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/ADT/None.h"
  11 #include "llvm/ADT/STLExtras.h"
  12 #include "llvm/MC/MCCodePadder.h"
  13 #include "llvm/MC/MCELFObjectWriter.h"
  14 #include "llvm/MC/MCFixupKindInfo.h"
  15 #include "llvm/MC/MCMachObjectWriter.h"
  16 #include "llvm/MC/MCObjectWriter.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(support::endianness Endian)
  27     : CodePadder(new MCCodePadder()), Endian(Endian) {}
  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)), OS,
  37                                  Endian == support::little);
  38   case Triple::MachO:
  39     return createMachObjectWriter(cast<MCMachObjectTargetWriter>(std::move(TW)),
  40                                   OS, Endian == support::little);
  41   case Triple::COFF:
  42     return createWinCOFFObjectWriter(
  43         cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS);
  44   case Triple::Wasm:
  45     return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)),
  46                                   OS);
  47   case Triple::XCOFF:
  48     return createXCOFFObjectWriter(
  49         cast<MCXCOFFObjectTargetWriter>(std::move(TW)), OS);
  50   default:
  51     llvm_unreachable("unexpected object format");
  52   }
  53 }
  54
  55 std::unique_ptr<MCObjectWriter>
  56 MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS,
  57                                     raw_pwrite_stream &DwoOS) const {
  58   auto TW = createObjectTargetWriter();
  59   if (TW->getFormat() != Triple::ELF)
  60     report_fatal_error("dwo only supported with ELF");
  61   return createELFDwoObjectWriter(cast<MCELFObjectTargetWriter>(std::move(TW)),
  62                                   OS, DwoOS, Endian == support::little);
  63 }
  64
  65 Optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
  66   return None;
  67 }
  68
  69 const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
  70   static const MCFixupKindInfo Builtins[] = {
  71       {"FK_NONE", 0, 0, 0},
  72       {"FK_Data_1", 0, 8, 0},
  73       {"FK_Data_2", 0, 16, 0},
  74       {"FK_Data_4", 0, 32, 0},
  75       {"FK_Data_8", 0, 64, 0},
  76       {"FK_Data_6b", 0, 6, 0},
  77       {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
  78       {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
  79       {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
  80       {"FK_PCRel_8", 0, 64, MCFixupKindInfo::FKF_IsPCRel},
  81       {"FK_GPRel_1", 0, 8, 0},
  82       {"FK_GPRel_2", 0, 16, 0},
  83       {"FK_GPRel_4", 0, 32, 0},
  84       {"FK_GPRel_8", 0, 64, 0},
  85       {"FK_DTPRel_4", 0, 32, 0},
  86       {"FK_DTPRel_8", 0, 64, 0},
  87       {"FK_TPRel_4", 0, 32, 0},
  88       {"FK_TPRel_8", 0, 64, 0},
  89       {"FK_SecRel_1", 0, 8, 0},
  90       {"FK_SecRel_2", 0, 16, 0},
  91       {"FK_SecRel_4", 0, 32, 0},
  92       {"FK_SecRel_8", 0, 64, 0},
  93       {"FK_Data_Add_1", 0, 8, 0},
  94       {"FK_Data_Add_2", 0, 16, 0},
  95       {"FK_Data_Add_4", 0, 32, 0},
  96       {"FK_Data_Add_8", 0, 64, 0},
  97       {"FK_Data_Add_6b", 0, 6, 0},
  98       {"FK_Data_Sub_1", 0, 8, 0},
  99       {"FK_Data_Sub_2", 0, 16, 0},
 100       {"FK_Data_Sub_4", 0, 32, 0},
 101       {"FK_Data_Sub_8", 0, 64, 0},
 102       {"FK_Data_Sub_6b", 0, 6, 0}};
 103
 104   assert((size_t)Kind <= array_lengthof(Builtins) && "Unknown fixup kind");
 105   return Builtins[Kind];
 106 }
 107
 108 bool MCAsmBackend::fixupNeedsRelaxationAdvanced(
 109     const MCFixup &Fixup, bool Resolved, uint64_t Value,
 110     const MCRelaxableFragment *DF, const MCAsmLayout &Layout,
 111     const bool WasForced) const {
 112   if (!Resolved)
 113     return true;
 114   return fixupNeedsRelaxation(Fixup, Value, DF, Layout);
 115 }
 116
 117 void MCAsmBackend::handleCodePaddingBasicBlockStart(
 118     MCObjectStreamer *OS, const MCCodePaddingContext &Context) {
 119   CodePadder->handleBasicBlockStart(OS, Context);
 120 }
 121
 122 void MCAsmBackend::handleCodePaddingBasicBlockEnd(
 123     const MCCodePaddingContext &Context) {
 124   CodePadder->handleBasicBlockEnd(Context);
 125 }
 126
 127 void MCAsmBackend::handleCodePaddingInstructionBegin(const MCInst &Inst) {
 128   CodePadder->handleInstructionBegin(Inst);
 129 }
 130
 131 void MCAsmBackend::handleCodePaddingInstructionEnd(const MCInst &Inst) {
 132   CodePadder->handleInstructionEnd(Inst);
 133 }
 134
 135 bool MCAsmBackend::relaxFragment(MCPaddingFragment *PF, MCAsmLayout &Layout) {
 136   return CodePadder->relaxFragment(PF, Layout);
 137 }