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/MCAssembler.h"
11#include "llvm/MC/MCDXContainerWriter.h"
12#include "llvm/MC/MCELFObjectWriter.h"
13#include "llvm/MC/MCFixupKindInfo.h"
14#include "llvm/MC/MCGOFFObjectWriter.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
25using namespace llvm;
26
27MCAsmBackend::~MCAsmBackend() = default;
28
29MCContext &MCAsmBackend::getContext() const { return Asm->getContext(); }
30
31std::unique_ptr<MCObjectWriter>
32MCAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
33 auto TW = createObjectTargetWriter();
34 bool IsLE = Endian == llvm::endianness::little;
35 switch (TW->getFormat()) {
36 case Triple::MachO:
37 return std::make_unique<MachObjectWriter>(
38 args: cast<MCMachObjectTargetWriter>(Val: std::move(TW)), args&: OS, args&: IsLE);
39 case Triple::COFF:
40 return createWinCOFFObjectWriter(
41 MOTW: cast<MCWinCOFFObjectTargetWriter>(Val: std::move(TW)), OS);
42 case Triple::ELF:
43 return std::make_unique<ELFObjectWriter>(
44 args: cast<MCELFObjectTargetWriter>(Val: std::move(TW)), args&: OS, args&: IsLE);
45 case Triple::SPIRV:
46 return createSPIRVObjectWriter(
47 MOTW: cast<MCSPIRVObjectTargetWriter>(Val: std::move(TW)), OS);
48 case Triple::Wasm:
49 return createWasmObjectWriter(MOTW: cast<MCWasmObjectTargetWriter>(Val: std::move(TW)),
50 OS);
51 case Triple::GOFF:
52 return createGOFFObjectWriter(MOTW: cast<MCGOFFObjectTargetWriter>(Val: std::move(TW)),
53 OS);
54 case Triple::XCOFF:
55 return createXCOFFObjectWriter(
56 MOTW: cast<MCXCOFFObjectTargetWriter>(Val: std::move(TW)), OS);
57 case Triple::DXContainer:
58 return std::make_unique<DXContainerObjectWriter>(
59 args: cast<MCDXContainerTargetWriter>(Val: std::move(TW)), args&: OS);
60 default:
61 llvm_unreachable("unexpected object format");
62 }
63}
64
65std::unique_ptr<MCObjectWriter>
66MCAsmBackend::createDwoObjectWriter(raw_pwrite_stream &OS,
67 raw_pwrite_stream &DwoOS) const {
68 auto TW = createObjectTargetWriter();
69 switch (TW->getFormat()) {
70 case Triple::COFF:
71 return createWinCOFFDwoObjectWriter(
72 MOTW: cast<MCWinCOFFObjectTargetWriter>(Val: std::move(TW)), OS, DwoOS);
73 case Triple::ELF:
74 return std::make_unique<ELFObjectWriter>(
75 args: cast<MCELFObjectTargetWriter>(Val: std::move(TW)), args&: OS, args&: DwoOS,
76 args: Endian == llvm::endianness::little);
77 case Triple::Wasm:
78 return createWasmDwoObjectWriter(
79 MOTW: cast<MCWasmObjectTargetWriter>(Val: std::move(TW)), OS, DwoOS);
80 default:
81 report_fatal_error(reason: "dwo only supported with COFF, ELF, and Wasm");
82 }
83}
84
85std::optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
86 return std::nullopt;
87}
88
89MCFixupKindInfo MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
90 static const MCFixupKindInfo Builtins[] = {
91 {.Name: "FK_NONE", .TargetOffset: 0, .TargetSize: 0, .Flags: 0},
92 {.Name: "FK_Data_1", .TargetOffset: 0, .TargetSize: 8, .Flags: 0},
93 {.Name: "FK_Data_2", .TargetOffset: 0, .TargetSize: 16, .Flags: 0},
94 {.Name: "FK_Data_4", .TargetOffset: 0, .TargetSize: 32, .Flags: 0},
95 {.Name: "FK_Data_8", .TargetOffset: 0, .TargetSize: 64, .Flags: 0},
96 {.Name: "FK_Data_leb128", .TargetOffset: 0, .TargetSize: 0, .Flags: 0},
97 {.Name: "FK_PCRel_1", .TargetOffset: 0, .TargetSize: 8, .Flags: MCFixupKindInfo::FKF_IsPCRel},
98 {.Name: "FK_PCRel_2", .TargetOffset: 0, .TargetSize: 16, .Flags: MCFixupKindInfo::FKF_IsPCRel},
99 {.Name: "FK_PCRel_4", .TargetOffset: 0, .TargetSize: 32, .Flags: MCFixupKindInfo::FKF_IsPCRel},
100 {.Name: "FK_PCRel_8", .TargetOffset: 0, .TargetSize: 64, .Flags: MCFixupKindInfo::FKF_IsPCRel},
101 {.Name: "FK_SecRel_1", .TargetOffset: 0, .TargetSize: 8, .Flags: 0},
102 {.Name: "FK_SecRel_2", .TargetOffset: 0, .TargetSize: 16, .Flags: 0},
103 {.Name: "FK_SecRel_4", .TargetOffset: 0, .TargetSize: 32, .Flags: 0},
104 {.Name: "FK_SecRel_8", .TargetOffset: 0, .TargetSize: 64, .Flags: 0},
105 };
106
107 assert(size_t(Kind - FK_NONE) < std::size(Builtins) && "Unknown fixup kind");
108 return Builtins[Kind - FK_NONE];
109}
110
111bool MCAsmBackend::fixupNeedsRelaxationAdvanced(const MCFixup &Fixup,
112 const MCValue &, uint64_t Value,
113 bool Resolved) const {
114 if (!Resolved)
115 return true;
116 return fixupNeedsRelaxation(Fixup, Value);
117}
118
119void MCAsmBackend::maybeAddReloc(const MCFragment &F, const MCFixup &Fixup,
120 const MCValue &Target, uint64_t &Value,
121 bool IsResolved) {
122 if (!IsResolved)
123 Asm->getWriter().recordRelocation(F, Fixup, Target, FixedValue&: Value);
124}
125
126bool MCAsmBackend::isDarwinCanonicalPersonality(const MCSymbol *Sym) const {
127 // Consider a NULL personality (ie., no personality encoding) to be canonical
128 // because it's always at 0.
129 if (!Sym)
130 return true;
131
132 if (!Sym->isMachO())
133 llvm_unreachable("Expected MachO symbols only");
134
135 StringRef name = Sym->getName();
136 // XXX: We intentionally leave out "___gcc_personality_v0" because, despite
137 // being system-defined like these two, it is not very commonly-used.
138 // Reserving an empty slot for it seems silly.
139 return name == "___gxx_personality_v0" || name == "___objc_personality_v0";
140}
141
142const MCSubtargetInfo *MCAsmBackend::getSubtargetInfo(const MCFragment &F) {
143 const MCSubtargetInfo *STI = nullptr;
144 switch (F.getKind()) {
145 case MCFragment::FT_Data: {
146 auto &DF = cast<MCDataFragment>(Val: F);
147 STI = DF.getSubtargetInfo();
148 assert(!DF.hasInstructions() || STI != nullptr);
149 break;
150 }
151 case MCFragment::FT_Relaxable: {
152 auto &RF = cast<MCRelaxableFragment>(Val: F);
153 STI = RF.getSubtargetInfo();
154 assert(!RF.hasInstructions() || STI != nullptr);
155 break;
156 }
157 default:
158 break;
159 }
160 return STI;
161}
162