[Bug tree-optimization/112939] New: ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[Bug tree-optimization/112939] New: ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[iamanonymous.cs at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112939

            Bug ID: 112939
           Summary: ICE: verify_ssa failed with -O
                    -ftrivial-auto-var-init=zero
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iamanonymous.cs at gmail dot com
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/4q74n5baY

*******************************************************************************
OS and Platform:
$ uname -a:
Linux ubuntu 4.15.0-213-generic #224-Ubuntu SMP Mon Jun 19 13:30:12 UTC 2023
x86_64 x86_64 x86_64 GNU/Linux
*******************************************************************************
gcc version:
$ gcc -v
Using built-in specs.
COLLECT_GCC=/root/gcc_set/202311291030/bin/gcc
COLLECT_LTO_WRAPPER=/root/gcc_set/202311291030/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/root/gcc_set/202311291030
--with-gmp=/root/build_essential --with-mpfr=/root/build_essential
--with-mpc=/root/build_essential --enable-languages=c,c++ --disable-multilib
--with-sanitizer=address,undefined,thread,leak
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231129 (experimental) (GCC) 

git version: 99fa0bfd63d97825c4221dcd3123940f1d0e6291
*******************************************************************************
Program:
$ cat mutant.c
int i;

void f (void)
{
  for (;;)
  {
    if (0)
      for (;;)
      {
        int *a;
        int *b = a;

 l1:
        *b = (*b != 0) ? 0 : 2;
      }

    if (i != 0)
      goto l1;
  }
}

*******************************************************************************
Command Lines:
$ gcc -O -ftrivial-auto-var-init=zero mutant.c
mutant.c: In function ‘f’:
mutant.c:20:1: error: definition in block 5 does not dominate use in block 3
   20 | }
      | ^
for SSA_NAME: a_11 in statement:
# VUSE <.MEM_5>
_1 = *a_11;
during GIMPLE pass: fre
mutant.c:20:1: internal compiler error: verify_ssa failed
0x1283220 verify_ssa(bool, bool)
        ../../gcc/gcc/tree-ssa.cc:1203
0xee93a5 execute_function_todo
        ../../gcc/gcc/passes.cc:2095
0xee980e execute_todo
        ../../gcc/gcc/passes.cc:2142
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.

[Bug tree-optimization/112939] [14 Regression] ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112939

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Target Milestone|---                         |14.0
   Last reconfirmed|                            |2023-12-09
           Keywords|                            |ice-on-valid-code,
                   |                            |needs-bisection
             Status|UNCONFIRMED                 |NEW
            Summary|ICE: verify_ssa failed with |[14 Regression] ICE:
                   |-O                          |verify_ssa failed with -O
                   |-ftrivial-auto-var-init=zer |-ftrivial-auto-var-init=zer
                   |o                           |o

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

A change in VN/FRE which is causing this.

[Bug tree-optimization/112939] [14 Regression] ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112939

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Obviously mine.

[Bug tree-optimization/112939] [14 Regression] ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112939

--- Comment #3 from GCC 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:f5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb

commit r14-6448-gf5f33b44b5dd4c41ae335445ae3f06b1ca3cfbcb
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Dec 11 13:00:18 2023 +0100

    tree-optimization/112939 - VN PHI visiting and -ftrivial-auto-var-init

    The following builds upon the last fix, making sure we only value-number
    to visited (un-)defs, otherwise prefer .VN_TOP.

            PR tree-optimization/112939
            * tree-ssa-sccvn.cc (visit_phi): When all args are undefined
            make sure we end up with a value that was visited, otherwise
            fall back to .VN_TOP.

            * gcc.dg/pr112939.c: New testcase.

[Bug tree-optimization/112939] [14 Regression] ICE: verify_ssa failed with -O -ftrivial-auto-var-init=zero

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112939

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

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

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.