[Bug target/48673] [4.7 Regression] GCC generates WAW and RAW conflicts on IA64.

[amonakov at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48673

Alexander Monakov <amonakov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|ia64-*-*                    |ia64-*-hpux
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.04.28 11:48:26
                 CC|                            |amonakov at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #3 from Alexander Monakov <amonakov at gcc dot gnu.org> 2011-04-28 11:48:26 UTC ---
The problem can be seen by visual inspection of generated assembly with a
cross-compiler configured with --target=ia64-hpux --enable-languages=c,fortran.

The issue must have appeared with this patch:

Author: bernds <bernds@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri Apr 1 17:42:35 2011 +0000
        * sched-ebb.c (schedule_ebbs): Honor the BB_DISABLE_SCHEDULE flag.

After that patch Haifa scheduler would not place TImodes on cycle boundaries,
as such basic blocks are not touched by the scheduler at all, but the back-end
relies on TImodes for placement of stop bits.  Selective scheduler handles
BB_DISABLE_SCHEDULE flag by skipping scheduling but still computing cycle
boundaries and calling target hooks in sel_region_target_finish.