[Bug tree-optimization/106198] New: [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[Bug tree-optimization/106198] New: [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

            Bug ID: 106198
           Summary: [13 Regression] 25_algorithms/find_end/constrained.cc
                    ICEs in check_loop_closed_ssa_def
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

Related to PR106182, another case where CFG cleanup causes virtual LC SSA form
to go out-of-date.

  /* This usually does nothing.  But sometimes parts of cfg that originally
     were inside a loop get out of it due to edge removal (since they
     become unreachable by back edges from latch).  Also a former
     irreducible loop can become reducible - in this case force a full
     rewrite into loop-closed SSA form.  */
  if (loops_state_satisfies_p (LOOP_CLOSED_SSA))
    rewrite_into_loop_closed_ssa (n_new_or_deleted_loops ? NULL : changed_bbs,
                                  TODO_update_ssa);

changing it to unconditionally pass NULL fixes the case.

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-reduction
   Target Milestone|---                         |13.0

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-07-05
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
reducing is slow but progressing, eventually fuzzers will find a simpler
duplicate as well ...

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[zhendong.su at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

Zhendong Su <zhendong.su at inf dot ethz.ch> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zhendong.su at inf dot ethz.ch

--- Comment #2 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
Here is one:

[564] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-sanitizers
--enable-languages=c,c++ --disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220705 (experimental) [master r13-1500-g510ac273a78] (GCC)
[565] %
[565] % gcctk -O3 small.c
during GIMPLE pass: unswitch
small.c: In function ‘main’:
small.c:5:5: internal compiler error: in check_loop_closed_ssa_def, at
tree-ssa-loop-manip.cc:717
    5 | int main() {
      |     ^~~~
0x76e5ab check_loop_closed_ssa_def
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:717
0x10572b4 check_loop_closed_ssa_bb
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:731
0x1058556 verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:767
0x1058556 verify_loop_closed_ssa(bool, loop*)
        ../../gcc-trunk/gcc/tree-ssa-loop-manip.cc:751
0xde6ac4 execute_function_todo
        ../../gcc-trunk/gcc/passes.cc:2109
0xde6f0b execute_todo
        ../../gcc-trunk/gcc/passes.cc:2145
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
[566] %
[566] % cat small.c
int printf(const char *, ...);
long a;
int b;
volatile int c;
int main() {
  long e = a;
  int f = a;
 L:
  if (b > 0) {
    printf("0");
    goto L;
  }
  if (f) {
    printf("%ld", (long)b);
    goto L;
  }
  e >= b && c;
  return 0;
}

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, that one is really the same as PR106182 but the fix there no longer works
(we don't remove a loop during fixup).

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:07dd0f7ba27d1fe9f0ce5b049ac5735dc5d361ad

commit r13-1505-g07dd0f7ba27d1fe9f0ce5b049ac5735dc5d361ad
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Jul 5 14:14:49 2022 +0200

    tree-optimization/106198 - CFG cleanup vs LC SSA

    This is another case like PR106182 where for the 2nd testcase in
    the bug there are no removed or discovered loops but still changing
    loop exits invalidates LC SSA and it is not enough to just scan for
    uses in the blocks that changed loop depth.  One might argue that
    if we'd include former exit destinations we'd pick up the original
    LC SSA use but for virtuals on block merging we'd have propagated
    those out (while for regular uses we insert copies).  CFG cleanup
    can also be entered with loops needing fixup so any heuristics
    based on loop structure are bound to fail.

            PR tree-optimization/106198
            * tree-cfgcleanup.cc (repair_loop_structures): Always do a
            full LC SSA rewrite but only if any blocks changed loop
            depth.

            * gcc.dg/pr106198.c: New testcase.

[Bug tree-optimization/106198] [13 Regression] 25_algorithms/find_end/constrained.cc ICEs in check_loop_closed_ssa_def

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106198

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.