Re: [PATCH] rs6000: Fix issue in specifying PTImode as an attribute [PR106895]

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

On 8/24/23 12:35 PM, Michael Meissner wrote:
> On Thu, Jul 20, 2023 at 10:05:28AM +0530, jeevitha wrote:
>> gcc/
>> 	PR target/110411
>> 	* config/rs6000/rs6000.h (enum rs6000_builtin_type_index): Add fields
>> 	to hold PTImode type.
>> 	* config/rs6000/rs6000-builtin.cc (rs6000_init_builtins): Add node
>> 	for PTImode type.
> 
> It is good as far as it goes, but I suspect we will eventually need to extend
> it.  In particular, the reason people need PTImode is they need the even/odd
> register layout.  What you've done enables users to declare this value.

Sure, it could be extended, but that is not what this patch is about.
It's purely to allow the kernel team access to the guaranteed even/odd
register layout for some inline asm code.  Any extension would be a
follow-on patch to this.



On 8/9/23 3:48 AM, Kewen.Lin wrote:
> IIUC, this builtin type registering makes this type expose to users, so
> I wonder if we want to actually expose this type for users' uses.
> If yes, we need to update the documentation (and not sure if the current
> name is good enough); otherwise, I wonder if there is some existing
> practice to declare a builtin type with a name which users can't actually
> use and is just for shadowing a mode.

Segher, Mike, Jeevitha and I talked about the patch and Segher mentioned
that under some conditions, it's fine to keep the type undocumented.
Hopefully he'll weigh in on whether this particular patch is one of
those cases or not.  


Peter