nir: add a helper for iterating over blocks in a cf node

We were already doing this internally for iterating over a function
implementation, so just expose it directly.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/nir/nir.c

@@ -1292,6 +1292,13 @@ foreach_cf_node(nir_cf_node *node, nir_foreach_block_cb cb,
    return false;
 }
 
+bool
+nir_foreach_block_in_cf_node(nir_cf_node *node, nir_foreach_block_cb cb,
+                             void *state)
+{
+   return foreach_cf_node(node, cb, false, state);
+}
+
 bool
 nir_foreach_block(nir_function_impl *impl, nir_foreach_block_cb cb, void *state)
 {

src/glsl/nir/nir.h

@@ -1726,6 +1726,8 @@ bool nir_foreach_block(nir_function_impl *impl, nir_foreach_block_cb cb,
                        void *state);
 bool nir_foreach_block_reverse(nir_function_impl *impl, nir_foreach_block_cb cb,
                                void *state);
+bool nir_foreach_block_in_cf_node(nir_cf_node *node, nir_foreach_block_cb cb,
+                                  void *state);
 
 /* If the following CF node is an if, this function returns that if.
  * Otherwise, it returns NULL.