llvm.org GIT mirror llvm / b29d4ba lib / Target / WebAssembly / WebAssemblyAsmPrinter.cpp
b29d4ba

Tree @b29d4ba (Download .tar.gz)

WebAssemblyAsmPrinter.cpp @b29d4baraw · history · blame

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
//===-- WebAssemblyAsmPrinter.cpp - WebAssembly LLVM assembly writer ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains a printer that converts from our internal
/// representation of machine-dependent LLVM code to the WebAssembly assembly
/// language.
///
//===----------------------------------------------------------------------===//

#include "WebAssemblyAsmPrinter.h"
#include "MCTargetDesc/WebAssemblyInstPrinter.h"
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "MCTargetDesc/WebAssemblyTargetStreamer.h"
#include "TargetInfo/WebAssemblyTargetInfo.h"
#include "WebAssembly.h"
#include "WebAssemblyMCInstLower.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblyRegisterInfo.h"
#include "WebAssemblyTargetMachine.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/BinaryFormat/Wasm.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Metadata.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSectionWasm.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolWasm.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"

using namespace llvm;

#define DEBUG_TYPE "asm-printer"

extern cl::opt<bool> WasmKeepRegisters;

//===----------------------------------------------------------------------===//
// Helpers.
//===----------------------------------------------------------------------===//

MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
  const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
  const TargetRegisterClass *TRC = MRI->getRegClass(RegNo);
  for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
                MVT::v4i32, MVT::v2i64, MVT::v4f32, MVT::v2f64})
    if (TRI->isTypeLegalForClass(*TRC, T))
      return T;
  LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
  llvm_unreachable("Unknown register type");
  return MVT::Other;
}

std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
  unsigned RegNo = MO.getReg();
  assert(TargetRegisterInfo::isVirtualRegister(RegNo) &&
         "Unlowered physical register encountered during assembly printing");
  assert(!MFI->isVRegStackified(RegNo));
  unsigned WAReg = MFI->getWAReg(RegNo);
  assert(WAReg != WebAssemblyFunctionInfo::UnusedReg);
  return '$' + utostr(WAReg);
}

WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
  MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
  return static_cast<WebAssemblyTargetStreamer *>(TS);
}

//===----------------------------------------------------------------------===//
// WebAssemblyAsmPrinter Implementation.
//===----------------------------------------------------------------------===//

void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
  for (auto &It : OutContext.getSymbols()) {
    // Emit a .globaltype and .eventtype declaration.
    auto Sym = cast<MCSymbolWasm>(It.getValue());
    if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_GLOBAL)
      getTargetStreamer()->emitGlobalType(Sym);
    else if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_EVENT)
      getTargetStreamer()->emitEventType(Sym);
  }

  for (const auto &F : M) {
    // Emit function type info for all undefined functions
    if (F.isDeclarationForLinker() && !F.isIntrinsic()) {
      SmallVector<MVT, 4> Results;
      SmallVector<MVT, 4> Params;
      computeSignatureVTs(F.getFunctionType(), F, TM, Params, Results);
      auto *Sym = cast<MCSymbolWasm>(getSymbol(&F));
      Sym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
      if (!Sym->getSignature()) {
        auto Signature = signatureFromMVTs(Results, Params);
        Sym->setSignature(Signature.get());
        addSignature(std::move(Signature));
      }
      // FIXME: this was originally intended for post-linking and was only used
      // for imports that were only called indirectly (i.e. s2wasm could not
      // infer the type from a call). With object files it applies to all
      // imports. so fix the names and the tests, or rethink how import
      // delcarations work in asm files.
      getTargetStreamer()->emitFunctionType(Sym);

      if (TM.getTargetTriple().isOSBinFormatWasm() &&
          F.hasFnAttribute("wasm-import-module")) {
        StringRef Name =
            F.getFnAttribute("wasm-import-module").getValueAsString();
        Sym->setImportModule(Name);
        getTargetStreamer()->emitImportModule(Sym, Name);
      }
      if (TM.getTargetTriple().isOSBinFormatWasm() &&
          F.hasFnAttribute("wasm-import-name")) {
        StringRef Name =
            F.getFnAttribute("wasm-import-name").getValueAsString();
        Sym->setImportName(Name);
        getTargetStreamer()->emitImportName(Sym, Name);
      }
    }
  }

