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//===-- PPCAsmBackend.cpp - PPC 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/PPCFixupKinds.h"
#include "MCTargetDesc/PPCMCTargetDesc.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/MC/MCMachObjectWriter.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCSymbolXCOFF.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
switch (Kind) {
default:
llvm_unreachable("Unknown fixup kind!");
case FK_Data_1:
case FK_Data_2:
case FK_Data_4:
case FK_Data_8:
case PPC::fixup_ppc_nofixup:
return Value;
case PPC::fixup_ppc_brcond14:
case PPC::fixup_ppc_brcond14abs:
return Value & 0xfffc;
case PPC::fixup_ppc_br24:
case PPC::fixup_ppc_br24abs:
case PPC::fixup_ppc_br24_notoc:
return Value & 0x3fffffc;
case PPC::fixup_ppc_half16:
return Value & 0xffff;
case PPC::fixup_ppc_half16ds:
case PPC::fixup_ppc_half16dq:
return Value & 0xfffc;
case PPC::fixup_ppc_pcrel34:
case PPC::fixup_ppc_imm34:
return Value & 0x3ffffffff;
}
}
static unsigned getFixupKindNumBytes(unsigned Kind) {
switch (Kind) {
default:
llvm_unreachable("Unknown fixup kind!");
case FK_Data_1:
return 1;
case FK_Data_2:
case PPC::fixup_ppc_half16:
case PPC::fixup_ppc_half16ds:
case PPC::fixup_ppc_half16dq:
return 2;
case FK_Data_4:
case PPC::fixup_ppc_brcond14:
case PPC::fixup_ppc_brcond14abs:
case PPC::fixup_ppc_br24:
case PPC::fixup_ppc_br24abs:
case PPC::fixup_ppc_br24_notoc:
return 4;
case PPC::fixup_ppc_pcrel34:
case PPC::fixup_ppc_imm34:
case FK_Data_8:
return 8;
case PPC::fixup_ppc_nofixup:
return 0;
}
}
namespace {
class PPCAsmBackend : public MCAsmBackend {
protected:
Triple TT;
public:
PPCAsmBackend(const Target &T, const Triple &TT)
: MCAsmBackend(TT.isLittleEndian() ? support::little : support::big),
TT(TT) {}
unsigned getNumFixupKinds() const override {
return PPC::NumTargetFixupKinds;
}
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = {
// name offset bits flags
{ "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_br24_notoc", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_br24abs", 6, 24, 0 },
{ "fixup_ppc_brcond14abs", 16, 14, 0 },
{ "fixup_ppc_half16", 0, 16, 0 },
{ "fixup_ppc_half16ds", 0, 14, 0 },
{ "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_imm34", 0, 34, 0 },
{ "fixup_ppc_nofixup", 0, 0, 0 }
};
const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = {
// name offset bits flags
{ "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_br24_notoc", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_br24abs", 2, 24, 0 },
{ "fixup_ppc_brcond14abs", 2, 14, 0 },
{ "fixup_ppc_half16", 0, 16, 0 },
{ "fixup_ppc_half16ds", 2, 14, 0 },
{ "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel },
{ "fixup_ppc_imm34", 0, 34, 0 },
{ "fixup_ppc_nofixup", 0, 0, 0 }
};
// Fixup kinds from .reloc directive are like R_PPC_NONE/R_PPC64_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 (Endian == support::little
? InfosLE
: InfosBE)[Kind - FirstTargetFixupKind];
}
void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
const MCValue &Target, MutableArrayRef<char> Data,
uint64_t Value, bool IsResolved,
const MCSubtargetInfo *STI) const override {
MCFixupKind Kind = Fixup.getKind();
if (Kind >= FirstLiteralRelocationKind)
return;
Value = adjustFixupValue(Kind, Value);
if (!Value) return; // Doesn't change encoding.
unsigned Offset = Fixup.getOffset();
unsigned NumBytes = getFixupKindNumBytes(Kind);
// For each byte of the fragment that the fixup touches, mask in the bits
// from the fixup value. The Value has been "split up" into the appropriate
// bitfields above.
for (unsigned i = 0; i != NumBytes; ++i) {
unsigned Idx = Endian == support::little ? i : (NumBytes - 1 - i);
Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff);
}
}
bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
const MCValue &Target) override {
MCFixupKind Kind = Fixup.getKind();
switch ((unsigned)Kind) {
default:
return Kind >= FirstLiteralRelocationKind;
case PPC::fixup_ppc_br24:
case PPC::fixup_ppc_br24abs:
case PPC::fixup_ppc_br24_notoc:
// If the target symbol has a local entry point we must not attempt
// to resolve the fixup directly. Emit a relocation and leave
// resolution of the final target address to the linker.
