[PATCH][i386] Fix PR83008

[Richard Biener]

This restores the vec_construct cost dependence on the vector element
count.  Honza removed this (accidentially?) during the rework.

Bootstrap / regtest running on x86_64-unknown-linux-gnu, ok for trunk?

Thanks,
Richard.

2017-12-08  Richard Biener  <rguent...@suse.de>

        PR target/83008
        * config/i386/i386.c (ix86_builtin_vectorization_cost): Restore
        vec_construct dependence on vector element count.

Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c      (revision 255499)
+++ gcc/config/i386/i386.c      (working copy)
@@ -44879,7 +44879,8 @@ ix86_builtin_vectorization_cost (enum ve
                              ix86_cost->sse_op, true);
 
       case vec_construct:
-       return ix86_vec_cost (mode, ix86_cost->sse_op, false);
+       return (ix86_vec_cost (mode, ix86_cost->sse_op, false)
+               * (TYPE_VECTOR_SUBPARTS (vectype) - 1));
 
       default:
         gcc_unreachable ();