1 //===-- WebAssemblyAsmPrinter.cpp - WebAssembly LLVM assembly writer ------===//
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 /// \file
11 /// This file contains a printer that converts from our internal
12 /// representation of machine-dependent LLVM code to the WebAssembly assembly
13 /// language.
14 ///
15 //===----------------------------------------------------------------------===//
16
17 #include "WebAssemblyAsmPrinter.h"
18 #include "InstPrinter/WebAssemblyInstPrinter.h"
19 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
20 #include "MCTargetDesc/WebAssemblyTargetStreamer.h"
21 #include "WebAssembly.h"
22 #include "WebAssemblyMCInstLower.h"
23 #include "WebAssemblyMachineFunctionInfo.h"
24 #include "WebAssemblyRegisterInfo.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/CodeGen/Analysis.h"
27 #include "llvm/CodeGen/AsmPrinter.h"
28 #include "llvm/CodeGen/MachineConstantPool.h"
29 #include "llvm/CodeGen/MachineInstr.h"
30 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
31 #include "llvm/IR/DataLayout.h"
32 #include "llvm/IR/GlobalVariable.h"
33 #include "llvm/MC/MCContext.h"
34 #include "llvm/MC/MCSectionWasm.h"
35 #include "llvm/MC/MCStreamer.h"
36 #include "llvm/MC/MCSymbol.h"
37 #include "llvm/MC/MCSymbolWasm.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/TargetRegistry.h"
40 #include "llvm/Support/raw_ostream.h"
41 using namespace llvm;
42
43 #define DEBUG_TYPE "asm-printer"
44
45 //===----------------------------------------------------------------------===//
46 // Helpers.
47 //===----------------------------------------------------------------------===//
48
getRegType(unsigned RegNo) const49 MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
50 const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
51 const TargetRegisterClass *TRC = MRI->getRegClass(RegNo);
52 for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
53 MVT::v4i32, MVT::v2i64, MVT::v4f32, MVT::v2f64})
54 if (TRI->isTypeLegalForClass(*TRC, T))
55 return T;
56 LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
57 llvm_unreachable("Unknown register type");
58 return MVT::Other;
59 }
60
regToString(const MachineOperand & MO)61 std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
62 unsigned RegNo = MO.getReg();
63 assert(TargetRegisterInfo::isVirtualRegister(RegNo) &&
64 "Unlowered physical register encountered during assembly printing");
65 assert(!MFI->isVRegStackified(RegNo));
66 unsigned WAReg = MFI->getWAReg(RegNo);
67 assert(WAReg != WebAssemblyFunctionInfo::UnusedReg);
68 return '$' + utostr(WAReg);
69 }
70
getTargetStreamer()71 WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
72 MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
73 return static_cast<WebAssemblyTargetStreamer *>(TS);
74 }
75
76 //===----------------------------------------------------------------------===//
77 // WebAssemblyAsmPrinter Implementation.
78 //===----------------------------------------------------------------------===//
79
EmitEndOfAsmFile(Module & M)80 void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
81 for (auto &It : OutContext.getSymbols()) {
82 // Emit a .globaltype and .eventtype declaration.
83 auto Sym = cast<MCSymbolWasm>(It.getValue());
84 if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_GLOBAL)
85 getTargetStreamer()->emitGlobalType(Sym);
86 else if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_EVENT)
87 getTargetStreamer()->emitEventType(Sym);
88 }
89
90 for (const auto &F : M) {
91 // Emit function type info for all undefined functions
92 if (F.isDeclarationForLinker() && !F.isIntrinsic()) {
93 SmallVector<MVT, 4> Results;
94 SmallVector<MVT, 4> Params;
95 ComputeSignatureVTs(F.getFunctionType(), F, TM, Params, Results);
96 auto *Sym = cast<MCSymbolWasm>(getSymbol(&F));
97 Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
98 if (!Sym->getSignature()) {
99 auto Signature = SignatureFromMVTs(Results, Params);
100 Sym->setSignature(Signature.get());
101 addSignature(std::move(Signature));
102 }
103 // FIXME: this was originally intended for post-linking and was only used
104 // for imports that were only called indirectly (i.e. s2wasm could not
105 // infer the type from a call). With object files it applies to all
106 // imports. so fix the names and the tests, or rethink how import
107 // delcarations work in asm files.
