[Bug tree-optimization/107447] New: [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[Bug tree-optimization/107447] New: [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107447

            Bug ID: 107447
           Summary: [13 Regression] ICE: verify_flow_info failed (error:
                    returns_twice call is not first in basic block 2)
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc 13.0.0 20221023 snapshot (g:0e37fd4dc74c1db99cdc7d71ef378e1221253c6f) ICEs
when compiling the following testcase w/ -O2:

int n;

void
bar (int, int);

__attribute__ ((noinline, returns_twice)) int
zero (void)
{
  return 0;
}

void
foo (void)
{
  (void) zero ();

  n = 0;

  for (;;)
    bar (zero (), n);
}

% gcc-13 -O2 -c ozyot3yy.c
ozyot3yy.c: In function 'foo':
ozyot3yy.c:13:1: error: returns_twice call is not first in basic block 2
   13 | foo (void)
      | ^~~
_7 = zero ();
during GIMPLE pass: lim
ozyot3yy.c:13:1: internal compiler error: verify_flow_info failed
0xa0dd1d verify_flow_info()
       
/var/tmp/portage/sys-devel/gcc-13.0.0_p20221023/work/gcc-13-20221023/gcc/cfghooks.cc:284
0xe08403 execute_function_todo
       
/var/tmp/portage/sys-devel/gcc-13.0.0_p20221023/work/gcc-13-20221023/gcc/passes.cc:2103
0xe0891e execute_todo
       
/var/tmp/portage/sys-devel/gcc-13.0.0_p20221023/work/gcc-13-20221023/gcc/passes.cc:2145

[Bug tree-optimization/107447] [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107447

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2022-10-28
           Priority|P3                          |P1
             Status|UNCONFIRMED                 |ASSIGNED
           Keywords|                            |ice-checking
     Ever confirmed|0                           |1
   Target Milestone|---                         |13.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  Let me fix this.  Note we are moving an entry to an irreducible
sub-region of the loop here, so doing this will create an outer loop and make
the inner loop have multiple latches.  All this is likely not worth handling
(code-gen wise it's simple to fix, but I'll look for the fallout).

The checking is new, thus a "regression"

[Bug tree-optimization/107447] [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107447

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Btw, there's also a stray incoming abnormal edge into bb2 here (as seen in
other bugs I've meanwhile fixed).  We've elided a call to zero() there but
failed
to eliminate the incoming abnormal edge.  CDDCE1 does this.

[Bug tree-optimization/107447] [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107447

--- Comment #3 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:1add3635563b39e3c0e9bed4930d11b3f605fdd3

commit r13-3545-g1add3635563b39e3c0e9bed4930d11b3f605fdd3
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Oct 28 14:20:36 2022 +0200

    tree-optimization/107447 - avoid hoisting returns-twice calls in LIM

    The following makes sure to not hoist returns-twice calls in LIM
    since we have no way to move the abnormal edge associated with it
    and we are prone having stray abnormal edges in the IL which will
    then cause IL verification failures even when the actual call
    does not return twice.

            PR tree-optimization/107447
            * tree-ssa-loop-im.cc (determine_max_movement): Do not
            hoist returns-twice calls.

            * gcc.dg/torture/pr107447.c: New testcase.

[Bug tree-optimization/107447] [13 Regression] ICE: verify_flow_info failed (error: returns_twice call is not first in basic block 2)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107447

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

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

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.