[Mesa-dev] [PATCH 3/8] nir: add a helper for getting the bitmask for a variable's location

[Timothy Arceri]

---
 src/compiler/nir/nir.h | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index fab2110f619..e52a1006896 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -351,6 +351,37 @@ typedef struct nir_variable {
 #define nir_foreach_variable_safe(var, var_list) \
    foreach_list_typed_safe(nir_variable, var, node, var_list)
 
+/**
+ * Returns the bits in the inputs_read, outputs_written, or
+ * system_values_read bitfield corresponding to this variable.
+ */
+static inline uint64_t
+nir_variable_get_io_mask(nir_variable *var, gl_shader_stage stage)
+{
+   /* TODO: add support for tess patches */
+   if (var->data.patch || var->data.location < 0)
+      return 0;
+
+   assert(var->data.mode == nir_var_shader_in ||
+          var->data.mode == nir_var_shader_out ||
+          var->data.mode == nir_var_system_value);
+   assert(var->data.location >= 0);
+
+   const struct glsl_type *var_type = var->type;
+   if ((var->data.mode == nir_var_shader_in &&
+        (stage == MESA_SHADER_GEOMETRY ||
+         stage == MESA_SHADER_TESS_CTRL ||
+         stage == MESA_SHADER_TESS_EVAL)) ||
+       (var->data.mode == nir_var_shader_out &&
+        stage == MESA_SHADER_TESS_CTRL)) {
+      if (glsl_type_is_array(var_type))
+         var_type = glsl_get_array_element(var_type);
+   }
+
+   unsigned slots = glsl_count_attribute_slots(var_type, false);
+   return ((1ull << slots) - 1) << var->data.location;
+}
+
 static inline bool
 nir_variable_is_global(const nir_variable *var)
 {
-- 
2.13.5