forked from OSchip/llvm-project
108 lines
3.5 KiB
C++
108 lines
3.5 KiB
C++
//===-- 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) {
|
|
return new BPFAsmBackend(/*IsLittleEndian=*/true);
|
|
}
|
|
|
|
MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
|
|
const MCRegisterInfo &MRI,
|
|
const Triple &TT, StringRef CPU) {
|
|
return new BPFAsmBackend(/*IsLittleEndian=*/false);
|
|
}
|