Initial import of v8-native WASM.

src/wasm/encoder.cc

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/signature.h"
+
+#include "src/handles.h"
+#include "src/v8.h"
+#include "src/zone-containers.h"
+
+#include "src/wasm/ast-decoder.h"
+#include "src/wasm/encoder.h"
+#include "src/wasm/wasm-module.h"
+#include "src/wasm/wasm-opcodes.h"
+
+#include "src/v8memory.h"
+
+namespace v8 {
+namespace internal {
+namespace wasm {
+
+/*TODO: add error cases for adding too many locals, too many functions and bad
+  indices in body */
+
+namespace {
+void EmitUint8(byte** b, uint8_t x) {
+  Memory::uint8_at(*b) = x;
+  *b += 1;
+}
+
+
+void EmitUint16(byte** b, uint16_t x) {
+  Memory::uint16_at(*b) = x;
+  *b += 2;
+}
+
+
+void EmitUint32(byte** b, uint32_t x) {
+  Memory::uint32_at(*b) = x;
+  *b += 4;
+}
+
+
+void EmitVarInt(byte** b, size_t val) {
+  while (true) {
+    size_t next = val >> 7;
+    byte out = static_cast<byte>(val & 0x7f);
+    if (next) {
+      *((*b)++) = 0x80 | out;
+      val = next;
+    } else {
+      *((*b)++) = out;
+      break;
+    }
+  }
+}
+}  // namespace
+
+
+struct WasmFunctionBuilder::Type {
+  bool param_;
+  LocalType type_;
+};
+
+
+WasmFunctionBuilder::WasmFunctionBuilder(Zone* zone, const unsigned char* name,
+                                         int name_length)
+    : return_type_(kAstI32),
+      locals_(zone),
+      exported_(0),
+      external_(0),
+      body_(zone),
+      local_indices_(zone),
+      name_(zone) {
+  if (name_length > 0) {
+    for (int i = 0; i < name_length; i++) {
+      name_.push_back(*(name + i));
+    }
+    name_.push_back('\0');
+  }
+}
+
+
+uint16_t WasmFunctionBuilder::AddParam(LocalType type) {
+  return AddVar(type, true);
+}
+
+
+uint16_t WasmFunctionBuilder::AddLocal(LocalType type) {
+  return AddVar(type, false);
+}
+
+
+uint16_t WasmFunctionBuilder::AddVar(LocalType type, bool param) {
+  locals_.push_back({param, type});
+  return static_cast<uint16_t>(locals_.size() - 1);
+}
+
+
+void WasmFunctionBuilder::ReturnType(LocalType type) { return_type_ = type; }
+
+
+void WasmFunctionBuilder::EmitCode(const byte* code, uint32_t code_size) {
+  EmitCode(code, code_size, NULL, 0);
+}
+
+
+void WasmFunctionBuilder::EmitCode(const byte* code, uint32_t code_size,
+                                   const uint32_t* local_indices,
+                                   uint32_t indices_size) {
+  size_t size = body_.size();
+  for (size_t i = 0; i < code_size; i++) {
+    body_.push_back(code[i]);
+  }
+  for (size_t i = 0; i < indices_size; i++) {
+    local_indices_.push_back(local_indices[i] + static_cast<uint32_t>(size));
+  }
+}
+
+
+void WasmFunctionBuilder::Emit(WasmOpcode opcode) {
+  body_.push_back(static_cast<byte>(opcode));
+}
+
+
+void WasmFunctionBuilder::EmitWithU8(WasmOpcode opcode, const byte immediate) {
+  body_.push_back(static_cast<byte>(opcode));
+  body_.push_back(immediate);
+}
+
+
+void WasmFunctionBuilder::EmitWithLocal(WasmOpcode opcode) {
+  body_.push_back(static_cast<byte>(opcode));
+  local_indices_.push_back(static_cast<uint32_t>(body_.size()) - 1);
+}
+
+
+uint32_t WasmFunctionBuilder::EmitEditableImmediate(const byte immediate) {
+  body_.push_back(immediate);
+  return static_cast<uint32_t>(body_.size()) - 1;
+}
+
+
