1 //===- lib/MC/MCWasmStreamer.cpp - Wasm Object Output ---------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file assembles .s files and emits Wasm .o object files.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/MC/MCWasmStreamer.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/MC/MCAsmBackend.h"
18 #include "llvm/MC/MCAsmLayout.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCCodeEmitter.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCInst.h"
24 #include "llvm/MC/MCObjectStreamer.h"
25 #include "llvm/MC/MCSection.h"
26 #include "llvm/MC/MCSectionWasm.h"
27 #include "llvm/MC/MCSymbol.h"
28 #include "llvm/MC/MCSymbolWasm.h"
29 #include "llvm/MC/MCValue.h"
30 #include "llvm/Support/Casting.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/TargetRegistry.h"
34 #include "llvm/Support/raw_ostream.h"
35
36 using namespace llvm;
37
~MCWasmStreamer()38 MCWasmStreamer::~MCWasmStreamer() {}
39
mergeFragment(MCDataFragment * DF,MCDataFragment * EF)40 void MCWasmStreamer::mergeFragment(MCDataFragment *DF, MCDataFragment *EF) {
41 flushPendingLabels(DF, DF->getContents().size());
42
43 for (unsigned i = 0, e = EF->getFixups().size(); i != e; ++i) {
44 EF->getFixups()[i].setOffset(EF->getFixups()[i].getOffset() +
45 DF->getContents().size());
46 DF->getFixups().push_back(EF->getFixups()[i]);
47 }
48 if (DF->getSubtargetInfo() == nullptr && EF->getSubtargetInfo())
49 DF->setHasInstructions(*EF->getSubtargetInfo());
50 DF->getContents().append(EF->getContents().begin(), EF->getContents().end());
51 }
52
EmitAssemblerFlag(MCAssemblerFlag Flag)53 void MCWasmStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
54 // Let the target do whatever target specific stuff it needs to do.
55 getAssembler().getBackend().handleAssemblerFlag(Flag);
56
57 // Do any generic stuff we need to do.
58 llvm_unreachable("invalid assembler flag!");
59 }
60
ChangeSection(MCSection * Section,const MCExpr * Subsection)61 void MCWasmStreamer::ChangeSection(MCSection *Section,
62 const MCExpr *Subsection) {
63 MCAssembler &Asm = getAssembler();
64 auto *SectionWasm = static_cast<const MCSectionWasm *>(Section);
65 const MCSymbol *Grp = SectionWasm->getGroup();
66 if (Grp)
67 Asm.registerSymbol(*Grp);
68
69 this->MCObjectStreamer::ChangeSection(Section, Subsection);
70 Asm.registerSymbol(*Section->getBeginSymbol());
71 }
72
EmitWeakReference(MCSymbol * Alias,const MCSymbol * Symbol)73 void MCWasmStreamer::EmitWeakReference(MCSymbol *Alias,
74 const MCSymbol *Symbol) {
75 getAssembler().registerSymbol(*Symbol);
76 const MCExpr *Value = MCSymbolRefExpr::create(
77 Symbol, MCSymbolRefExpr::VK_WEAKREF, getContext());
78 Alias->setVariableValue(Value);
79 }
80
EmitSymbolAttribute(MCSymbol * S,MCSymbolAttr Attribute)81 bool MCWasmStreamer::EmitSymbolAttribute(MCSymbol *S, MCSymbolAttr Attribute) {
82 assert(Attribute != MCSA_IndirectSymbol && "indirect symbols not supported");
83
84 auto *Symbol = cast<MCSymbolWasm>(S);
85
86 // Adding a symbol attribute always introduces the symbol; note that an
87 // important side effect of calling registerSymbol here is to register the
88 // symbol with the assembler.
