[turbofan] Add operators for float32 support.

src/conversions-inl.h

 // Copyright 2011 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_CONVERSIONS_INL_H_
 #define V8_CONVERSIONS_INL_H_
 
 #include <float.h>         // Required for DBL_MAX and on Win32 for finite()
 #include <limits.h>        // Required for INT_MAX etc.
 #include <stdarg.h>
@@ skipping 49 matching lines @@
 #endif
     // Copy least significant 32 bits of mantissa.
     memcpy(&result, mantissa_ptr, sizeof(result));
     return negative ? ~result + 1 : result;
   }
   // Large number (outside uint32 range), Infinity or NaN.
   return 0x80000000u;  // Return integer indefinite.
 }
 
 
+inline float DoubleToFloat32(double x) {
+  // TODO(yanggou): This static_cast is implementation-defined behaviour in C++,
+  // so we may need to do the conversion manually instead to match the spec.
+  volatile float f = static_cast<float>(x);
+  return f;
+}
+
+
 inline double DoubleToInteger(double x) {
   if (std::isnan(x)) return 0;
   if (!std::isfinite(x) || x == 0) return x;
   return (x >= 0) ? std::floor(x) : std::ceil(x);
 }
 
 
 int32_t DoubleToInt32(double x) {
   int32_t i = FastD2I(x);
   if (FastI2D(i) == x) return i;
@@ skipping 597 matching lines @@
   SLOW_DCHECK(buffer_pos < kBufferSize);
   buffer[buffer_pos] = '\0';
 
   double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
   return (sign == NEGATIVE) ? -converted : converted;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONVERSIONS_INL_H_