[Bug tree-optimization/70840] revisit reassoc handling of pow / powi, amend match.pd for powi

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70840

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Apr 28 12:34:28 2016
New Revision: 235566

URL: https://gcc.gnu.org/viewcvs?rev=235566&root=gcc&view=rev
Log:
2016-04-28  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/70840
        * match.pd: powi(-x, y) and powi(|x|,y) -> powi(x,y) if y is even;
        Fix pow(copysign(x, y), z) -> pow(x, z) and add powi variant;
        Mark x * pow(x,c) -> pow(x,c+1) commutative.
        Add powi(x,y) * powi(z,y) -> powi(x*z,y).

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/match.pd