[Bug rtl-optimization/51023] [4.7 Regression] likely integer wrong code bug

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51023

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-11-09 09:39:28 UTC ---
Created attachment 25765
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25765
gcc47-pr51023.patch

Part of that patch is clearly bogus, as const_op here is a constant in wider
mode than the inner mode of SIGN_EXTEND, thus before the comparison checked
not just that the sign bit is clear, but also any bits above it.

The simplify_set change from the same patch is questionable too.