1 //===- MCAsmBackend.cpp - Target MC Assembly 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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/MC/MCAsmBackend.h" 10 #include "llvm/MC/MCAssembler.h" 11 #include "llvm/MC/MCDXContainerWriter.h" 12 #include "llvm/MC/MCELFObjectWriter.h" 13 #include "llvm/MC/MCFixupKindInfo.h" 14 #include "llvm/MC/MCGOFFObjectWriter.h" 15 #include "llvm/MC/MCMachObjectWriter.h" 16 #include "llvm/MC/MCObjectWriter.h" 17 #include "llvm/MC/MCSPIRVObjectWriter.h" 18 #include "llvm/MC/MCWasmObjectWriter.h" 19 #include "llvm/MC/MCWinCOFFObjectWriter.h" 20 #include "llvm/MC/MCXCOFFObjectWriter.h" 21 #include <cassert> 22 #include <cstddef> 23 #include <cstdint> 24 25 using namespace llvm; 26 27 MCAsmBackend::MCAsmBackend(llvm::endianness Endian, unsigned RelaxFixupKind) 28 : Endian(Endian), RelaxFixupKind(RelaxFixupKind) {} 29 30 MCAsmBackend::~MCAsmBackend() = default; 31 32 std::unique_ptr<MCObjectWriter> 33 MCAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const { 34 auto TW = createObjectTargetWriter(); 35 bool IsLE = Endian == llvm::endianness::little; 36 switch (TW->getFormat()) { 37 case Triple::MachO: 38 return createMachObjectWriter(cast<MCMachObjectTargetWriter>(std::move(TW)), 39 OS, IsLE); 40 case Triple::COFF: 41 return createWinCOFFObjectWriter( 42 cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS); 43 case Triple::ELF: 44 return std::make_unique<ELFObjectWriter>( 45 cast<MCELFObjectTargetWriter>(std::move(TW)), OS, IsLE); 46 case Triple::SPIRV: 47 return createSPIRVObjectWriter( 48 cast<MCSPIRVObjectTargetWriter>(std::move(TW)), OS); 49 case Triple::Wasm: 50 return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)), 51 OS); 52 case Triple::GOFF: 53 return createGOFFObjectWriter(cast<MCGOFFObjectTargetWriter>(std::move(TW)), 54 OS); 55 case Triple::XCOFF: 56 return createXCOFFObjectWriter( 57 cast<MCXCOFFObjectTargetWriter>(std::move(TW)), OS); 58 case Triple::DXContainer: 59 return createDXContainerObjectWriter( 60 cast<MCDXContainerTargetWriter>(std::move(TW)), OS); 61 default: 62 llvm_unreachable("unexpected object format"); 63 } 64 } 65 66 std::unique_ptr<MCObjectWriter> 67 MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS, 68 raw_pwrite_stream &DwoOS) const { 69 auto TW = createObjectTargetWriter(); 70 switch (TW->getFormat()) { 71 case Triple::COFF: 72 return createWinCOFFDwoObjectWriter( 73 cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS, DwoOS); 74 case Triple::ELF: 75 return std::make_unique<ELFObjectWriter>( 76 cast<MCELFObjectTargetWriter>(std::move(TW)), OS, DwoOS, 77 Endian == llvm::endianness::little); 78 case Triple::Wasm: 79 return createWasmDwoObjectWriter( 80 cast<MCWasmObjectTargetWriter>(std::move(TW)), OS, DwoOS); 81 default: 82 report_fatal_error("dwo only supported with COFF, ELF, and Wasm"); 83 } 84 } 85 86 std::optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const { 87 return std::nullopt; 88 } 89 90 const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 91 static const MCFixupKindInfo Builtins[] = { 92 {"FK_NONE", 0, 0, 0}, 93 {"FK_Data_1", 0, 8, 0}, 94 {"FK_Data_2", 0, 16, 0}, 95 {"FK_Data_4", 0, 32, 0}, 96 {"FK_Data_8", 0, 64, 0}, 97 {"FK_Data_leb128", 0, 0, 0}, 98 {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel}, 99 {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel}, 100 {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel}, 101 {"FK_PCRel_8", 0, 64, MCFixupKindInfo::FKF_IsPCRel}, 102 {"FK_GPRel_1", 0, 8, 0}, 103 {"FK_GPRel_2", 0, 16, 0}, 104 {"FK_GPRel_4", 0, 32, 0}, 105 {"FK_GPRel_8", 0, 64, 0}, 106 {"FK_DTPRel_4", 0, 32, 0}, 107 {"FK_DTPRel_8", 0, 64, 0}, 108 {"FK_TPRel_4", 0, 32, 0}, 109 {"FK_TPRel_8", 0, 64, 0}, 110 {"FK_SecRel_1", 0, 8, 0}, 111 {"FK_SecRel_2", 0, 16, 0}, 112 {"FK_SecRel_4", 0, 32, 0}, 113 {"FK_SecRel_8", 0, 64, 0}, 114 }; 115 116 assert((size_t)Kind <= std::size(Builtins) && "Unknown fixup kind"); 117 return Builtins[Kind]; 118 } 119 120 bool MCAsmBackend::fixupNeedsRelaxationAdvanced(const MCAssembler &Asm, 121 const MCFixup &Fixup, 122 bool Resolved, uint64_t Value, 123 const MCRelaxableFragment *DF, 124 const bool WasForced) const { 125 if (!Resolved) 126 return true; 127 return fixupNeedsRelaxation(Fixup, Value); 128 } 129 130 bool MCAsmBackend::isDarwinCanonicalPersonality(const MCSymbol *Sym) const { 131 // Consider a NULL personality (ie., no personality encoding) to be canonical 132 // because it's always at 0. 133 if (!Sym) 134 return true; 135 136 if (!Sym->isMachO()) 137 llvm_unreachable("Expected MachO symbols only"); 138 139 StringRef name = Sym->getName(); 140 // XXX: We intentionally leave out "___gcc_personality_v0" because, despite 141 // being system-defined like these two, it is not very commonly-used. 142 // Reserving an empty slot for it seems silly. 143 return name == "___gxx_personality_v0" || name == "___objc_personality_v0"; 144 } 145