108 getTargetStreamer()->emitFunctionType(Sym);
109
110 if (TM.getTargetTriple().isOSBinFormatWasm() &&
111 F.hasFnAttribute("wasm-import-module")) {
112 StringRef Name =
113 F.getFnAttribute("wasm-import-module").getValueAsString();
114 Sym->setImportModule(Name);
115 getTargetStreamer()->emitImportModule(Sym, Name);
116 }
117 if (TM.getTargetTriple().isOSBinFormatWasm() &&
118 F.hasFnAttribute("wasm-import-name")) {
119 StringRef Name =
120 F.getFnAttribute("wasm-import-name").getValueAsString();
121 Sym->setImportName(Name);
122 getTargetStreamer()->emitImportName(Sym, Name);
123 }
124 }
125 }
126
127 for (const auto &G : M.globals()) {
128 if (!G.hasInitializer() && G.hasExternalLinkage()) {
129 if (G.getValueType()->isSized()) {
130 uint16_t Size = M.getDataLayout().getTypeAllocSize(G.getValueType());
131 OutStreamer->emitELFSize(getSymbol(&G),
132 MCConstantExpr::create(Size, OutContext));
133 }
134 }
135 }
136
137 if (const NamedMDNode *Named = M.getNamedMetadata("wasm.custom_sections")) {
138 for (const Metadata *MD : Named->operands()) {
139 const MDTuple *Tuple = dyn_cast<MDTuple>(MD);
140 if (!Tuple || Tuple->getNumOperands() != 2)
141 continue;
142 const MDString *Name = dyn_cast<MDString>(Tuple->getOperand(0));
143 const MDString *Contents = dyn_cast<MDString>(Tuple->getOperand(1));
144 if (!Name || !Contents)
145 continue;
146
147 OutStreamer->PushSection();
148 std::string SectionName = (".custom_section." + Name->getString()).str();
149 MCSectionWasm *mySection =
150 OutContext.getWasmSection(SectionName, SectionKind::getMetadata());
151 OutStreamer->SwitchSection(mySection);
152 OutStreamer->EmitBytes(Contents->getString());
153 OutStreamer->PopSection();
154 }
155 }
156 }
157
EmitConstantPool()158 void WebAssemblyAsmPrinter::EmitConstantPool() {
159 assert(MF->getConstantPool()->getConstants().empty() &&
160 "WebAssembly disables constant pools");
161 }
162
EmitJumpTableInfo()163 void WebAssemblyAsmPrinter::EmitJumpTableInfo() {
164 // Nothing to do; jump tables are incorporated into the instruction stream.
165 }
166
EmitFunctionBodyStart()167 void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
168 const Function &F = MF->getFunction();
169 SmallVector<MVT, 1> ResultVTs;
170 SmallVector<MVT, 4> ParamVTs;
171 ComputeSignatureVTs(F.getFunctionType(), F, TM, ParamVTs, ResultVTs);
172 auto Signature = SignatureFromMVTs(ResultVTs, ParamVTs);
173 auto *WasmSym = cast<MCSymbolWasm>(CurrentFnSym);
174 WasmSym->setSignature(Signature.get());
175 addSignature(std::move(Signature));
176 WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
177
178 // FIXME: clean up how params and results are emitted (use signatures)
179 getTargetStreamer()->emitFunctionType(WasmSym);
180
181 // Emit the function index.
182 if (MDNode *Idx = F.getMetadata("wasm.index")) {
183 assert(Idx->getNumOperands() == 1);
184
185 getTargetStreamer()->emitIndIdx(AsmPrinter::lowerConstant(
186 cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
187 }
188
189 SmallVector<wasm::ValType, 16> Locals;
190 ValTypesFromMVTs(MFI->getLocals(), Locals);
191 getTargetStreamer()->emitLocal(Locals);
192
193 AsmPrinter::EmitFunctionBodyStart();
194 }
195
EmitInstruction(const MachineInstr * MI)196 void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
197 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
198
199 switch (MI->getOpcode()) {
200 case WebAssembly::ARGUMENT_i32:
201 case WebAssembly::ARGUMENT_i32_S:
202 case WebAssembly::ARGUMENT_i64:
203 case WebAssembly::ARGUMENT_i64_S:
204 case WebAssembly::ARGUMENT_f32:
205 case WebAssembly::ARGUMENT_f32_S:
206 case WebAssembly::ARGUMENT_f64:
207 case WebAssembly::ARGUMENT_f64_S:
208 case WebAssembly::ARGUMENT_v16i8:
209 case WebAssembly::ARGUMENT_v16i8_S:
210 case WebAssembly::ARGUMENT_v8i16:
211 case WebAssembly::ARGUMENT_v8i16_S:
212 case WebAssembly::ARGUMENT_v4i32:
213 case WebAssembly::ARGUMENT_v4i32_S:
214 case WebAssembly::ARGUMENT_v2i64:
215 case WebAssembly::ARGUMENT_v2i64_S:
216 case WebAssembly::ARGUMENT_v4f32:
217 case WebAssembly::ARGUMENT_v4f32_S:
218 case WebAssembly::ARGUMENT_v2f64:
219 case WebAssembly::ARGUMENT_v2f64_S:
220 // These represent values which are live into the function entry, so there's
221 // no instruction to emit.
