1 //===- lib/MC/MCWasmStreamer.cpp - Wasm Object Output ---------------------===//
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 // This file assembles .s files and emits Wasm .o object files.
10 //
11 //===----------------------------------------------------------------------===//
12
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"
34
35 using namespace llvm;
36
37 MCWasmStreamer::~MCWasmStreamer() = default; // anchor.
38
mergeFragment(MCDataFragment * DF,MCDataFragment * EF)39 void MCWasmStreamer::mergeFragment(MCDataFragment *DF, MCDataFragment *EF) {
40 flushPendingLabels(DF, DF->getContents().size());
41
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]);
46 }
47 if (DF->getSubtargetInfo() == nullptr && EF->getSubtargetInfo())
48 DF->setHasInstructions(*EF->getSubtargetInfo());
49 DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
50 }
51
emitAssemblerFlag(MCAssemblerFlag Flag)52 void MCWasmStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
53 // Let the target do whatever target specific stuff it needs to do.
54 getAssembler().getBackend().handleAssemblerFlag(Flag);
55
56 // Do any generic stuff we need to do.
57 llvm_unreachable("invalid assembler flag!");
58 }
59
changeSection(MCSection * Section,const MCExpr * Subsection)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();
65 if (Grp)
66 Asm.registerSymbol(*Grp);
67
68 this->MCObjectStreamer::changeSection(Section, Subsection);
69 Asm.registerSymbol(*Section->getBeginSymbol());
70 }
71
emitWeakReference(MCSymbol * Alias,const MCSymbol * Symbol)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);
78 }
79
emitSymbolAttribute(MCSymbol * S,MCSymbolAttr Attribute)80 bool MCWasmStreamer::emitSymbolAttribute(MCSymbol *S, MCSymbolAttr Attribute) {
81 assert(Attribute != MCSA_IndirectSymbol && "indirect symbols not supported");
82
83 auto *Symbol = cast<MCSymbolWasm>(S);
84
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);
89
90 switch (Attribute) {
91 case MCSA_LazyReference:
92 case MCSA_Reference:
93 case MCSA_SymbolResolver:
94 case MCSA_PrivateExtern:
95 case MCSA_WeakDefinition:
96 case MCSA_WeakDefAutoPrivate:
97 case MCSA_Invalid:
98 case MCSA_IndirectSymbol:
99 case MCSA_Protected:
100 return false;
101
102 case MCSA_Hidden:
103 Symbol->setHidden(true);
104 break;
105
106 case MCSA_Weak:
107 case MCSA_WeakReference:
108 Symbol->setWeak(true);
109 Symbol->setExternal(true);
110 break;
111
112 case MCSA_Global:
113 Symbol->setExternal(true);
114 break;
115
116 case MCSA_ELF_TypeFunction:
117 Symbol->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
118 break;
119
120 case MCSA_ELF_TypeObject:
121 case MCSA_Cold:
122 break;
123
124 case MCSA_NoDeadStrip:
125 Symbol->setNoStrip();
126 break;
127
128 default:
129 // unrecognized directive
130 llvm_unreachable("unexpected MCSymbolAttr");
131 return false;
132 }
133
134 return true;
135 }
136
emitCommonSymbol(MCSymbol * S,uint64_t Size,unsigned ByteAlignment)137 void MCWasmStreamer::emitCommonSymbol(MCSymbol *S, uint64_t Size,
138 unsigned ByteAlignment) {
139 llvm_unreachable("Common symbols are not yet implemented for Wasm");
140 }
141
emitELFSize(MCSymbol * Symbol,const MCExpr * Value)142 void MCWasmStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
143 cast<MCSymbolWasm>(Symbol)->setSize(Value);
144 }
145
emitLocalCommonSymbol(MCSymbol * S,uint64_t Size,unsigned ByteAlignment)146 void MCWasmStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
147 unsigned ByteAlignment) {
148 llvm_unreachable("Local common symbols are not yet implemented for Wasm");
149 }
150
emitIdent(StringRef IdentString)151 void MCWasmStreamer::emitIdent(StringRef IdentString) {
152 // TODO(sbc): Add the ident section once we support mergable strings
153 // sections in the object format
154 }
155
emitInstToFragment(const MCInst & Inst,const MCSubtargetInfo & STI)156 void MCWasmStreamer::emitInstToFragment(const MCInst &Inst,
157 const MCSubtargetInfo &STI) {
158 this->MCObjectStreamer::emitInstToFragment(Inst, STI);
159 }
160
emitInstToData(const MCInst & Inst,const MCSubtargetInfo & STI)161 void MCWasmStreamer::emitInstToData(const MCInst &Inst,
162 const MCSubtargetInfo &STI) {
163 MCAssembler &Assembler = getAssembler();
164 SmallVector<MCFixup, 4> Fixups;
165 SmallString<256> Code;
166 raw_svector_ostream VecOS(Code);
167 Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
168
169 // Append the encoded instruction to the current data fragment (or create a
170 // new such fragment if the current fragment is not a data fragment).
171 MCDataFragment *DF = getOrCreateDataFragment();
172
173 // Add the fixups and data.
174 for (unsigned I = 0, E = Fixups.size(); I != E; ++I) {
175 Fixups[I].setOffset(Fixups[I].getOffset() + DF->getContents().size());
176 DF->getFixups().push_back(Fixups[I]);
177 }
178 DF->setHasInstructions(STI);
179 DF->getContents().append(Code.begin(), Code.end());
180 }
181
finishImpl()182 void MCWasmStreamer::finishImpl() {
183 emitFrames(nullptr);
184
185 this->MCObjectStreamer::finishImpl();
186 }
187
createWasmStreamer(MCContext & Context,std::unique_ptr<MCAsmBackend> && MAB,std::unique_ptr<MCObjectWriter> && OW,std::unique_ptr<MCCodeEmitter> && CE,bool RelaxAll)188 MCStreamer *llvm::createWasmStreamer(MCContext &Context,
189 std::unique_ptr<MCAsmBackend> &&MAB,
190 std::unique_ptr<MCObjectWriter> &&OW,
191 std::unique_ptr<MCCodeEmitter> &&CE,
192 bool RelaxAll) {
193 MCWasmStreamer *S =
194 new MCWasmStreamer(Context, std::move(MAB), std::move(OW), std::move(CE));
195 if (RelaxAll)
196 S->getAssembler().setRelaxAll(true);
197 return S;
198 }
199
emitThumbFunc(MCSymbol * Func)200 void MCWasmStreamer::emitThumbFunc(MCSymbol *Func) {
201 llvm_unreachable("Generic Wasm doesn't support this directive");
202 }
203
emitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)204 void MCWasmStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
205 llvm_unreachable("Wasm doesn't support this directive");
206 }
207
emitZerofill(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,SMLoc Loc)208 void MCWasmStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
209 uint64_t Size, unsigned ByteAlignment,
210 SMLoc Loc) {
211 llvm_unreachable("Wasm doesn't support this directive");
212 }
213
emitTBSSSymbol(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)214 void MCWasmStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
215 uint64_t Size, unsigned ByteAlignment) {
216 llvm_unreachable("Wasm doesn't support this directive");
217 }
218