text: // 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.
  
  #include "src/compiler/js-frame-specialization.h"
  
  #include "src/compiler/js-graph.h"
  #include "src/compiler/linkage.h"
  #include "src/frames-inl.h"
  
  namespace v8 {
  namespace internal {
  namespace compiler {
  
  Reduction JSFrameSpecialization::Reduce(Node* node) {
    switch (node->opcode()) {
      case IrOpcode::kOsrValue:
        return ReduceOsrValue(node);
      case IrOpcode::kParameter:
        return ReduceParameter(node);
      default:
        break;
    }
    return NoChange();
  }
  
  Reduction JSFrameSpecialization::ReduceOsrValue(Node* node) {
    // JSFrameSpecialization should never run on interpreted frames, since the
    // code below assumes standard stack frame layouts.
    DCHECK(!frame()->is_interpreted());
    DCHECK_EQ(IrOpcode::kOsrValue, node->opcode());
    Handle<Object> value;
    int index = OsrValueIndexOf(node->op());
    int const parameters_count = frame()->ComputeParametersCount() + 1;
    if (index == Linkage::kOsrContextSpillSlotIndex) {
      value = handle(frame()->context(), isolate());
    } else if (index >= parameters_count) {
      value = handle(frame()->GetExpression(index - parameters_count), isolate());
    } else {
      // The OsrValue index 0 is the receiver.
      value =
          handle(index ? frame()->GetParameter(index - 1) : frame()->receiver(),
                 isolate());
    }
    return Replace(jsgraph()->Constant(value));
  }
  
  Reduction JSFrameSpecialization::ReduceParameter(Node* node) {
    DCHECK_EQ(IrOpcode::kParameter, node->opcode());
    Handle<Object> value;
    int const index = ParameterIndexOf(node->op());
    int const parameters_count = frame()->ComputeParametersCount() + 1;
    if (index == Linkage::kJSCallClosureParamIndex) {
      // The Parameter index references the closure.
      value = handle(frame()->function(), isolate());
    } else if (index == Linkage::GetJSCallArgCountParamIndex(parameters_count)) {
      // The Parameter index references the parameter count.
      value = handle(Smi::FromInt(parameters_count - 1), isolate());
    } else if (index == Linkage::GetJSCallContextParamIndex(parameters_count)) {
      // The Parameter index references the context.
      value = handle(frame()->context(), isolate());
    } else {
      // The Parameter index 0 is the receiver.
      value =
          handle(index ? frame()->GetParameter(index - 1) : frame()->receiver(),
                 isolate());
    }
    return Replace(jsgraph()->Constant(value));
  }
  
  
  Isolate* JSFrameSpecialization::isolate() const { return jsgraph()->isolate(); }
  
  }  // namespace compiler
  }  // namespace internal
  }  // namespace v8
  