On December 30, 2017 8:27:44 PM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>Ths chunk of code wants to expand 16-bit rotate by 8 as bswaphi, but
>if mode is a vector mode (or complex mode), trying to use bswaphi
>pattern to
>swap say V16HImode vector is just wrong.
>
>This patch arranges to use bswapv16hi etc. instead in those cases,
>which
>isn't 100% clear to me from the docs if they only swap bytes of each of
>the
>vector element, but from looking at a few backends it seems like that
>is the
>case and if it wasn't, e.g. simplify-rtx.c would missimplify stuff.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
>2017-12-30 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/83623
> * expmed.c (expand_shift_1): For 2-byte rotates by BITS_PER_UNIT,
> check for bswap in mode rather than HImode and use that in expand_unop
> too.
>
> * gcc.dg/pr83623.c: New test.
>
>--- gcc/expmed.c.jj 2017-12-20 20:40:18.000000000 +0100
>+++ gcc/expmed.c 2017-12-30 11:44:47.045433528 +0100
>@@ -2490,9 +2490,8 @@ expand_shift_1 (enum tree_code code, mac
> && CONST_INT_P (op1)
> && INTVAL (op1) == BITS_PER_UNIT
> && GET_MODE_SIZE (scalar_mode) == 2
>- && optab_handler (bswap_optab, HImode) != CODE_FOR_nothing)
>- return expand_unop (HImode, bswap_optab, shifted, NULL_RTX,
>- unsignedp);
>+ && optab_handler (bswap_optab, mode) != CODE_FOR_nothing)
>+ return expand_unop (mode, bswap_optab, shifted, NULL_RTX,
>unsignedp);
>
> if (op1 == const0_rtx)
> return shifted;
>--- gcc/testsuite/gcc.dg/pr83623.c.jj 2017-12-30 11:49:23.259470538
>+0100
>+++ gcc/testsuite/gcc.dg/pr83623.c 2017-12-30 11:49:01.309467592 +0100
>@@ -0,0 +1,12 @@
>+/* PR middle-end/83623 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2" } */
>+/* { dg-additional-options "-mmovbe" { target i?86-*-* x86_64-*-* } }
>*/
>+
>+unsigned short __attribute__ ((__vector_size__ (16))) x;
>+
>+void
>+foo (void)
>+{
>+ x = x << 8 | x >> 8;
>+}
>
> Jakub
