This patch is to add the support for float from/to long conversion

This patch is to add the support for float from/to long conversion
vectorization on port rs6000.

gcc/ChangeLog

2019-09-29  Kewen Lin  <linkw@gcc.gnu.org>

    * config/rs6000/vsx.md (vec_pack[su]_float_v2di): New define_expand.
    (vec_unpack_[su]fix_trunc_hi_v4sf): Likewise.
    (vec_unpack_[su]fix_trunc_lo_v4sf): Likewise.

gcc/testsuite/ChangeLog

2019-09-29  Kewen Lin  <linkw@gcc.gnu.org>

    * gcc.target/powerpc/conv-vectorize-1.c: New test.
    * gcc.target/powerpc/conv-vectorize-2.c: New test.

From-SVN: r276266