[turbofan] Add constant-folding for CheckedFloat64ToInt32.

src/compiler/simplified-operator-reducer.cc

 // Copyright 2014 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/simplified-operator-reducer.h"
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 111 matching lines @@
       if (m.HasValue()) return ReplaceInt32(DoubleToInt32(m.Value()));
       if (m.IsChangeInt31ToTaggedSigned() || m.IsChangeInt32ToTagged() ||
           m.IsChangeUint32ToTagged()) {
         return Replace(m.InputAt(0));
       }
       if (m.IsChangeFloat64ToTagged() || m.IsChangeFloat64ToTaggedPointer()) {
         return Change(node, machine()->TruncateFloat64ToWord32(), m.InputAt(0));
       }
       break;
     }
+    case IrOpcode::kCheckedFloat64ToInt32: {
+      Float64Matcher m(node->InputAt(0));
+      if (m.HasValue() && IsInt32Double(m.Value())) {
+        Node* value = jsgraph()->Int32Constant(static_cast<int32_t>(m.Value()));
+        ReplaceWithValue(node, value);
+        return Replace(value);
+      }
+      break;
+    }
     case IrOpcode::kCheckedTaggedToInt32:
     case IrOpcode::kCheckedTaggedSignedToInt32: {
       NodeMatcher m(node->InputAt(0));
       if (m.IsConvertTaggedHoleToUndefined()) {
         node->ReplaceInput(0, m.InputAt(0));
         return Changed(node);
       }
       break;
     }
     case IrOpcode::kCheckIf: {
@@ skipping 111 matching lines @@
   return jsgraph()->isolate();
 }
 
 MachineOperatorBuilder* SimplifiedOperatorReducer::machine() const {
   return jsgraph()->machine();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8