st/mesa: optimize pipe_sampler_view validation

Before, st_get_texture_sampler_view_from_stobj() did a lot of work to
check if the texture parameters matched the sampler view (format,
swizzle, min/max lod, first/last layer, etc).  We did this every time
we validated the texture state.

Now, we use a ctx->Driver.TexParameter() callback and a couple other
checks to proactively release texture views when we know that
view-related parameters have changed.  Then, the validation step is
simplified:
- Search the texture's list of sampler views (just match the context).
- If found, we're done.
- Else, create a new sampler view.

There will never be old, out-of-date sampler views attached to texture
objects that we have to test.

Most apps create textures and set the texture parameters once.  This
make sampler view validation much cheaper for that case.

Note that the old texture/sampler comparison code has been converted
into a set of assertions to verify that the sampler view is in fact
consistent with the texture parameters.  This should help to spot any
potential regressions.

Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_texture.h b/src/mesa/state_tracker/st_texture.h
index d2c4f3f..9c9a05b 100644
--- a/src/mesa/state_tracker/st_texture.h
+++ b/src/mesa/state_tracker/st_texture.h
@@ -107,6 +107,11 @@ struct st_texture_object
     * views and surfaces instead of pt->format.
     */
    enum pipe_format surface_format;
+
+   /** The glsl version of the shader seen during the previous validation */
+   unsigned prev_glsl_version;
+   /** The value of the sampler's sRGBDecode state at the previous validation */
+   GLenum prev_sRGBDecode;
 };