[Bug tree-optimization/127970] [14/15/16/17 Regression] wrong code at -O1 and above: _Decimal64 (x == C) ? C : x returns x, changing the quantum exponent

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127970

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2026-10-17
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.  uncprop is wrong thing.

```
                  /* For IEEE, -0.0 == 0.0, so we don't necessarily know
                     the sign of a variable compared against zero.  If
                     we're honoring signed zeros, then we cannot record
                     this value unless we know that the value is nonzero.  */
                  if (HONOR_SIGNED_ZEROS (op0)
                      && (TREE_CODE (op1) != REAL_CST
                          || real_equal (&dconst0, &TREE_REAL_CST (op1))))
                    continue;

```