[Bug rtl-optimization/45792] New: [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[Bug rtl-optimization/45792] New: [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

           Summary: [4.6 Regression]: cris-elf build failure (hangs) due
                    to fix for PR44374
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Keywords: build
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hp@gcc.gnu.org
                CC: bernds@gcc.gnu.org
              Host: x86_64-unknown-linux-gnu
            Target: cris-*-*


Created attachment 21882
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=21882
Preprocessed dtoa.c

At r164551 the tree built with few regressions.
At r164560 building newlib/libc/stdlib/dtoa.c hangs (cpu-time > 38 hours) and
at r164619 the build is at a similar state (didn't wait 38 hours, but see
below).

Attaching a gdb-session to the running cc1 at r164619 shows an infinite loop in
gcc/emit-rtl.c:reorder_insns:

4027          for (x = from; x != NEXT_INSN (to); x = NEXT_INSN (x))
4028            if (!BARRIER_P (x))
4029              df_insn_change_bb (x, bb);

But "x" is bogus; it seems to have been deleted or at least removed from the
insn stream:
(insn 2210 2210 2210 239 (set (cc0)
        (compare (reg/v/f:SI 3 r3 [orig:95 mlo ] [95])
            (reg/v/f:SI 4 r4 [orig:97 mhi ] [97])))
/tmp/hpautotest-gcc1/gcc/newlib/libc/stdlib/dtoa.c:808 11 {*cmpsi}
     (nil))

The call to df_insn_change_bb takes the (old_bb == new_bb) early return.

Author of suspect patch in revision range CC:ed.
Preprocessed dtoa.c attached.  Compile with -O2.

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.6.0

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2010.09.25 22:14:30
               date|                            |
     Ever Confirmed|0                           |1

--- Comment #1 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2010-09-25 22:14:30 UTC ---
FWIW I had a private report that it also happens with host i686-darwin9 target
cris-elf, at r165605.

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch
                URL|                            |http://gcc.gnu.org/ml/gcc-p
                   |                            |atches/2010-09/msg02097.htm
                   |                            |l
         AssignedTo|unassigned at gcc dot       |hp at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #2 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2010-09-27 09:16:59 UTC ---
I'd better take it, now that I have a patch.  Bernd, I certainly don't mind if
you grab this PR for yourself, definitely if you don't like the patch.

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

--- Comment #3 from Bernd Schmidt <bernds at gcc dot gnu.org> 2010-09-27 09:32:14 UTC ---
Looking at it now.

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|http://gcc.gnu.org/ml/gcc-p |http://gcc.gnu.org/ml/gcc-p
                   |atches/2010-09/msg02097.htm |atches/2010-09/msg02117.htm
                   |l                           |l

--- Comment #4 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2010-09-27 17:34:15 UTC ---
For the record, updated patch URL to point to Bernds patch.

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

--- Comment #5 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2010-09-27 19:55:31 UTC ---
Author: hp
Date: Mon Sep 27 19:55:29 2010
New Revision: 164663

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164663
Log:
    PR rtl-optimization/45792
    * cfgcleanup.c (try_head_merge_bb): New rtx vector nextptr.
    If not all insns are to be merged, for each edge, stash the
    next candidate after the to-be-merged insns before doing the
    merge, and use them for the retry at the new insertion point.
    Handle CC0 targets when retrying.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgcleanup.c

[Bug rtl-optimization/45792] [4.6 Regression]: cris-elf build failure (hangs) due to fix for PR44374

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45792

Hans-Peter Nilsson <hp at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #6 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2010-09-27 19:58:07 UTC ---
committed