[llvm-commits] [PATCH] To enable struct byval for ARM

[Manman Ren]

Hi Tim,

For memcpy, the default is to call the library function, and we don't want to expand it to a loop.
For struct byval, there were problems calling into the library function.
We can't expand 'struct byval' to a loop at SelectionDAG since SelectionDAG is supposedly not aware of control flow.

Correct me if I am wrong, I am kind of new to this too :)

Thanks,
Manman

On May 30, 2012, at 10:22 AM, Tim Northover wrote:

> Hi Manman,
> 
>> This patch is to enable struct byval for ARM.
>> It inserts a pseudo op for each struct byval argument and the pseudo ops will be expanded to a loop or unrolled scalar copies.
> 
> Is there any particular reason you're not using SelectionDAG's
> getMemcpy function? It looks like EmitTargetCodeForMemCpy is a little
> naive on ARM at the moment (it seems to generate no loops), but that
> seems like a more natural place to put the bulk of your code when it
> really is the best way to expand the copy.
> 
> I may be missing something fundamental, of course.
> 
> Tim.