[Bug tree-optimization/95045] New: wrong code at -O3 on x86_64-linux-gnu

[Bug tree-optimization/95045] New: wrong code at -O3 on x86_64-linux-gnu

[qrzhang at gatech dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

            Bug ID: 95045
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: qrzhang at gatech dot edu
  Target Milestone: ---

Recent regression. Bisection points to g:283cb9ea6293e813e4


$ gcc-trunk -v
gcc version 11.0.0 20200510 (experimental) [master revision
4ae915cdbf0:8eedda9eef3:ef6394205d7bcab00dca01182d708ad5a6360a7b] (GCC)


$ gcc-trunk abc.c ; ./a.out
4


$ gcc-trunk -O3  abc.c ; ./a.out
0


$ cat abc.c
int a, c, f;
long b;
char d;
int e[3];
int g[9][3][2];
int main() {
  {
  h:
    for (f = 0; f <= 5; f++) {
      b = 3;
      for (; b >= 0; b--) {
        e[2] = d = 0;
        for (; d <= 3; d++) {
          g[8][2][0] = e[1] = c = 0;
          for (; c <= 1; c++)
            e[c + 1] = g[d + 5][2][c] = 4;
        }
        if (a)
          goto h;
      }
    }
  }
  printf("%d\n", e[2]);
}

[Bug tree-optimization/95045] wrong code at -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2020-05-11
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Mine.

[Bug tree-optimization/95045] [11 Regression] wrong code at -O3 on x86_64-linux-gnu

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
      Known to work|                            |10.1.0
                 CC|                            |marxin at gcc dot gnu.org
            Summary|wrong code at -O3 on        |[11 Regression] wrong code
                   |x86_64-linux-gnu            |at -O3 on x86_64-linux-gnu
      Known to fail|                            |11.0
            Version|unknown                     |11.0

[Bug tree-optimization/95045] [11 Regression] wrong code at -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, this one is an interesting one (might be also latent before the rewrite). 
I'll deal with it separately.  The issue is around the inner loop having
multiple exits, one being also the exit from the outer loop and edge
inserts on that edge getting mis-ordered (we commit them only after processing
all inserts).

[Bug tree-optimization/95045] [11 Regression] wrong code at -O3 on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

--- 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:bb63ca63e744c08bc5a9ffa53df62ea35f098b0b

commit r11-308-gbb63ca63e744c08bc5a9ffa53df62ea35f098b0b
Author: Richard Biener <rguenther@suse.de>
Date:   Mon May 11 15:26:09 2020 +0200

    tree-optimization/95045 - fix SM with exit exiting multiple loops

    Since we apply SM to an edge which exits multiple loops we have
    to make sure to commit insertions on it immediately since otherwise
    store order is not preserved.

    2020-05-12  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/95045
            * dbgcnt.def (lim): Add debug-counter.
            * tree-ssa-loop-im.c: Include dbgcnt.h.
            (find_refs_for_sm): Use lim debug counter for store motion
            candidates.
            (do_store_motion): Rename form store_motion.  Commit edge
            insertions...
            (store_motion_loop): ... here.
            (tree_ssa_lim): Adjust.

[Bug tree-optimization/95045] [11 Regression] wrong code at -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95045

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.