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src/compiler/graph-builder.h

Index: src/compiler/graph-builder.h
diff --git a/src/compiler/graph-builder.h b/src/compiler/graph-builder.h
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+// 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_GRAPH_BUILDER_H_
+#define V8_COMPILER_GRAPH_BUILDER_H_
+
+#include "src/v8.h"
+
+#include "src/allocation.h"
+#include "src/compiler/common-operator.h"
+#include "src/compiler/graph.h"
+#include "src/unique.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+class Node;
+
+// A common base class for anything that creates nodes in a graph.
+class GraphBuilder {
+ public:
+  explicit GraphBuilder(Graph* graph) : graph_(graph) {}
+  virtual ~GraphBuilder() {}
+
+  Node* NewNode(Operator* op) {
+    return MakeNode(op, 0, static_cast<Node**>(NULL));
+  }
+
+  Node* NewNode(Operator* op, Node* n1) { return MakeNode(op, 1, &n1); }
+
+  Node* NewNode(Operator* op, Node* n1, Node* n2) {
+    Node* buffer[] = {n1, n2};
+    return MakeNode(op, ARRAY_SIZE(buffer), buffer);
+  }
+
+  Node* NewNode(Operator* op, Node* n1, Node* n2, Node* n3) {
+    Node* buffer[] = {n1, n2, n3};
+    return MakeNode(op, ARRAY_SIZE(buffer), buffer);
+  }
+
+  Node* NewNode(Operator* op, Node* n1, Node* n2, Node* n3, Node* n4) {
+    Node* buffer[] = {n1, n2, n3, n4};
+    return MakeNode(op, ARRAY_SIZE(buffer), buffer);
+  }
+
+  Node* NewNode(Operator* op, Node* n1, Node* n2, Node* n3, Node* n4,
+                Node* n5) {
+    Node* buffer[] = {n1, n2, n3, n4, n5};
+    return MakeNode(op, ARRAY_SIZE(buffer), buffer);
+  }
+
+  Node* NewNode(Operator* op, Node* n1, Node* n2, Node* n3, Node* n4, Node* n5,
+                Node* n6) {
+    Node* nodes[] = {n1, n2, n3, n4, n5, n6};
+    return MakeNode(op, ARRAY_SIZE(nodes), nodes);
+  }
+
+  Node* NewNode(Operator* op, int value_input_count, Node** value_inputs) {
+    return MakeNode(op, value_input_count, value_inputs);
+  }
+
+  Graph* graph() const { return graph_; }
+
+ protected:
+  // Base implementation used by all factory methods.
+  virtual Node* MakeNode(Operator* op, int value_input_count,
+                         Node** value_inputs) = 0;
+
+ private:
+  Graph* graph_;
+};
+
+
+// The StructuredGraphBuilder produces a high-level IR graph. It is used as the
+// base class for concrete implementations (e.g the AstGraphBuilder or the
+// StubGraphBuilder).
+class StructuredGraphBuilder : public GraphBuilder {
+ public:
+  StructuredGraphBuilder(Graph* graph, CommonOperatorBuilder* common);
+  virtual ~StructuredGraphBuilder() {}
+
+  // Creates a new Phi node having {count} input values.
+  Node* NewPhi(int count, Node* input, Node* control);
+  Node* NewEffectPhi(int count, Node* input, Node* control);
+
+  // Helpers for merging control, effect or value dependencies.
+  Node* MergeControl(Node* control, Node* other);
+  Node* MergeEffect(Node* value, Node* other, Node* control);
+  Node* MergeValue(Node* value, Node* other, Node* control);
+
+  // Helpers to create new control nodes.
+  Node* NewIfTrue() { return NewNode(common()->IfTrue()); }
+  Node* NewIfFalse() { return NewNode(common()->IfFalse()); }
+  Node* NewMerge() { return NewNode(common()->Merge(1)); }
+  Node* NewLoop() { return NewNode(common()->Loop(1)); }
+  Node* NewBranch(Node* condition) {
+    return NewNode(common()->Branch(), condition);
+  }
+
+ protected:
+  class Environment;
+  friend class ControlBuilder;
+
+  // The following method creates a new node having the specified operator and
+  // ensures effect and control dependencies are wired up. The dependencies
+  // tracked by the environment might be mutated.
