[Bug middle-end/49946] New: Thread jumps confuse loop unrolling

[Bug middle-end/49946] New: Thread jumps confuse loop unrolling

[izamyatin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

           Summary: Thread jumps confuse loop unrolling
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: izamyatin@gmail.com


Created attachment 24892
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24892
test for loop unrolling

I see exactly the case that was mentioned here -
http://gcc.gnu.org/ml/gcc/2010-01/msg00057.html:

exp_gcc/gcc -c -O3 test_unroll.c -fno-tree-dominator-opts performs complete
unroll and

exp_gcc/gcc -c -O3 test_unroll.c does not do the unroll

[Bug middle-end/49946] Thread jumps confuse loop unrolling

[izamyatin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

--- Comment #1 from Igor Zamyatin <izamyatin at gmail dot com> 2011-08-03 15:26:57 UTC ---
Used compiler:

Target: x86_64-unknown-linux-gnu
Thread model: posix
gcc version 4.7.0 20110802 (experimental) (GCC)

[Bug middle-end/49946] Thread jumps confuse loop unrolling

[izamyatin at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

--- Comment #2 from Igor Zamyatin <izamyatin at gmail dot com> 2011-08-08 11:35:32 UTC ---
cunrolli does not handle the loop in the testcase because of the condition "ul
== UL_NO_GROWTH && unr_insns > ninsns" in try_unroll_loop_completely. Meanwhile
may_increase_size is true in tree_unroll_loops_completely.

[Bug tree-optimization/49946] Thread jumps confuse loop unrolling

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection
   Last reconfirmed|                            |2021-11-29
          Component|middle-end                  |tree-optimization
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, though it looks like it was fixed on the trunk.
There has been a "few" jump threading patches which would have improved this
situation.

[Bug tree-optimization/49946] Thread jumps confuse loop unrolling

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aldyh at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
      Known to fail|                            |11.2.0
      Known to work|                            |12.0
           Keywords|needs-bisection             |

--- Comment #4 from Martin Liška <marxin at gcc dot gnu.org> ---
Fixed with r12-2591-g2e96b5f14e402569.

[Bug tree-optimization/49946] Thread jumps confuse loop unrolling

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49946

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.