218 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "MCTargetDesc/XtensaFixupKinds.h"10#include "MCTargetDesc/XtensaMCTargetDesc.h"11#include "llvm/MC/MCAsmBackend.h"12#include "llvm/MC/MCAssembler.h"13#include "llvm/MC/MCContext.h"14#include "llvm/MC/MCELFObjectWriter.h"15#include "llvm/MC/MCInst.h"16#include "llvm/MC/MCObjectWriter.h"17#include "llvm/MC/MCSubtargetInfo.h"18#include "llvm/MC/MCValue.h"19#include "llvm/Support/raw_ostream.h"20 21using namespace llvm;22 23namespace llvm {24class MCObjectTargetWriter;25}26namespace {27class XtensaAsmBackend : public MCAsmBackend {28 uint8_t OSABI;29 bool IsLittleEndian;30 31public:32 XtensaAsmBackend(uint8_t osABI, bool isLE)33 : MCAsmBackend(llvm::endianness::little), OSABI(osABI),34 IsLittleEndian(isLE) {}35 36 MCFixupKindInfo getFixupKindInfo(MCFixupKind Kind) const override;37 std::optional<bool> evaluateFixup(const MCFragment &, MCFixup &, MCValue &,38 uint64_t &) override;39 void applyFixup(const MCFragment &, const MCFixup &, const MCValue &Target,40 uint8_t *Data, uint64_t Value, bool IsResolved) override;41 bool writeNopData(raw_ostream &OS, uint64_t Count,42 const MCSubtargetInfo *STI) const override;43 44 std::unique_ptr<MCObjectTargetWriter> createObjectTargetWriter() const override {45 return createXtensaObjectWriter(OSABI, IsLittleEndian);46 }47};48} // namespace49 50MCFixupKindInfo XtensaAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {51 const static MCFixupKindInfo Infos[Xtensa::NumTargetFixupKinds] = {52 // name offset bits flags53 {"fixup_xtensa_branch_6", 0, 16, 0},54 {"fixup_xtensa_branch_8", 16, 8, 0},55 {"fixup_xtensa_branch_12", 12, 12, 0},56 {"fixup_xtensa_jump_18", 6, 18, 0},57 {"fixup_xtensa_call_18", 6, 18, 0},58 {"fixup_xtensa_l32r_16", 8, 16, 0},59 {"fixup_xtensa_loop_8", 16, 8, 0},60 };61 62 if (Kind < FirstTargetFixupKind)63 return MCAsmBackend::getFixupKindInfo(Kind);64 assert(unsigned(Kind - FirstTargetFixupKind) < Xtensa::NumTargetFixupKinds &&65 "Invalid kind!");66 return Infos[Kind - FirstTargetFixupKind];67}68 69static uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value,70 MCContext &Ctx) {71 unsigned Kind = Fixup.getKind();72 switch (Kind) {73 default:74 llvm_unreachable("Unknown fixup kind!");75 case FK_Data_1:76 case FK_Data_2:77 case FK_Data_4:78 case FK_Data_8:79 return Value;80 case Xtensa::fixup_xtensa_branch_6: {81 if (!Value)82 return 0;83 Value -= 4;84 if (!isUInt<6>(Value))85 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");86 unsigned Hi2 = (Value >> 4) & 0x3;87 unsigned Lo4 = Value & 0xf;88 return (Hi2 << 4) | (Lo4 << 12);89 }90 case Xtensa::fixup_xtensa_branch_8:91 Value -= 4;92 if (!isInt<8>(Value))93 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");94 return (Value & 0xff);95 case Xtensa::fixup_xtensa_branch_12:96 Value -= 4;97 if (!isInt<12>(Value))98 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");99 return (Value & 0xfff);100 case Xtensa::fixup_xtensa_jump_18:101 Value -= 4;102 if (!isInt<18>(Value))103 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");104 return (Value & 0x3ffff);105 case Xtensa::fixup_xtensa_call_18:106 Value -= 4;107 if (!isInt<20>(Value))108 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");109 if (Value & 0x3)110 Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");111 return (Value & 0xffffc) >> 2;112 case Xtensa::fixup_xtensa_loop_8:113 Value -= 4;114 if (!isUInt<8>(Value))115 Ctx.reportError(Fixup.getLoc(), "loop fixup value out of range");116 return (Value & 0xff);117 case Xtensa::fixup_xtensa_l32r_16:118 unsigned Offset = Fixup.getOffset();119 if (Offset & 0x3)120 Value -= 4;121 if (!isInt<18>(Value) && (Value & 0x20000))122 Ctx.reportError(Fixup.getLoc(), "fixup value out of range");123 if (Value & 0x3)124 Ctx.reportError(Fixup.getLoc(), "fixup value must be 4-byte aligned");125 return (Value & 0x3fffc) >> 2;126 }127}128 129static unsigned getSize(unsigned Kind) {130 switch (Kind) {131 default:132 return 3;133 case FK_Data_4:134 return 4;135 case Xtensa::fixup_xtensa_branch_6:136 return 2;137 }138}139 140std::optional<bool> XtensaAsmBackend::evaluateFixup(const MCFragment &F,141 MCFixup &Fixup, MCValue &,142 uint64_t &Value) {143 // For a few PC-relative fixups, offsets need to be aligned down. We144 // compensate here because the default handler's `Value` decrement doesn't145 // account for this alignment.146 switch (Fixup.getKind()) {147 case Xtensa::fixup_xtensa_call_18:148 case Xtensa::fixup_xtensa_l32r_16:149 Value = (Asm->getFragmentOffset(F) + Fixup.getOffset()) % 4;150 }151 return {};152}153 154void XtensaAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup,155 const MCValue &Target, uint8_t *Data,156 uint64_t Value, bool IsResolved) {157 maybeAddReloc(F, Fixup, Target, Value, IsResolved);158 MCContext &Ctx = getContext();159 MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());160 161 Value = adjustFixupValue(Fixup, Value, Ctx);162 163 // Shift the value into position.164 Value <<= Info.TargetOffset;165 166 if (!Value)167 return; // Doesn't change encoding.168 169 unsigned FullSize = getSize(Fixup.getKind());170 171 for (unsigned i = 0; i != FullSize; ++i) {172 Data[i] |= uint8_t((Value >> (i * 8)) & 0xff);173 }174}175 176bool XtensaAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,177 const MCSubtargetInfo *STI) const {178 uint64_t NumNops24b = Count / 3;179 180 for (uint64_t i = 0; i != NumNops24b; ++i) {181 // Currently just little-endian machine supported,182 // but probably big-endian will be also implemented in future183 if (IsLittleEndian) {184 OS.write("\xf0", 1);185 OS.write("\x20", 1);186 OS.write("\0x00", 1);187 } else {188 report_fatal_error("Big-endian mode currently is not supported!");189 }190 Count -= 3;191 }192 193 // TODO maybe function should return error if (Count > 0)194 switch (Count) {195 default:196 break;197 case 1:198 OS.write("\0", 1);199 break;200 case 2:201 // NOP.N instruction202 OS.write("\x3d", 1);203 OS.write("\xf0", 1);204 break;205 }206 207 return true;208}209 210MCAsmBackend *llvm::createXtensaAsmBackend(const Target &T,211 const MCSubtargetInfo &STI,212 const MCRegisterInfo &MRI,213 const MCTargetOptions &Options) {214 uint8_t OSABI =215 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS());216 return new XtensaAsmBackend(OSABI, true);217}218