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//===-- BPFAsmBackend.cpp - BPF Assembler Backend -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/BPFMCTargetDesc.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class BPFAsmBackend : public MCAsmBackend {
public:
bool IsLittleEndian;
BPFAsmBackend(bool IsLittleEndian)
: MCAsmBackend(), IsLittleEndian(IsLittleEndian) {}
~BPFAsmBackend() 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 { return 1; }
bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
MCInst &Res) const override {}
bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
};
bool BPFAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
if ((Count % 8) != 0)
return false;
for (uint64_t i = 0; i < Count; i += 8)
OW->write64(0x15000000);
return true;
}
void BPFAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
unsigned DataSize, uint64_t Value,
bool IsPCRel) const {
if (Fixup.getKind() == FK_SecRel_4 || Fixup.getKind() == FK_SecRel_8) {
assert(Value == 0);
} else if (Fixup.getKind() == FK_Data_4 || Fixup.getKind() == FK_Data_8) {
unsigned Size = Fixup.getKind() == FK_Data_4 ? 4 : 8;
for (unsigned i = 0; i != Size; ++i) {
unsigned Idx = IsLittleEndian ? i : Size - i;
Data[Fixup.getOffset() + Idx] = uint8_t(Value >> (i * 8));
}
} else {
assert(Fixup.getKind() == FK_PCRel_2);
Value = (uint16_t)((Value - 8) / 8);
if (IsLittleEndian) {
Data[Fixup.getOffset() + 2] = Value & 0xFF;
Data[Fixup.getOffset() + 3] = Value >> 8;
} else {
Data[Fixup.getOffset() + 2] = Value >> 8;
Data[Fixup.getOffset() + 3] = Value & 0xFF;
}
}
}
MCObjectWriter *BPFAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
return createBPFELFObjectWriter(OS, 0, IsLittleEndian);
}
}
MCAsmBackend *llvm::createBPFAsmBackend(const Target &T,
const MCRegisterInfo &MRI,
const Triple &TT, StringRef CPU,
const MCTargetOptions&) {
return new BPFAsmBackend(/*IsLittleEndian=*/true);
}
MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
const MCRegisterInfo &MRI,
const Triple &TT, StringRef CPU,
const MCTargetOptions&) {
return new BPFAsmBackend(/*IsLittleEndian=*/false);
}
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