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src/compiler/control-builders.h

+// Copyright 2013 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_COMPILER_CONTROL_BUILDERS_H_
+#define V8_COMPILER_CONTROL_BUILDERS_H_
+
+#include "src/v8.h"
+
+#include "src/compiler/graph-builder.h"
+#include "src/compiler/node.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+
+// Base class for all control builders. Also provides a common interface for
+// control builders to handle 'break' and 'continue' statements when they are
+// used to model breakable statements.
+class ControlBuilder {
+ public:
+  explicit ControlBuilder(StructuredGraphBuilder* builder)
+      : builder_(builder) {}
+  virtual ~ControlBuilder() {}
+
+  // Interface for break and continue.
+  virtual void Break() { UNREACHABLE(); }
+  virtual void Continue() { UNREACHABLE(); }
+
+ protected:
+  typedef StructuredGraphBuilder Builder;
+  typedef StructuredGraphBuilder::Environment Environment;
+
+  Zone* zone() const { return builder_->zone(); }
+  Environment* environment() { return builder_->environment_internal(); }
+  void set_environment(Environment* env) { builder_->set_environment(env); }
+
+  Builder* builder_;
+};
+
+
+// Tracks control flow for a conditional statement.
+class IfBuilder : public ControlBuilder {
+ public:
+  explicit IfBuilder(StructuredGraphBuilder* builder)
+      : ControlBuilder(builder),
+        then_environment_(NULL),
+        else_environment_(NULL) {}
+
+  // Primitive control commands.
+  void If(Node* condition);
+  void Then();
+  void Else();
+  void End();
+
+ private:
+  Environment* then_environment_;  // Environment after the 'then' body.
+  Environment* else_environment_;  // Environment for the 'else' body.
+};
+
+
+// Tracks control flow for an iteration statement.
+class LoopBuilder : public ControlBuilder {
+ public:
+  explicit LoopBuilder(StructuredGraphBuilder* builder)
+      : ControlBuilder(builder),
+        loop_environment_(NULL),
+        continue_environment_(NULL),
+        break_environment_(NULL) {}
+
+  // Primitive control commands.
+  void BeginLoop();
+  void EndBody();
+  void EndLoop();
+
+  // Primitive support for break and continue.
+  virtual void Continue();
+  virtual void Break();
+
+  // Compound control command for conditional break.
+  void BreakUnless(Node* condition);
+
+ private:
+  Environment* loop_environment_;      // Environment of the loop header.
+  Environment* continue_environment_;  // Environment after the loop body.
+  Environment* break_environment_;     // Environment after the loop exits.
+};
+
+
+// Tracks control flow for a switch statement.
+class SwitchBuilder : public ControlBuilder {
+ public:
+  explicit SwitchBuilder(StructuredGraphBuilder* builder, int case_count)
+      : ControlBuilder(builder),
+        body_environment_(NULL),
+        label_environment_(NULL),
+        break_environment_(NULL),
+        body_environments_(case_count, zone()) {}
+
+  // Primitive control commands.
+  void BeginSwitch();
+  void BeginLabel(int index, Node* condition);
+  void EndLabel();
+  void DefaultAt(int index);
+  void BeginCase(int index);
+  void EndCase();
+  void EndSwitch();
+
+  // Primitive support for break.
+  virtual void Break();
+
+  // The number of cases within a switch is statically known.
+  int case_count() const { return body_environments_.capacity(); }
+
+ private:
+  Environment* body_environment_;   // Environment after last case body.
+  Environment* label_environment_;  // Environment for next label condition.
+  Environment* break_environment_;  // Environment after the switch exits.
+  ZoneList<Environment*> body_environments_;
+};
+
+
+// Tracks control flow for a block statement.
+class BlockBuilder : public ControlBuilder {
+ public:
+  explicit BlockBuilder(StructuredGraphBuilder* builder)
+      : ControlBuilder(builder), break_environment_(NULL) {}
+
+  // Primitive control commands.
+  void BeginBlock();
+  void EndBlock();
+
+  // Primitive support for break.
+  virtual void Break();
+
+ private:
+  Environment* break_environment_;  // Environment after the block exits.
+};
+}
+}
+}  // namespace v8::internal::compiler
+
+#endif  // V8_COMPILER_CONTROL_BUILDERS_H_