[Bug target/84986] [8 Regression] Performance regression: loop no longer vectorized (x86-64)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84986

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue Mar 20 14:35:46 2018
New Revision: 258684

URL: https://gcc.gnu.org/viewcvs?rev=258684&root=gcc&view=rev
Log:
2018-03-20  Richard Biener  <rguenther@suse.de>

        PR target/84986
        * config/i386/i386.c (ix86_add_stmt_cost): Only cost
        sign-conversions as zero, fall back to standard scalar_stmt
        cost for the rest.

        * gcc.dg/vect/costmodel/x86_64/costmodel-pr84986.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-pr84986.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386.c
    trunk/gcc/testsuite/ChangeLog