[turbofan] Add backend support for Float32Constant.

test/cctest/compiler/test-run-machops.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 <functional>
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/compiler/generic-node-inl.h"
 #include "test/cctest/cctest.h"
@@ skipping 4257 matching lines @@
       m.TruncateFloat64ToFloat32(m.LoadFromPointer(&input, kMachFloat64)));
   m.Return(m.Int32Constant(0));
   FOR_FLOAT64_INPUTS(i) {
     input = *i;
     volatile double expected = DoubleToFloat32(input);
     CHECK_EQ(0, m.Call());
     CHECK_EQ(expected, actual);
   }
 }
 
+
+TEST(RunFloat32Constant) {
+  FOR_FLOAT32_INPUTS(i) {
+    float expected = *i;
+    float actual = *i;
+    RawMachineAssemblerTester<int32_t> m;
+    m.StoreToPointer(&actual, kMachFloat32, m.Float32Constant(expected));
+    m.Return(m.Int32Constant(0));
+    CHECK_EQ(0, m.Call());
+    CHECK_EQ(expected, actual);
+  }
+}
+
 #endif  // V8_TURBOFAN_TARGET