handler-table-builder.h

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// Copyright 2016 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.
 
#ifndef V8_INTERPRETER_HANDLER_TABLE_BUILDER_H_
#define V8_INTERPRETER_HANDLER_TABLE_BUILDER_H_
 
#include "src/codegen/handler-table.h"
#include "src/interpreter/bytecode-register.h"
#include "src/objects/fixed-array.h"
#include "src/zone/zone-containers.h"
 
namespace v8 {
namespace internal {
 
class HandlerTable;
 
namespace interpreter {
 
// A helper class for constructing exception handler tables for the interpreter.
class V8_EXPORT_PRIVATE HandlerTableBuilder final {
 public:
  explicit HandlerTableBuilder(Zone* zone);
  HandlerTableBuilder(const HandlerTableBuilder&) = delete;
  HandlerTableBuilder& operator=(const HandlerTableBuilder&) = delete;
 
  // Builds the actual handler table by copying the current values into a heap
  // object. Any further mutations to the builder won't be reflected.
  template <typename IsolateT>
  DirectHandle<TrustedByteArray> ToHandlerTable(IsolateT* isolate);
 
  // Creates a new handler table entry and returns a {hander_id} identifying the
  // entry, so that it can be referenced by below setter functions.
  int NewHandlerEntry();
 
  // Setter functions that modify certain values within the handler table entry
  // being referenced by the given {handler_id}. All values will be encoded by
  // the resulting {HandlerTable} class when copied into the heap.
  void SetTryRegionStart(int handler_id, size_t offset);
  void SetTryRegionEnd(int handler_id, size_t offset);
  void SetHandlerTarget(int handler_id, size_t offset);
  void SetPrediction(int handler_id, HandlerTable::CatchPrediction prediction);
  void SetContextRegister(int handler_id, Register reg);
 
 private:
  struct Entry {
    size_t offset_start;   // Bytecode offset starting try-region.
    size_t offset_end;     // Bytecode offset ending try-region.
    size_t offset_target;  // Bytecode offset of handler target.
    Register context;      // Register holding context for handler.
                           // Optimistic prediction for handler.
    HandlerTable::CatchPrediction catch_prediction_;
  };
 
  ZoneVector<Entry> entries_;
};
 
}  // namespace interpreter
}  // namespace internal
}  // namespace v8
 
#endif  // V8_INTERPRETER_HANDLER_TABLE_BUILDER_H_