+void WasmFunctionBuilder::EditImmediate(uint32_t offset, const byte immediate) {
+  DCHECK(offset < body_.size());
+  body_[offset] = immediate;
+}
+
+
+void WasmFunctionBuilder::Exported(uint8_t flag) { exported_ = flag; }
+
+
+void WasmFunctionBuilder::External(uint8_t flag) { external_ = flag; }
+
+
+WasmFunctionEncoder* WasmFunctionBuilder::Build(Zone* zone,
+                                                WasmModuleBuilder* mb) const {
+  WasmFunctionEncoder* e =
+      new (zone) WasmFunctionEncoder(zone, return_type_, exported_, external_);
+  auto var_index = new uint16_t[locals_.size()];
+  IndexVars(e, var_index);
+  const byte* start = body_.data();
+  const byte* end = start + body_.size();
+  size_t local_index = 0;
+  for (size_t i = 0; i < body_.size();) {
+    if (local_index < local_indices_.size() &&
+        i == local_indices_[local_index]) {
+      int length = 0;
+      uint32_t index;
+      ReadUnsignedLEB128Operand(start + i, end, &length, &index);
+      uint16_t new_index = var_index[index];
+      const std::vector<uint8_t>& index_vec = UnsignedLEB128From(new_index);
+      for (size_t j = 0; j < index_vec.size(); j++) {
+        e->body_.push_back(index_vec.at(j));
+      }
+      i += length;
+      local_index++;
+    } else {
+      e->body_.push_back(*(start + i));
+      i++;
+    }
+  }
+  FunctionSig::Builder sig(zone, return_type_ == kAstStmt ? 0 : 1,
+                           e->params_.size());
+  if (return_type_ != kAstStmt) {
+    sig.AddReturn(static_cast<LocalType>(return_type_));
+  }
+  for (size_t i = 0; i < e->params_.size(); i++) {
+    sig.AddParam(static_cast<LocalType>(e->params_[i]));
+  }
+  e->signature_index_ = mb->AddSignature(sig.Build());
+  delete[] var_index;
+  e->name_.insert(e->name_.begin(), name_.begin(), name_.end());
+  return e;
+}
+
+
+void WasmFunctionBuilder::IndexVars(WasmFunctionEncoder* e,
+                                    uint16_t* var_index) const {
+  uint16_t param = 0;
+  uint16_t int32 = 0;
+  uint16_t int64 = 0;
+  uint16_t float32 = 0;
+  uint16_t float64 = 0;
+  for (size_t i = 0; i < locals_.size(); i++) {
+    if (locals_.at(i).param_) {
+      param++;
+    } else if (locals_.at(i).type_ == kAstI32) {
+      int32++;
+    } else if (locals_.at(i).type_ == kAstI64) {
+      int64++;
+    } else if (locals_.at(i).type_ == kAstF32) {
+      float32++;
+    } else if (locals_.at(i).type_ == kAstF64) {
+      float64++;
+    }
+  }
+  e->local_int32_count_ = int32;
+  e->local_int64_count_ = int64;
+  e->local_float32_count_ = float32;
+  e->local_float64_count_ = float64;
+  float64 = param + int32 + int64 + float32;
+  float32 = param + int32 + int64;
+  int64 = param + int32;
+  int32 = param;
+  param = 0;
+  for (size_t i = 0; i < locals_.size(); i++) {
+    if (locals_.at(i).param_) {
+      e->params_.push_back(locals_.at(i).type_);
+      var_index[i] = param++;
+    } else if (locals_.at(i).type_ == kAstI32) {
+      var_index[i] = int32++;
+    } else if (locals_.at(i).type_ == kAstI64) {
+      var_index[i] = int64++;
+    } else if (locals_.at(i).type_ == kAstF32) {
+      var_index[i] = float32++;
+    } else if (locals_.at(i).type_ == kAstF64) {
+      var_index[i] = float64++;
+    }
+  }
+}
+
+
+WasmFunctionEncoder::WasmFunctionEncoder(Zone* zone, LocalType return_type,
