https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126118
--- Comment #4 from Drea Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Oleg Endo from comment #3)
> (In reply to Drea Pinski from comment #2)
> > (clobber:QI (const_int 0 [0]))
> > Happens when creating the subreg:
> > (subreg:QI (reg:SI 147 t) 0)
> > fails.
> >
> >
> > Which most likely points to r16-718-geb2ea476db2182 causing the difference.
> > See PR 119966 also.
>
> Thanks for the pointer.
>
> Any suggestion how/what to adjust in the SH backend?
It is about allowing different modes for the t register.
I don't know if you want to allow QI/HI modes for the t register though since
that requires maybe other changes to the backend.
Something like this:
diff --git a/gcc/config/sh/sh.cc b/gcc/config/sh/sh.cc
index 09e4ff77c20..a3da90fa057 100644
--- a/gcc/config/sh/sh.cc
+++ b/gcc/config/sh/sh.cc
@@ -10564,6 +10564,10 @@ sh_hard_regno_nregs (unsigned int regno, machine_mode
mode)
static bool
sh_hard_regno_mode_ok (unsigned int regno, machine_mode mode)
{
+
+ if (regno == T_REG)
+ return mode == SImode || mode == QImode || mode == HImode;
+
if (SPECIAL_REGISTER_P (regno))
return mode == SImode;
But then you need to fix up some places where had `(subreg:QI (reg:SI T))` to
instead use `(reg:QI T)`. I don't know if that is an acceptable change or an
easy change to make though.
