nir/spirv: Fix handling of gl_PrimitiveId

Before, we were always treating it as an output which bogus.  The only
stage in which this it can be an output is the geometry stage.  In all
other stages, it's an input which, in the back-end, we actually want to be
a system value.

Cc: "13.0" <[email protected]>
Reviewed-by: Dave Airlie <[email protected]>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index bbcca146107..c064de8d683 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -806,8 +806,12 @@ vtn_get_builtin_location(struct vtn_builder *b,
       set_mode_system_value(mode);
       break;
    case SpvBuiltInPrimitiveId:
-      *location = VARYING_SLOT_PRIMITIVE_ID;
-      *mode = nir_var_shader_out;
+      if (*mode == nir_var_shader_out) {
+         *location = VARYING_SLOT_PRIMITIVE_ID;
+      } else {
+         *location = SYSTEM_VALUE_PRIMITIVE_ID;
+         set_mode_system_value(mode);
+      }
       break;
    case SpvBuiltInInvocationId:
       *location = SYSTEM_VALUE_INVOCATION_ID;