nir: Add a nir_deref_tail helper

Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

src/glsl/nir/nir.h

@@ -785,6 +785,15 @@ NIR_DEFINE_CAST(nir_deref_as_var, nir_deref, nir_deref_var, deref)
 NIR_DEFINE_CAST(nir_deref_as_array, nir_deref, nir_deref_array, deref)
 NIR_DEFINE_CAST(nir_deref_as_struct, nir_deref, nir_deref_struct, deref)
 
+/* Returns the last deref in the chain. */
+static inline nir_deref *
+nir_deref_tail(nir_deref *deref)
+{
+   while (deref->child)
+      deref = deref->child;
+   return deref;
+}
+
 typedef struct {
    nir_instr instr;
 

src/glsl/nir/nir_lower_var_copies.c

@@ -53,17 +53,6 @@ deref_next_wildcard_parent(nir_deref *deref)
    return NULL;
 }
 
-/* Returns the last deref in the chain.
- */
-static nir_deref *
-get_deref_tail(nir_deref *deref)
-{
-   while (deref->child)
-      deref = deref->child;
-
-   return deref;
-}
-
 /* This function recursively walks the given deref chain and replaces the
  * given copy instruction with an equivalent sequence load/store
  * operations.
@@ -121,8 +110,8 @@ emit_copy_load_store(nir_intrinsic_instr *copy_instr,
    } else {
       /* In this case, we have no wildcards anymore, so all we have to do
        * is just emit the load and store operations. */
-      src_tail = get_deref_tail(src_tail);
-      dest_tail = get_deref_tail(dest_tail);
+      src_tail = nir_deref_tail(src_tail);
+      dest_tail = nir_deref_tail(dest_tail);
 
       assert(src_tail->type == dest_tail->type);
 

src/glsl/nir/nir_split_var_copies.c

@@ -67,14 +67,6 @@ struct split_var_copies_state {
    bool progress;
 };
 
-static nir_deref *
-get_deref_tail(nir_deref *deref)
-{
-   while (deref->child != NULL)
-      deref = deref->child;
-   return deref;
-}
-
 /* Recursively constructs deref chains to split a copy instruction into
  * multiple (if needed) copy instructions with full-length deref chains.
  * External callers of this function should pass the tail and head of the
@@ -227,8 +219,8 @@ split_var_copies_block(nir_block *block, void *void_state)
 
       nir_deref *dest_head = &intrinsic->variables[0]->deref;
       nir_deref *src_head = &intrinsic->variables[1]->deref;
-      nir_deref *dest_tail = get_deref_tail(dest_head);
-      nir_deref *src_tail = get_deref_tail(src_head);
+      nir_deref *dest_tail = nir_deref_tail(dest_head);
+      nir_deref *src_tail = nir_deref_tail(src_head);
 
       switch (glsl_get_base_type(src_tail->type)) {
       case GLSL_TYPE_ARRAY: