[Bug rtl-optimization/41511] [4.5 Regression] combine behaves differently with/without -g

["jakub at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #3 from jakub at gcc dot gnu dot org  2009-10-02 16:35 -------
Created an attachment (id=18693)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18693&action=view)
gcc45-pr41511.patch

Agreed.  Patch I'm going to bootstrap/regtested on x86_64-linux and i686-linux
now, fixes this -fcompare-debug issue on the testcase in x86_64-linux ->
sh4-linux cross.

The zero extension is indeed unneeded in this case, perhaps
reg_num_sign_bit_copies_for_combine could try harder.  The thing is that if
get_last_value before the final validation finds it is MEM and only the
validation changes it into a clobber because it is unknown what value will the
memory have, if LOAD_EXTEND_OP is SIGN_EXTEND for the mode, it doesn't really
matter what value the memory has for num_sign_bit_copies.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41511