llvm/lib/MC/MCAsmBackend.cpp

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