[Bug tree-optimization/101394] New: ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[Bug tree-optimization/101394] New: ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[cnsun at uwaterloo dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

            Bug ID: 101394
           Summary: ICE on valid code with -O2: SSA corruption: Unable to
                    coalesce ssa_names 10 and 19 which are marked as MUST
                    COALESCE.
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: cnsun at uwaterloo dot ca
  Target Milestone: ---

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/scratch/software/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/12.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/configure
--enable-languages=c,c++,lto --enable-checking-yes --enable-multiarch
--prefix=/scratch/software/gcc-trunk --disable-bootstrap
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.0 20210709 (experimental) [master revision
:aa0aefd8a:fdc4d2a516d042bc9a6936fad3f887aff353a296] (GCC)

$ cat mutant.c
a, b, c, d;
e() __attribute__((returns_twice));
f() {
  int *g = c;
  if (b) {
    h();
    g--;
    if (a)
      if (d)
        h();
  }
  if (g++)
    e();
  c = g;
}

$ gcc-trunk -w -O2 mutant.c
Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.
g_10(ab) and  g_19(ab)
during RTL pass: expand
mutant.c: In function ‘f’:
mutant.c:3:1: internal compiler error: SSA corruption
    3 | f() {
      | ^
0x104b21c fail_abnormal_edge_coalesce
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/tree-ssa-coalesce.c:1003
0x104b21c coalesce_partitions
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/tree-ssa-coalesce.c:1425
0x104b21c coalesce_ssa_name(_var_map*)
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/tree-ssa-coalesce.c:1755
0xfe32a9 remove_ssa_form
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/tree-outof-ssa.c:1065
0xfe32a9 rewrite_out_of_ssa(ssaexpand*)
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/tree-outof-ssa.c:1323
0xa6299a execute
        /tmp/tmp.RJV1U21mAq-gcc-builder/gcc/gcc/cfgexpand.c:6588
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug tree-optimization/101394] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think the problem comes from PRE when it does:
   # g_25 = PHI <g_19(ab)(5), g_19(ab)(4)>
-  g_27 = g_25 + 4;
+  pretmp_28 = g_17(ab);

[Bug tree-optimization/101394] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-07-12
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I will have a look.

[Bug tree-optimization/101394] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> ---
Just for the record, started with r9-2475-g4864297f7858617a.

[Bug tree-optimization/101394] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- 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:92343e0ba4d47f21ae20ffcb83d736bdbc15dae0

commit r12-2244-g92343e0ba4d47f21ae20ffcb83d736bdbc15dae0
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Jul 12 10:49:03 2021 +0200

    tree-optimization/101394 - fix PRE full redundancy wrt abnormals

    This avoids adding a copy from an abnormal picked up from PHI
    translation much like we'd avoid inserting the translated
    expression on pred edges.

    2021-07-12  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/101394
            * tree-ssa-pre.c (do_pre_regular_insertion): Avoid inserting
            copies from abnormals for a full redundancy.

            * gcc.dg/torture/pr101394.c: New testcase.

[Bug tree-optimization/101394] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |12.0

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

[Bug tree-optimization/101394] [9/10/11 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE on valid code with -O2: |[9/10/11 Regression] ICE on
                   |SSA corruption: Unable to   |valid code with -O2: SSA
                   |coalesce ssa_names 10 and   |corruption: Unable to
                   |19 which are marked as MUST |coalesce ssa_names 10 and
                   |COALESCE.                   |19 which are marked as MUST
                   |                            |COALESCE.
   Target Milestone|---                         |9.5

[Bug tree-optimization/101394] [9/10/11 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Martin Liška from comment #3)
> Just for the record, started with r9-2475-g4864297f7858617a.

That definitely looks more like it was exposing the issue really as that was to
VRP while the fix in comment #4 is for PRE.

[Bug tree-optimization/101394] [9/10/11 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:7d060844c0de1ed65da84374cae6fa1598011f4a

commit r11-8724-g7d060844c0de1ed65da84374cae6fa1598011f4a
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Jul 12 10:49:03 2021 +0200

    tree-optimization/101394 - fix PRE full redundancy wrt abnormals

    This avoids adding a copy from an abnormal picked up from PHI
    translation much like we'd avoid inserting the translated
    expression on pred edges.

    2021-07-12  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/101394
            * tree-ssa-pre.c (do_pre_regular_insertion): Avoid inserting
            copies from abnormals for a full redundancy.

            * gcc.dg/torture/pr101394.c: New testcase.

    (cherry picked from commit 92343e0ba4d47f21ae20ffcb83d736bdbc15dae0)

[Bug tree-optimization/101394] [9/10 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:424737442fb7cd6ea8f0e63098c26cebdaf82a51

commit r10-10099-g424737442fb7cd6ea8f0e63098c26cebdaf82a51
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Jul 12 10:49:03 2021 +0200

    tree-optimization/101394 - fix PRE full redundancy wrt abnormals

    This avoids adding a copy from an abnormal picked up from PHI
    translation much like we'd avoid inserting the translated
    expression on pred edges.

    2021-07-12  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/101394
            * tree-ssa-pre.c (do_pre_regular_insertion): Avoid inserting
            copies from abnormals for a full redundancy.

            * gcc.dg/torture/pr101394.c: New testcase.

    (cherry picked from commit 92343e0ba4d47f21ae20ffcb83d736bdbc15dae0)

[Bug tree-optimization/101394] [9 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |10.3.0
            Summary|[9/10 Regression] ICE on    |[9 Regression] ICE on valid
                   |valid code with -O2: SSA    |code with -O2: SSA
                   |corruption: Unable to       |corruption: Unable to
                   |coalesce ssa_names 10 and   |coalesce ssa_names 10 and
                   |19 which are marked as MUST |19 which are marked as MUST
                   |COALESCE.                   |COALESCE.
           Priority|P3                          |P2
      Known to work|                            |10.3.1

[Bug tree-optimization/101394] [9 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:a091e66e510804a29ba2a685b027f5d15aa69f1b

commit r9-9771-ga091e66e510804a29ba2a685b027f5d15aa69f1b
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Jul 12 10:49:03 2021 +0200

    tree-optimization/101394 - fix PRE full redundancy wrt abnormals

    This avoids adding a copy from an abnormal picked up from PHI
    translation much like we'd avoid inserting the translated
    expression on pred edges.

    2021-07-12  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/101394
            * tree-ssa-pre.c (do_pre_regular_insertion): Avoid inserting
            copies from abnormals for a full redundancy.

            * gcc.dg/torture/pr101394.c: New testcase.

    (cherry picked from commit 92343e0ba4d47f21ae20ffcb83d736bdbc15dae0)

[Bug tree-optimization/101394] [9 Regression] ICE on valid code with -O2: SSA corruption: Unable to coalesce ssa_names 10 and 19 which are marked as MUST COALESCE.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101394

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
      Known to fail|                            |9.4.0

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.