[Bug tree-optimization/112721] New: [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[Bug tree-optimization/112721] New: [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

            Bug ID: 112721
           Summary: [14 Regression] Wrong code at -O1/s on
                    x86_64-linux-gnu since r14-5831-gaae723d360c
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: mjambor at suse dot cz
  Target Milestone: ---

gcc at -O1/s produces the wrong code.

Bisected to r14-5831-gaae723d360c

Compiler explorer: https://godbolt.org/z/671M9YPPj

$ cat a.c
int printf(const char *, ...);
struct a {
  int b;
};
int c, e;
long d;
unsigned *f(unsigned *g) {
  for (; c;)
    e = d;
  return g;
}
int main() {
  int *h;
  struct a i = {8};
  int *j = &i.b;
  h = f(j);
  *h = 0;
  printf("%d\n", i.b);
}
$
$ gcc -O0 a.c && ./a.out
0
$ gcc -O1 a.c && ./a.out
8
$

[Bug tree-optimization/112721] [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jamborm at gcc dot gnu.org
   Last reconfirmed|                            |2023-11-27
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jamborm at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Most likely the same reason as PR 112711.  Mine.

[Bug tree-optimization/112721] [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.0

[Bug tree-optimization/112721] [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

--- Comment #2 from Martin Jambor <jamborm at gcc dot gnu.org> ---
I have proposed a fix on the mailing list:

https://gcc.gnu.org/pipermail/gcc-patches/2023-November/638318.html

[Bug tree-optimization/112721] [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Jambor <jamborm@gcc.gnu.org>:

https://gcc.gnu.org/g:302461ad9a04d82fee904bddac69811d13d5bb6a

commit r14-5971-g302461ad9a04d82fee904bddac69811d13d5bb6a
Author: Martin Jambor <mjambor@suse.cz>
Date:   Wed Nov 29 16:24:33 2023 +0100

    tree-sra: Avoid returns of references to SRA candidates

    The enhancement to address PR 109849 contained an importsnt thinko,
    and that any reference that is passed to a function and does not
    escape, must also not happen to be aliased by the return value of the
    function.  This has quickly transpired as bugs PR 112711 and PR
    112721.

    Just as IPA-modref does a good enough job to allow us to rely on the
    escaped set of variables, it sems to be doing well also on updating
    EAF_NOT_RETURNED_DIRECTLY call argument flag which happens to address
    exactly the situation we need to avoid.  Of course, if a call
    statement ignores any returned value, we also do not need to check the
    flag.

    Hopefully this does not pessimize things too much, I have verified
    that the PR 109849 testcae remains quick and so should also the
    benchmark it is derived from.

    gcc/ChangeLog:

    2023-11-27  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/112711
            PR tree-optimization/112721
            * tree-sra.cc (build_access_from_call_arg): New parameter
            CAN_BE_RETURNED, disqualify any candidate passed by reference if it
is
            true.  Adjust leading comment.
            (scan_function): Pass appropriate value to CAN_BE_RETURNED of
            build_access_from_call_arg.

    gcc/testsuite/ChangeLog:

    2023-11-29  Martin Jambor  <mjambor@suse.cz>

            PR tree-optimization/112711
            PR tree-optimization/112721
            * g++.dg/tree-ssa/pr112711.C: New test.
            * gcc.dg/tree-ssa/pr112721.c: Likewise.

[Bug tree-optimization/112721] [14 Regression] Wrong code at -O1/s on x86_64-linux-gnu since r14-5831-gaae723d360c

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112721

Martin Jambor <jamborm at gcc dot gnu.org> changed:

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

--- Comment #4 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Fixed