xref: /freebsd/contrib/llvm-project/llvm/lib/MC/MCWasmStreamer.cpp (revision cfd6422a5217410fbd66f7a7a8a64d9d85e61229)
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 
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 
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 
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 
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 
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 
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 
142 void MCWasmStreamer::emitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
143   cast<MCSymbolWasm>(Symbol)->setSize(Value);
144 }
145 
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 
151 void MCWasmStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,
152                                    SMLoc Loc) {
153   MCObjectStreamer::emitValueImpl(Value, Size, Loc);
154 }
155 
156 void MCWasmStreamer::emitValueToAlignment(unsigned ByteAlignment, int64_t Value,
157                                           unsigned ValueSize,
158                                           unsigned MaxBytesToEmit) {
159   MCObjectStreamer::emitValueToAlignment(ByteAlignment, Value, ValueSize,
160                                          MaxBytesToEmit);
161 }
162 
163 void MCWasmStreamer::emitIdent(StringRef IdentString) {
164   // TODO(sbc): Add the ident section once we support mergable strings
165   // sections in the object format
166 }
167 
168 void MCWasmStreamer::emitInstToFragment(const MCInst &Inst,
169                                         const MCSubtargetInfo &STI) {
170   this->MCObjectStreamer::emitInstToFragment(Inst, STI);
171 }
172 
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);
180 
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();
184 
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]);
189   }
190   DF->setHasInstructions(STI);
191   DF->getContents().append(Code.begin(), Code.end());
192 }
193 
194 void MCWasmStreamer::finishImpl() {
195   emitFrames(nullptr);
196 
197   this->MCObjectStreamer::finishImpl();
198 }
199 
200 MCStreamer *llvm::createWasmStreamer(MCContext &Context,
201                                      std::unique_ptr<MCAsmBackend> &&MAB,
202                                      std::unique_ptr<MCObjectWriter> &&OW,
203                                      std::unique_ptr<MCCodeEmitter> &&CE,
204                                      bool RelaxAll) {
205   MCWasmStreamer *S =
206       new MCWasmStreamer(Context, std::move(MAB), std::move(OW), std::move(CE));
207   if (RelaxAll)
208     S->getAssembler().setRelaxAll(true);
209   return S;
210 }
211 
212 void MCWasmStreamer::emitThumbFunc(MCSymbol *Func) {
213   llvm_unreachable("Generic Wasm doesn't support this directive");
214 }
215 
216 void MCWasmStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
217   llvm_unreachable("Wasm doesn't support this directive");
218 }
219 
220 void MCWasmStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
221                                   uint64_t Size, unsigned ByteAlignment,
222                                   SMLoc Loc) {
223   llvm_unreachable("Wasm doesn't support this directive");
224 }
225 
226 void MCWasmStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
227                                     uint64_t Size, unsigned ByteAlignment) {
228   llvm_unreachable("Wasm doesn't support this directive");
229 }
230