[interpreter] Implement exception handler table building.

src/interpreter/handler-table-builder.h

+// 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/handles.h"
+#include "src/interpreter/bytecodes.h"
+#include "src/zone-containers.h"
+
+namespace v8 {
+namespace internal {
+
+class HandlerTable;
+class Isolate;
+
+namespace interpreter {
+
+// A helper class for constructing exception handler tables for the interpreter.
+class HandlerTableBuilder final BASE_EMBEDDED {
+ public:
+  HandlerTableBuilder(Isolate* isolate, Zone* zone);
+
+  // Builds the actual handler table by copying the current values into a heap
+  // object. Any further mutations to the builder won't be reflected.
+  Handle<HandlerTable> ToHandlerTable();
+
+  // 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, bool will_catch);
+  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.
+    bool will_catch;       // Optimistic prediction for handler.
+  };
+
+  Isolate* isolate_;
+  ZoneVector<Entry> entries_;
+
+  DISALLOW_COPY_AND_ASSIGN(HandlerTableBuilder);
+};
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTERPRETER_HANDLER_TABLE_BUILDER_H_