forked from OSchip/llvm-project
103 lines
3.4 KiB
C++
103 lines
3.4 KiB
C++
//===-- WebAssemblyAsmBackend.cpp - WebAssembly Assembler Backend ---------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
///
|
|
/// \file
|
|
/// \brief This file implements the WebAssemblyAsmBackend class.
|
|
///
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
|
|
#include "llvm/MC/MCAsmBackend.h"
|
|
#include "llvm/MC/MCAssembler.h"
|
|
#include "llvm/MC/MCDirectives.h"
|
|
#include "llvm/MC/MCELFObjectWriter.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/Support/ErrorHandling.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
class WebAssemblyAsmBackend final : public MCAsmBackend {
|
|
bool Is64Bit;
|
|
|
|
public:
|
|
explicit WebAssemblyAsmBackend(bool Is64Bit)
|
|
: MCAsmBackend(), Is64Bit(Is64Bit) {}
|
|
~WebAssemblyAsmBackend() override {}
|
|
|
|
void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
|
|
uint64_t Value, bool IsPCRel) const override;
|
|
|
|
MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override;
|
|
|
|
// No instruction requires relaxation
|
|
bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
|
|
const MCRelaxableFragment *DF,
|
|
const MCAsmLayout &Layout) const override {
|
|
return false;
|
|
}
|
|
|
|
unsigned getNumFixupKinds() const override {
|
|
// We currently just use the generic fixups in MCFixup.h and don't have any
|
|
// target-specific fixups.
|
|
return 0;
|
|
}
|
|
|
|
bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
|
|
|
|
void relaxInstruction(const MCInst &Inst, MCInst &Res) const override {}
|
|
|
|
bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
|
|
};
|
|
|
|
bool WebAssemblyAsmBackend::writeNopData(uint64_t Count,
|
|
MCObjectWriter *OW) const {
|
|
if (Count == 0)
|
|
return true;
|
|
|
|
// FIXME: Do something.
|
|
return false;
|
|
}
|
|
|
|
void WebAssemblyAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
|
|
unsigned DataSize, uint64_t Value,
|
|
bool IsPCRel) const {
|
|
const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
|
|
assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
|
|
|
|
unsigned NumBytes = (Info.TargetSize + 7) / 8;
|
|
if (Value == 0)
|
|
return; // Doesn't change encoding.
|
|
|
|
// Shift the value into position.
|
|
Value <<= Info.TargetOffset;
|
|
|
|
unsigned Offset = Fixup.getOffset();
|
|
assert(Offset + NumBytes <= DataSize && "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);
|
|
}
|
|
|
|
MCObjectWriter *
|
|
WebAssemblyAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
|
|
return createWebAssemblyELFObjectWriter(OS, Is64Bit, 0);
|
|
}
|
|
} // end anonymous namespace
|
|
|
|
MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Triple &TT) {
|
|
return new WebAssemblyAsmBackend(TT.isArch64Bit());
|
|
}
|