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//===-- XtensaMCAsmBackend.cpp - Xtensa assembler backend -----------------===//
//
// The LLVM Compiler Infrastructure
//
// 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
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/XtensaFixupKinds.h"
#include "MCTargetDesc/XtensaMCTargetDesc.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace llvm {
class MCObjectTargetWriter;
class XtensaMCAsmBackend : public MCAsmBackend {
uint8_t OSABI;
bool IsLittleEndian;
public:
XtensaMCAsmBackend(uint8_t osABI, bool isLE)
: MCAsmBackend(llvm::endianness::little), OSABI(osABI),
IsLittleEndian(isLE) {}
unsigned getNumFixupKinds() const override {
return Xtensa::NumTargetFixupKinds;
}
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
const MCValue &Target, MutableArrayRef<char> Data,
uint64_t Value, bool IsResolved,
const MCSubtargetInfo *STI) const override;
bool mayNeedRelaxation(const MCInst &Inst,
const MCSubtargetInfo &STI) const override;
void relaxInstruction(MCInst &Inst,
const MCSubtargetInfo &STI) const override;
bool writeNopData(raw_ostream &OS, uint64_t Count,
const MCSubtargetInfo *STI) const override;
std::unique_ptr<MCObjectTargetWriter> createObjectTargetWriter() const override {
return createXtensaObjectWriter(OSABI, IsLittleEndian);
}
};
} // namespace llvm
const MCFixupKindInfo &
XtensaMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
const static MCFixupKindInfo Infos[Xtensa::NumTargetFixupKinds] = {
// name offset bits flags
{"fixup_xtensa_branch_6", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_xtensa_branch_8", 16, 8, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_xtensa_branch_12", 12, 12, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_xtensa_jump_18", 6, 18, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_xtensa_call_18", 6, 18,
MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits},
{"fixup_xtensa_l32r_16", 8, 16,
MCFixupKindInfo::FKF_IsPCRel |
MCFixupKindInfo::FKF_IsAlignedDownTo32Bits}};
if (Kind < FirstTargetFixupKind)
return MCAsmBackend::getFixupKindInfo(Kind);
assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
"Invalid kind!");
return Infos[Kind - FirstTargetFixupKind];
}
static uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
MCContext &Ctx) {
unsigned Kind = Fixup.getKind();
switch (Kind) {
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 Xtensa::fixup_xtensa_branch_6: {
Value -= 4;
if (!isInt<6>(Value))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
unsigned Hi2 = (Value >> 4) & 0x3;
unsigned Lo4 = Value & 0xf;
return (Hi2 << 4) | (Lo4 << 12);
}
case Xtensa::fixup_xtensa_branch_8:
Value -= 4;
if (!isInt<8>(Value))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
return (Value & 0xff);
case Xtensa::fixup_xtensa_branch_12:
Value -= 4;
if (!isInt<12>(Value))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
return (Value & 0xfff);
case Xtensa::fixup_xtensa_jump_18:
Value -= 4;
if (!isInt<18>(Value))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
return (Value & 0x3ffff);
case Xtensa::fixup_xtensa_call_18:
Value -= 4;
if (!isInt<20>(Value))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
if (Value & 0x3)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");
return (Value & 0xffffc) >> 2;
case Xtensa::fixup_xtensa_l32r_16:
unsigned Offset = Fixup.getOffset();
if (Offset & 0x3)
Value -= 4;
if (!isInt<18>(Value) && (Value & 0x20000))
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
if (Value & 0x3)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");
return (Value & 0x3fffc) >> 2;
}
}
static unsigned getSize(unsigned Kind) {
switch (Kind) {
default:
return 3;
case MCFixupKind::FK_Data_4:
return 4;
case Xtensa::fixup_xtensa_branch_6:
return 2;
}
}
void XtensaMCAsmBackend::applyFixup(const MCAssembler &Asm,
const MCFixup &Fixup, const MCValue &Target,
MutableArrayRef<char> Data, uint64_t Value,
bool IsResolved,
const MCSubtargetInfo *STI) const {
MCContext &Ctx = Asm.getContext();
MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());
Value = adjustFixupValue(Fixup, Value, Ctx);
// Shift the value into position.
Value <<= Info.TargetOffset;
if (!Value)
return; // Doesn't change encoding.
unsigned Offset = Fixup.getOffset();
unsigned FullSize = getSize(Fixup.getKind());
for (unsigned i = 0; i != FullSize; ++i) {
Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff);
}
}
bool XtensaMCAsmBackend::mayNeedRelaxation(const MCInst &Inst,
const MCSubtargetInfo &STI) const {
return false;
}
void XtensaMCAsmBackend::relaxInstruction(MCInst &Inst,
const MCSubtargetInfo &STI) const {}
bool XtensaMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
const MCSubtargetInfo *STI) const {
uint64_t NumNops24b = Count / 3;
for (uint64_t i = 0; i != NumNops24b; ++i) {
// Currently just little-endian machine supported,
// but probably big-endian will be also implemented in future
if (IsLittleEndian) {
OS.write("\xf0", 1);
OS.write("\x20", 1);
OS.write("\0x00", 1);
} else {
report_fatal_error("Big-endian mode currently is not supported!");
}
Count -= 3;
}
// TODO maybe function should return error if (Count > 0)
switch (Count) {
default:
break;
case 1:
OS.write("\0", 1);
break;
case 2:
// NOP.N instruction
OS.write("\x3d", 1);
OS.write("\xf0", 1);
break;
}
return true;
}
MCAsmBackend *llvm::createXtensaMCAsmBackend(const Target &T,
const MCSubtargetInfo &STI,
const MCRegisterInfo &MRI,
const MCTargetOptions &Options) {
uint8_t OSABI =
MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS());
return new llvm::XtensaMCAsmBackend(OSABI, true);
}
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