nir: Make nir_foo_first/last_cf_node return a block instead

One of NIR's invariants is that control flow lists always start and end
with blocks.  There's no good reason why we should return a cf_node from
these functions since we know that it's always a block.  Making it a block
lets us remove a bunch of code.

Signed-off-by: Jason Ekstrand <[email protected]>
Reviewed-by: Connor Abbott <[email protected]>

2 files changed, 6 insertions, 11 deletions

diff --git a/src/gallium/drivers/freedreno/ir3/ir3_nir_lower_if_else.c b/src/gallium/drivers/freedreno/ir3/ir3_nir_lower_if_else.c
index 6e1395c9001..b781fa7663f 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3_nir_lower_if_else.c
+++ b/src/gallium/drivers/freedreno/ir3/ir3_nir_lower_if_else.c
@@ -224,17 +224,14 @@ lower_if_else_block(nir_block *block, nir_builder *b, void *mem_ctx)
 		return false;
 
 	nir_if *if_stmt = nir_cf_node_as_if(prev_node);
-	nir_cf_node *then_node = nir_if_first_then_node(if_stmt);
-	nir_cf_node *else_node = nir_if_first_else_node(if_stmt);
+	nir_block *then_block = nir_if_first_then_block(if_stmt);
+	nir_block *else_block = nir_if_first_else_block(if_stmt);
 
 	/* We can only have one block in each side ... */
-	if (nir_if_last_then_node(if_stmt) != then_node ||
-			nir_if_last_else_node(if_stmt) != else_node)
+	if (nir_if_last_then_block(if_stmt) != then_block ||
+			nir_if_last_else_block(if_stmt) != else_block)
 		return false;
 
-	nir_block *then_block = nir_cf_node_as_block(then_node);
-	nir_block *else_block = nir_cf_node_as_block(else_node);
-
 	/* ... and those blocks must only contain "allowed" instructions. */
 	if (!block_check_for_allowed_instrs(then_block) ||
 			!block_check_for_allowed_instrs(else_block))
diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
index 81c67168c18..84add5253ff 100644
--- a/src/gallium/drivers/vc4/vc4_program.c
+++ b/src/gallium/drivers/vc4/vc4_program.c
@@ -1777,11 +1777,9 @@ ntq_emit_if(struct vc4_compile *c, nir_if *if_stmt)
                 return;
         }
 
-        nir_cf_node *nir_first_else_node = nir_if_first_else_node(if_stmt);
-        nir_cf_node *nir_last_else_node = nir_if_last_else_node(if_stmt);
-        nir_block *nir_else_block = nir_cf_node_as_block(nir_first_else_node);
+        nir_block *nir_else_block = nir_if_first_else_block(if_stmt);
         bool empty_else_block =
-                (nir_first_else_node == nir_last_else_node  &&
+                (nir_else_block == nir_if_last_else_block(if_stmt) &&
                  exec_list_is_empty(&nir_else_block->instr_list));
 
         struct qblock *then_block = qir_new_block(c);