[LLVMdev] promotion of return value.

[Dale Johannesen]

On Mar 12, 2009, at 11:31 AMPDT, Andrew Haley wrote:

> Rafael Espindola wrote:
>>>> 1) The return value promotion will be removed from llvm backend and
>>>>  implemented in both front-ends (clang and llvm-gcc)
>>>>
>>>> 2) The promotions are only applied to the return value in the body
>>>>  of the function.
>>>>  Return value of function definition and declaration will not be
>>>> promoted
>>
>> You might want to look at bug http://llvm.org/bugs/show_bug.cgi?id=3779 
>> .
>>
>> If I understand what you are proposing, it is exactly the opposite of
>> what gcc does, which would be annoying for someone trying to link gcc
>> and llvm compiled code.
>
> That's right.  In gcc we used to do this in the front-ends but we
> stopped.  This required quite a lot of discussion with the Linux ABI
> standardization people.

Yes, I trust we're taking into account that some ABIs have  
requirements about this.
For example, ARM AAPCS requires the caller promote arguments, and the  
callee
promote return values.