[Bug tree-optimization/52943] [4.7/4.8 Regression] likely wrong code bug caused by predictive commoning

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52943

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-04-12 11:39:12 UTC ---
Author: rguenth
Date: Thu Apr 12 11:38:47 2012
New Revision: 186374

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186374
Log:
2012-04-12  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/52943
    * tree-chrec.h (chrec_is_positive): Remove.
    * tree-scalar-evolution.c (chrec_is_positive): Move ...
    * tree-data-ref.c (chrec_is_positive): ... here.  Make static.
    Return false for a constant zero instead of negative.
    (analyze_siv_subscript_cst_affine): Handle zero difference
    in the initial condition explicitely.

    * gcc.dg/torture/pr52943.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr52943.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-chrec.h
    trunk/gcc/tree-data-ref.c
    trunk/gcc/tree-scalar-evolution.c