  for (const auto &G : M.globals()) {
    if (!G.hasInitializer() && G.hasExternalLinkage()) {
      if (G.getValueType()->isSized()) {
        uint16_t Size = M.getDataLayout().getTypeAllocSize(G.getValueType());
        OutStreamer->emitELFSize(getSymbol(&G),
                                 MCConstantExpr::create(Size, OutContext));
      }
    }
  }

  if (const NamedMDNode *Named = M.getNamedMetadata("wasm.custom_sections")) {
    for (const Metadata *MD : Named->operands()) {
      const auto *Tuple = dyn_cast<MDTuple>(MD);
      if (!Tuple || Tuple->getNumOperands() != 2)
        continue;
      const MDString *Name = dyn_cast<MDString>(Tuple->getOperand(0));
      const MDString *Contents = dyn_cast<MDString>(Tuple->getOperand(1));
      if (!Name || !Contents)
        continue;

      OutStreamer->PushSection();
      std::string SectionName = (".custom_section." + Name->getString()).str();
      MCSectionWasm *MySection =
          OutContext.getWasmSection(SectionName, SectionKind::getMetadata());
      OutStreamer->SwitchSection(MySection);
      OutStreamer->EmitBytes(Contents->getString());
      OutStreamer->PopSection();
    }
  }

  EmitProducerInfo(M);
  EmitTargetFeatures(M);
}

void WebAssemblyAsmPrinter::EmitProducerInfo(Module &M) {
  llvm::SmallVector<std::pair<std::string, std::string>, 4> Languages;
  if (const NamedMDNode *Debug = M.getNamedMetadata("llvm.dbg.cu")) {
    llvm::SmallSet<StringRef, 4> SeenLanguages;
    for (size_t I = 0, E = Debug->getNumOperands(); I < E; ++I) {
      const auto *CU = cast<DICompileUnit>(Debug->getOperand(I));
      StringRef Language = dwarf::LanguageString(CU->getSourceLanguage());
      Language.consume_front("DW_LANG_");
      if (SeenLanguages.insert(Language).second)
        Languages.emplace_back(Language.str(), "");
    }
  }

  llvm::SmallVector<std::pair<std::string, std::string>, 4> Tools;
  if (const NamedMDNode *Ident = M.getNamedMetadata("llvm.ident")) {
    llvm::SmallSet<StringRef, 4> SeenTools;
    for (size_t I = 0, E = Ident->getNumOperands(); I < E; ++I) {
      const auto *S = cast<MDString>(Ident->getOperand(I)->getOperand(0));
      std::pair<StringRef, StringRef> Field = S->getString().split("version");
      StringRef Name = Field.first.trim();
      StringRef Version = Field.second.trim();
      if (SeenTools.insert(Name).second)
        Tools.emplace_back(Name.str(), Version.str());
    }
  }

  int FieldCount = int(!Languages.empty()) + int(!Tools.empty());
  if (FieldCount != 0) {
    MCSectionWasm *Producers = OutContext.getWasmSection(
        ".custom_section.producers", SectionKind::getMetadata());
    OutStreamer->PushSection();
    OutStreamer->SwitchSection(Producers);
    OutStreamer->EmitULEB128IntValue(FieldCount);
    for (auto &Producers : {std::make_pair("language", &Languages),
            std::make_pair("processed-by", &Tools)}) {
      if (Producers.second->empty())
        continue;
      OutStreamer->EmitULEB128IntValue(strlen(Producers.first));
      OutStreamer->EmitBytes(Producers.first);
      OutStreamer->EmitULEB128IntValue(Producers.second->size());
      for (auto &Producer : *Producers.second) {
        OutStreamer->EmitULEB128IntValue(Producer.first.size());
        OutStreamer->EmitBytes(Producer.first);
        OutStreamer->EmitULEB128IntValue(Producer.second.size());
        OutStreamer->EmitBytes(Producer.second);
      }
    }
    OutStreamer->PopSection();
  }
}

void WebAssemblyAsmPrinter::EmitTargetFeatures(Module &M) {
  struct FeatureEntry {
    uint8_t Prefix;
    StringRef Name;
  };

  // Read target features and linkage policies from module metadata
  SmallVector<FeatureEntry, 4> EmittedFeatures;
  for (const SubtargetFeatureKV &KV : WebAssemblyFeatureKV) {
    std::string MDKey = (StringRef("wasm-feature-") + KV.Key).str();
    Metadata *Policy = M.getModuleFlag(MDKey);
    if (Policy == nullptr)
      continue;

