154 lines · cpp
1//===-- LanaiAsmBackend.cpp - Lanai Assembler Backend ---------------------===//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 "LanaiFixupKinds.h"10#include "MCTargetDesc/LanaiMCTargetDesc.h"11#include "llvm/MC/MCAsmBackend.h"12#include "llvm/MC/MCAssembler.h"13#include "llvm/MC/MCELFObjectWriter.h"14#include "llvm/MC/MCObjectWriter.h"15#include "llvm/MC/MCSubtargetInfo.h"16#include "llvm/MC/MCValue.h"17#include "llvm/Support/ErrorHandling.h"18#include "llvm/Support/raw_ostream.h"19 20using namespace llvm;21 22// Prepare value for the target space23static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {24 switch (Kind) {25 case FK_Data_1:26 case FK_Data_2:27 case FK_Data_4:28 case FK_Data_8:29 return Value;30 case Lanai::FIXUP_LANAI_21:31 case Lanai::FIXUP_LANAI_21_F:32 case Lanai::FIXUP_LANAI_25:33 case Lanai::FIXUP_LANAI_32:34 case Lanai::FIXUP_LANAI_HI16:35 case Lanai::FIXUP_LANAI_LO16:36 return Value;37 default:38 llvm_unreachable("Unknown fixup kind!");39 }40}41 42namespace {43class LanaiAsmBackend : public MCAsmBackend {44 Triple::OSType OSType;45 46public:47 LanaiAsmBackend(const Target &T, Triple::OSType OST)48 : MCAsmBackend(llvm::endianness::big), OSType(OST) {}49 50 void applyFixup(const MCFragment &, const MCFixup &, const MCValue &Target,51 uint8_t *Data, uint64_t Value, bool IsResolved) override;52 53 std::unique_ptr<MCObjectTargetWriter>54 createObjectTargetWriter() const override;55 56 MCFixupKindInfo getFixupKindInfo(MCFixupKind Kind) const override;57 58 bool writeNopData(raw_ostream &OS, uint64_t Count,59 const MCSubtargetInfo *STI) const override;60};61 62bool LanaiAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,63 const MCSubtargetInfo *STI) const {64 if ((Count % 4) != 0)65 return false;66 67 for (uint64_t i = 0; i < Count; i += 4)68 OS.write("\x15\0\0\0", 4);69 70 return true;71}72 73void LanaiAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup,74 const MCValue &Target, uint8_t *Data,75 uint64_t Value, bool IsResolved) {76 if (!IsResolved)77 Asm->getWriter().recordRelocation(F, Fixup, Target, Value);78 79 MCFixupKind Kind = Fixup.getKind();80 Value = adjustFixupValue(static_cast<unsigned>(Kind), Value);81 if (!Value)82 return; // This value doesn't change the encoding83 84 // Where in the object and where the number of bytes that need85 // fixing up86 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;87 unsigned FullSize = 4;88 89 // Grab current value, if any, from bits.90 uint64_t CurVal = 0;91 92 // Load instruction and apply value93 for (unsigned i = 0; i != NumBytes; ++i) {94 unsigned Idx = (FullSize - 1 - i);95 CurVal |= static_cast<uint64_t>(static_cast<uint8_t>(Data[Idx])) << (i * 8);96 }97 98 uint64_t Mask =99 (static_cast<uint64_t>(-1) >> (64 - getFixupKindInfo(Kind).TargetSize));100 CurVal |= Value & Mask;101 102 // Write out the fixed up bytes back to the code/data bits.103 for (unsigned i = 0; i != NumBytes; ++i) {104 unsigned Idx = (FullSize - 1 - i);105 Data[Idx] = static_cast<uint8_t>((CurVal >> (i * 8)) & 0xff);106 }107}108 109std::unique_ptr<MCObjectTargetWriter>110LanaiAsmBackend::createObjectTargetWriter() const {111 return createLanaiELFObjectWriter(MCELFObjectTargetWriter::getOSABI(OSType));112}113 114MCFixupKindInfo LanaiAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {115 static const MCFixupKindInfo Infos[Lanai::NumTargetFixupKinds] = {116 // This table *must* be in same the order of fixup_* kinds in117 // LanaiFixupKinds.h.118 // Note: The number of bits indicated here are assumed to be contiguous.119 // This does not hold true for LANAI_21 and LANAI_21_F which are applied120 // to bits 0x7cffff and 0x7cfffc, respectively. Since the 'bits' counts121 // here are used only for cosmetic purposes, we set the size to 16 bits122 // for these 21-bit relocation as llvm/lib/MC/MCAsmStreamer.cpp checks123 // no bits are set in the fixup range.124 //125 // name offset bits flags126 {"FIXUP_LANAI_NONE", 0, 32, 0},127 {"FIXUP_LANAI_21", 16, 16 /*21*/, 0},128 {"FIXUP_LANAI_21_F", 16, 16 /*21*/, 0},129 {"FIXUP_LANAI_25", 7, 25, 0},130 {"FIXUP_LANAI_32", 0, 32, 0},131 {"FIXUP_LANAI_HI16", 16, 16, 0},132 {"FIXUP_LANAI_LO16", 16, 16, 0}};133 134 if (Kind < FirstTargetFixupKind)135 return MCAsmBackend::getFixupKindInfo(Kind);136 137 assert(unsigned(Kind - FirstTargetFixupKind) < Lanai::NumTargetFixupKinds &&138 "Invalid kind!");139 return Infos[Kind - FirstTargetFixupKind];140}141 142} // namespace143 144MCAsmBackend *llvm::createLanaiAsmBackend(const Target &T,145 const MCSubtargetInfo &STI,146 const MCRegisterInfo & /*MRI*/,147 const MCTargetOptions & /*Options*/) {148 const Triple &TT = STI.getTargetTriple();149 if (!TT.isOSBinFormatELF())150 llvm_unreachable("OS not supported");151 152 return new LanaiAsmBackend(T, TT.getOS());153}154