[turbofan] Add backend support for Float32Constant.

src/compiler/instruction-selector-impl.h

 // 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.
 
 #ifndef V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/linkage.h"
@@ skipping 128 matching lines @@
   Isolate* isolate() const { return zone()->isolate(); }
   Zone* zone() const { return selector()->instruction_zone(); }
 
  private:
   static Constant ToConstant(const Node* node) {
     switch (node->opcode()) {
       case IrOpcode::kInt32Constant:
         return Constant(OpParameter<int32_t>(node));
       case IrOpcode::kInt64Constant:
         return Constant(OpParameter<int64_t>(node));
+      case IrOpcode::kFloat32Constant:
+        return Constant(OpParameter<float>(node));
+      case IrOpcode::kFloat64Constant:
       case IrOpcode::kNumberConstant:
-      case IrOpcode::kFloat64Constant:
         return Constant(OpParameter<double>(node));
       case IrOpcode::kExternalConstant:
         return Constant(OpParameter<ExternalReference>(node));
       case IrOpcode::kHeapConstant:
         return Constant(OpParameter<Unique<HeapObject> >(node).handle());
       default:
         break;
     }
     UNREACHABLE();
     return Constant(static_cast<int32_t>(0));
@@ skipping 190 matching lines @@
                : (frame_state_descriptor->GetTotalSize() +
                   1);  // Include deopt id.
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_