[Bug tree-optimization/113796] [14 Regression] RISC-V rv64gcv vector: Runtime mismatch at -O2

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113796

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=110252
   Target Milestone|---                         |14.0
            Summary|[14] RISC-V rv64gcv vector: |[14 Regression] RISC-V
                   |Runtime mismatch at -O2     |rv64gcv vector: Runtime
                   |                            |mismatch at -O2
                 CC|                            |pinskia at gcc dot gnu.org
          Component|target                      |tree-optimization
   Last reconfirmed|                            |2024-02-07

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, the issue is in ifcvt.

Before ifcvt we had:
```
  if (_1 >= 0)
    goto <bb 5>; [59.00%]
  else
    goto <bb 6>; [41.00%]

  <bb 5> [local count: 563821836]:
  iftmp.1_9 = _1 >> 6;

  <bb 6> [local count: 955630226]:
  # iftmp.1_5 = PHI <iftmp.1_9(5), 1(4)>
```
Which is fine.

Note the range for _1 is:
```
  # RANGE [irange] signed char [0, 1]
  iftmp.1_9 = _1 >> 6;
```

After ifcvt we get:
```
  iftmp.1_9 = _1 >> 6;
  _25 = _1 < 0;
  _4 = (signed charD.14) _25;
  # RANGE [irange] signed char [0, 1]
  iftmp.1_5 = _4 | iftmp.1_9;
```
Which is incorrect.

ifcvt needs to something similar to what phiopt did in r14-2650-g8c79b49cd4fa74
.