[Bug debug/44023] [4.6 Regression] -fcompare-debug failure (length) for alphaev67 target (bootstrap failure)

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

------- Comment #9 from jakub at gcc dot gnu dot org  2010-05-10 10:13 -------
Created an attachment (id=20617)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20617&action=view)
gcc46-pr44023.patch

The bug is that if a debug insn references more than one dead pseudo, only the
first one is recorded using dead_debug_add.  That means the other pseudos
stay alive beyond REG_DEAD notes and affect e.g. RA decisions.

Attached patch fixes this by calling dead_debug_add on all the uses instead of
just one.  This alone crashes badly, because dead_debug_insert_before which
replaces one of the uses in a debug insn calls df_insn_rescan on it, which
invalidates all the other uses.  So we need to queue rescanning it until
dead_debug_finish (or, at least until all dead debug records referencing the
debug_insn are gone).

I'll bootstrap/regtest the patch on x86_64-linux and i686-linux, Uros, can you
please do the same on alpha*-*?


-- 

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|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44023