[Bug target/104698] Inefficient code for DI to TI sign extend on power10

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104698

Segher Boessenkool <segher at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-02-26
     Ever confirmed|0                           |1

--- Comment #2 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Trying 6 -> 12:
    6: r120:TI=unspec[r121:DI] 190
      REG_DEAD r121:DI
   12: %3:TI=unspec[r120:TI] 189
      REG_DEAD r120:TI
Failed to match this instruction:
(set (reg/i:TI 3 3)
    (unspec:TI [
            (unspec:TI [
                    (reg:DI 121)
                ] UNSPEC_MTVSRD_DITI_W1)
        ] UNSPEC_EXTENDDITI2))

If this was expressed as RTL, it would just work.