+  virtual Node* MakeNode(Operator* op, int value_input_count,
+                         Node** value_inputs);
+
+  Environment* environment_internal() const { return environment_; }
+  void set_environment(Environment* env) { environment_ = env; }
+
+  Node* current_context() const { return current_context_; }
+  void set_current_context(Node* context) { current_context_ = context; }
+
+  Node* exit_control() const { return exit_control_; }
+  void set_exit_control(Node* node) { exit_control_ = node; }
+
+  Node* dead_control();
+
+  // TODO(mstarzinger): Use phase-local zone instead!
+  Zone* zone() const { return graph()->zone(); }
+  Isolate* isolate() const { return zone()->isolate(); }
+  CommonOperatorBuilder* common() const { return common_; }
+
+  // Helper to wrap a Handle<T> into a Unique<T>.
+  template <class T>
+  PrintableUnique<T> MakeUnique(Handle<T> object) {
+    return PrintableUnique<T>::CreateUninitialized(zone(), object);
+  }
+
+  // Support for control flow builders. The concrete type of the environment
+  // depends on the graph builder, but environments themselves are not virtual.
+  virtual Environment* CopyEnvironment(Environment* env);
+
+  // Helper when creating node that depends on control.
+  Node* GetControlDependency();
+
+  // Helper when creating node that updates control.
+  void UpdateControlDependency(Node* new_control);
+
+  // Helper to indicate a node exits the function body.
+  void UpdateControlDependencyToLeaveFunction(Node* exit);
+
+ private:
+  CommonOperatorBuilder* common_;
+  Environment* environment_;
+
+  // Node representing the control dependency for dead code.
+  SetOncePointer<Node> dead_control_;
+
+  // Node representing the current context within the function body.
+  Node* current_context_;
+
+  // Merge of all control nodes that exit the function body.
+  Node* exit_control_;
+
+  DISALLOW_COPY_AND_ASSIGN(StructuredGraphBuilder);
+};
+
+
+// The abstract execution environment contains static knowledge about
+// execution state at arbitrary control-flow points. It allows for
+// simulation of the control-flow at compile time.
+class StructuredGraphBuilder::Environment : public ZoneObject {
+ public:
+  Environment(StructuredGraphBuilder* builder, Node* control_dependency);
+  Environment(const Environment& copy);
+
+  // Control dependency tracked by this environment.
+  Node* GetControlDependency() { return control_dependency_; }
+  void UpdateControlDependency(Node* dependency) {
+    control_dependency_ = dependency;
+  }
+
+  // Effect dependency tracked by this environment.
+  Node* GetEffectDependency() { return effect_dependency_; }
+  void UpdateEffectDependency(Node* dependency) {
+    effect_dependency_ = dependency;
+  }
+
+  // Mark this environment as being unreachable.
+  void MarkAsUnreachable() {
+    UpdateControlDependency(builder()->dead_control());
+  }
+  bool IsMarkedAsUnreachable() {
+    return GetControlDependency()->opcode() == IrOpcode::kDead;
+  }
+
+  // Merge another environment into this one.
+  void Merge(Environment* other);
+
+  // Copies this environment at a control-flow split point.
+  Environment* CopyForConditional() { return builder()->CopyEnvironment(this); }
+
+  // Copies this environment to a potentially unreachable control-flow point.
+  Environment* CopyAsUnreachable() {
+    Environment* env = builder()->CopyEnvironment(this);
+    env->MarkAsUnreachable();
+    return env;
+  }
+
+  // Copies this environment at a loop header control-flow point.
+  Environment* CopyForLoop() {
+    PrepareForLoop();
+    return builder()->CopyEnvironment(this);
+  }
+
+ protected:
+  // TODO(mstarzinger): Use phase-local zone instead!
+  Zone* zone() const { return graph()->zone(); }
+  Graph* graph() const { return builder_->graph(); }
+  StructuredGraphBuilder* builder() const { return builder_; }
+  CommonOperatorBuilder* common() { return builder_->common(); }
+  NodeVector* values() { return &values_; }
+
+  // Prepare environment to be used as loop header.
+  void PrepareForLoop();
+
+ private:
+  StructuredGraphBuilder* builder_;
+  Node* control_dependency_;
+  Node* effect_dependency_;
+  NodeVector values_;
+};
+}
+}
+}  // namespace v8::internal::compiler
+
+#endif  // V8_COMPILER_GRAPH_BUILDER_H__