[Mesa-dev] [PATCH 03/14] mesa: move _NEW_BUFFER_OBJECT flagging from BufferData to drivers

[Eric Anholt]

Marek Olšák <maraeo at gmail.com> writes:

> A driver doesn't have to set _NEW_BUFFER_OBJECT if it doesn't reallocate
> the buffer from core Mesa's point of view, which avoids unnecessary state
> validation.
>
> Gallium drivers can be asked to reallocate a buffer privately by setting
> PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE.
>
> st/mesa doesn't set _NEW_BUFFER_OBJECT if transfer_inline_write is used.

_NEW_BUFFER_OBJECT is used in Mesa core only for MaxElement updates.  So
Mesa core could flag its state update only when size changes and have
its state tracking correct, and then the question is what drivers need
to track internally when they need to, say, shove a new BO data pointer
down to the hardware.

Elsewhere, your plan seems to be for drivers to define their own flags,
while in this case you have the driver start adding core flags to
NewState.  We have a few cases of that already (radeon FBOs, and a piece
in st_cb_fbo.c that looks dubious), but I think I'd rather see progress
towards making that go away in favor of NewDriverState like you do in
the rest of the series.

> diff --git a/src/mesa/drivers/dri/nouveau/nouveau_bufferobj.c b/src/mesa/drivers/dri/nouveau/nouveau_bufferobj.c
> index 717c0b8..2508933 100644
> --- a/src/mesa/drivers/dri/nouveau/nouveau_bufferobj.c
> +++ b/src/mesa/drivers/dri/nouveau/nouveau_bufferobj.c
> @@ -79,7 +79,9 @@ nouveau_bufferobj_data(struct gl_context *ctx, GLenum target, GLsizeiptrARB size
>  	struct nouveau_bufferobj *nbo = to_nouveau_bufferobj(obj);
>  	int ret;
>  
> -	obj->Size = size;
> +        ctx->NewState |= _NEW_BUFFER_OBJECT;
> +
> +        obj->Size = size;
>  	obj->Usage = usage;
>  
>  	/* Free previous storage */

nouveau is tab indentation (quite consistently, too).  I should dump in
the .dir-locals.el needed, since I threw some together for my recent
swrast work.
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