    FeatureEntry Entry;
    Entry.Prefix = 0;
    Entry.Name = KV.Key;

    if (auto *MD = cast<ConstantAsMetadata>(Policy))
      if (auto *I = cast<ConstantInt>(MD->getValue()))
        Entry.Prefix = I->getZExtValue();

    // Silently ignore invalid metadata
    if (Entry.Prefix != wasm::WASM_FEATURE_PREFIX_USED &&
        Entry.Prefix != wasm::WASM_FEATURE_PREFIX_REQUIRED &&
        Entry.Prefix != wasm::WASM_FEATURE_PREFIX_DISALLOWED)
      continue;

    EmittedFeatures.push_back(Entry);
  }

  if (EmittedFeatures.size() == 0)
    return;

  // Emit features and linkage policies into the "target_features" section
  MCSectionWasm *FeaturesSection = OutContext.getWasmSection(
      ".custom_section.target_features", SectionKind::getMetadata());
  OutStreamer->PushSection();
  OutStreamer->SwitchSection(FeaturesSection);

  OutStreamer->EmitULEB128IntValue(EmittedFeatures.size());
  for (auto &F : EmittedFeatures) {
    OutStreamer->EmitIntValue(F.Prefix, 1);
    OutStreamer->EmitULEB128IntValue(F.Name.size());
    OutStreamer->EmitBytes(F.Name);
  }

  OutStreamer->PopSection();
}

void WebAssemblyAsmPrinter::EmitConstantPool() {
  assert(MF->getConstantPool()->getConstants().empty() &&
         "WebAssembly disables constant pools");
}

void WebAssemblyAsmPrinter::EmitJumpTableInfo() {
  // Nothing to do; jump tables are incorporated into the instruction stream.
}

void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
  const Function &F = MF->getFunction();
  SmallVector<MVT, 1> ResultVTs;
  SmallVector<MVT, 4> ParamVTs;
  computeSignatureVTs(F.getFunctionType(), F, TM, ParamVTs, ResultVTs);
  auto Signature = signatureFromMVTs(ResultVTs, ParamVTs);
  auto *WasmSym = cast<MCSymbolWasm>(CurrentFnSym);
  WasmSym->setSignature(Signature.get());
  addSignature(std::move(Signature));
  WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);

  // FIXME: clean up how params and results are emitted (use signatures)
  getTargetStreamer()->emitFunctionType(WasmSym);

  // Emit the function index.
  if (MDNode *Idx = F.getMetadata("wasm.index")) {
    assert(Idx->getNumOperands() == 1);

    getTargetStreamer()->emitIndIdx(AsmPrinter::lowerConstant(
        cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
  }

  SmallVector<wasm::ValType, 16> Locals;
  valTypesFromMVTs(MFI->getLocals(), Locals);
  getTargetStreamer()->emitLocal(Locals);

  AsmPrinter::EmitFunctionBodyStart();
}

void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
  LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');

