[Bug target/120888] [16 regression] promotion of unsigned char and short function arguments sign extends them since r16-170-ga670ebde3995

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120888

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to jcmvbkbc from comment #5)
> Thanks, the attachment 61770 [details] fixes almost all regressions
> introduced by the r16-170-ga670ebde3995, except one:
> gfortran.dg/c_char_tests_5.f90 is still broken.
> 
> This patch also introduces one new regression: gcc.dg/tree-ssa/pr84436-5.c
> now fails because the foo() return value is zero-extended.

You can update xtensa_promote_function_mode to control how to promote
return value.