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//===-- LoongArchAsmBackend.cpp - LoongArch Assembler Backend -*- C++ -*---===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the LoongArchAsmBackend class.
//
//===----------------------------------------------------------------------===//
#include "LoongArchAsmBackend.h"
#include "LoongArchFixupKinds.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/EndianStream.h"
#define DEBUG_TYPE "loongarch-asmbackend"
using namespace llvm;
std::optional<MCFixupKind>
LoongArchAsmBackend::getFixupKind(StringRef Name) const {
if (STI.getTargetTriple().isOSBinFormatELF()) {
auto Type = llvm::StringSwitch<unsigned>(Name)
#define ELF_RELOC(X, Y) .Case(#X, Y)
#include "llvm/BinaryFormat/ELFRelocs/LoongArch.def"
#undef ELF_RELOC
.Case("BFD_RELOC_NONE", ELF::R_LARCH_NONE)
.Case("BFD_RELOC_32", ELF::R_LARCH_32)
.Case("BFD_RELOC_64", ELF::R_LARCH_64)
.Default(-1u);
if (Type != -1u)
return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
}
return std::nullopt;
}
const MCFixupKindInfo &
LoongArchAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
const static MCFixupKindInfo Infos[] = {
// This table *must* be in the order that the fixup_* kinds are defined in
// LoongArchFixupKinds.h.
//
// {name, offset, bits, flags}
{"fixup_loongarch_b16", 10, 16, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_loongarch_b21", 0, 26, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_loongarch_b26", 0, 26, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_loongarch_abs_hi20", 5, 20, 0},
{"fixup_loongarch_abs_lo12", 10, 12, 0},
{"fixup_loongarch_abs64_lo20", 5, 20, 0},
{"fixup_loongarch_abs64_hi12", 10, 12, 0},
{"fixup_loongarch_tls_le_hi20", 5, 20, 0},
{"fixup_loongarch_tls_le_lo12", 10, 12, 0},
{"fixup_loongarch_tls_le64_lo20", 5, 20, 0},
{"fixup_loongarch_tls_le64_hi12", 10, 12, 0},
// TODO: Add more fixup kinds.
};
static_assert((std::size(Infos)) == LoongArch::NumTargetFixupKinds,
"Not all fixup kinds added to Infos array");
// Fixup kinds from .reloc directive are like R_LARCH_NONE. They
// do not require any extra processing.
if (Kind >= FirstLiteralRelocationKind)
return MCAsmBackend::getFixupKindInfo(FK_NONE);
if (Kind < FirstTargetFixupKind)
return MCAsmBackend::getFixupKindInfo(Kind);
assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
"Invalid kind!");
return Infos[Kind - FirstTargetFixupKind];
}
static void reportOutOfRangeError(MCContext &Ctx, SMLoc Loc, unsigned N) {
Ctx.reportError(Loc, "fixup value out of range [" + Twine(llvm::minIntN(N)) +
", " + Twine(llvm::maxIntN(N)) + "]");
}
static uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
MCContext &Ctx) {
switch (Fixup.getTargetKind()) {
default:
llvm_unreachable("Unknown fixup kind");
case FK_Data_1:
case FK_Data_2:
case FK_Data_4:
case FK_Data_8:
return Value;
case LoongArch::fixup_loongarch_b16: {
if (!isInt<18>(Value))
reportOutOfRangeError(Ctx, Fixup.getLoc(), 18);
if (Value % 4)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");
return (Value >> 2) & 0xffff;
}
case LoongArch::fixup_loongarch_b21: {
if (!isInt<23>(Value))
reportOutOfRangeError(Ctx, Fixup.getLoc(), 23);
if (Value % 4)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");
return ((Value & 0x3fffc) << 8) | ((Value >> 18) & 0x1f);
}
case LoongArch::fixup_loongarch_b26: {
if (!isInt<28>(Value))
reportOutOfRangeError(Ctx, Fixup.getLoc(), 28);
if (Value % 4)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");
return ((Value & 0x3fffc) << 8) | ((Value >> 18) & 0x3ff);
}
case LoongArch::fixup_loongarch_abs_hi20:
case LoongArch::fixup_loongarch_tls_le_hi20:
return (Value >> 12) & 0xfffff;
case LoongArch::fixup_loongarch_abs_lo12:
case LoongArch::fixup_loongarch_tls_le_lo12:
return Value & 0xfff;
case LoongArch::fixup_loongarch_abs64_lo20:
case LoongArch::fixup_loongarch_tls_le64_lo20:
return (Value >> 32) & 0xfffff;
case LoongArch::fixup_loongarch_abs64_hi12:
case LoongArch::fixup_loongarch_tls_le64_hi12:
return (Value >> 52) & 0xfff;
}
}
void LoongArchAsmBackend::applyFixup(const MCAssembler &Asm,
const MCFixup &Fixup,
const MCValue &Target,
MutableArrayRef<char> Data, uint64_t Value,
bool IsResolved,
const MCSubtargetInfo *STI) const {
if (!Value)
return; // Doesn't change encoding.
MCFixupKind Kind = Fixup.getKind();
if (Kind >= FirstLiteralRelocationKind)
return;
MCFixupKindInfo Info = getFixupKindInfo(Kind);
MCContext &Ctx = Asm.getContext();
// Apply any target-specific value adjustments.
Value = adjustFixupValue(Fixup, Value, Ctx);
// Shift the value into position.
Value <<= Info.TargetOffset;
unsigned Offset = Fixup.getOffset();
unsigned NumBytes = alignTo(Info.TargetSize + Info.TargetOffset, 8) / 8;
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);
}
}
bool LoongArchAsmBackend::shouldForceRelocation(const MCAssembler &Asm,
const MCFixup &Fixup,
const MCValue &Target) {
if (Fixup.getKind() >= FirstLiteralRelocationKind)
return true;
switch (Fixup.getTargetKind()) {
default:
return false;
case FK_Data_1:
case FK_Data_2:
case FK_Data_4:
case FK_Data_8:
return !Target.isAbsolute();
}
}
bool LoongArchAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
const MCSubtargetInfo *STI) const {
// We mostly follow binutils' convention here: align to 4-byte boundary with a
// 0-fill padding.
OS.write_zeros(Count % 4);
// The remainder is now padded with 4-byte nops.
// nop: andi r0, r0, 0
for (; Count >= 4; Count -= 4)
OS.write("\0\0\x40\x03", 4);
return true;
}
std::unique_ptr<MCObjectTargetWriter>
LoongArchAsmBackend::createObjectTargetWriter() const {
return createLoongArchELFObjectWriter(OSABI, Is64Bit);
}
MCAsmBackend *llvm::createLoongArchAsmBackend(const Target &T,
const MCSubtargetInfo &STI,
const MCRegisterInfo &MRI,
const MCTargetOptions &Options) {
const Triple &TT = STI.getTargetTriple();
uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
return new LoongArchAsmBackend(STI, OSABI, TT.isArch64Bit());
}
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