|
#include "llvm/MC/MCSubtargetInfo.h"
|
|
#include "llvm/MC/MCSymbol.h"
|
|
#include "llvm/MC/MCWasmObjectWriter.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
class WebAssemblyAsmBackend final : public MCAsmBackend {
|
|
bool Is64Bit;
|
|
bool IsEmscripten;
|
|
|
|
public:
|
|
explicit WebAssemblyAsmBackend(bool Is64Bit, bool IsEmscripten)
|
|
: MCAsmBackend(llvm::endianness::little), Is64Bit(Is64Bit),
|
|
IsEmscripten(IsEmscripten) {}
|
|
|
|
MCFixupKindInfo getFixupKindInfo(MCFixupKind Kind) const override;
|
|
|
|
void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
|
|
const MCValue &Target, MutableArrayRef<char> Data,
|
|
uint64_t Value, bool IsPCRel,
|
|
const MCSubtargetInfo *STI) const override;
|
|
|
|
std::unique_ptr<MCObjectTargetWriter>
|
|
createObjectTargetWriter() const override;
|
|
|
|
bool writeNopData(raw_ostream &OS, uint64_t Count,
|
|
const MCSubtargetInfo *STI) const override;
|
|
};
|
|
|
|
MCFixupKindInfo
|
|
WebAssemblyAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
|
|
const static MCFixupKindInfo Infos[WebAssembly::NumTargetFixupKinds] = {
|
|
// This table *must* be in the order that the fixup_* kinds are defined in
|
|
// WebAssemblyFixupKinds.h.
|
|
//
|
|
// Name Offset (bits) Size (bits) Flags
|
|
{"fixup_sleb128_i32", 0, 5 * 8, 0},
|
|
{"fixup_sleb128_i64", 0, 10 * 8, 0},
|
|
{"fixup_uleb128_i32", 0, 5 * 8, 0},
|
|
{"fixup_uleb128_i64", 0, 10 * 8, 0},
|
|
};
|
|
|
|
if (Kind < FirstTargetFixupKind)
|
|
return MCAsmBackend::getFixupKindInfo(Kind);
|
|
|
|
assert(unsigned(Kind - FirstTargetFixupKind) <
|
|
WebAssembly::NumTargetFixupKinds &&
|
|
"Invalid kind!");
|
|
return Infos[Kind - FirstTargetFixupKind];
|
|
}
|
|
|
|
bool WebAssemblyAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
|
|
const MCSubtargetInfo *STI) const {
|
|
for (uint64_t I = 0; I < Count; ++I)
|
|
OS << char(WebAssembly::Nop);
|
|
|
|
return true;
|
|
}
|
|
|
|
void WebAssemblyAsmBackend::applyFixup(const MCAssembler &Asm,
|
|
const MCFixup &Fixup,
|
|
const MCValue &Target,
|
|
MutableArrayRef<char> Data,
|
|
uint64_t Value, bool IsPCRel,
|
|
const MCSubtargetInfo *STI) const {
|
|
MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());
|
|
assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
|
|
|
|
unsigned NumBytes = alignTo(Info.TargetSize, 8) / 8;
|
|
if (Value == 0)
|
|
return; // Doesn't change encoding.
|
|
|
|
// Shift the value into position.
|
|
Value <<= Info.TargetOffset;
|
|
|
|
unsigned Offset = Fixup.getOffset();
|
|
assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
|
|
|
|
// For each byte of the fragment that the fixup touches, mask in the
|
|
// bits from the fixup value.
|
|
for (unsigned I = 0; I != NumBytes; ++I)
|
|
Data[Offset + I] |= uint8_t((Value >> (I * 8)) & 0xff);
|
|
}
|
|
|
|
std::unique_ptr<MCObjectTargetWriter>
|
|
WebAssemblyAsmBackend::createObjectTargetWriter() const {
|
|
return createWebAssemblyWasmObjectWriter(Is64Bit, IsEmscripten);
|
|
}
|
|
|
|
} // end anonymous namespace
|
|
|
|
MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Triple &TT) {
|
|
return new WebAssemblyAsmBackend(TT.isArch64Bit(), TT.isOSEmscripten());
|
|
}
|