[Bug tree-optimization/49770] New: [4.7 Regression] wrong code with -fno-tree-forwprop

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49770

           Summary: [4.7 Regression] wrong code with -fno-tree-forwprop
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 24781
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24781
reduced testcase

There are several libstdc++ test that FAIL with -fno-tree-ccp
-fno-tree-forwprop. Attached is testcase that FAILs with -fno-tree-forwprop.

Output:
$ g++ -O2 -std=gnu++0x -fno-tree-forwprop testcase.C
$ ./a.out 
Aborted

Tested revisions:
r176370 - fail
4.6 r176280 - OK