[Bug rtl-optimization/51505] [4.5/4.6/4.7 Regression] ICE: in form_sum, at reload.c:5349 with -O --param max-cse-insns=1

[abel at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51505

--- Comment #5 from Andrey Belevantsev <abel at gcc dot gnu.org> 2012-01-17 16:05:26 UTC ---
Created attachment 26353
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26353
untested patch

I've tried to implement what Paolo suggests, the attached patch bootstraps but
otherwise untested.  The code is somewhat ugly as we need to purge all
registers reffered to from the note we delete also from EQ_USES list (or we get
verification errors).  I've never tried to dig deeply in DF core so sorry if
the patch is completely in the wrong direction.