[Bug tree-optimization/92819] [10 Regression] Worse code generated on avx2 due to simplify_vector_constructor

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92819

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Guenther <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:fc98d038618b792c413212759057b2125507d3ef

commit r10-6425-gfc98d038618b792c413212759057b2125507d3ef
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Feb 4 10:03:03 2020 +0100

    tree-optimization/92819 restrict new vector CTOR canonicalization

    The PR shows that code generation ends up pessimized by the new
    canonicalization rules that end up nailing do-not-care elements
    to specific values making it hard to generate good code later.

    The temporary solution is to avoid this for the cases we also
    obviously know the canonicalization will create more GIMPLE stmts than
    before.

    2020-02-04  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/92819
        * tree-ssa-forwprop.c (simplify_vector_constructor): Avoid
        generating more stmts than before.

        * gcc.target/i386/pr92819.c: New testcase.
        * gcc.target/i386/pr92803.c: Adjust.