glsl: mark xfb inputs as always_active_io

We won't split varyings marked as always active because there
is no point in doing so. This means we need to mark both
sides of the interface as always active otherwise we will have
a mismatch and start removing things we shouldn't.

Reviewed-by: Eric Anholt <eric@anholt.net>

diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
index ed3bf41687822bed4c45abaf1b596d4e42469dae..29842ecacda4e7fa1974495728241b4e0c2077a6 100644 (file)
--- a/src/compiler/glsl/link_varyings.cpp
+++ b/src/compiler/glsl/link_varyings.cpp
@@ -2268,9 +2268,6 @@ assign_varying_locations(struct gl_context *ctx,
       }
    }
 
-   _mesa_hash_table_destroy(consumer_inputs, NULL);
-   _mesa_hash_table_destroy(consumer_interface_inputs, NULL);
-
    for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
       if (!tfeedback_decls[i].is_varying())
          continue;
@@ -2286,12 +2283,31 @@ assign_varying_locations(struct gl_context *ctx,
       /* Mark xfb varyings as always active */
       matched_candidate->toplevel_var->data.always_active_io = 1;
 
+      /* Mark any corresponding inputs as always active also. We must do this
+       * because we have a NIR pass that lowers vectors to scalars and another
+       * that removes unused varyings.
+       * We don't split varyings marked as always active because there is no
+       * point in doing so. This means we need to mark both sides of the
+       * interface as always active otherwise we will have a mismatch and
+       * start removing things we shouldn't.
+       */
+      ir_variable *const input_var =
+         linker::get_matching_input(mem_ctx, matched_candidate->toplevel_var,
+                                    consumer_inputs,
+                                    consumer_interface_inputs,
+                                    consumer_inputs_with_locations);
+      if (input_var)
+         input_var->data.always_active_io = 1;
+
       if (matched_candidate->toplevel_var->data.is_unmatched_generic_inout) {
          matched_candidate->toplevel_var->data.is_xfb_only = 1;
          matches.record(matched_candidate->toplevel_var, NULL);
       }
    }
 
+   _mesa_hash_table_destroy(consumer_inputs, NULL);
+   _mesa_hash_table_destroy(consumer_interface_inputs, NULL);
+
    uint8_t components[MAX_VARYINGS_INCL_PATCH] = {0};
    const unsigned slots_used = matches.assign_locations(
          prog, components, reserved_slots);