clang + ARM + byval structures

[Stepan Dyatkovskiy]

Hi Manman,

Currently I have no data. I just wanted to say, you welcome to send me 
some clang requests related to "byval" attribute.
On LLVM level now it works according to AAPCS, so now front-end 
developers can feel free with this attribute, and again if you have some 
issues/requests - let me know.

-Stepan.


Manman Ren wrote:
>
> Hi Stepan,
>
> We already use byval to pass structs with size > 64 bytes.
> We should be able to use byval for all structs in terms of correctness. The threshold was chosen to be 64 because of efficiency concerns.
> If you think 64 is not a great threshold, feel free to present some data and use byval for small structs.
>
> Thanks,
> Manman
>
> On May 6, 2013, at 11:30 AM, Stepan Dyatkovskiy wrote:
>
>> Hi Manman. Since we have fixed byval in LLVM, it is possible to pass byval structures "directly" to llvm core: I mean without casting it to arrays. The only two questions:
>> 1. Do we really need that? :-) (I hope, but not sure :-) )
>> 2. If so, in which cases we can pass structs "as-is" ?
>>
>> -Stepan
>