simd-2.c failing on powerpc-linux

[Joern Rennecke]

Aldy Hernandez wrote:
> it's a compilation failure (see below).  i don't think it's related, but i 
> haven't tried, since all 4 of my trees are in a big mess right now.
> 
> however...
> 
> it seems to me like, this should be folded by simplify_gen_subreg().  hmmm:
> 
>  unrecognizable insn:
> (insn 403 407 404 0 (nil) (set (subreg:SI (reg:V8HI 123) 0)
>         (subreg:SI (const_vector:V8HI [
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                     (const_int 0 [0x0])
>                 ]) 0)) -1 (insn_list 407 (nil))

I've seen just the same kind of failure.  And my patch fixed it.
simplify_gen_subreg calls simplify_subreg.  And I patched the latter to
do the folding in the aforementioned patch.