[Bug target/101021] PSHUFB is emitted instead of PSHUFD, PSHUFLW and PSHUFHW with -msse4

Fri, 11 Jun 2021 03:33:02 -0700 

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101021

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Uros Bizjak <[email protected]>:

https://gcc.gnu.org/g:1fa991d1d74cb1ce96c48ede70ae0be7a9683ce3

commit r12-1384-g1fa991d1d74cb1ce96c48ede70ae0be7a9683ce3
Author: Uros Bizjak <[email protected]>
Date:   Fri Jun 11 12:31:42 2021 +0200

    i386: Try to avoid variable permutation instruction [PR101021]

    Some permutations can be implemented without costly PSHUFB instruction,
e.g.:

    { 8,9,10,11,12,13,14,15, 0,1,2,3,4,5,6,7 } with PALIGNR,

    { 0,1,2,3, 4,5,6,7, 4,5,6,7, 12,13,14,15 } with PSHUFD,

    { 0,1, 2,3, 2,3, 6,7, 8,9,10,11,12,13,14,15 } with PSHUFLW and

    { 0,1,2,3,4,5,6,7, 8,9, 10,11, 10,11, 14,15 } with PSHUFHW.

    All these instructions have constant shuffle control mask and do not
    need to load shuffle mask from a memory to a temporary XMM register.

    2021-06-11  UroÅ¡ Bizjak  <[email protected]>

    gcc/
            PR target/101021
            * config/i386/i386-expand.c (expand_vec_perm_pshufb): Return
            false if the permutation can be implemented with constant
            permutation instruction in wider mode.
            (canonicalize_vector_int_perm): Move above expand_vec_perm_pshufb.
            Handle V8QImode and V4HImode.

    gcc/testsuite/

            PR target/101021
            * gcc.target/i386/pr101021-1.c: New test.
            * gcc.target/i386/pr101021-2.c: Ditto.

Reply via email to