[turbofan] Rip out the unused OsrGuard node.

src/compiler/js-frame-specialization.cc

 // 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::kOsrGuard:
-      return ReduceOsrGuard(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::ReduceOsrGuard(Node* node) {
-  DCHECK_EQ(IrOpcode::kOsrGuard, node->opcode());
-  ReplaceWithValue(node, node->InputAt(0),
-                   NodeProperties::GetEffectInput(node));
-  return Changed(node);
-}
-
 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