v8/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/compiler/bytecode-branch-analysis.h"
#include "src/compiler/bytecode-loop-analysis.h"
#include "src/compiler/js-graph.h"
#include "src/compiler/liveness-analyzer.h"
#include "src/compiler/state-values-utils.h"
#include "src/compiler/type-hint-analyzer.h"
#include "src/interpreter/bytecode-array-iterator.h"
#include "src/interpreter/bytecode-flags.h"
#include "src/interpreter/bytecodes.h"

namespace v8 {
namespace internal {

class CompilationInfo;

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();

 private:
  class Environment;
  class FrameStateBeforeAndAfter;

  void VisitBytecodes();

  // Get or create the node that represents the outer function closure.
  Node* GetFunctionClosure();

  // Get or create the node that represents the outer function context.
  Node* GetFunctionContext();

  // Get or create the node that represents the incoming new target value.
  Node* GetNewTarget();

  // Builder for loading the a native context field.
  Node* BuildLoadNativeContextField(int index);

  // Helper function for creating a pair containing type feedback vector and
  // a feedback slot.
  VectorSlotPair CreateVectorSlotPair(int slot_id);

  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**>(nullptr), 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* NewNode(const Operator* op, Node* n1, Node* n2, Node* n3) {
    Node* buffer[] = {n1, n2, n3};
    return MakeNode(op, arraysize(buffer), buffer, false);
  }

  Node* NewNode(const Operator* op, Node* n1, Node* n2, Node* n3, Node* n4) {
    Node* buffer[] = {n1, n2, n3, n4};
    return MakeNode(op, arraysize(buffer), buffer, false);
  }

  // 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), true); }
  Node* NewLoop() { return NewNode(common()->Loop(1), true); }
  Node* NewBranch(Node* condition, BranchHint hint = BranchHint::kNone) {
    return NewNode(common()->Branch(hint), condition);
  }

  // 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* effect, Node* other_effect, Node* control);
  Node* MergeValue(Node* value, Node* other_value, Node* control);

  // The main node creation chokepoint. Adds context, frame state, effect,
  // and control dependencies depending on the operator.
  Node* MakeNode(const Operator* op, int value_input_count, Node** value_inputs,
                 bool incomplete);

  Node** EnsureInputBufferSize(int size);

  Node* ProcessCallArguments(const Operator* call_op, Node* callee,
                             interpreter::Register receiver, size_t arity);
  Node* ProcessCallNewArguments(const Operator* call_new_op, Node* callee,
                                Node* new_target,
                                interpreter::Register first_arg, size_t arity);
  Node* ProcessCallRuntimeArguments(const Operator* call_runtime_op,
                                    interpreter::Register first_arg,
                                    size_t arity);

  // Computes register liveness and replaces dead ones in frame states with the
  // undefined values.
  void ClearNonLiveSlotsInFrameStates();

  void BuildCreateLiteral(const Operator* op);
  void BuildCreateArguments(CreateArgumentsType type);
  Node* BuildLoadContextSlot();
  Node* BuildLoadGlobal(TypeofMode typeof_mode);
  void BuildStoreGlobal(LanguageMode language_mode);
  Node* BuildNamedLoad();
  void BuildNamedStore(LanguageMode language_mode);
  Node* BuildKeyedLoad();
  void BuildKeyedStore(LanguageMode language_mode);
  void BuildLdaLookupSlot(TypeofMode typeof_mode);
  void BuildStaLookupSlot(LanguageMode language_mode);
  void BuildCall(TailCallMode tail_call_mode);
  void BuildThrow();
  void BuildBinaryOp(const Operator* op);
  void BuildBinaryOpWithImmediate(const Operator* op);
  void BuildCompareOp(const Operator* op);
  void BuildDelete(LanguageMode language_mode);
  void BuildCastOperator(const Operator* op);
  void BuildForInPrepare();
  void BuildForInNext();
  void BuildInvokeIntrinsic();

  // Helper function to create binary operation hint from the recorded
  // type feedback.
  BinaryOperationHint GetBinaryOperationHint(int operand_index);

  // Helper function to create compare operation hint from the recorded
  // type feedback.
  CompareOperationHint GetCompareOperationHint();

  // Helper function to compute call frequency from the recorded type
  // feedback.
  float ComputeCallFrequency(int slot_id) const;

  // Control flow plumbing.
  void BuildJump();
  void BuildJumpIf(Node* condition);
  void BuildJumpIfNot(Node* condition);
  void BuildJumpIfEqual(Node* comperand);
  void BuildJumpIfTrue();
  void BuildJumpIfFalse();
  void BuildJumpIfToBooleanTrue();
  void BuildJumpIfToBooleanFalse();
  void BuildJumpIfNotHole();

  // Simulates control flow by forward-propagating environments.
  void MergeIntoSuccessorEnvironment(int target_offset);
  void BuildLoopHeaderEnvironment(int current_offset);
  void SwitchToMergeEnvironment(int current_offset);

