[Bug target/108516] Useless movzx instruction emitted when loading 8 bits from 24 bit struct

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108516

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-01-24
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed:

Trying 16 -> 6:
   16: r86:QI#0=zero_extract(r87:HI,0x8,0x8)
      REG_DEAD r87:HI
    6: r84:SI=zero_extend(r86:QI)
      REG_DEAD r86:QI
Failed to match this instruction:
(set (reg:SI 84 [ s.e2 ])
    (zero_extract:SI (reg:HI 87)
        (const_int 8 [0x8])
        (const_int 8 [0x8])))