gallivm: Add some notes about sampler static state construction.

Recover some logic to make state canonical, although it is admittedly very
shy compared with what could be done.

We really need an helper module to make state canonical.

1 files changed, 17 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_sample.c b/src/gallium/auxiliary/gallivm/lp_bld_sample.c
index 6a026e468e1..29cadcc15ae 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_sample.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_sample.c
@@ -62,6 +62,18 @@ lp_sampler_static_state(struct lp_sampler_static_state *state,
    if(!sampler)
       return;
 
+   /*
+    * We don't copy sampler state over unless it is actually enabled, to avoid
+    * spurious recompiles, as the sampler static state is part of the shader
+    * key.
+    *
+    * Ideally the state tracker or cso_cache module would make all state
+    * canonical, but until that happens it's better to be safe than sorry here.
+    *
+    * XXX: Actually there's much more than can be done here, especially
+    * regarding 1D/2D/3D/CUBE textures, wrap modes, etc.
+    */
+
    state->format            = texture->format;
    state->target            = texture->target;
    state->pot_width         = util_is_pot(texture->width0);
@@ -74,8 +86,12 @@ lp_sampler_static_state(struct lp_sampler_static_state *state,
    state->min_img_filter    = sampler->min_img_filter;
    state->min_mip_filter    = sampler->min_mip_filter;
    state->mag_img_filter    = sampler->mag_img_filter;
+
    state->compare_mode      = sampler->compare_mode;
-   state->compare_func      = sampler->compare_func;
+   if (sampler->compare_mode != PIPE_TEX_COMPARE_NONE) {
+      state->compare_func   = sampler->compare_func;
+   }
+
    state->normalized_coords = sampler->normalized_coords;
    state->lod_bias          = sampler->lod_bias;
    state->min_lod           = sampler->min_lod;