222 break;
223 case WebAssembly::FALLTHROUGH_RETURN_I32:
224 case WebAssembly::FALLTHROUGH_RETURN_I32_S:
225 case WebAssembly::FALLTHROUGH_RETURN_I64:
226 case WebAssembly::FALLTHROUGH_RETURN_I64_S:
227 case WebAssembly::FALLTHROUGH_RETURN_F32:
228 case WebAssembly::FALLTHROUGH_RETURN_F32_S:
229 case WebAssembly::FALLTHROUGH_RETURN_F64:
230 case WebAssembly::FALLTHROUGH_RETURN_F64_S:
231 case WebAssembly::FALLTHROUGH_RETURN_v16i8:
232 case WebAssembly::FALLTHROUGH_RETURN_v16i8_S:
233 case WebAssembly::FALLTHROUGH_RETURN_v8i16:
234 case WebAssembly::FALLTHROUGH_RETURN_v8i16_S:
235 case WebAssembly::FALLTHROUGH_RETURN_v4i32:
236 case WebAssembly::FALLTHROUGH_RETURN_v4i32_S:
237 case WebAssembly::FALLTHROUGH_RETURN_v2i64:
238 case WebAssembly::FALLTHROUGH_RETURN_v2i64_S:
239 case WebAssembly::FALLTHROUGH_RETURN_v4f32:
240 case WebAssembly::FALLTHROUGH_RETURN_v4f32_S:
241 case WebAssembly::FALLTHROUGH_RETURN_v2f64:
242 case WebAssembly::FALLTHROUGH_RETURN_v2f64_S: {
243 // These instructions represent the implicit return at the end of a
244 // function body. Always pops one value off the stack.
245 if (isVerbose()) {
246 OutStreamer->AddComment("fallthrough-return-value");
247 OutStreamer->AddBlankLine();
248 }
249 break;
250 }
251 case WebAssembly::FALLTHROUGH_RETURN_VOID:
252 case WebAssembly::FALLTHROUGH_RETURN_VOID_S:
253 // This instruction represents the implicit return at the end of a
254 // function body with no return value.
255 if (isVerbose()) {
256 OutStreamer->AddComment("fallthrough-return-void");
257 OutStreamer->AddBlankLine();
258 }
259 break;
260 default: {
261 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
262 MCInst TmpInst;
263 MCInstLowering.Lower(MI, TmpInst);
264 EmitToStreamer(*OutStreamer, TmpInst);
265 break;
266 }
267 }
268 }
269
lowerConstant(const Constant * CV)270 const MCExpr *WebAssemblyAsmPrinter::lowerConstant(const Constant *CV) {
271 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
272 if (GV->getValueType()->isFunctionTy()) {
273 return MCSymbolRefExpr::create(
274 getSymbol(GV), MCSymbolRefExpr::VK_WebAssembly_FUNCTION, OutContext);
275 }
276 return AsmPrinter::lowerConstant(CV);
277 }
278
PrintAsmOperand(const MachineInstr * MI,unsigned OpNo,unsigned AsmVariant,const char * ExtraCode,raw_ostream & OS)279 bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
280 unsigned OpNo, unsigned AsmVariant,
281 const char *ExtraCode,
282 raw_ostream &OS) {
283 if (AsmVariant != 0)
284 report_fatal_error("There are no defined alternate asm variants");
285
286 // First try the generic code, which knows about modifiers like 'c' and 'n'.
287 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, OS))
288 return false;
289
290 if (!ExtraCode) {
291 const MachineOperand &MO = MI->getOperand(OpNo);
292 switch (MO.getType()) {
293 case MachineOperand::MO_Immediate:
294 OS << MO.getImm();
295 return false;
296 case MachineOperand::MO_Register:
297 // FIXME: only opcode that still contains registers, as required by
298 // MachineInstr::getDebugVariable().
299 assert(MI->getOpcode() == WebAssembly::INLINEASM);
300 OS << regToString(MO);
301 return false;
302 case MachineOperand::MO_GlobalAddress:
303 getSymbol(MO.getGlobal())->print(OS, MAI);
304 printOffset(MO.getOffset(), OS);
305 return false;
306 case MachineOperand::MO_ExternalSymbol:
307 GetExternalSymbolSymbol(MO.getSymbolName())->print(OS, MAI);
308 printOffset(MO.getOffset(), OS);
309 return false;
310 case MachineOperand::MO_MachineBasicBlock:
311 MO.getMBB()->getSymbol()->print(OS, MAI);
312 return false;
313 default:
314 break;
315 }
316 }
317
318 return true;
319 }
320
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNo,unsigned AsmVariant,const char * ExtraCode,raw_ostream & OS)321 bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
322 unsigned OpNo,
323 unsigned AsmVariant,
324 const char *ExtraCode,
325 raw_ostream &OS) {
326 if (AsmVariant != 0)
327 report_fatal_error("There are no defined alternate asm variants");
328
329 // The current approach to inline asm is that "r" constraints are expressed
330 // as local indices, rather than values on the operand stack. This simplifies
331 // using "r" as it eliminates the need to push and pop the values in a
332 // particular order, however it also makes it impossible to have an "m"
333 // constraint. So we don't support it.
334
335 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, AsmVariant, ExtraCode, OS);
336 }
337
338 // Force static initialization.
LLVMInitializeWebAssemblyAsmPrinter()339 extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
340 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
341 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
342 }
343