[Bug rtl-optimization/48702] [4.6/4.7 Regression] optimization regression with gcc-4.6 on x86_64-unknown-linux-gnu

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|4.7.0                       |
            Summary|[4.6 Regression]            |[4.6/4.7 Regression]
                   |optimization regression     |optimization regression
                   |with gcc-4.6 on             |with gcc-4.6 on
                   |x86_64-unknown-linux-gnu    |x86_64-unknown-linux-gnu
      Known to fail|                            |4.7.0

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-20 
15:08:32 UTC ---
I have a patch that makes it fail on trunk as well.  IVOPTs generates

  for (p = &a; p != &a - 3; --p)
    *(p + 3) = ...

and alias analysis doesn't like this invalid pointer.