[Bug tree-optimization/95866] vectorized shift with scalar argument not correctly costed

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95866

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:86ce59b4f05d8f68ec4d9a14a7732acb370412db

commit r11-1647-g86ce59b4f05d8f68ec4d9a14a7732acb370412db
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jun 25 11:21:20 2020 +0200

    tree-optimization/95866 - avoid using scalar ops for vectorized shift

    This avoids using the original scalar SSA operand when vectorizing
    a shift with a vectorized shift operand where we know all vector
    components have the same value and thus we can use a vector by
    scalar shift.  Using the scalar SSA operand causes a possibly
    long chain of scalar computation to be retained so it's better
    to simply extract lane zero from the available vectorized shift
    operand.

    2020-06-25  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/95866
            * tree-vect-stmts.c (vectorizable_shift): Reject incompatible
            vectorized shift operands.  For scalar shifts use lane zero
            of a vectorized shift operand.

            * gcc.dg/vect/bb-slp-pr95866.c: New testcase.