[Bug tree-optimization/109327] New: ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[Bug tree-optimization/109327] New: ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[zhendong.su at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

            Bug ID: 109327
           Summary: ICE on valid code at -O1 and above with
                    "-fno-tree-ccp": Segmentation fault
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

It appears to be a very recent regression. 

[554] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/13.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
--with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.1 20230329 (experimental) [master r13-6922-g91293ffb6af] (GCC)
[555] %
[555] % gcctk -O1 -fno-tree-ccp small.c
during GIMPLE pass: forwprop
small.c: In function ‘main’:
small.c:11:1: internal compiler error: Segmentation fault
   11 | }
      | ^
0xeeb24f crash_signal
        ../../gcc-trunk/gcc/toplev.cc:314
0xbab1a7 phi_nodes_ptr(basic_block_def*)
        ../../gcc-trunk/gcc/gimple.h:4684
0xbab1a7 gsi_start_phis(basic_block_def*)
        ../../gcc-trunk/gcc/gimple-iterator.cc:935
0xbab1a7 gsi_for_stmt(gimple*)
        ../../gcc-trunk/gcc/gimple-iterator.cc:620
0x10314f3 execute
        ../../gcc-trunk/gcc/tree-ssa-forwprop.cc:4070
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
[556] %
[556] % cat small.c
int a;
void b(int c) {}
int main() {
  int d = 0, *e = &a;
  if (d) {
    int *f = e;
    while (a)
      b(e != f);
  }
  return 0;
}

[Bug tree-optimization/109327] ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |13.0
   Last reconfirmed|                            |2023-03-29
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

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

[Bug tree-optimization/109327] ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's really an old issue I think.  We record a lattice in forwprop, marking
stmts to be removed.  But the early forwprop phase runs on the IL with
the stmt operands not substituted, instead relying on old get_prop_source_stmt
and remove_prop_source_from_use.  That mechanism can interfere with the
lattice recorded stmt removal.

Testing a patch.

[Bug tree-optimization/109327] ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

--- 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:7fd1d28d2436065da7fc0fe01d787fcdf3c14b83

commit r13-6926-g7fd1d28d2436065da7fc0fe01d787fcdf3c14b83
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Mar 29 09:51:58 2023 +0200

    tree-optimization/109327 - forwprop stmt removal issue

    There's interfering between the to_removed queue and other mechanisms
    removing stmts, in this case remove_prop_source_from_use.  The following
    makes the to_remove queue draining more permissive.

            PR tree-optimization/109327
            * tree-ssa-forwprop.cc (pass_forwprop::execute): Deal with
            already removed stmts when draining to_remove.

            * gcc.dg/pr109327.c: New testcase.

[Bug tree-optimization/109327] ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
           Keywords|                            |ice-on-valid-code
         Resolution|---                         |FIXED

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed (it's probably latent on the branches).

[Bug tree-optimization/109327] [13 Regression] ICE on valid code at -O1 and above with "-fno-tree-ccp": Segmentation fault

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109327

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE on valid code at -O1    |[13 Regression] ICE on
                   |and above with              |valid code at -O1 and above
                   |"-fno-tree-ccp":            |with "-fno-tree-ccp":
                   |Segmentation fault          |Segmentation fault
   Target Milestone|---                         |13.0