[Bug target/124605] GCC fails to generate uxth for extracting lower 16-bit on cortex-m0plus

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124605

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |arm
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2026-03-22

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Trying 7 -> 8:
    7: r117:SI=r118:SI<<0x10
      REG_DEAD r118:SI
    8: r116:SI=r117:SI 0>>0x10
      REG_DEAD r117:SI
Successfully matched this instruction:
(set (reg:SI 116 [ _3 ])
    (zero_extend:SI (subreg:HI (reg:SI 118 [ aD.4668 ]) 0)))
rejecting combination of insns 7 and 8
original costs 4 + 4 = 8
replacement cost 99

So just a cost model issue.
I have no idea why 99 though.