intel/cfg: Document bblock_t::num

So that the next person doesn't hope it means "number of instructions,"
then have to go figure it out.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/intel/compiler/brw_cfg.h b/src/intel/compiler/brw_cfg.h
index 591d9b4dae2..6f958d85438 100644
--- a/src/intel/compiler/brw_cfg.h
+++ b/src/intel/compiler/brw_cfg.h
@@ -118,6 +118,12 @@ struct bblock_t {
    struct exec_list instructions;
    struct exec_list parents;
    struct exec_list children;
+
+   /**
+    * Unique index of the basic block in the CFG.
+    *
+    * Value may change as blocks are added to and removed from the CFG.
+    */
    int num;
 };