Help with an ABI peculiarity

Richard Sandiford richard.sandiford@arm.com
Thu Jan 20 22:32:06 GMT 2022


Iain Sandoe <iain@sandoe.co.uk> writes:
>> On 10 Jan 2022, at 10:46, Richard Sandiford <richard.sandiford@arm.com> wrot>> An alternative might be to make promote_function_arg a “proper”
>> ABI hook, taking a cumulative_args_t and a function_arg_info.
>> Perhaps the return case should become a separate hook at the
>> same time.
>> 
>> That would probably require more extensive changes than just
>> updating the call sites, and I haven't really checked how much
>> work it would be, but hopefully it wouldn't be too bad.
>> 
>> The new hook would still be called before function_arg, but that
>> should no longer be a problem, since the new hook arguments would
>> give the target the information it needs to decide whether the
>> argument is passed in registers.
>
> Yeah, this was my next port of call (I have looked at it ~10 times and then
> decided “not today, maybe there’s a simpler way”).

BTW, finally catching up on old email, I see this is essentially also
the approach that Maxim was taking with the TARGET_FUNCTION_ARG_BOUNDARY
patches.  What's the situation with those?  Sorry for not responding
to them earlier.

Thanks,
Richard


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