[Mesa-dev] [PATCH] spirv: handle FragCoord and SamplePosition builtins

[Alejandro Piñeiro]

Those builtins need to fill origin_upper_left and pixel_center_integer
on the nir variable. Those depends on the execution mode, that moved
recently to be handled after creating the variables. This commit adds
a pass over the fragment shader inputs to set the proper value once we
have all the execution mode values.

Fixes: e68871f6a ("spirv: Handle constants and types before execution
                   modes")

v2: remove superfluous setting of origin_upper_left
---
 src/compiler/spirv/spirv_to_nir.c  | 13 +++++++++++++
 src/compiler/spirv/vtn_variables.c |  8 ++------
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 1cbc926c818..6825d23a238 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -4463,6 +4463,19 @@ spirv_to_nir(const uint32_t *words, size_t word_count,
    vtn_foreach_execution_mode(b, b->entry_point,
                               vtn_handle_execution_mode, NULL);
 
+   /* Update variables data that depends on the execution modes */
+   if (b->shader->info.stage == MESA_SHADER_FRAGMENT) {
+      nir_foreach_variable(var, &b->shader->inputs) {
+         switch (var->data.location) {
+         case VARYING_SLOT_POS: /* FragCoord */
+            var->data.pixel_center_integer = b->pixel_center_integer;
+            /* fallthrough */
+         case SYSTEM_VALUE_SAMPLE_POS:
+            var->data.origin_upper_left = b->origin_upper_left;
+         }
+      }
+   }
+
    if (b->workgroup_size_builtin) {
       vtn_assert(b->workgroup_size_builtin->type->type ==
                  glsl_vector_type(GLSL_TYPE_UINT, 3));
diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index f6b458b7e78..d4b64fd962d 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -1448,12 +1448,8 @@ apply_var_decoration(struct vtn_builder *b,
       case SpvBuiltInCullDistance:
          var_data->compact = true;
          break;
-      case SpvBuiltInFragCoord:
-         var_data->pixel_center_integer = b->pixel_center_integer;
-         /* fallthrough */
-      case SpvBuiltInSamplePosition:
-         var_data->origin_upper_left = b->origin_upper_left;
-         break;
+      /* FragCoord and SamplePosition depends on having the correct value for
+       * the execution mode. Will be handled later */
       default:
          break;
       }
-- 
2.19.1