+                                         bool exported, bool external)
+    : params_(zone),
+      exported_(exported),
+      external_(external),
+      body_(zone),
+      name_(zone) {}
+
+
+uint32_t WasmFunctionEncoder::HeaderSize() const {
+  uint32_t size = 3;
+  if (HasLocals()) size += 8;
+  if (!external_) size += 2;
+  if (HasName()) size += 4;
+  return size;
+}
+
+
+uint32_t WasmFunctionEncoder::BodySize(void) const {
+  return external_ ? 0 : static_cast<uint32_t>(body_.size());
+}
+
+
+uint32_t WasmFunctionEncoder::NameSize() const {
+  return exported_ ? static_cast<uint32_t>(name_.size()) : 0;
+}
+
+
+void WasmFunctionEncoder::Serialize(byte* buffer, byte** header,
+                                    byte** body) const {
+  uint8_t decl_bits = (exported_ ? kDeclFunctionExport : 0) |
+                      (external_ ? kDeclFunctionImport : 0) |
+                      (HasLocals() ? kDeclFunctionLocals : 0) |
+                      (HasName() ? kDeclFunctionName : 0);
+
+  EmitUint8(header, decl_bits);
+  EmitUint16(header, signature_index_);
+
+  if (HasName()) {
+    uint32_t name_offset = static_cast<uint32_t>(*body - buffer);
+    EmitUint32(header, name_offset);
+    std::memcpy(*body, name_.data(), name_.size());
+    (*body) += name_.size();
+  }
+
+  if (HasLocals()) {
+    EmitUint16(header, local_int32_count_);
+    EmitUint16(header, local_int64_count_);
+    EmitUint16(header, local_float32_count_);
+    EmitUint16(header, local_float64_count_);
+  }
+
+  if (!external_) {
+    EmitUint16(header, static_cast<uint16_t>(body_.size()));
+    std::memcpy(*header, body_.data(), body_.size());
+    (*header) += body_.size();
+  }
+}
+
+
+WasmDataSegmentEncoder::WasmDataSegmentEncoder(Zone* zone, const byte* data,
+                                               uint32_t size, uint32_t dest)
+    : data_(zone), dest_(dest) {
+  for (size_t i = 0; i < size; i++) {
+    data_.push_back(data[i]);
+  }
+}
+
+
+uint32_t WasmDataSegmentEncoder::HeaderSize() const {
+  static const int kDataSegmentSize = 13;
+  return kDataSegmentSize;
+}
+
+
+uint32_t WasmDataSegmentEncoder::BodySize() const {
+  return static_cast<uint32_t>(data_.size());
+}
+
+
+void WasmDataSegmentEncoder::Serialize(byte* buffer, byte** header,
+                                       byte** body) const {
+  uint32_t body_offset = static_cast<uint32_t>(*body - buffer);
+  EmitUint32(header, dest_);
+  EmitUint32(header, body_offset);
+  EmitUint32(header, static_cast<uint32_t>(data_.size()));
+  EmitUint8(header, 1);  // init
+
+  std::memcpy(*body, data_.data(), data_.size());
+  (*body) += data_.size();
+}
+
+
+WasmModuleBuilder::WasmModuleBuilder(Zone* zone)
+    : zone_(zone),
+      signatures_(zone),
+      functions_(zone),
+      data_segments_(zone),
+      indirect_functions_(zone),
+      globals_(zone),
+      signature_map_(zone) {}
+
+
+uint16_t WasmModuleBuilder::AddFunction(const unsigned char* name,
+                                        int name_length) {
+  functions_.push_back(new (zone_)
+                           WasmFunctionBuilder(zone_, name, name_length));
+  return static_cast<uint16_t>(functions_.size() - 1);
+}
+
+
+WasmFunctionBuilder* WasmModuleBuilder::FunctionAt(size_t index) {
+  if (functions_.size() > index) {
+    return functions_.at(index);
+  } else {
