1 //===- lib/MC/MCWasmStreamer.cpp - Wasm Object Output ---------------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file assembles .s files and emits Wasm .o object files.
11 //===----------------------------------------------------------------------===//
13 #include "llvm/MC/MCWasmStreamer.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/ADT/SmallPtrSet.h"
16 #include "llvm/MC/MCAsmBackend.h"
17 #include "llvm/MC/MCAsmLayout.h"
18 #include "llvm/MC/MCAssembler.h"
19 #include "llvm/MC/MCCodeEmitter.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCExpr.h"
22 #include "llvm/MC/MCInst.h"
23 #include "llvm/MC/MCObjectStreamer.h"
24 #include "llvm/MC/MCSection.h"
25 #include "llvm/MC/MCSectionWasm.h"
26 #include "llvm/MC/MCSymbol.h"
27 #include "llvm/MC/MCSymbolWasm.h"
28 #include "llvm/MC/MCValue.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/TargetRegistry.h"
33 #include "llvm/Support/raw_ostream.h"
37 MCWasmStreamer::~MCWasmStreamer() = default; // anchor.
39 void MCWasmStreamer::mergeFragment(MCDataFragment *DF, MCDataFragment *EF) {
40 flushPendingLabels(DF, DF->getContents().size());
42 for (unsigned I = 0, E = EF->getFixups().size(); I != E; ++I) {
43 EF->getFixups()[I].setOffset(EF->getFixups()[I].getOffset() +
44 DF->getContents().size());
45 DF->getFixups().push_back(EF->getFixups()[I]);
47 if (DF->getSubtargetInfo() == nullptr && EF->getSubtargetInfo())
48 DF->setHasInstructions(*EF->getSubtargetInfo());
49 DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
52 void MCWasmStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
53 // Let the target do whatever target specific stuff it needs to do.
54 getAssembler().getBackend().handleAssemblerFlag(Flag);
56 // Do any generic stuff we need to do.
57 llvm_unreachable("invalid assembler flag!");
60 void MCWasmStreamer::changeSection(MCSection *Section,
61 const MCExpr *Subsection) {
62 MCAssembler &Asm = getAssembler();
63 auto *SectionWasm = cast<MCSectionWasm>(Section);
64 const MCSymbol *Grp = SectionWasm->getGroup();
66 Asm.registerSymbol(*Grp);
68 this->MCObjectStreamer::changeSection(Section, Subsection);
69 Asm.registerSymbol(*Section->getBeginSymbol());
72 void MCWasmStreamer::emitWeakReference(MCSymbol *Alias,
73 const MCSymbol *Symbol) {
74 getAssembler().registerSymbol(*Symbol);
75 const MCExpr *Value = MCSymbolRefExpr::create(
76 Symbol, MCSymbolRefExpr::VK_WEAKREF, getContext());
77 Alias->setVariableValue(Value);
80 bool MCWasmStreamer::emitSymbolAttribute(MCSymbol *S, MCSymbolAttr Attribute) {
81 assert(Attribute != MCSA_IndirectSymbol && "indirect symbols not supported");
83 auto *Symbol = cast<MCSymbolWasm>(S);
85 // Adding a symbol attribute always introduces the symbol; note that an
86 // important side effect of calling registerSymbol here is to register the
87 // symbol with the assembler.
88 getAssembler().registerSymbol(*Symbol);
91 case MCSA_LazyReference:
93 case MCSA_SymbolResolver:
94 case MCSA_PrivateExtern:
95 case MCSA_WeakDefinition:
96 case MCSA_WeakDefAutoPrivate:
98 case MCSA_IndirectSymbol:
103 Symbol->setHidden(true);
107 case MCSA_WeakReference:
108 Symbol->setWeak(true);
109 Symbol->setExternal(true);
113 Symbol->setExternal(true);
116 case MCSA_ELF_TypeFunction:
117 Symbol->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
120 case MCSA_ELF_TypeObject:
124 case MCSA_NoDeadStrip:
125 Symbol->setNoStrip();
129 // unrecognized directive
130 llvm_unreachable("unexpected MCSymbolAttr");
137 void MCWasmStreamer::emitCommonSymbol(MCSymbol *S, uint64_t Size,
138 unsigned ByteAlignment) {
139 llvm_unreachable("Common symbols are not yet implemented for Wasm");
142 void MCWasmStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
143 cast<MCSymbolWasm>(Symbol)->setSize(Value);
146 void MCWasmStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
147 unsigned ByteAlignment) {
148 llvm_unreachable("Local common symbols are not yet implemented for Wasm");
151 void MCWasmStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,
153 MCObjectStreamer::emitValueImpl(Value, Size, Loc);
156 void MCWasmStreamer::emitValueToAlignment(unsigned ByteAlignment, int64_t Value,
158 unsigned MaxBytesToEmit) {
159 MCObjectStreamer::emitValueToAlignment(ByteAlignment, Value, ValueSize,
163 void MCWasmStreamer::emitIdent(StringRef IdentString) {
164 // TODO(sbc): Add the ident section once we support mergable strings
165 // sections in the object format
168 void MCWasmStreamer::emitInstToFragment(const MCInst &Inst,
169 const MCSubtargetInfo &STI) {
170 this->MCObjectStreamer::emitInstToFragment(Inst, STI);
173 void MCWasmStreamer::emitInstToData(const MCInst &Inst,
174 const MCSubtargetInfo &STI) {
175 MCAssembler &Assembler = getAssembler();
176 SmallVector<MCFixup, 4> Fixups;
177 SmallString<256> Code;
178 raw_svector_ostream VecOS(Code);
179 Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
181 // Append the encoded instruction to the current data fragment (or create a
182 // new such fragment if the current fragment is not a data fragment).
183 MCDataFragment *DF = getOrCreateDataFragment();
185 // Add the fixups and data.
186 for (unsigned I = 0, E = Fixups.size(); I != E; ++I) {
187 Fixups[I].setOffset(Fixups[I].getOffset() + DF->getContents().size());
188 DF->getFixups().push_back(Fixups[I]);
190 DF->setHasInstructions(STI);
191 DF->getContents().append(Code.begin(), Code.end());
194 void MCWasmStreamer::finishImpl() {
197 this->MCObjectStreamer::finishImpl();
200 MCStreamer *llvm::createWasmStreamer(MCContext &Context,
201 std::unique_ptr<MCAsmBackend> &&MAB,
202 std::unique_ptr<MCObjectWriter> &&OW,
203 std::unique_ptr<MCCodeEmitter> &&CE,
206 new MCWasmStreamer(Context, std::move(MAB), std::move(OW), std::move(CE));
208 S->getAssembler().setRelaxAll(true);
212 void MCWasmStreamer::emitThumbFunc(MCSymbol *Func) {
213 llvm_unreachable("Generic Wasm doesn't support this directive");
216 void MCWasmStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
217 llvm_unreachable("Wasm doesn't support this directive");
220 void MCWasmStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
221 uint64_t Size, unsigned ByteAlignment,
223 llvm_unreachable("Wasm doesn't support this directive");
226 void MCWasmStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
227 uint64_t Size, unsigned ByteAlignment) {
228 llvm_unreachable("Wasm doesn't support this directive");