iris: Always reserve binding table space for NIR constants

Don't have a separate mechanism for NIR constants to be removed from
the table.  If unused, we will compact it away.  The use_null_surface
is needed when INTEL_DISABLE_COMPACT_BINDING_TABLE is set.

Reviewed-by: Kenneth Graunke <[email protected]>

2 files changed, 14 insertions, 9 deletions

diff --git a/src/gallium/drivers/iris/iris_program.c b/src/gallium/drivers/iris/iris_program.c
index f18c914f62d..3f8896ffd7d 100644
--- a/src/gallium/drivers/iris/iris_program.c
+++ b/src/gallium/drivers/iris/iris_program.c
@@ -678,14 +678,14 @@ iris_setup_binding_table(struct nir_shader *nir,
 
    bt->sizes[IRIS_SURFACE_GROUP_IMAGE] = info->num_images;
 
-   /* Allocate a slot in the UBO section for NIR constants if present.
+   /* Allocate an extra slot in the UBO section for NIR constants.
+    * Binding table compaction will remove it if unnecessary.
+    *
     * We don't include them in iris_compiled_shader::num_cbufs because
     * they are uploaded separately from shs->constbuf[], but from a shader
     * point of view, they're another UBO (at the end of the section).
     */
-   if (nir->constant_data_size > 0)
-      num_cbufs++;
-   bt->sizes[IRIS_SURFACE_GROUP_UBO] = num_cbufs;
+   bt->sizes[IRIS_SURFACE_GROUP_UBO] = num_cbufs + 1;
 
    /* The first IRIS_MAX_ABOs indices in the SSBO group are for atomics, real
     * SSBOs start after that.  Compaction will remove unused ABOs.
diff --git a/src/gallium/drivers/iris/iris_state.c b/src/gallium/drivers/iris/iris_state.c
index abfd812c572..9cab4625b81 100644
--- a/src/gallium/drivers/iris/iris_state.c
+++ b/src/gallium/drivers/iris/iris_state.c
@@ -4191,11 +4191,16 @@ iris_populate_binding_table(struct iris_context *ice,
    foreach_surface_used(i, IRIS_SURFACE_GROUP_UBO) {
       uint32_t addr;
 
-      if ((i == bt->sizes[IRIS_SURFACE_GROUP_UBO] - 1) && ish->const_data) {
-         iris_use_pinned_bo(batch, iris_resource_bo(ish->const_data), false);
-         iris_use_pinned_bo(batch, iris_resource_bo(ish->const_data_state.res),
-                            false);
-         addr = ish->const_data_state.offset;
+      if (i == bt->sizes[IRIS_SURFACE_GROUP_UBO] - 1) {
+         if (ish->const_data) {
+            iris_use_pinned_bo(batch, iris_resource_bo(ish->const_data), false);
+            iris_use_pinned_bo(batch, iris_resource_bo(ish->const_data_state.res),
+                               false);
+            addr = ish->const_data_state.offset;
+         } else {
+            /* This can only happen with INTEL_DISABLE_COMPACT_BINDING_TABLE=1. */
+            addr = use_null_surface(batch, ice);
+         }
       } else {
          addr = use_ubo_ssbo(batch, ice, &shs->constbuf[i],
                              &shs->constbuf_surf_state[i], false);