Re: [PATCH] middle-end: Skip initialization of opaque type register variables [PR103127]

[Peter Bergner <bergner@linux.ibm.com>]

On 11/30/21 11:51 AM, Qing Zhao wrote:
> So, looks like that the variable with OPAQUE_TYPE cannot be all explicitly initialized even at source code level. 
> 
> The only way to initialize such variable (only __vector_quad, not for __vector_pairs) at source code level is through call to __builtin_mma_xxsetaccz as:
> 
> void
> foo (__vector_quad *dst)
> {
>   __vector_quad acc;
>   __builtin_mma_xxsetaccz(&acc);
>   *dst = acc;
> }
> 
> Is this the correct understanding?

Correct.  Or via...


> Is there way to initialize such variable to other values than zero at source code level?

Not for any constant values.  You can load it from memory though like below,
which is also allowed for __vector_pair:

void
foo (__vector_quad *dst, __vector_quad *src)
{
  __vector_quad acc;
  acc = *src;
  ...
}
void
bar (__vector_pair *dst, __vector_pair *src)
{
  __vector_pair pair;
  pair = *src;
  ...
}

We do not accept things like:

  acc = 0;
  acc = {0, 0, ... };
  etc.

Peter