[Bug debug/104564] New: '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[Bug debug/104564] New: '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104564

            Bug ID: 104564
           Summary: '-fcompare-debug' failure w/ -std=c++20 -O1
                    -fharden-conditional-branches -fopenacc
                    -gno-statement-frontiers
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: compare-debug-failure
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: aarch64-linux-gnu

gcc 12.0.1 20220213 snapshot (g:58aeb75d4097010ad9bb72b964265b18ab284f93) fails
-fcompare-debug check when compiling the following testcase, partially reduced
from libstdc++-v3/testsuite/25_algorithms/inplace_merge/1.cc, w/ -std=c++20 -O1
-fharden-conditional-branches -fopenacc -gno-statement-frontiers:

#include <algorithm>
#include <testsuite_iterators.h>

typedef
  __gnu_test::test_container<int, __gnu_test::bidirectional_iterator_wrapper>
  container;

void test1() {
  int array[] = {};
  container con2(array, array);
  std::inplace_merge(con2.begin(), con2.begin(), con2.end());
}

% aarch64-linux-gnu-g++-12.0.1 -std=c++20 -O1 -fcompare-debug
-fharden-conditional-branches -fopenacc -gno-statement-frontiers -c bdxhor92.cc
aarch64-linux-gnu-g++-12.0.1: error: bdxhor92.cc: '-fcompare-debug' failure

It is very fragile, even adding -save-temps makes the failure disappear, so I
could not reduce it any further. If I get the dumps right, the difference
starts in einline.

[Bug debug/104564] '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104564

--- Comment #1 from Arseny Solokha <asolokha at gmx dot com> ---
#include <testsuite_iterators.h>

is from -Ilibstdc++-v3/testsuite/util, if invoking g++ from the top of the
source tree.

[Bug debug/104564] '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[aoliva at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104564

Alexandre Oliva <aoliva at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-03-24
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |aoliva at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
Created attachment 52677
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52677&action=edit
Candidate patch

Mine.  Looks like it's the copied identifiers that get -fcompare-debug to fail.
 We don't need them, and without them, the failure is gone.

[Bug debug/104564] '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104564

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexandre Oliva <aoliva@gcc.gnu.org>:

https://gcc.gnu.org/g:fb488cba571539b6644e8f99f1dd997cdb4c82c1

commit r12-7801-gfb488cba571539b6644e8f99f1dd997cdb4c82c1
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Thu Mar 24 10:02:29 2022 -0300

    hardened conditionals: drop copied identifiers

    The copies of identifiers, indended to associate hardening SSA
    temporaries to the original variables they refer to, end up causing
    -fcompare-debug to fail, because DECL_UIDs are not identical, and the
    nouid flag used in compare-debug dumps doesn't affect the uids in
    naked identifiers, so the divergence becomes apparent.

    This patch drops the naked identifiers.  Though somewhat desirable,
    they're not necessary.


    for  gcc/ChangeLog

            PR debug/104564
            * gimple-harden-conditionals.cc (detach_value): Keep temps
            anonymous.

    for  gcc/testsuite/ChangeLog

            PR debug/104564
            * c-c++-common/torture/harden-comp.c: Adjust.
            * c-c++-common/torture/harden-cond.c: Adjust.

[Bug debug/104564] '-fcompare-debug' failure w/ -std=c++20 -O1 -fharden-conditional-branches -fopenacc -gno-statement-frontiers

[aoliva at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104564

Alexandre Oliva <aoliva at gcc dot gnu.org> changed:

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

--- Comment #4 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
Fixed