Mesa (master): nir: Handle compact variables when assigning i/o locations

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Module: Mesa
Branch: master
Commit: dd81d8808d30459592a1fff2673e768951426364
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=dd81d8808d30459592a1fff2673e768951426364

Author: Connor Abbott <cwabbott0 at gmail.com>
Date:   Tue May 14 14:08:46 2019 +0200

nir: Handle compact variables when assigning i/o locations

These are used in Vulkan for clip/cull distances, instead of the GLSL
lowering when the clip/cull arrays are shared.

Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

---

 src/compiler/nir/nir_linking_helpers.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_linking_helpers.c b/src/compiler/nir/nir_linking_helpers.c
index d25b350a75e..b85690983d5 100644
--- a/src/compiler/nir/nir_linking_helpers.c
+++ b/src/compiler/nir/nir_linking_helpers.c
@@ -1011,15 +1011,35 @@ nir_assign_io_var_locations(struct exec_list *var_list, unsigned *size,
       (int) FRAG_RESULT_DATA0 : (int) VARYING_SLOT_VAR0;
 
    int UNUSED last_loc = 0;
+   bool last_partial = false;
    nir_foreach_variable(var, var_list) {
-
       const struct glsl_type *type = var->type;
       if (nir_is_per_vertex_io(var, stage)) {
          assert(glsl_type_is_array(type));
          type = glsl_get_array_element(type);
       }
 
-      unsigned var_size = glsl_count_attribute_slots(type, false);
+      unsigned var_size;
+      if (var->data.compact) {
+         /* compact variables must be arrays of scalars */
+         assert(glsl_type_is_array(type));
+         assert(glsl_type_is_scalar(glsl_get_array_element(type)));
+         unsigned start = 4 * location + var->data.location_frac;
+         unsigned end = start + glsl_get_length(type);
+         var_size = end / 4 - location;
+         last_partial = end % 4 != 0;
+      } else {
+         /* Compact variables bypass the normal varying compacting pass,
+          * which means they cannot be in the same vec4 slot as a normal
+          * variable. If part of the current slot is taken up by a compact
+          * variable, we need to go to the next one.
+          */
+         if (last_partial) {
+            location++;
+            last_partial = false;
+         }
+         var_size = glsl_count_attribute_slots(type, false);
+      }
 
       /* Builtins don't allow component packing so we only need to worry about
        * user defined varyings sharing the same location.