[Interpreter] Bytecode graph builder

src/compiler/bytecode-graph-builder.h

+// Copyright 2015 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_BYTECODE_GRAPH_BUILDER_H_
+#define V8_COMPILER_BYTECODE_GRAPH_BUILDER_H_
+
+#include "src/interpreter/bytecodes.h"
+
+#include "src/compiler.h"
+#include "src/compiler/js-graph.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// The BytecodeGraphBuilder produces a high-level IR graph based on
+// interpreter bytecodes.
+class BytecodeGraphBuilder {
+ public:
+  BytecodeGraphBuilder(Zone* local_zone, CompilationInfo* info,
+                       JSGraph* jsgraph);
+
+  // Creates a graph by visiting bytecodes.
+  bool CreateGraph(bool stack_check = true);
+
+  Graph* graph() const { return jsgraph_->graph(); }
+
+ private:
+  class Environment;
+
+  void CreateGraphBody(bool stack_check);
+  void VisitBytecodes();
+
+  Node* LoadAccumulator(Node* value);
+
+  Node* GetFunctionContext();
+
+  // Convert values in bytecode_array to convenient to handle forms.

[rmcilroy, 2015/09/03 12:41:57]

nit - I would just replace this with a comment describing bytecode_at

[oth, 2015/09/04 11:06:36]

Done.

+  interpreter::Bytecode bytecode_at(int offset) const;
+  // Get constant from operand at position |offset| in bytecode array.

[rmcilroy, 2015/09/03 12:41:58]

nit - could you make the comment clearer that this get's the constant in the
constant pool which is specified by the index operand at position |offset| in
the bytecode array.

[oth, 2015/09/04 11:06:36]

Done.

+  Handle<Object> constant_at(int offset) const;
+  // Get smi8 value from operand at position |offset| in bytecode array.
+  int8_t smi8_at(int offset) const;
+  // Get register from operand at position |offset| in bytecode array.
+  interpreter::Register register_at(int offset) const;

[rmcilroy, 2015/09/03 12:41:58]

Optional suggestion (fine with doing this in a later CL if you agree it would be
worth while). Could we encapsulate these operations in something like a
BytecodeArrayWrapper (or some better name) class - i.e.:

class BytecodeArrayWrapper {
 public:
  BytecodeArrayWrapper(BytecodeArrayWrapper);
  
  void next();

  interpreter::Bytecode current_bytecode();
  interpreter::Register register_at(int operand_index);
  Handle<Object> constant_at(int operand_index);
  int8_t smi8_at(int operand_index);

 private:
  size_t offset;
}

That way, next() could advance by Bytecodes::Size(current_bytecode()) and the
register_at, constant_at, smi8_at etc. could all DCHECK that the operands are
the expected type - i.e.:
  DCHECK_EQ(interpreter::OperandType::kImm8,
            interpreter::Bytecodes::GetOperandType(current_bytecode(),
operand_index));

And then the VisitBytecodeX(int offset) functions could be replaced with
VisitBytecodeX(const ByteCodeArrayWrapper& bytecode);

[oth, 2015/09/04 11:06:36]

Done with BytecodeArrayIterator.

+
+  void set_environment(Environment* env) { environment_ = env; }
+  const Environment* environment() const { return environment_; }
+  Environment* environment() { return environment_; }
+
+  // Node creation helpers
+  Node* NewNode(const Operator* op, bool incomplete = false) {
+    return MakeNode(op, 0, static_cast<Node**>(NULL), incomplete);
+  }
+
+  Node* NewNode(const Operator* op, Node* n1) {
+    Node* buffer[] = {n1};
+    return MakeNode(op, arraysize(buffer), buffer, false);
+  }
+
+  Node* NewNode(const Operator* op, Node* n1, Node* n2) {
+    Node* buffer[] = {n1, n2};
+    return MakeNode(op, arraysize(buffer), buffer, false);
+  }
+
+  Node* MakeNode(const Operator* op, int value_input_count, Node** value_inputs,
+                 bool incomplete);
+
+  Node* MergeControl(Node* control, Node* other);
+
+  Node** EnsureInputBufferSize(int size);
+
+  void UpdateControlDependencyToLeaveFunction(Node* exit);
+
+  void FinishBinaryOperation(Node* node);

[rmcilroy, 2015/09/03 12:41:57]

How about we replace this with "Node* BuildBinaryOp(Node* left, Node* right,
Token::Value op);" like ASTGraphBuilder?". I.e., instead of:
  Node* node = NewNode(js_op, left, right);
  FinishBinaryOperation(node);

just:
  Node* node = BuildBinaryOp(js_op, left, right);

[oth, 2015/09/04 11:06:36]

Done.

