[Bug target/86209] Peephole does not happen because the type of zero/sign extended operands is not the same.

[ktkachov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86209

--- Comment #7 from ktkachov at gcc dot gnu.org ---
The other thing to consider with merging loads is how the result is used.
In your example if you merge the 16-bit loads into a single 32-bit register
load you'll have to add instructions to extract the low and high parts into
separate registers in order to add them together and that can end up be more
expensive overall.