[Bug middle-end/55481] [4.8 regression] -O2 generates a wrong-code infinite loop in C++Benchmark's simple_types_constant_folding int8 xor test

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55481

--- Comment #17 from Richard Biener <rguenth at gcc dot gnu.org> 2012-12-12 13:07:26 UTC ---
Author: rguenth
Date: Wed Dec 12 13:07:19 2012
New Revision: 194444

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194444
Log:
2012-12-12  Zdenek Dvorak  <ook@ucw.cz>

    PR tree-optimization/55481
    * tree-ssa-loop-ivopts.c (rewrite_use_nonlinear_expr): Fall
    back to general rewriting if we cannot leave an original biv
    definition alone.

    * gcc.dg/torture/pr55481.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr55481.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-loop-ivopts.c