RFC: Update Intel386, x86-64 and IA MCU psABIs for passing/returning empty struct

[Richard Smith]

On Thu, Feb 18, 2016 at 6:35 AM, Michael Matz <matz@suse.de> wrote:
> Hi,
>
> On Tue, 16 Feb 2016, H.J. Lu wrote:
>
>> Here is the new definition:
>>
>> An empty type is a type where it and all of its subobjects (recursively)
>> are of class, structure, union, or array type.  No memory slot nor
>> register should be used to pass or return an object of empty type.
>
> The trivially copyable is gone again.  Why is it not necessary?

The C++ ABI doesn't defer to the C psABI for types that aren't
trivially-copyable. See
http://mentorembedded.github.io/cxx-abi/abi.html#normal-call