[Bug c/128355] New: Compilation time hangs on GIMPLE pass

[haoxintu at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=128355

            Bug ID: 128355
           Summary: Compilation time hangs on GIMPLE pass
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: memory-hog
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

Hi,

This case is not a crash but a hang. (Should be the last report for GIMPLE FEs
as I think it's different from crash-on-invalid cases).

$cat case.c
int __GIMPLE (ssa) f (void)
{
  int r;
  __BB(2):
  goto __BB3;

  __BB(3):
  r_1 = __PHI (__BB2: 1;
  return r_1;
}


$gcc-trunk -c -fgimple case.c # (be careful and better to add `timeout 10` to
aviod significant memory consumption)
case.c: In function ‘f’:
case.c:8:24: error: expected expression before ‘;’ token
    8 |   r_1 = __PHI (__BB2: 1;
      |                        ^

... (hang)


>From Godbolt https://godbolt.org/z/KE1sx4xEK, the hang has happened since GCC
7.1.


Thanks.