[turbofan] Add backend support for Float32Constant.

src/compiler/instruction.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_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <map>
 #include <set>
@@ skipping 636 matching lines @@
     DCHECK(!source_position_.IsInvalid());
     DCHECK(!source_position_.IsUnknown());
   }
 
   SourcePosition source_position_;
 };
 
 
 class Constant FINAL {
  public:
-  enum Type { kInt32, kInt64, kFloat64, kExternalReference, kHeapObject };
+  enum Type {
+    kInt32,
+    kInt64,
+    kFloat32,
+    kFloat64,
+    kExternalReference,
+    kHeapObject
+  };
 
   explicit Constant(int32_t v) : type_(kInt32), value_(v) {}
   explicit Constant(int64_t v) : type_(kInt64), value_(v) {}
+  explicit Constant(float v) : type_(kFloat32), value_(bit_cast<int32_t>(v)) {}
   explicit Constant(double v) : type_(kFloat64), value_(bit_cast<int64_t>(v)) {}
   explicit Constant(ExternalReference ref)
       : type_(kExternalReference), value_(bit_cast<intptr_t>(ref)) {}
   explicit Constant(Handle<HeapObject> obj)
       : type_(kHeapObject), value_(bit_cast<intptr_t>(obj)) {}
 
   Type type() const { return type_; }
 
   int32_t ToInt32() const {
     DCHECK_EQ(kInt32, type());
     return static_cast<int32_t>(value_);
   }
 
   int64_t ToInt64() const {
     if (type() == kInt32) return ToInt32();
     DCHECK_EQ(kInt64, type());
     return value_;
   }
 
+  float ToFloat32() const {
+    DCHECK_EQ(kFloat32, type());
+    return bit_cast<float>(static_cast<int32_t>(value_));
+  }
+
   double ToFloat64() const {
     if (type() == kInt32) return ToInt32();
     DCHECK_EQ(kFloat64, type());
     return bit_cast<double>(value_);
   }
 
   ExternalReference ToExternalReference() const {
     DCHECK_EQ(kExternalReference, type());
     return bit_cast<ExternalReference>(static_cast<intptr_t>(value_));
   }
@@ skipping 241 matching lines @@
   DeoptimizationVector deoptimization_entries_;
 };
 
 OStream& operator<<(OStream& os, const InstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_