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//===-- AMDGPUAsmBackend.cpp - AMDGPU Assembler Backend -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
/// \file
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "MCTargetDesc/AMDGPUFixupKinds.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/TargetRegistry.h"
using namespace llvm;
namespace {
class AMDGPUMCObjectWriter : public MCObjectWriter {
public:
AMDGPUMCObjectWriter(raw_pwrite_stream &OS) : MCObjectWriter(OS, true) {}
void executePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) override {
//XXX: Implement if necessary.
}
void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, bool &IsPCRel,
uint64_t &FixedValue) override {
assert(!"Not implemented");
}
void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
};
class AMDGPUAsmBackend : public MCAsmBackend {
public:
AMDGPUAsmBackend(const Target &T)
: MCAsmBackend() {}
unsigned getNumFixupKinds() const override { return AMDGPU::NumTargetFixupKinds; };
void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
uint64_t Value, bool IsPCRel) const override;
bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) const override {
return false;
}
void relaxInstruction(const MCInst &Inst, MCInst &Res) const override {
assert(!"Not implemented");
}
bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
};
} //End anonymous namespace
void AMDGPUMCObjectWriter::writeObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
for (MCAssembler::iterator I = Asm.begin(), E = Asm.end(); I != E; ++I) {
Asm.writeSectionData(&*I, Layout);
}
}
static unsigned getFixupKindNumBytes(unsigned Kind) {
switch (Kind) {
case FK_Data_1:
return 1;
case FK_Data_2:
return 2;
case FK_Data_4:
return 4;
case FK_Data_8:
return 8;
default:
llvm_unreachable("Unknown fixup kind!");
}
}
void AMDGPUAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
unsigned DataSize, uint64_t Value,
bool IsPCRel) const {
switch ((unsigned)Fixup.getKind()) {
case AMDGPU::fixup_si_sopp_br: {
uint16_t *Dst = (uint16_t*)(Data + Fixup.getOffset());
*Dst = (Value - 4) / 4;
break;
}
case AMDGPU::fixup_si_rodata: {
uint32_t *Dst = (uint32_t*)(Data + Fixup.getOffset());
// We emit constant data at the end of the text section and generate its
// address using the following code sequence:
// s_getpc_b64 s[0:1]
// s_add_u32 s0, s0, $symbol
// s_addc_u32 s1, s1, 0
//
// s_getpc_b64 returns the address of the s_add_u32 instruction and then
// the fixup replaces $symbol with a literal constant, which is a
// pc-relative offset from the encoding of the $symbol operand to the
// constant data.
//
// What we want here is an offset from the start of the s_add_u32
// instruction to the constant data, but since the encoding of $symbol
// starts 4 bytes after the start of the add instruction, we end up
// with an offset that is 4 bytes too small. This requires us to
// add 4 to the fixup value before applying it.
*Dst = Value + 4;
break;
}
default: {
// FIXME: Copied from AArch64
unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
if (!Value)
return; // Doesn't change encoding.
MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());
// Shift the value into position.
Value <<= Info.TargetOffset;
unsigned Offset = Fixup.getOffset();
assert(Offset + NumBytes <= DataSize && "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);
}
}
}
const MCFixupKindInfo &AMDGPUAsmBackend::getFixupKindInfo(
MCFixupKind Kind) const {
const static MCFixupKindInfo Infos[AMDGPU::NumTargetFixupKinds] = {
// name offset bits flags
{ "fixup_si_sopp_br", 0, 16, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_si_rodata", 0, 32, MCFixupKindInfo::FKF_IsPCRel }
};
if (Kind < FirstTargetFixupKind)
return MCAsmBackend::getFixupKindInfo(Kind);
return Infos[Kind - FirstTargetFixupKind];
}
bool AMDGPUAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
OW->WriteZeros(Count);
return true;
}
//===----------------------------------------------------------------------===//
// ELFAMDGPUAsmBackend class
//===----------------------------------------------------------------------===//
namespace {
class ELFAMDGPUAsmBackend : public AMDGPUAsmBackend {
bool Is64Bit;
public:
ELFAMDGPUAsmBackend(const Target &T, bool Is64Bit) :
AMDGPUAsmBackend(T), Is64Bit(Is64Bit) { }
MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override {
return createAMDGPUELFObjectWriter(Is64Bit, OS);
}
};
} // end anonymous namespace
MCAsmBackend *llvm::createAMDGPUAsmBackend(const Target &T,
const MCRegisterInfo &MRI,
const Triple &TT, StringRef CPU) {
Triple TargetTriple(TT);
// Use 64-bit ELF for amdgcn
return new ELFAMDGPUAsmBackend(T, TargetTriple.getArch() == Triple::amdgcn);
}
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