  // Simulates control flow that exits the function body.
  void MergeControlToLeaveFunction(Node* exit);

  // Builds entry points that are used by OSR deconstruction.
  void BuildOSRLoopEntryPoint(int current_offset);
  void BuildOSRNormalEntryPoint();

  // Builds loop exit nodes for every exited loop between the current bytecode
  // offset and {target_offset}.
  void BuildLoopExitsForBranch(int target_offset);
  void BuildLoopExitsForFunctionExit();
  void BuildLoopExitsUntilLoop(int loop_offset);

  // Simulates entry and exit of exception handlers.
  void EnterAndExitExceptionHandlers(int current_offset);

  // Growth increment for the temporary buffer used to construct input lists to
  // new nodes.
  static const int kInputBufferSizeIncrement = 64;

  // An abstract representation for an exception handler that is being
  // entered and exited while the graph builder is iterating over the
  // underlying bytecode. The exception handlers within the bytecode are
  // well scoped, hence will form a stack during iteration.
  struct ExceptionHandler {
    int start_offset_;      // Start offset of the handled area in the bytecode.
    int end_offset_;        // End offset of the handled area in the bytecode.
    int handler_offset_;    // Handler entry offset within the bytecode.
    int context_register_;  // Index of register holding handler context.
  };

  // Field accessors
  Graph* graph() const { return jsgraph_->graph(); }
  CommonOperatorBuilder* common() const { return jsgraph_->common(); }
  Zone* graph_zone() const { return graph()->zone(); }
  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_;
  }
  const Handle<HandlerTable>& exception_handler_table() const {
    return exception_handler_table_;
  }
  const Handle<TypeFeedbackVector>& feedback_vector() const {
    return feedback_vector_;
  }
  const FrameStateFunctionInfo* frame_state_function_info() const {
    return frame_state_function_info_;
  }

  const interpreter::BytecodeArrayIterator& bytecode_iterator() const {
    return *bytecode_iterator_;
  }

  void set_bytecode_iterator(
      const interpreter::BytecodeArrayIterator* bytecode_iterator) {
    bytecode_iterator_ = bytecode_iterator;
  }

  const BytecodeBranchAnalysis* branch_analysis() const {
    return branch_analysis_;
  }

  void set_branch_analysis(const BytecodeBranchAnalysis* branch_analysis) {
    branch_analysis_ = branch_analysis;
  }

  const BytecodeLoopAnalysis* loop_analysis() const { return loop_analysis_; }

  void set_loop_analysis(const BytecodeLoopAnalysis* loop_analysis) {
    loop_analysis_ = loop_analysis;
  }

  LivenessAnalyzer* liveness_analyzer() { return &liveness_analyzer_; }

  bool IsLivenessAnalysisEnabled() const {
    return this->is_liveness_analysis_enabled_;
  }

#define DECLARE_VISIT_BYTECODE(name, ...) void Visit##name();
  BYTECODE_LIST(DECLARE_VISIT_BYTECODE)
#undef DECLARE_VISIT_BYTECODE

  Zone* local_zone_;
  JSGraph* jsgraph_;
  Handle<BytecodeArray> bytecode_array_;
  Handle<HandlerTable> exception_handler_table_;
  Handle<TypeFeedbackVector> feedback_vector_;
  const FrameStateFunctionInfo* frame_state_function_info_;
  const interpreter::BytecodeArrayIterator* bytecode_iterator_;
  const BytecodeBranchAnalysis* branch_analysis_;
  const BytecodeLoopAnalysis* loop_analysis_;
  Environment* environment_;
  BailoutId osr_ast_id_;

  // Merge environments are snapshots of the environment at points where the
  // control flow merges. This models a forward data flow propagation of all
  // values from all predecessors of the merge in question.
  ZoneMap<int, Environment*> merge_environments_;

  // Exception handlers currently entered by the iteration.
  ZoneStack<ExceptionHandler> exception_handlers_;
  int current_exception_handler_;

  // 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_;
  SetOncePointer<Node> function_closure_;
  SetOncePointer<Node> new_target_;

  // Control nodes that exit the function body.
  ZoneVector<Node*> exit_controls_;

  bool const is_liveness_analysis_enabled_;

  StateValuesCache state_values_cache_;

  // Analyzer of register liveness.
  LivenessAnalyzer liveness_analyzer_;

  static int const kBinaryOperationHintIndex = 1;
  static int const kCountOperationHintIndex = 0;
  static int const kBinaryOperationSmiHintIndex = 2;

  DISALLOW_COPY_AND_ASSIGN(BytecodeGraphBuilder);
};

}  // namespace compiler
}  // namespace internal
}  // namespace v8

#endif  // V8_COMPILER_BYTECODE_GRAPH_BUILDER_H_