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| //===-- MSP430AsmBackend.cpp - MSP430 Assembler Backend -------------------===//
//
// 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/MSP430FixupKinds.h"
#include "MCTargetDesc/MSP430MCTargetDesc.h"
#include "llvm/ADT/APInt.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class MSP430AsmBackend : public MCAsmBackend {
uint8_t OSABI;
uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
MCContext &Ctx) const;
public:
MSP430AsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI)
: MCAsmBackend(support::little), OSABI(OSABI) {}
~MSP430AsmBackend() 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;
std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const override {
return createMSP430ELFObjectWriter(OSABI);
}
bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) const override {
return false;
}
bool fixupNeedsRelaxationAdvanced(const MCFixup &Fixup, bool Resolved,
uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout,
const bool WasForced) const override {
return false;
}
unsigned getNumFixupKinds() const override {
return MSP430::NumTargetFixupKinds;
}
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
const static MCFixupKindInfo Infos[MSP430::NumTargetFixupKinds] = {
// This table must be in the same order of enum in MSP430FixupKinds.h.
//
// name offset bits flags
{"fixup_32", 0, 32, 0},
{"fixup_10_pcrel", 0, 10, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_16", 0, 16, 0},
{"fixup_16_pcrel", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_16_byte", 0, 16, 0},
{"fixup_16_pcrel_byte", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_2x_pcrel", 0, 10, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_rl_pcrel", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
{"fixup_8", 0, 8, 0},
{"fixup_sym_diff", 0, 32, 0},
};
static_assert((array_lengthof(Infos)) == MSP430::NumTargetFixupKinds,
"Not all fixup kinds added to Infos array");
if (Kind < FirstTargetFixupKind)
return MCAsmBackend::getFixupKindInfo(Kind);
return Infos[Kind - FirstTargetFixupKind];
}
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;
};
uint64_t MSP430AsmBackend::adjustFixupValue(const MCFixup &Fixup,
uint64_t Value,
MCContext &Ctx) const {
unsigned Kind = Fixup.getKind();
switch (Kind) {
case MSP430::fixup_10_pcrel: {
if (Value & 0x1)
Ctx.reportError(Fixup.getLoc(), "fixup value must be 2-byte aligned");
// Offset is signed
int16_t Offset = Value;
// Jumps are in words
Offset >>= 1;
// PC points to the next instruction so decrement by one
--Offset;
if (Offset < -512 || Offset > 511)
Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
// Mask 10 bits
Offset &= 0x3ff;
return Offset;
}
default:
return Value;
}
}
void MSP430AsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
const MCValue &Target,
MutableArrayRef<char> Data,
uint64_t Value, bool IsResolved,
const MCSubtargetInfo *STI) const {
Value = adjustFixupValue(Fixup, Value, Asm.getContext());
MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());
if (!Value)
return; // Doesn't change encoding.
// 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 MSP430AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
if ((Count % 2) != 0)
return false;
// The canonical nop on MSP430 is mov #0, r3
uint64_t NopCount = Count / 2;
while (NopCount--)
OS.write("\x03\x43", 2);
return true;
}
} // end anonymous namespace
MCAsmBackend *llvm::createMSP430MCAsmBackend(const Target &T,
const MCSubtargetInfo &STI,
const MCRegisterInfo &MRI,
const MCTargetOptions &Options) {
return new MSP430AsmBackend(STI, ELF::ELFOSABI_STANDALONE);
}
|