  switch (MI->getOpcode()) {
  case WebAssembly::ARGUMENT_i32:
  case WebAssembly::ARGUMENT_i32_S:
  case WebAssembly::ARGUMENT_i64:
  case WebAssembly::ARGUMENT_i64_S:
  case WebAssembly::ARGUMENT_f32:
  case WebAssembly::ARGUMENT_f32_S:
  case WebAssembly::ARGUMENT_f64:
  case WebAssembly::ARGUMENT_f64_S:
  case WebAssembly::ARGUMENT_v16i8:
  case WebAssembly::ARGUMENT_v16i8_S:
  case WebAssembly::ARGUMENT_v8i16:
  case WebAssembly::ARGUMENT_v8i16_S:
  case WebAssembly::ARGUMENT_v4i32:
  case WebAssembly::ARGUMENT_v4i32_S:
  case WebAssembly::ARGUMENT_v2i64:
  case WebAssembly::ARGUMENT_v2i64_S:
  case WebAssembly::ARGUMENT_v4f32:
  case WebAssembly::ARGUMENT_v4f32_S:
  case WebAssembly::ARGUMENT_v2f64:
  case WebAssembly::ARGUMENT_v2f64_S:
    // These represent values which are live into the function entry, so there's
    // no instruction to emit.
    break;
  case WebAssembly::FALLTHROUGH_RETURN_I32:
  case WebAssembly::FALLTHROUGH_RETURN_I32_S:
  case WebAssembly::FALLTHROUGH_RETURN_I64:
  case WebAssembly::FALLTHROUGH_RETURN_I64_S:
  case WebAssembly::FALLTHROUGH_RETURN_F32:
  case WebAssembly::FALLTHROUGH_RETURN_F32_S:
  case WebAssembly::FALLTHROUGH_RETURN_F64:
  case WebAssembly::FALLTHROUGH_RETURN_F64_S:
  case WebAssembly::FALLTHROUGH_RETURN_v16i8:
  case WebAssembly::FALLTHROUGH_RETURN_v16i8_S:
  case WebAssembly::FALLTHROUGH_RETURN_v8i16:
  case WebAssembly::FALLTHROUGH_RETURN_v8i16_S:
  case WebAssembly::FALLTHROUGH_RETURN_v4i32:
  case WebAssembly::FALLTHROUGH_RETURN_v4i32_S:
  case WebAssembly::FALLTHROUGH_RETURN_v2i64:
  case WebAssembly::FALLTHROUGH_RETURN_v2i64_S:
  case WebAssembly::FALLTHROUGH_RETURN_v4f32:
  case WebAssembly::FALLTHROUGH_RETURN_v4f32_S:
  case WebAssembly::FALLTHROUGH_RETURN_v2f64:
  case WebAssembly::FALLTHROUGH_RETURN_v2f64_S: {
    // These instructions represent the implicit return at the end of a
    // function body. Always pops one value off the stack.
    if (isVerbose()) {
      OutStreamer->AddComment("fallthrough-return-value");
      OutStreamer->AddBlankLine();
    }
    break;
  }
  case WebAssembly::FALLTHROUGH_RETURN_VOID:
  case WebAssembly::FALLTHROUGH_RETURN_VOID_S:
    // This instruction represents the implicit return at the end of a
    // function body with no return value.
    if (isVerbose()) {
      OutStreamer->AddComment("fallthrough-return-void");
      OutStreamer->AddBlankLine();
    }
    break;
  case WebAssembly::COMPILER_FENCE:
    // This is a compiler barrier that prevents instruction reordering during
    // backend compilation, and should not be emitted.
    break;
  case WebAssembly::EXTRACT_EXCEPTION_I32:
  case WebAssembly::EXTRACT_EXCEPTION_I32_S:
    // These are pseudo instructions that simulates popping values from stack.
    // We print these only when we have -wasm-keep-registers on for assembly
    // readability.
    if (!WasmKeepRegisters)
      break;
    LLVM_FALLTHROUGH;
  default: {
    WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
    MCInst TmpInst;
    MCInstLowering.lower(MI, TmpInst);
    EmitToStreamer(*OutStreamer, TmpInst);
    break;
  }
  }
}

bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
                                            unsigned OpNo,
                                            const char *ExtraCode,
                                            raw_ostream &OS) {
  // First try the generic code, which knows about modifiers like 'c' and 'n'.
  if (!AsmPrinter::PrintAsmOperand(MI, OpNo, ExtraCode, OS))
    return false;

  if (!ExtraCode) {
    const MachineOperand &MO = MI->getOperand(OpNo);
    switch (MO.getType()) {
    case MachineOperand::MO_Immediate:
      OS << MO.getImm();
      return false;
    case MachineOperand::MO_Register:
      // FIXME: only opcode that still contains registers, as required by
      // MachineInstr::getDebugVariable().
      assert(MI->getOpcode() == WebAssembly::INLINEASM);
      OS << regToString(MO);
      return false;
    case MachineOperand::MO_GlobalAddress:
      PrintSymbolOperand(MO, OS);
      return false;
    case MachineOperand::MO_ExternalSymbol:
      GetExternalSymbolSymbol(MO.getSymbolName())->print(OS, MAI);
      printOffset(MO.getOffset(), OS);
      return false;
    case MachineOperand::MO_MachineBasicBlock:
      MO.getMBB()->getSymbol()->print(OS, MAI);
      return false;
    default:
      break;
    }
  }

  return true;
}

bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
                                                  unsigned OpNo,
                                                  const char *ExtraCode,
                                                  raw_ostream &OS) {
  // The current approach to inline asm is that "r" constraints are expressed
  // as local indices, rather than values on the operand stack. This simplifies
  // using "r" as it eliminates the need to push and pop the values in a
  // particular order, however it also makes it impossible to have an "m"
  // constraint. So we don't support it.

  return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, ExtraCode, OS);
}

// Force static initialization.
extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
  RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
  RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());
}