+    return nullptr;
+  }
+}
+
+
+void WasmModuleBuilder::AddDataSegment(WasmDataSegmentEncoder* data) {
+  data_segments_.push_back(data);
+}
+
+
+int WasmModuleBuilder::CompareFunctionSigs::operator()(FunctionSig* a,
+                                                       FunctionSig* b) {
+  if (a->return_count() < b->return_count()) return -1;
+  if (a->return_count() > b->return_count()) return 1;
+  if (a->parameter_count() < b->parameter_count()) return -1;
+  if (a->parameter_count() > b->parameter_count()) return 1;
+  for (size_t r = 0; r < a->return_count(); r++) {
+    if (a->GetReturn(r) < b->GetReturn(r)) return -1;
+    if (a->GetReturn(r) > b->GetReturn(r)) return 1;
+  }
+  for (size_t p = 0; p < a->parameter_count(); p++) {
+    if (a->GetParam(p) < b->GetParam(p)) return -1;
+    if (a->GetParam(p) > b->GetParam(p)) return 1;
+  }
+  return 0;
+}
+
+
+uint16_t WasmModuleBuilder::AddSignature(FunctionSig* sig) {
+  SignatureMap::iterator pos = signature_map_.find(sig);
+  if (pos != signature_map_.end()) {
+    return pos->second;
+  } else {
+    uint16_t index = static_cast<uint16_t>(signatures_.size());
+    signature_map_[sig] = index;
+    signatures_.push_back(sig);
+    return index;
+  }
+}
+
+
+void WasmModuleBuilder::AddIndirectFunction(uint16_t index) {
+  indirect_functions_.push_back(index);
+}
+
+
+WasmModuleWriter* WasmModuleBuilder::Build(Zone* zone) {
+  WasmModuleWriter* writer = new (zone) WasmModuleWriter(zone);
+  for (auto function : functions_) {
+    writer->functions_.push_back(function->Build(zone, this));
+  }
+  for (auto segment : data_segments_) {
+    writer->data_segments_.push_back(segment);
+  }
+  for (auto sig : signatures_) {
+    writer->signatures_.push_back(sig);
+  }
+  for (auto index : indirect_functions_) {
+    writer->indirect_functions_.push_back(index);
+  }
+  for (auto global : globals_) {
+    writer->globals_.push_back(global);
+  }
+  return writer;
+}
+
+
+uint32_t WasmModuleBuilder::AddGlobal(MachineType type, bool exported) {
+  globals_.push_back(std::make_pair(type, exported));
+  return static_cast<uint32_t>(globals_.size() - 1);
+}
+
+
+WasmModuleWriter::WasmModuleWriter(Zone* zone)
+    : functions_(zone),
+      data_segments_(zone),
+      signatures_(zone),
+      indirect_functions_(zone),
+      globals_(zone) {}
+
+
+struct Sizes {
+  size_t header_size;
+  size_t body_size;
+
+  size_t total() { return header_size + body_size; }
+
+  void Add(size_t header, size_t body) {
+    header_size += header;
+    body_size += body;
+  }
+
+  void AddSection(size_t size) {
+    if (size > 0) {
+      Add(1, 0);
+      while (size > 0) {
+        Add(1, 0);
+        size = size >> 7;
+      }
+    }
+  }
+};
+
+
+WasmModuleIndex* WasmModuleWriter::WriteTo(Zone* zone) const {
+  Sizes sizes = {0, 0};
+
+  sizes.Add(1, 0);
+  sizes.Add(kDeclMemorySize, 0);
+
+  sizes.AddSection(signatures_.size());
+  for (auto sig : signatures_) {
+    sizes.Add(2 + sig->parameter_count(), 0);
+  }
+
+  sizes.AddSection(globals_.size());
+  if (globals_.size() > 0) {
+    sizes.Add(kDeclGlobalSize * globals_.size(), 0);
+  }
+
+  sizes.AddSection(functions_.size());
+  for (auto function : functions_) {
+    sizes.Add(function->HeaderSize() + function->BodySize(),
+              function->NameSize());
+  }
+
