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      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/MCELFObjectWriter.h"
     13 #include "llvm/MC/MCFixupKindInfo.h"
     14 #include "llvm/MC/MCMachObjectWriter.h"
     15 #include "llvm/MC/MCObjectWriter.h"
     16 #include "llvm/MC/MCWasmObjectWriter.h"
     17 #include "llvm/MC/MCWinCOFFObjectWriter.h"
     18 #include "llvm/MC/MCXCOFFObjectWriter.h"
     19 #include <cassert>
     20 #include <cstddef>
     21 #include <cstdint>
     22 
     23 using namespace llvm;
     24 
     25 MCAsmBackend::MCAsmBackend(support::endianness Endian) : Endian(Endian) {}
     26 
     27 MCAsmBackend::~MCAsmBackend() = default;
     28 
     29 std::unique_ptr<MCObjectWriter>
     30 MCAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
     31   auto TW = createObjectTargetWriter();
     32   switch (TW->getFormat()) {
     33   case Triple::ELF:
     34     return createELFObjectWriter(cast<MCELFObjectTargetWriter>(std::move(TW)), OS,
     35                                  Endian == support::little);
     36   case Triple::MachO:
     37     return createMachObjectWriter(cast<MCMachObjectTargetWriter>(std::move(TW)),
     38                                   OS, Endian == support::little);
     39   case Triple::COFF:
     40     return createWinCOFFObjectWriter(
     41         cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS);
     42   case Triple::Wasm:
     43     return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)),
     44                                   OS);
     45   case Triple::XCOFF:
     46     return createXCOFFObjectWriter(
     47         cast<MCXCOFFObjectTargetWriter>(std::move(TW)), OS);
     48   default:
     49     llvm_unreachable("unexpected object format");
     50   }
     51 }
     52 
     53 std::unique_ptr<MCObjectWriter>
     54 MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS,
     55                                     raw_pwrite_stream &DwoOS) const {
     56   auto TW = createObjectTargetWriter();
     57   switch (TW->getFormat()) {
     58   case Triple::ELF:
     59     return createELFDwoObjectWriter(
     60         cast<MCELFObjectTargetWriter>(std::move(TW)), OS, DwoOS,
     61         Endian == support::little);
     62   case Triple::Wasm:
     63     return createWasmDwoObjectWriter(
     64         cast<MCWasmObjectTargetWriter>(std::move(TW)), OS, DwoOS);
     65   default:
     66     report_fatal_error("dwo only supported with ELF and Wasm");
     67   }
     68 }
     69 
     70 Optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
     71   return None;
     72 }
     73 
     74 const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
     75   static const MCFixupKindInfo Builtins[] = {
     76       {"FK_NONE", 0, 0, 0},
     77       {"FK_Data_1", 0, 8, 0},
     78       {"FK_Data_2", 0, 16, 0},
     79       {"FK_Data_4", 0, 32, 0},
     80       {"FK_Data_8", 0, 64, 0},
     81       {"FK_Data_6b", 0, 6, 0},
     82       {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
     83       {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
     84       {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
     85       {"FK_PCRel_8", 0, 64, MCFixupKindInfo::FKF_IsPCRel},
     86       {"FK_GPRel_1", 0, 8, 0},
     87       {"FK_GPRel_2", 0, 16, 0},
     88       {"FK_GPRel_4", 0, 32, 0},
     89       {"FK_GPRel_8", 0, 64, 0},
     90       {"FK_DTPRel_4", 0, 32, 0},
     91       {"FK_DTPRel_8", 0, 64, 0},
     92       {"FK_TPRel_4", 0, 32, 0},
     93       {"FK_TPRel_8", 0, 64, 0},
     94       {"FK_SecRel_1", 0, 8, 0},
     95       {"FK_SecRel_2", 0, 16, 0},
     96       {"FK_SecRel_4", 0, 32, 0},
     97       {"FK_SecRel_8", 0, 64, 0},
     98       {"FK_Data_Add_1", 0, 8, 0},
     99       {"FK_Data_Add_2", 0, 16, 0},
    100       {"FK_Data_Add_4", 0, 32, 0},
    101       {"FK_Data_Add_8", 0, 64, 0},
    102       {"FK_Data_Add_6b", 0, 6, 0},
    103       {"FK_Data_Sub_1", 0, 8, 0},
    104       {"FK_Data_Sub_2", 0, 16, 0},
    105       {"FK_Data_Sub_4", 0, 32, 0},
    106       {"FK_Data_Sub_8", 0, 64, 0},
    107       {"FK_Data_Sub_6b", 0, 6, 0}};
    108 
    109   assert((size_t)Kind <= array_lengthof(Builtins) && "Unknown fixup kind");
    110   return Builtins[Kind];
    111 }
    112 
    113 bool MCAsmBackend::fixupNeedsRelaxationAdvanced(
    114     const MCFixup &Fixup, bool Resolved, uint64_t Value,
    115     const MCRelaxableFragment *DF, const MCAsmLayout &Layout,
    116     const bool WasForced) const {
    117   if (!Resolved)
    118     return true;
    119   return fixupNeedsRelaxation(Fixup, Value, DF, Layout);
    120 }
    121