89 getAssembler().registerSymbol(*Symbol);
90
91 switch (Attribute) {
92 case MCSA_LazyReference:
93 case MCSA_Reference:
94 case MCSA_SymbolResolver:
95 case MCSA_PrivateExtern:
96 case MCSA_WeakDefinition:
97 case MCSA_WeakDefAutoPrivate:
98 case MCSA_Invalid:
99 case MCSA_IndirectSymbol:
100 case MCSA_Protected:
101 return false;
102
103 case MCSA_Hidden:
104 Symbol->setHidden(true);
105 break;
106
107 case MCSA_Weak:
108 case MCSA_WeakReference:
109 Symbol->setWeak(true);
110 Symbol->setExternal(true);
111 break;
112
113 case MCSA_Global:
114 Symbol->setExternal(true);
115 break;
116
117 case MCSA_ELF_TypeFunction:
118 Symbol->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
119 break;
120
121 case MCSA_ELF_TypeObject:
122 Symbol->setType(wasm::WASM_SYMBOL_TYPE_DATA);
123 break;
124
125 default:
126 // unrecognized directive
127 llvm_unreachable("unexpected MCSymbolAttr");
128 return false;
129 }
130
131 return true;
132 }
133
EmitCommonSymbol(MCSymbol * S,uint64_t Size,unsigned ByteAlignment)134 void MCWasmStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
135 unsigned ByteAlignment) {
136 llvm_unreachable("Common symbols are not yet implemented for Wasm");
137 }
138
emitELFSize(MCSymbol * Symbol,const MCExpr * Value)139 void MCWasmStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
140 cast<MCSymbolWasm>(Symbol)->setSize(Value);
141 }
142
EmitLocalCommonSymbol(MCSymbol * S,uint64_t Size,unsigned ByteAlignment)143 void MCWasmStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
144 unsigned ByteAlignment) {
145 llvm_unreachable("Local common symbols are not yet implemented for Wasm");
146 }
147
EmitValueImpl(const MCExpr * Value,unsigned Size,SMLoc Loc)148 void MCWasmStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
149 SMLoc Loc) {
150 MCObjectStreamer::EmitValueImpl(Value, Size, Loc);
151 }
152
EmitValueToAlignment(unsigned ByteAlignment,int64_t Value,unsigned ValueSize,unsigned MaxBytesToEmit)153 void MCWasmStreamer::EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
154 unsigned ValueSize,
155 unsigned MaxBytesToEmit) {
156 MCObjectStreamer::EmitValueToAlignment(ByteAlignment, Value, ValueSize,
157 MaxBytesToEmit);
158 }
159
EmitIdent(StringRef IdentString)160 void MCWasmStreamer::EmitIdent(StringRef IdentString) {
161 // TODO(sbc): Add the ident section once we support mergable strings
162 // sections in the object format
163 }
164
EmitInstToFragment(const MCInst & Inst,const MCSubtargetInfo & STI)165 void MCWasmStreamer::EmitInstToFragment(const MCInst &Inst,
166 const MCSubtargetInfo &STI) {
167 this->MCObjectStreamer::EmitInstToFragment(Inst, STI);
168 }
169
EmitInstToData(const MCInst & Inst,const MCSubtargetInfo & STI)170 void MCWasmStreamer::EmitInstToData(const MCInst &Inst,
171 const MCSubtargetInfo &STI) {
172 MCAssembler &Assembler = getAssembler();
173 SmallVector<MCFixup, 4> Fixups;
174 SmallString<256> Code;
175 raw_svector_ostream VecOS(Code);
176 Assembler.getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
177
178 // Append the encoded instruction to the current data fragment (or create a
179 // new such fragment if the current fragment is not a data fragment).
180 MCDataFragment *DF = getOrCreateDataFragment();
181
182 // Add the fixups and data.
183 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
184 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
185 DF->getFixups().push_back(Fixups[i]);
186 }
187 DF->setHasInstructions(STI);
188 DF->getContents().append(Code.begin(), Code.end());
189 }
190
FinishImpl()191 void MCWasmStreamer::FinishImpl() {
192 EmitFrames(nullptr);
193
194 this->MCObjectStreamer::FinishImpl();
195 }
196
createWasmStreamer(MCContext & Context,std::unique_ptr<MCAsmBackend> && MAB,std::unique_ptr<MCObjectWriter> && OW,std::unique_ptr<MCCodeEmitter> && CE,bool RelaxAll)197 MCStreamer *llvm::createWasmStreamer(MCContext &Context,
198 std::unique_ptr<MCAsmBackend> &&MAB,
199 std::unique_ptr<MCObjectWriter> &&OW,
200 std::unique_ptr<MCCodeEmitter> &&CE,
201 bool RelaxAll) {
202 MCWasmStreamer *S =
203 new MCWasmStreamer(Context, std::move(MAB), std::move(OW), std::move(CE));
204 if (RelaxAll)
205 S->getAssembler().setRelaxAll(true);
206 return S;
207 }
208
EmitThumbFunc(MCSymbol * Func)209 void MCWasmStreamer::EmitThumbFunc(MCSymbol *Func) {
210 llvm_unreachable("Generic Wasm doesn't support this directive");
211 }
212
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)213 void MCWasmStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
214 llvm_unreachable("Wasm doesn't support this directive");
215 }
216
EmitZerofill(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment,SMLoc Loc)217 void MCWasmStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
218 uint64_t Size, unsigned ByteAlignment,
219 SMLoc Loc) {
220 llvm_unreachable("Wasm doesn't support this directive");
221 }
222
EmitTBSSSymbol(MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)223 void MCWasmStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
224 uint64_t Size, unsigned ByteAlignment) {
225 llvm_unreachable("Wasm doesn't support this directive");
226 }
227