https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68273
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |ABI
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=65956
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
So in
/* Implement TARGET_FUNCTION_ARG_BOUNDARY. Every parameter gets at
least PARM_BOUNDARY bits of alignment, but will be given anything up
to STACK_BOUNDARY bits if the type requires it. */
static unsigned int
mips_function_arg_boundary (machine_mode mode, const_tree type)
{
unsigned int alignment;
alignment = type ? TYPE_ALIGN (type) : GET_MODE_ALIGNMENT (mode);
if (alignment < PARM_BOUNDARY)
alignment = PARM_BOUNDARY;
if (alignment > STACK_BOUNDARY)
alignment = STACK_BOUNDARY;
return alignment;
}
drop the TYPE_ALIGN use if mode is not BLKmode (and assert it is not VOIDmode?
I wonder what we get for integer constants here).
Similar to arm I'm curious what the ABI documentation says for
typedef int myint __attribute__((align(1)));
int foo (myint, myint);
calling convention vs. any other alignment of the args and whether it is
really intended to make those incompatible.
With C11 aligning a type is no longer a GCC extension(?), for previous
C versions either GCC shouldn't change the ABI or document the ABI
extension.
But I really doubt this is an intended behavior.
I see another use in va-arg processing (and va-args are usually the argument
why port maintainers say they need to look at the types of the actual
passed values - but I think the mode and its alignment is what matters)
/* If the actual alignment is less than the alignment of the type,
adjust the type accordingly so that we don't assume strict alignment
when dereferencing the pointer. */
boundary *= BITS_PER_UNIT;
if (boundary < TYPE_ALIGN (type))
{
type = build_variant_type_copy (type);
TYPE_ALIGN (type) = boundary;
}
Aggregates are tricky (but again, don't look at alignment of actual passed
values! Look at most at the type alignment of the prototype arg type!
[or for values not passed by reference simply ignore it and use the alignment
of the main variant]).