+
+  // Growth increment for the temporary buffer used to construct input lists to
+  // new nodes.
+  static const int kInputBufferSizeIncrement = 64;
+
+  // Field accessors
+  CommonOperatorBuilder* common() const { return jsgraph_->common(); }
+  Zone* graph_zone() const { return graph()->zone(); }
+  CompilationInfo* info() const { return info_; }
+  JSGraph* jsgraph() const { return jsgraph_; }
+  JSOperatorBuilder* javascript() const { return jsgraph_->javascript(); }
+  Zone* local_zone() const { return local_zone_; }
+  const Handle<BytecodeArray>& bytecode_array() const {
+    return bytecode_array_;
+  }
+
+  LanguageMode language_mode() const {
+    // TODO(oth): need to propagate language mode through
+    return LanguageMode::SLOPPY;
+  }
+
+#define DECLARE_VISIT_BYTECODE(name, ...) void Visit##name(int operand_offset);
+  BYTECODE_LIST(DECLARE_VISIT_BYTECODE)
+#undef DECLARE_VISIT_BYTECODE
+
+  Zone* local_zone_;
+  CompilationInfo* info_;
+  JSGraph* jsgraph_;
+  Handle<BytecodeArray> bytecode_array_;
+  Environment* environment_;
+
+  // Temporary storage for building node input lists.
+  int input_buffer_size_;
+  Node** input_buffer_;
+
+  // Nodes representing values in the activation record.
+  SetOncePointer<Node> function_context_;
+
+  // Control nodes that exit the function body.
+  ZoneVector<Node*> exit_controls_;
+
+  DISALLOW_COPY_AND_ASSIGN(BytecodeGraphBuilder);
+};
+
+
+class BytecodeGraphBuilder::Environment : public ZoneObject {
+ public:
+  Environment(BytecodeGraphBuilder* builder, int locals_count,
+              int parameter_count, Node* control_dependency, Node* context);
+
+  int parameters_count() const { return parameters_count_; }
+  int locals_count() const { return locals_count_; }
+
+  void BindRegister(interpreter::Register the_register, Node* node);
+  Node* LookupRegister(interpreter::Register the_register) const;
+
+  void BindAccumulator(Node* node);
+  Node* LookupAccumulator() const;
+
+  bool IsMarkedAsUnreachable() const;
+  void MarkAsUnreachable();
+
+  // Effect dependency tracked by this environment.
+  Node* GetEffectDependency() { return effect_dependency_; }
+  void UpdateEffectDependency(Node* dependency) {
+    effect_dependency_ = dependency;
+  }
+
+  // Control dependency tracked by this environment.
+  Node* GetControlDependency() const { return control_dependency_; }
+  void UpdateControlDependency(Node* dependency) {
+    control_dependency_ = dependency;
+  }
+
+  Node* Context() const { return context_; }
+
+ private:
+  BytecodeGraphBuilder* builder_;
+  int locals_count_;
+  int parameters_count_;
+  Node* accumulator_;
+  Node* context_;
+  Node* control_dependency_;
+  Node* effect_dependency_;
+  NodeVector values_;
+  int register_base_;
+
+  Zone* zone() const { return builder_->local_zone(); }
+  Graph* graph() const { return builder_->graph(); }
+  CommonOperatorBuilder* common() const { return builder_->common(); }
+  BytecodeGraphBuilder* builder() const { return builder_; }
+  const NodeVector* values() const { return &values_; }
+  NodeVector* values() { return &values_; }
+  Node* accumulator() { return accumulator_; }
+  int register_base() const { return register_base_; }
+
+  int RegisterToValuesIndex(interpreter::Register the_register) const;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_BYTECODE_GRAPH_BUILDER_H_