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/STLArrayExtras.h"
12 #include "llvm/MC/MCDXContainerWriter.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/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(support::endianness Endian) : 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::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::XCOFF:
51     return createXCOFFObjectWriter(
52         cast<MCXCOFFObjectTargetWriter>(std::move(TW)), OS);
53   case Triple::DXContainer:
54     return createDXContainerObjectWriter(
55         cast<MCDXContainerTargetWriter>(std::move(TW)), OS);
56   default:
57     llvm_unreachable("unexpected object format");
58   }
59 }
60 
61 std::unique_ptr<MCObjectWriter>
62 MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS,
63                                     raw_pwrite_stream &DwoOS) const {
64   auto TW = createObjectTargetWriter();
65   switch (TW->getFormat()) {
66   case Triple::ELF:
67     return createELFDwoObjectWriter(
68         cast<MCELFObjectTargetWriter>(std::move(TW)), OS, DwoOS,
69         Endian == support::little);
70   case Triple::Wasm:
71     return createWasmDwoObjectWriter(
72         cast<MCWasmObjectTargetWriter>(std::move(TW)), OS, DwoOS);
73   default:
74     report_fatal_error("dwo only supported with ELF and Wasm");
75   }
76 }
77 
78 Optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
79   return None;
80 }
81 
82 const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
83   static const MCFixupKindInfo Builtins[] = {
84       {"FK_NONE", 0, 0, 0},
85       {"FK_Data_1", 0, 8, 0},
86       {"FK_Data_2", 0, 16, 0},
87       {"FK_Data_4", 0, 32, 0},
88       {"FK_Data_8", 0, 64, 0},
89       {"FK_Data_6b", 0, 6, 0},
90       {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
91       {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
92       {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
93       {"FK_PCRel_8", 0, 64, MCFixupKindInfo::FKF_IsPCRel},
94       {"FK_GPRel_1", 0, 8, 0},
95       {"FK_GPRel_2", 0, 16, 0},
96       {"FK_GPRel_4", 0, 32, 0},
97       {"FK_GPRel_8", 0, 64, 0},
98       {"FK_DTPRel_4", 0, 32, 0},
99       {"FK_DTPRel_8", 0, 64, 0},
100       {"FK_TPRel_4", 0, 32, 0},
101       {"FK_TPRel_8", 0, 64, 0},
102       {"FK_SecRel_1", 0, 8, 0},
103       {"FK_SecRel_2", 0, 16, 0},
104       {"FK_SecRel_4", 0, 32, 0},
105       {"FK_SecRel_8", 0, 64, 0},
106   };
107 
108   assert((size_t)Kind <= array_lengthof(Builtins) && "Unknown fixup kind");
109   return Builtins[Kind];
110 }
111 
112 bool MCAsmBackend::fixupNeedsRelaxationAdvanced(
113     const MCFixup &Fixup, bool Resolved, uint64_t Value,
114     const MCRelaxableFragment *DF, const MCAsmLayout &Layout,
115     const bool WasForced) const {
116   if (!Resolved)
117     return true;
118   return fixupNeedsRelaxation(Fixup, Value, DF, Layout);
119 }
120