[Bug tree-optimization/64193] [4.8/4.9/5 Regression] Decreased performance after r173250

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64193

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 34229
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34229&action=edit
patch

Ok, I see the regression introduced by that rev., but on trunk (r218479)
I get the same code generated with/without the attached fix.  I'm using
-O3 -m32 -march=i686 on x86_64-linux.

Probably the regression was mitigated by the partial fix for PR63677:

2014-11-20   Richard Biener  <rguenther@suse.de>

        PR tree-optimization/63677
        * tree-ssa-dom.c: Include gimplify.h for unshare_expr.
        (avail_exprs_stack): Make a vector of pairs.
        (struct hash_expr_elt): Replace stmt member with vop member.
        (expr_elt_hasher::equal): Simplify.
...

where DOM now catches the CSE opportunities FRE no longer did.