[Bug tree-optimization/40436] [4.5/4.6 regression] 0.5% code size regression caused by r147852

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40436

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

--- Comment #46 from Jan Hubicka <hubicka at gcc dot gnu.org> 2010-11-19 08:18:11 UTC ---
I think CCP is not folding one way or another as it might lead to inconsistent
control flows (i.e. one place assuming that the given undefined value is 0,
other that 1). Initializing them to 0 is one consistent way to get stuff
optimized out.  I am not biggest friend of that (I think they should stay
undefined and liveness should handle it well) but givent hat RTL land does it
anyway there is no point to bother.

Anyway I looked at the date for jump in CSiBE sizes in our tester.  It is May
30 2009
It coincide with Richard's EH unwind reorg
2009-05-29  Richard Henderson  <rth@redhat.com>

        * cfgcleanup.c (try_crossjump_to_edge): Only skip past
        NOTE_INSN_BASIC_BLOCK.
        * cfglayout.c (duplicate_insn_chain): Copy epilogue insn marks.
        Duplicate NOTE_INSN_EPILOGUE_BEG notes.
        * cfgrtl.c (can_delete_note_p): Allow NOTE_INSN_EPILOGUE_BEG
        to be deleted.
        * dwarf2out.c (struct cfa_loc): Change indirect field to bitfield,
        add in_use field.
        (add_cfi): Disable check redefining cfa away from drap.
        (lookup_cfa_1): Add remember argument; handle remember/restore.
        (lookup_cfa): Pass remember argument.
        (cfa_remember): New.

given that it makes tables asynchronous and it is thus correcntess issue and
given that it is misaccounted as code size by "size" command and thus also
CSiBE and given that I analyzed quite few testcases and found no inliner bugs,
I think the bug no longer exists (-Os inliner was improved a lot).

It would be nice if someone tested it using the cross, for now I am putting it
into waiting stage and will open new PRs for the few new issues I noticed.