[SubZero] Fix f64 to/from i64 moves

crosstest/test_cast.h

 //===- subzero/crosstest/test_cast.h - Test prototypes ----------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the function prototypes used for crosstesting cast
 // operations.
 //
 //===----------------------------------------------------------------------===//
 
 // The driver and the test program may be compiled by different
 // versions of clang, with different standard libraries that have
 // different definitions of int8_t.  Specifically, int8_t may be
 // typedef'd as either 'char' or 'signed char', which mangle to
 // different strings.  Avoid int8_t and use an explicit myint8_t.
 typedef signed char myint8_t;
 
 template <typename FromType, typename ToType> ToType cast(FromType a);
 template <typename FromType, typename ToType> ToType castBits(FromType a);
+#ifdef MIPS32

[Jim Stichnoth, 2016/10/21 14:18:56]

What do you think about running this set of tests for all targets, not just
MIPS32?  If that were done, I would suggest a few other modifications:

1. Maybe add a dummy int arg both before and after the main arg, in case some
target passes args in the opposite memory order.

2. Would be nice to refactor the great similarities in the .cpp files.  Maybe
use variadic macros?

3. Document somewhere (here?) why these dummy-arg functions are tested
(specifically for bitcast).

[jaydeep.patil, 2016/10/26 07:47:31]

Done.

+template <typename FromType, typename ToType> ToType cast(int i, FromType a);
+template <typename FromType, typename ToType> ToType castBits(int i,
+                                                              FromType a);
+#endif