if (const MCSymbolRefExpr *A = Target.getSymA()) {
if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) {
// The "other" values are stored in the last 6 bits of the second
// byte. The traditional defines for STO values assume the full byte
// and thus the shift to pack it.
unsigned Other = S->getOther() << 2;
if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0)
return true;
} else if (const auto *S = dyn_cast<MCSymbolXCOFF>(&A->getSymbol())) {
return !Target.isAbsolute() && S->isExternal() &&
S->getStorageClass() == XCOFF::C_WEAKEXT;
}
}
return false;
}
}
bool fixupNeedsRelaxation(const MCFixup &Fixup,
uint64_t Value,
const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) const override {
// FIXME.
llvm_unreachable("relaxInstruction() unimplemented");
}
void relaxInstruction(MCInst &Inst,
const MCSubtargetInfo &STI) const override {
// FIXME.
llvm_unreachable("relaxInstruction() unimplemented");
}
bool writeNopData(raw_ostream &OS, uint64_t Count,
const MCSubtargetInfo *STI) const override {
uint64_t NumNops = Count / 4;
for (uint64_t i = 0; i != NumNops; ++i)
support::endian::write<uint32_t>(OS, 0x60000000, Endian);
OS.write_zeros(Count % 4);
return true;
}
};
} // end anonymous namespace
// FIXME: This should be in a separate file.
namespace {
class ELFPPCAsmBackend : public PPCAsmBackend {
public:
ELFPPCAsmBackend(const Target &T, const Triple &TT) : PPCAsmBackend(T, TT) {}
std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const override {
uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
bool Is64 = TT.isPPC64();
return createPPCELFObjectWriter(Is64, OSABI);
}
std::optional<MCFixupKind> getFixupKind(StringRef Name) const override;
};
class XCOFFPPCAsmBackend : public PPCAsmBackend {
public:
XCOFFPPCAsmBackend(const Target &T, const Triple &TT)
: PPCAsmBackend(T, TT) {}
std::unique_ptr<MCObjectTargetWriter>
createObjectTargetWriter() const override {
return createPPCXCOFFObjectWriter(TT.isArch64Bit());
}
std::optional<MCFixupKind> getFixupKind(StringRef Name) const override;
};
} // end anonymous namespace
std::optional<MCFixupKind>
ELFPPCAsmBackend::getFixupKind(StringRef Name) const {
if (TT.isOSBinFormatELF()) {
unsigned Type;
if (TT.isPPC64()) {
Type = llvm::StringSwitch<unsigned>(Name)
#define ELF_RELOC(X, Y) .Case(#X, Y)
#include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
#undef ELF_RELOC
.Case("BFD_RELOC_NONE", ELF::R_PPC64_NONE)
.Case("BFD_RELOC_16", ELF::R_PPC64_ADDR16)
.Case("BFD_RELOC_32", ELF::R_PPC64_ADDR32)
.Case("BFD_RELOC_64", ELF::R_PPC64_ADDR64)
.Default(-1u);
} else {
Type = llvm::StringSwitch<unsigned>(Name)
#define ELF_RELOC(X, Y) .Case(#X, Y)
#include "llvm/BinaryFormat/ELFRelocs/PowerPC.def"
#undef ELF_RELOC
.Case("BFD_RELOC_NONE", ELF::R_PPC_NONE)
.Case("BFD_RELOC_16", ELF::R_PPC_ADDR16)
.Case("BFD_RELOC_32", ELF::R_PPC_ADDR32)
.Default(-1u);
}
if (Type != -1u)
return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
}
return std::nullopt;
}
std::optional<MCFixupKind>
XCOFFPPCAsmBackend::getFixupKind(StringRef Name) const {
return StringSwitch<std::optional<MCFixupKind>>(Name)
.Case("R_REF", (MCFixupKind)PPC::fixup_ppc_nofixup)
.Default(std::nullopt);
}
MCAsmBackend *llvm::createPPCAsmBackend(const Target &T,
const MCSubtargetInfo &STI,
const MCRegisterInfo &MRI,
const MCTargetOptions &Options) {
const Triple &TT = STI.getTargetTriple();
if (TT.isOSBinFormatXCOFF())
return new XCOFFPPCAsmBackend(T, TT);
return new ELFPPCAsmBackend(T, TT);
}
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