nir: Move get_const_initializer_load from vars_to_ssa to NIR core

Reviewed-by: Connor Abbott <[email protected]>

1 files changed, 60 insertions, 0 deletions

diff --git a/src/glsl/nir/nir.c b/src/glsl/nir/nir.c
index c6e53612b2a..a7ee3613fcf 100644
--- a/src/glsl/nir/nir.c
+++ b/src/glsl/nir/nir.c
@@ -589,6 +589,66 @@ nir_copy_deref(void *mem_ctx, nir_deref *deref)
    return NULL;
 }
 
+/* Returns a load_const instruction that represents the constant
+ * initializer for the given deref chain.  The caller is responsible for
+ * ensuring that there actually is a constant initializer.
+ */
+nir_load_const_instr *
+nir_deref_get_const_initializer_load(nir_shader *shader, nir_deref_var *deref)
+{
+   nir_constant *constant = deref->var->constant_initializer;
+   assert(constant);
+
+   const nir_deref *tail = &deref->deref;
+   unsigned matrix_offset = 0;
+   while (tail->child) {
+      switch (tail->child->deref_type) {
+      case nir_deref_type_array: {
+         nir_deref_array *arr = nir_deref_as_array(tail->child);
+         assert(arr->deref_array_type == nir_deref_array_type_direct);
+         if (glsl_type_is_matrix(tail->type)) {
+            assert(arr->deref.child == NULL);
+            matrix_offset = arr->base_offset;
+         } else {
+            constant = constant->elements[arr->base_offset];
+         }
+         break;
+      }
+
+      case nir_deref_type_struct: {
+         constant = constant->elements[nir_deref_as_struct(tail->child)->index];
+         break;
+      }
+
+      default:
+         unreachable("Invalid deref child type");
+      }
+
+      tail = tail->child;
+   }
+
+   nir_load_const_instr *load =
+      nir_load_const_instr_create(shader, glsl_get_vector_elements(tail->type));
+
+   matrix_offset *= load->def.num_components;
+   for (unsigned i = 0; i < load->def.num_components; i++) {
+      switch (glsl_get_base_type(tail->type)) {
+      case GLSL_TYPE_FLOAT:
+      case GLSL_TYPE_INT:
+      case GLSL_TYPE_UINT:
+         load->value.u[i] = constant->value.u[matrix_offset + i];
+         break;
+      case GLSL_TYPE_BOOL:
+         load->value.u[i] = constant->value.b[matrix_offset + i] ?
+                             NIR_TRUE : NIR_FALSE;
+         break;
+      default:
+         unreachable("Invalid immediate type");
+      }
+   }
+
+   return load;
+}
 
 /**
  * \name Control flow modification