http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53101
--- Comment #4 from Marc Glisse <marc.glisse at normalesup dot org> 2012-05-03
19:19:00 UTC ---
(define_peephole2
[(set (mem:VI8F_256 (match_operand 2))
(match_operand:VI8F_256 1 "register_operand"))
(set (match_operand:<ssehalfvecmode> 0 "register_operand")
(mem:<ssehalfvecmode> (match_dup 2)))]
"TARGET_AVX"
[(set (match_dup 0)
(vec_select:<ssehalfvecmode> (match_dup 1)
(parallel [(const_int 0) (const_int
1)])))]
)
(and similar for VI4F_256) is much less hackish than the XEXP stuff. I was
quite sure I'd tested exactly this and it didn't work, but now it looks like it
does :-/
Except that following http://gcc.gnu.org/ml/gcc-patches/2012-05/msg00197.html ,
this is not the right place to try and add such logic. That's a good thing
because it is way too fragile, another instruction can easily squeeze between
the two sets and disable the peephole.
