glsl: disable varying packing for varying used by interpolateAt*

Currently the NIR backends depend on GLSL IR copy propagation to
fix up the interpolateAt* function params after varying packing
changes the shader input to a global. It's possible copy propagation
might not always do what we need it too, and we also shouldn't
depend on optimisations to do this type of thing for us.

I'm not sure if the same is true for TGSI, but the following
commit should re-enable packing for most cases in a safer way,
so we just disable it everywhere.

No change in shader-db for i965 (BDW)

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

1 files changed, 13 insertions, 4 deletions

diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
index e6947692aff..6bcec72f5fc 100644
--- a/src/compiler/glsl/link_varyings.cpp
+++ b/src/compiler/glsl/link_varyings.cpp
@@ -1461,17 +1461,24 @@ varying_matches::record(ir_variable *producer_var, ir_variable *consumer_var)
       ? consumer_stage : producer_stage;
    const glsl_type *type = get_varying_type(var, stage);
 
+   if (producer_var && consumer_var &&
+       consumer_var->data.must_be_shader_input) {
+      producer_var->data.must_be_shader_input = 1;
+   }
+
    this->matches[this->num_matches].packing_class
       = this->compute_packing_class(var);
    this->matches[this->num_matches].packing_order
       = this->compute_packing_order(var);
-   if (this->disable_varying_packing && !is_varying_packing_safe(type, var)) {
+   if ((this->disable_varying_packing && !is_varying_packing_safe(type, var)) ||
+       var->data.must_be_shader_input) {
       unsigned slots = type->count_attribute_slots(false);
       this->matches[this->num_matches].num_components = slots * 4;
    } else {
       this->matches[this->num_matches].num_components
          = type->component_slots();
    }
+
    this->matches[this->num_matches].producer_var = producer_var;
    this->matches[this->num_matches].consumer_var = consumer_var;
    this->num_matches++;
@@ -1544,7 +1551,8 @@ varying_matches::assign_locations(struct gl_shader_program *prog,
        * we can pack varyings together that are only used for transform
        * feedback.
        */
-      if ((this->disable_varying_packing &&
+      if (var->data.must_be_shader_input ||
+          (this->disable_varying_packing &&
            !(previous_var_xfb_only && var->data.is_xfb_only)) ||
           (i > 0 && this->matches[i - 1].packing_class
           != this->matches[i].packing_class )) {
@@ -1660,8 +1668,9 @@ varying_matches::compute_packing_class(const ir_variable *var)
     * Therefore, the packing class depends only on the interpolation type.
     */
    unsigned packing_class = var->data.centroid | (var->data.sample << 1) |
-                            (var->data.patch << 2);
-   packing_class *= 4;
+                            (var->data.patch << 2) |
+                            (var->data.must_be_shader_input << 3);
+   packing_class *= 8;
    packing_class += var->is_interpolation_flat()
       ? unsigned(INTERP_MODE_FLAT) : var->data.interpolation;
    return packing_class;