57f661bd7d
On targets like Arm some relaxations may only be performed when certain architectural features are available. As functions can be compiled with differing levels of architectural support we must make a judgement on whether we can relax based on the MCSubtargetInfo for the function. This change passes through the MCSubtargetInfo for the function to fixupNeedsRelaxation so that the decision on whether to relax can be made per function. In this patch, only the ARM backend makes use of this information. We must also pass the MCSubtargetInfo to applyFixup because some fixups skip error checking on the assumption that relaxation has occurred, to prevent code-generation errors applyFixup must see the same MCSubtargetInfo as fixupNeedsRelaxation. Differential Revision: https://reviews.llvm.org/D44928 llvm-svn: 334078
114 lines
4.0 KiB
C++
114 lines
4.0 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/ADT/StringRef.h"
|
|
#include "llvm/MC/MCAsmBackend.h"
|
|
#include "llvm/MC/MCFixup.h"
|
|
#include "llvm/MC/MCObjectWriter.h"
|
|
#include "llvm/Support/EndianStream.h"
|
|
#include <cassert>
|
|
#include <cstdint>
|
|
|
|
using namespace llvm;
|
|
|
|
namespace {
|
|
|
|
class BPFAsmBackend : public MCAsmBackend {
|
|
public:
|
|
BPFAsmBackend(support::endianness Endian) : MCAsmBackend(Endian) {}
|
|
~BPFAsmBackend() override = default;
|
|
|
|
void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
|
|
const MCValue &Target, MutableArrayRef<char> Data,
|
|
uint64_t Value, bool IsResolved,
|
|
const MCSubtargetInfo *STI) const override;
|
|
|
|
std::unique_ptr<MCObjectTargetWriter>
|
|
createObjectTargetWriter() 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 MCSubtargetInfo &STI) const override {
|
|
return false;
|
|
}
|
|
|
|
void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
|
|
MCInst &Res) const override {}
|
|
|
|
bool writeNopData(raw_ostream &OS, uint64_t Count) const override;
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
bool BPFAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
|
|
if ((Count % 8) != 0)
|
|
return false;
|
|
|
|
for (uint64_t i = 0; i < Count; i += 8)
|
|
support::endian::write<uint64_t>(OS, 0x15000000, Endian);
|
|
|
|
return true;
|
|
}
|
|
|
|
void BPFAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
|
|
const MCValue &Target,
|
|
MutableArrayRef<char> Data, uint64_t Value,
|
|
bool IsResolved,
|
|
const MCSubtargetInfo *STI) const {
|
|
if (Fixup.getKind() == FK_SecRel_4 || Fixup.getKind() == FK_SecRel_8) {
|
|
assert(Value == 0);
|
|
} else if (Fixup.getKind() == FK_Data_4) {
|
|
support::endian::write<uint32_t>(&Data[Fixup.getOffset()], Value, Endian);
|
|
} else if (Fixup.getKind() == FK_Data_8) {
|
|
support::endian::write<uint64_t>(&Data[Fixup.getOffset()], Value, Endian);
|
|
} else if (Fixup.getKind() == FK_PCRel_4) {
|
|
Value = (uint32_t)((Value - 8) / 8);
|
|
if (Endian == support::little) {
|
|
Data[Fixup.getOffset() + 1] = 0x10;
|
|
support::endian::write32le(&Data[Fixup.getOffset() + 4], Value);
|
|
} else {
|
|
Data[Fixup.getOffset() + 1] = 0x1;
|
|
support::endian::write32be(&Data[Fixup.getOffset() + 4], Value);
|
|
}
|
|
} else {
|
|
assert(Fixup.getKind() == FK_PCRel_2);
|
|
Value = (uint16_t)((Value - 8) / 8);
|
|
support::endian::write<uint16_t>(&Data[Fixup.getOffset() + 2], Value,
|
|
Endian);
|
|
}
|
|
}
|
|
|
|
std::unique_ptr<MCObjectTargetWriter>
|
|
BPFAsmBackend::createObjectTargetWriter() const {
|
|
return createBPFELFObjectWriter(0);
|
|
}
|
|
|
|
MCAsmBackend *llvm::createBPFAsmBackend(const Target &T,
|
|
const MCSubtargetInfo &STI,
|
|
const MCRegisterInfo &MRI,
|
|
const MCTargetOptions &) {
|
|
return new BPFAsmBackend(support::little);
|
|
}
|
|
|
|
MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
|
|
const MCSubtargetInfo &STI,
|
|
const MCRegisterInfo &MRI,
|
|
const MCTargetOptions &) {
|
|
return new BPFAsmBackend(support::big);
|
|
}
|