274 lines
9.2 KiB
C++
274 lines
9.2 KiB
C++
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//===-- PPCAsmBackend.cpp - PPC Assembler Backend -------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/PPCFixupKinds.h"
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#include "MCTargetDesc/PPCMCTargetDesc.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/BinaryFormat/MachO.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCELFObjectWriter.h"
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#include "llvm/MC/MCFixupKindInfo.h"
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#include "llvm/MC/MCMachObjectWriter.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSectionMachO.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/MC/MCSymbolELF.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/TargetRegistry.h"
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using namespace llvm;
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static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
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switch (Kind) {
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default:
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llvm_unreachable("Unknown fixup kind!");
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case FK_Data_1:
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case FK_Data_2:
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case FK_Data_4:
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case FK_Data_8:
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case PPC::fixup_ppc_nofixup:
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return Value;
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case PPC::fixup_ppc_brcond14:
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case PPC::fixup_ppc_brcond14abs:
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return Value & 0xfffc;
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case PPC::fixup_ppc_br24:
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case PPC::fixup_ppc_br24abs:
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case PPC::fixup_ppc_br24_notoc:
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return Value & 0x3fffffc;
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case PPC::fixup_ppc_half16:
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return Value & 0xffff;
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case PPC::fixup_ppc_half16ds:
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return Value & 0xfffc;
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case PPC::fixup_ppc_pcrel34:
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case PPC::fixup_ppc_imm34:
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return Value & 0x3ffffffff;
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}
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}
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static unsigned getFixupKindNumBytes(unsigned Kind) {
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switch (Kind) {
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default:
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llvm_unreachable("Unknown fixup kind!");
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case FK_Data_1:
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return 1;
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case FK_Data_2:
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case PPC::fixup_ppc_half16:
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case PPC::fixup_ppc_half16ds:
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return 2;
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case FK_Data_4:
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case PPC::fixup_ppc_brcond14:
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case PPC::fixup_ppc_brcond14abs:
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case PPC::fixup_ppc_br24:
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case PPC::fixup_ppc_br24abs:
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case PPC::fixup_ppc_br24_notoc:
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return 4;
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case PPC::fixup_ppc_pcrel34:
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case PPC::fixup_ppc_imm34:
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case FK_Data_8:
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return 8;
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case PPC::fixup_ppc_nofixup:
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return 0;
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}
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}
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namespace {
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class PPCAsmBackend : public MCAsmBackend {
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protected:
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Triple TT;
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public:
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PPCAsmBackend(const Target &T, const Triple &TT)
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: MCAsmBackend(TT.isLittleEndian() ? support::little : support::big),
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TT(TT) {}
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unsigned getNumFixupKinds() const override {
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return PPC::NumTargetFixupKinds;
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}
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const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
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const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = {
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// name offset bits flags
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{ "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_br24_notoc", 6, 24, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_br24abs", 6, 24, 0 },
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{ "fixup_ppc_brcond14abs", 16, 14, 0 },
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{ "fixup_ppc_half16", 0, 16, 0 },
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{ "fixup_ppc_half16ds", 0, 14, 0 },
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{ "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_imm34", 0, 34, 0 },
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{ "fixup_ppc_nofixup", 0, 0, 0 }
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};
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const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = {
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// name offset bits flags
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{ "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_br24_notoc", 2, 24, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_br24abs", 2, 24, 0 },
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{ "fixup_ppc_brcond14abs", 2, 14, 0 },
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{ "fixup_ppc_half16", 0, 16, 0 },
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{ "fixup_ppc_half16ds", 2, 14, 0 },
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{ "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel },
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{ "fixup_ppc_imm34", 0, 34, 0 },
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{ "fixup_ppc_nofixup", 0, 0, 0 }
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};
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// Fixup kinds from .reloc directive are like R_PPC_NONE/R_PPC64_NONE. They
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// do not require any extra processing.
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if (Kind >= FirstLiteralRelocationKind)
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return MCAsmBackend::getFixupKindInfo(FK_NONE);
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if (Kind < FirstTargetFixupKind)
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return MCAsmBackend::getFixupKindInfo(Kind);
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assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
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"Invalid kind!");
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return (Endian == support::little
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? InfosLE
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: InfosBE)[Kind - FirstTargetFixupKind];
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}
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void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target, MutableArrayRef<char> Data,
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uint64_t Value, bool IsResolved,
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const MCSubtargetInfo *STI) const override {
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MCFixupKind Kind = Fixup.getKind();
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if (Kind >= FirstLiteralRelocationKind)
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return;
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Value = adjustFixupValue(Kind, Value);
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if (!Value) return; // Doesn't change encoding.
