nir: Add support for cloning shaders

This commit is heavily based on one by Rob Clark <[email protected]> but
reworked to re-use nir_create functions and do less hashing.

Signed-off-by: Jason Ekstrand <[email protected]>
Reviewed-by: Rob Clark <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/glsl/nir/nir.c b/src/glsl/nir/nir.c
index bb7a5fa5835..93c18fbaea5 100644
--- a/src/glsl/nir/nir.c
+++ b/src/glsl/nir/nir.c
@@ -312,6 +312,14 @@ nir_block_create(nir_shader *shader)
    block->predecessors = _mesa_set_create(block, _mesa_hash_pointer,
                                           _mesa_key_pointer_equal);
    block->imm_dom = NULL;
+   /* XXX maybe it would be worth it to defer allocation?  This
+    * way it doesn't get allocated for shader ref's that never run
+    * nir_calc_dominance?  For example, state-tracker creates an
+    * initial IR, clones that, runs appropriate lowering pass, passes
+    * to driver which does common lowering/opt, and then stores ref
+    * which is later used to do state specific lowering and futher
+    * opt.  Do any of the references not need dominance metadata?
+    */
    block->dom_frontier = _mesa_set_create(block, _mesa_hash_pointer,
                                           _mesa_key_pointer_equal);