[Bug tree-optimization/103793] New: [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability

[Bug tree-optimization/103793] New: [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103793

            Bug ID: 103793
           Summary: [12 Regression] ICE: in to_reg_br_prob_base, at
                    profile-count.h:277 with -O3
                    -fno-guess-branch-probability
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu

Created attachment 52040
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52040&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O3 -fno-guess-branch-probability testcase.c
during GIMPLE pass: lsplit
testcase.c: In function 'foo':
testcase.c:4:1: internal compiler error: in to_reg_br_prob_base, at
profile-count.h:277
    4 | foo (int x, int w)
      | ^~~
0x7c38c2 profile_probability::to_reg_br_prob_base() const
        /repo/gcc-trunk/gcc/profile-count.h:277
0x7c38c2 profile_probability::to_reg_br_prob_base() const
        /repo/gcc-trunk/gcc/profile-count.h:275
0x7c38c2 split_loop
        /repo/gcc-trunk/gcc/tree-ssa-loop-split.c:630
0x14ea62b tree_ssa_split_loops
        /repo/gcc-trunk/gcc/tree-ssa-loop-split.c:1693
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r12-6087-20211220211250-g51a24e4a984-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r12-6087-20211220211250-g51a24e4a984-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20211221 (experimental) (GCC)

[Bug tree-optimization/103793] [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability since r12-6086-gcd5ae148c47c6dee

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103793

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-12-21
     Ever confirmed|0                           |1
                 CC|                            |luoxhu at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
   Target Milestone|---                         |12.0
            Summary|[12 Regression] ICE: in     |[12 Regression] ICE: in
                   |to_reg_br_prob_base, at     |to_reg_br_prob_base, at
                   |profile-count.h:277 with    |profile-count.h:277 with
                   |-O3                         |-O3
                   |-fno-guess-branch-probabili |-fno-guess-branch-probabili
                   |ty                          |ty since
                   |                            |r12-6086-gcd5ae148c47c6dee

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r12-6086-gcd5ae148c47c6dee.

[Bug tree-optimization/103793] [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability since r12-6086-gcd5ae148c47c6dee

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103793

luoxhu at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |luoxhu at gcc dot gnu.org

--- Comment #2 from luoxhu at gcc dot gnu.org ---

Confirmed. -fno-guess-branch-probability requires the profile_count be
initialized, so add guard like this?


+       if (true_edge->probability.initialized_p ())
+         {
+           edge exit_to_latch1 = single_pred_edge (loop1->latch);
+           exit_to_latch1->probability
+             = exit_to_latch1->probability.apply_scale (
+               true_edge->probability.to_reg_br_prob_base (),
+               REG_BR_PROB_BASE);
+           single_exit (loop1)->probability
+             = exit_to_latch1->probability.invert ();
+         }

[Bug tree-optimization/103793] [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability since r12-6086-gcd5ae148c47c6dee

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103793

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Xiong Hu Luo <luoxhu@gcc.gnu.org>:

https://gcc.gnu.org/g:44372676e81358de29d5c853685a7664a95d8a96

commit r12-6140-g44372676e81358de29d5c853685a7664a95d8a96
Author: Xionghu Luo <luoxhu@linux.ibm.com>
Date:   Tue Dec 28 19:09:14 2021 -0600

    Fix ICE in lsplit when built with -O3 -fno-guess-branch-probability
[PR103793]

    no-guess-branch-probability option requires profile_count scaling with
    initialized_p guard, use multiply instead of apply_scale, which will do
    the right thing to undefined probabilities and will not cause unnecesary
    roundoff errors and precision info loss.
    Also merge the missed part of r12-6086 of factor out function to avoid
    duplicate code.

    Regression testest pass on Power and X86.

    gcc/ChangeLog:

            PR tree-optimization/103793
            * tree-ssa-loop-split.c (fix_loop_bb_probability): New function.
            (split_loop): Use multiply to scale loop1's exit probability.
            (do_split_loop_on_cond): Call fix_loop_bb_probability.

    gcc/testsuite/ChangeLog:

            PR tree-optimization/103793
            * gcc.dg/pr103793.c: New test.

[Bug tree-optimization/103793] [12 Regression] ICE: in to_reg_br_prob_base, at profile-count.h:277 with -O3 -fno-guess-branch-probability since r12-6086-gcd5ae148c47c6dee

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103793

luoxhu at gcc dot gnu.org changed:

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

--- Comment #4 from luoxhu at gcc dot gnu.org ---
Fixed on master.