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unsigned Offset = Fixup.getOffset();
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unsigned NumBytes = getFixupKindNumBytes(Kind);
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// For each byte of the fragment that the fixup touches, mask in the bits
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// from the fixup value. The Value has been "split up" into the appropriate
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// bitfields above.
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for (unsigned i = 0; i != NumBytes; ++i) {
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unsigned Idx = Endian == support::little ? i : (NumBytes - 1 - i);
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Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff);
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}
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}
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bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target) override {
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MCFixupKind Kind = Fixup.getKind();
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switch ((unsigned)Kind) {
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default:
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return Kind >= FirstLiteralRelocationKind;
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case PPC::fixup_ppc_br24:
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case PPC::fixup_ppc_br24abs:
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case PPC::fixup_ppc_br24_notoc:
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// If the target symbol has a local entry point we must not attempt
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// to resolve the fixup directly. Emit a relocation and leave
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// resolution of the final target address to the linker.
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if (const MCSymbolRefExpr *A = Target.getSymA()) {
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if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) {
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// The "other" values are stored in the last 6 bits of the second
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// byte. The traditional defines for STO values assume the full byte
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// and thus the shift to pack it.
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unsigned Other = S->getOther() << 2;
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if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0)
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return true;
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}
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}
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return false;
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}
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}
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bool fixupNeedsRelaxation(const MCFixup &Fixup,
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uint64_t Value,
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const MCRelaxableFragment *DF,
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const MCAsmLayout &Layout) const override {
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// FIXME.
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llvm_unreachable("relaxInstruction() unimplemented");
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}
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void relaxInstruction(MCInst &Inst,
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const MCSubtargetInfo &STI) const override {
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// FIXME.
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llvm_unreachable("relaxInstruction() unimplemented");
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}
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bool writeNopData(raw_ostream &OS, uint64_t Count) const override {
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uint64_t NumNops = Count / 4;
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for (uint64_t i = 0; i != NumNops; ++i)
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support::endian::write<uint32_t>(OS, 0x60000000, Endian);
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OS.write_zeros(Count % 4);
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return true;
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}
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};
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} // end anonymous namespace
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// FIXME: This should be in a separate file.
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namespace {
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class ELFPPCAsmBackend : public PPCAsmBackend {
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public:
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ELFPPCAsmBackend(const Target &T, const Triple &TT) : PPCAsmBackend(T, TT) {}
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std::unique_ptr<MCObjectTargetWriter>
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createObjectTargetWriter() const override {
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uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS());
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bool Is64 = TT.isPPC64();
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return createPPCELFObjectWriter(Is64, OSABI);
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}
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Optional<MCFixupKind> getFixupKind(StringRef Name) const override;
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};
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class XCOFFPPCAsmBackend : public PPCAsmBackend {
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public:
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XCOFFPPCAsmBackend(const Target &T, const Triple &TT)
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: PPCAsmBackend(T, TT) {}
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std::unique_ptr<MCObjectTargetWriter>
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createObjectTargetWriter() const override {
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return createPPCXCOFFObjectWriter(TT.isArch64Bit());
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}
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};
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} // end anonymous namespace
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Optional<MCFixupKind> ELFPPCAsmBackend::getFixupKind(StringRef Name) const {
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if (TT.isOSBinFormatELF()) {
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unsigned Type;
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if (TT.isPPC64()) {
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Type = llvm::StringSwitch<unsigned>(Name)
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#define ELF_RELOC(X, Y) .Case(#X, Y)
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#include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
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#undef ELF_RELOC
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.Default(-1u);
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} else {
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Type = llvm::StringSwitch<unsigned>(Name)
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#define ELF_RELOC(X, Y) .Case(#X, Y)
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#include "llvm/BinaryFormat/ELFRelocs/PowerPC.def"
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#undef ELF_RELOC
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.Default(-1u);
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}
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if (Type != -1u)
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return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
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}
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return None;
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}
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MCAsmBackend *llvm::createPPCAsmBackend(const Target &T,
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const MCSubtargetInfo &STI,
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const MCRegisterInfo &MRI,
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const MCTargetOptions &Options) {
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const Triple &TT = STI.getTargetTriple();
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if (TT.isOSBinFormatXCOFF())
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return new XCOFFPPCAsmBackend(T, TT);
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return new ELFPPCAsmBackend(T, TT);
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}
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