https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78355
--- Comment #3 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> if (!SLOW_UNALIGNED_ACCESS (mode, MEM_ALIGN (reg))
> || (MEM_ALIGN (reg) < GET_MODE_ALIGNMENT (innermode)
> && SLOW_UNALIGNED_ACCESS (innermode, MEM_ALIGN (reg)))
> || MEM_ALIGN (reg) >= GET_MODE_ALIGNMENT (mode))
> return true;
>
> looks good to me given
>
> gcc/defaults.h:#define SLOW_UNALIGNED_ACCESS(MODE, ALIGN) STRICT_ALIGNMENT
>
> doesn't do that check itself (maybe it and all ports should be fixed
> instead...)
The documentation for SLOW_UNALIGNED_ACCESS implicitly says that it's for
unaligned accesses only:
-- Macro: SLOW_UNALIGNED_ACCESS (MODE, ALIGNMENT)
Define this macro to be the value 1 if memory accesses described
by the MODE and ALIGNMENT parameters have a cost many times greater
than aligned accesses, for example if they are emulated in a trap
handler.
and all other uses of SLOW_UNALIGNED_ACCESS in the compiler do it correctly, so
it's an isolated bug in lra-constraints.c. That being said, I can make the
wording in the documentation stronger.
