nir: store the results of divergence analysis on loops

Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7726>

src/compiler/nir/nir.c

@@ -465,6 +465,8 @@ nir_loop_create(nir_shader *shader)
    nir_loop *loop = rzalloc(shader, nir_loop);
 
    cf_init(&loop->cf_node, nir_cf_node_loop);
+   /* Assume that loops are divergent until proven otherwise */
+   loop->divergent = true;
 
    nir_block *body = nir_block_create(shader);
    exec_list_make_empty(&loop->body);

src/compiler/nir/nir.h

@@ -2783,6 +2783,7 @@ typedef struct {
    nir_loop_info *info;
    nir_loop_control control;
    bool partially_unrolled;
+   bool divergent;
 } nir_loop;
 
 /**

src/compiler/nir/nir_divergence_analysis.c

@@ -890,6 +890,8 @@ visit_loop(nir_loop *loop, struct divergence_state *state)
                                       loop_state.divergent_loop_break);
    }
 
+   loop->divergent = (loop_state.divergent_loop_break || loop_state.divergent_loop_continue);
+
    return progress;
 }