[Bug tree-optimization/49073] [4.6/4.7 Regression] g++ optimizer breaks do-while code

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49073

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-05-20 
14:19:07 UTC ---
Author: jakub
Date: Fri May 20 14:19:05 2011
New Revision: 173948

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=173948
Log:
    PR tree-optimization/49073
    * gimple-fold.c (and_comparisons_1, or_comparisons_1): Return
    NULL if PHI argument is SSA_NAME, whose def_stmt is dominated
    by the PHI.
    * tree-ssa-ifcombine.c (tree_ssa_ifcombine): Calculate dominators.

    * gcc.c-torture/execute/pr49073.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr49073.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimple-fold.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-ifcombine.c