runtime/vm/compiler/frontend/bytecode_reader.h

// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#ifndef RUNTIME_VM_COMPILER_FRONTEND_BYTECODE_READER_H_
#define RUNTIME_VM_COMPILER_FRONTEND_BYTECODE_READER_H_

#include "vm/compiler/frontend/kernel_translation_helper.h"
#include "vm/constants_kbc.h"
#include "vm/object.h"

#if !defined(DART_PRECOMPILED_RUNTIME)

namespace dart {
namespace kernel {

// Helper class which provides access to bytecode metadata.
class BytecodeMetadataHelper : public MetadataHelper {
 public:
  static const char* tag() { return "vm.bytecode"; }

  explicit BytecodeMetadataHelper(KernelReaderHelper* helper,
                                  TypeTranslator* type_translator,
                                  ActiveClass* active_class);

  bool HasBytecode(intptr_t node_offset);

  void ReadMetadata(const Function& function);

 private:
  // Returns the index of the last read pool entry.
  intptr_t ReadPoolEntries(const Function& function,
                           const Function& inner_function,
                           const ObjectPool& pool,
                           intptr_t from_index);
  RawBytecode* ReadBytecode(const ObjectPool& pool);
  void ReadExceptionsTable(const Bytecode& bytecode, bool has_exceptions_table);
  void ReadSourcePositions(const Bytecode& bytecode, bool has_source_positions);
  RawTypedData* NativeEntry(const Function& function,
                            const String& external_name);

  TypeTranslator& type_translator_;
  ActiveClass* const active_class_;

  DISALLOW_COPY_AND_ASSIGN(BytecodeMetadataHelper);
};

class BytecodeReader : public AllStatic {
 public:
  // Reads bytecode for the given function and sets its bytecode field.
  // Returns error (if any), or null.
  static RawError* ReadFunctionBytecode(Thread* thread,
                                        const Function& function);
};

class BytecodeSourcePositionsIterator : ValueObject {
 public:
  BytecodeSourcePositionsIterator(Zone* zone, const Bytecode& bytecode)
      : reader_(ExternalTypedData::Handle(zone, bytecode.GetBinary(zone))),
        pairs_remaining_(0),
        cur_bci_(0),
        cur_token_pos_(TokenPosition::kNoSource.value()) {
    if (bytecode.HasSourcePositions()) {
      reader_.set_offset(bytecode.source_positions_binary_offset());
      pairs_remaining_ = reader_.ReadUInt();
    }
  }

  bool MoveNext() {
    if (pairs_remaining_ == 0) {
      return false;
    }
    ASSERT(pairs_remaining_ > 0);
    --pairs_remaining_;
    cur_bci_ += reader_.ReadUInt();
    cur_token_pos_ += reader_.ReadSLEB128();
    return true;
  }

  intptr_t BytecodeInstructionIndex() const { return cur_bci_; }

  uword PcOffset() const {
    return KernelBytecode::BytecodePcToOffset(BytecodeInstructionIndex(),
                                              /* is_return_address = */ true);
  }

  TokenPosition TokenPos() const { return TokenPosition(cur_token_pos_); }

 private:
  Reader reader_;
  intptr_t pairs_remaining_;
  intptr_t cur_bci_;
  intptr_t cur_token_pos_;
};

}  // namespace kernel
}  // namespace dart

#endif  // !defined(DART_PRECOMPILED_RUNTIME)
#endif  // RUNTIME_VM_COMPILER_FRONTEND_BYTECODE_READER_H_