[turbofan] Only mark non-smis as references.

src/compiler/instruction-selector.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/instruction-selector.h"
 
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
 #include "src/compiler/pipeline.h"
@@ skipping 683 matching lines @@
       return VisitProjection(node);
     case IrOpcode::kInt32Constant:
     case IrOpcode::kInt64Constant:
     case IrOpcode::kExternalConstant:
       return VisitConstant(node);
     case IrOpcode::kFloat32Constant:
       return MarkAsDouble(node), VisitConstant(node);
     case IrOpcode::kFloat64Constant:
       return MarkAsDouble(node), VisitConstant(node);
     case IrOpcode::kHeapConstant:
-    case IrOpcode::kNumberConstant:
-      // TODO(turbofan): only mark non-smis as references.
       return MarkAsReference(node), VisitConstant(node);
+    case IrOpcode::kNumberConstant: {
+      double value = OpParameter<double>(node);
+      if (!IsSmiDouble(value)) MarkAsReference(node);
+      return VisitConstant(node);
+    }
     case IrOpcode::kCall:
       return VisitCall(node);
     case IrOpcode::kFrameState:
     case IrOpcode::kStateValues:
       return;
     case IrOpcode::kLoad: {
       LoadRepresentation rep = OpParameter<LoadRepresentation>(node);
       MarkAsRepresentation(rep, node);
       return VisitLoad(node);
     }
@@ skipping 444 matching lines @@
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
   return MachineOperatorBuilder::Flag::kNoFlags;
 }
 
 #endif  // !V8_TURBOFAN_BACKEND
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8