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      1 // Copyright 2015 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "src/compiler/js-frame-specialization.h"
      6 
      7 #include "src/compiler/js-graph.h"
      8 #include "src/compiler/linkage.h"
      9 #include "src/frames-inl.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 namespace compiler {
     14 
     15 Reduction JSFrameSpecialization::Reduce(Node* node) {
     16   switch (node->opcode()) {
     17     case IrOpcode::kOsrValue:
     18       return ReduceOsrValue(node);
     19     case IrOpcode::kOsrGuard:
     20       return ReduceOsrGuard(node);
     21     case IrOpcode::kParameter:
     22       return ReduceParameter(node);
     23     default:
     24       break;
     25   }
     26   return NoChange();
     27 }
     28 
     29 Reduction JSFrameSpecialization::ReduceOsrValue(Node* node) {
     30   // JSFrameSpecialization should never run on interpreted frames, since the
     31   // code below assumes standard stack frame layouts.
     32   DCHECK(!frame()->is_interpreted());
     33   DCHECK_EQ(IrOpcode::kOsrValue, node->opcode());
     34   Handle<Object> value;
     35   int index = OsrValueIndexOf(node->op());
     36   int const parameters_count = frame()->ComputeParametersCount() + 1;
     37   if (index == Linkage::kOsrContextSpillSlotIndex) {
     38     value = handle(frame()->context(), isolate());
     39   } else if (index >= parameters_count) {
     40     value = handle(frame()->GetExpression(index - parameters_count), isolate());
     41   } else {
     42     // The OsrValue index 0 is the receiver.
     43     value =
     44         handle(index ? frame()->GetParameter(index - 1) : frame()->receiver(),
     45                isolate());
     46   }
     47   return Replace(jsgraph()->Constant(value));
     48 }
     49 
     50 Reduction JSFrameSpecialization::ReduceOsrGuard(Node* node) {
     51   DCHECK_EQ(IrOpcode::kOsrGuard, node->opcode());
     52   ReplaceWithValue(node, node->InputAt(0),
     53                    NodeProperties::GetEffectInput(node));
     54   return Changed(node);
     55 }
     56 
     57 Reduction JSFrameSpecialization::ReduceParameter(Node* node) {
     58   DCHECK_EQ(IrOpcode::kParameter, node->opcode());
     59   Handle<Object> value;
     60   int const index = ParameterIndexOf(node->op());
     61   int const parameters_count = frame()->ComputeParametersCount() + 1;
     62   if (index == Linkage::kJSCallClosureParamIndex) {
     63     // The Parameter index references the closure.
     64     value = handle(frame()->function(), isolate());
     65   } else if (index == Linkage::GetJSCallArgCountParamIndex(parameters_count)) {
     66     // The Parameter index references the parameter count.
     67     value = handle(Smi::FromInt(parameters_count - 1), isolate());
     68   } else if (index == Linkage::GetJSCallContextParamIndex(parameters_count)) {
     69     // The Parameter index references the context.
     70     value = handle(frame()->context(), isolate());
     71   } else {
     72     // The Parameter index 0 is the receiver.
     73     value =
     74         handle(index ? frame()->GetParameter(index - 1) : frame()->receiver(),
     75                isolate());
     76   }
     77   return Replace(jsgraph()->Constant(value));
     78 }
     79 
     80 
     81 Isolate* JSFrameSpecialization::isolate() const { return jsgraph()->isolate(); }
     82 
     83 }  // namespace compiler
     84 }  // namespace internal
     85 }  // namespace v8
     86