+  sizes.AddSection(data_segments_.size());
+  for (auto segment : data_segments_) {
+    sizes.Add(segment->HeaderSize(), segment->BodySize());
+  }
+
+  sizes.AddSection(indirect_functions_.size());
+  sizes.Add(2 * static_cast<uint32_t>(indirect_functions_.size()), 0);
+
+  if (sizes.body_size > 0) sizes.Add(1, 0);
+
+  ZoneVector<uint8_t> buffer_vector(sizes.total(), zone);
+  byte* buffer = buffer_vector.data();
+  byte* header = buffer;
+  byte* body = buffer + sizes.header_size;
+
+  // -- emit memory declaration ------------------------------------------------
+  EmitUint8(&header, kDeclMemory);
+  EmitUint8(&header, 16);  // min memory size
+  EmitUint8(&header, 16);  // max memory size
+  EmitUint8(&header, 0);   // memory export
+
+  // -- emit globals -----------------------------------------------------------
+  if (globals_.size() > 0) {
+    EmitUint8(&header, kDeclGlobals);
+    EmitVarInt(&header, globals_.size());
+
+    for (auto global : globals_) {
+      EmitUint32(&header, 0);
+      EmitUint8(&header, WasmOpcodes::MemTypeCodeFor(global.first));
+      EmitUint8(&header, global.second);
+    }
+  }
+
+  // -- emit signatures --------------------------------------------------------
+  if (signatures_.size() > 0) {
+    EmitUint8(&header, kDeclSignatures);
+    EmitVarInt(&header, signatures_.size());
+
+    for (FunctionSig* sig : signatures_) {
+      EmitUint8(&header, static_cast<byte>(sig->parameter_count()));
+      if (sig->return_count() > 0) {
+        EmitUint8(&header, WasmOpcodes::LocalTypeCodeFor(sig->GetReturn()));
+      } else {
+        EmitUint8(&header, kLocalVoid);
+      }
+      for (size_t j = 0; j < sig->parameter_count(); j++) {
+        EmitUint8(&header, WasmOpcodes::LocalTypeCodeFor(sig->GetParam(j)));
+      }
+    }
+  }
+
+  // -- emit functions ---------------------------------------------------------
+  if (functions_.size() > 0) {
+    EmitUint8(&header, kDeclFunctions);
+    EmitVarInt(&header, functions_.size());
+
+    for (auto func : functions_) {
+      func->Serialize(buffer, &header, &body);
+    }
+  }
+
+  // -- emit data segments -----------------------------------------------------
+  if (data_segments_.size() > 0) {
+    EmitUint8(&header, kDeclDataSegments);
+    EmitVarInt(&header, data_segments_.size());
+
+    for (auto segment : data_segments_) {
+      segment->Serialize(buffer, &header, &body);
+    }
+  }
+
+  // -- emit function table ----------------------------------------------------
+  if (indirect_functions_.size() > 0) {
+    EmitUint8(&header, kDeclFunctionTable);
+    EmitVarInt(&header, indirect_functions_.size());
+
+    for (auto index : indirect_functions_) {
+      EmitUint16(&header, index);
+    }
+  }
+
+  if (sizes.body_size > 0) EmitUint8(&header, kDeclEnd);
+
+  return new (zone) WasmModuleIndex(buffer, buffer + sizes.total());
+}
+
+
+std::vector<uint8_t> UnsignedLEB128From(uint32_t result) {
+  std::vector<uint8_t> output;
+  uint8_t next = 0;
+  int shift = 0;
+  do {
+    next = static_cast<uint8_t>(result >> shift);
+    if (((result >> shift) & 0xFFFFFF80) != 0) {
+      next = next | 0x80;
+    }
+    output.push_back(next);
+    shift += 7;
+  } while ((next & 0x80) != 0);
+  return output;
+}
+}  // namespace wasm
+}  // namespace internal
+}  // namespace v8