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 <cassert>
  20 #include <cstddef>
  21 #include <cstdint>
  22
  23 using namespace llvm;
  24
  25 MCAsmBackend::MCAsmBackend(support::endianness Endian)
  26     : CodePadder(new MCCodePadder()), Endian(Endian) {}
  27
  28 MCAsmBackend::~MCAsmBackend() = default;
  29
  30 std::unique_ptr<MCObjectWriter>
  31 MCAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
  32   auto TW = createObjectTargetWriter();
  33   switch (TW->getFormat()) {
  34   case Triple::ELF:
  35     return createELFObjectWriter(cast<MCELFObjectTargetWriter>(std::move(TW)), OS,
  36                                  Endian == support::little);
  37   case Triple::MachO:
  38     return createMachObjectWriter(cast<MCMachObjectTargetWriter>(std::move(TW)),
  39                                   OS, Endian == support::little);
  40   case Triple::COFF:
  41     return createWinCOFFObjectWriter(
  42         cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS);
  43   case Triple::Wasm:
  44     return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)),
  45                                   OS);
  46   default:
  47     llvm_unreachable("unexpected object format");
  48   }
  49 }
  50
  51 std::unique_ptr<MCObjectWriter>
  52 MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS,
  53                                     raw_pwrite_stream &DwoOS) const {
  54   auto TW = createObjectTargetWriter();
  55   if (TW->getFormat() != Triple::ELF)
  56     report_fatal_error("dwo only supported with ELF");
  57   return createELFDwoObjectWriter(cast<MCELFObjectTargetWriter>(std::move(TW)),
  58                                   OS, DwoOS, Endian == support::little);
  59 }
  60
  61 Optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
  62   return None;
  63 }
  64
  65 const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
  66   static const MCFixupKindInfo Builtins[] = {
  67       {"FK_NONE", 0, 0, 0},
  68       {"FK_Data_1", 0, 8, 0},
  69       {"FK_Data_2", 0, 16, 0},
  70       {"FK_Data_4", 0, 32, 0},
  71       {"FK_Data_8", 0, 64, 0},
  72       {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
  73       {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
  74       {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
  75       {"FK_PCRel_8", 0, 64, MCFixupKindInfo::FKF_IsPCRel},
  76       {"FK_GPRel_1", 0, 8, 0},
  77       {"FK_GPRel_2", 0, 16, 0},
  78       {"FK_GPRel_4", 0, 32, 0},
  79       {"FK_GPRel_8", 0, 64, 0},
  80       {"FK_DTPRel_4", 0, 32, 0},
  81       {"FK_DTPRel_8", 0, 64, 0},
  82       {"FK_TPRel_4", 0, 32, 0},
  83       {"FK_TPRel_8", 0, 64, 0},
  84       {"FK_SecRel_1", 0, 8, 0},
  85       {"FK_SecRel_2", 0, 16, 0},
  86       {"FK_SecRel_4", 0, 32, 0},
  87       {"FK_SecRel_8", 0, 64, 0},
  88       {"FK_Data_Add_1", 0, 8, 0},
  89       {"FK_Data_Add_2", 0, 16, 0},
  90       {"FK_Data_Add_4", 0, 32, 0},
  91       {"FK_Data_Add_8", 0, 64, 0},
  92       {"FK_Data_Sub_1", 0, 8, 0},
  93       {"FK_Data_Sub_2", 0, 16, 0},
  94       {"FK_Data_Sub_4", 0, 32, 0},
  95       {"FK_Data_Sub_8", 0, 64, 0}};
  96
  97   assert((size_t)Kind <= array_lengthof(Builtins) && "Unknown fixup kind");
  98   return Builtins[Kind];
  99 }
 100
 101 bool MCAsmBackend::fixupNeedsRelaxationAdvanced(
 102     const MCFixup &Fixup, bool Resolved, uint64_t Value,
 103     const MCRelaxableFragment *DF, const MCAsmLayout &Layout,
 104     const bool WasForced) const {
 105   if (!Resolved)
 106     return true;
 107   return fixupNeedsRelaxation(Fixup, Value, DF, Layout);
 108 }
 109
 110 void MCAsmBackend::handleCodePaddingBasicBlockStart(
 111     MCObjectStreamer *OS, const MCCodePaddingContext &Context) {
 112   CodePadder->handleBasicBlockStart(OS, Context);
 113 }
 114
 115 void MCAsmBackend::handleCodePaddingBasicBlockEnd(
 116     const MCCodePaddingContext &Context) {
 117   CodePadder->handleBasicBlockEnd(Context);
 118 }
 119
 120 void MCAsmBackend::handleCodePaddingInstructionBegin(const MCInst &Inst) {
 121   CodePadder->handleInstructionBegin(Inst);
 122 }
 123
 124 void MCAsmBackend::handleCodePaddingInstructionEnd(const MCInst &Inst) {
 125   CodePadder->handleInstructionEnd(Inst);
 126 }
 127
 128 bool MCAsmBackend::relaxFragment(MCPaddingFragment *PF, MCAsmLayout &Layout) {
 129   return CodePadder->relaxFragment(PF, Layout);
 130 }