[Bug middle-end/119167] New: gimple testcase with startwith does not always get the same CFG as what was provided with

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119167

            Bug ID: 119167
           Summary: gimple testcase with startwith does not always get the
                    same CFG as what was provided with
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
            Blocks: 101057
  Target Milestone: ---

Created attachment 60687
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60687&action=edit
testcase

Take the attached testcase, we don't get the exact CFG structure as it is
supplied in phiopt2.

What we get is:
```
  <bb 5> :
  if (h_6 != 0)
    goto <bb 10>; [INV]
  else
    goto <bb 9>; [INV]

  <bb 10> :
  goto <bb 7>; [100.00%]

  <bb 9> :

  <bb 6> :
  # h_6 = PHI <0(4), 1(9)>

  <bb 7> :
  # f_8 = PHI <0(10), h_6(6)>
```
Which looks like the critial edges were split.

This makes it harder to debug phiopt and other passes which need the exact same
CFG input that is done in the gimple testcase.

Note I don't mind if this is closed as won't fix but I am recording it so I can
point to it later on if needed.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101057
[Bug 101057] [meta-bug] [gimplefe] GIMPLE frontend issues