[Mesa-dev] [PATCH 4/5] nir: Convert the NIR instruction insertion API to use cursors.

[Kenneth Graunke]

This patch implements a general nir_instr_insert() function that takes a
nir_cursor for the insertion point.  It then reworks the existing API to
simply be a wrapper around that for compatibility.

This largely involves moving the existing code into a new function.

Suggested by Connor Abbott.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/glsl/nir/nir.c | 115 ++++++++++++++++++++++++++---------------------------
 src/glsl/nir/nir.h |   7 ++++
 2 files changed, 63 insertions(+), 59 deletions(-)

diff --git a/src/glsl/nir/nir.c b/src/glsl/nir/nir.c
index ff758f4..a3e7966 100644
--- a/src/glsl/nir/nir.c
+++ b/src/glsl/nir/nir.c
@@ -664,102 +664,99 @@ add_defs_uses(nir_instr *instr)
 }
 
 void
+nir_instr_insert(nir_cursor cursor, nir_instr *instr)
+{
+   switch (cursor.option) {
+   case nir_cursor_before_block:
+      /* Only allow inserting jumps into empty blocks. */
+      if (instr->type == nir_instr_type_jump)
+         assert(exec_list_is_empty(&cursor.block->instr_list));
+
+      instr->block = cursor.block;
+      add_defs_uses(instr);
+      exec_list_push_head(&cursor.block->instr_list, &instr->node);
+      break;
+   case nir_cursor_after_block: {
+      /* Inserting instructions after a jump is illegal. */
+      nir_instr *last = nir_block_last_instr(cursor.block);
+      assert(last == NULL || last->type != nir_instr_type_jump);
+      (void) last;
+
+      instr->block = cursor.block;
+      add_defs_uses(instr);
+      exec_list_push_tail(&cursor.block->instr_list, &instr->node);
+      break;
+   }
+   case nir_cursor_before_instr:
+      assert(instr->type != nir_instr_type_jump);
+      instr->block = cursor.instr->block;
+      add_defs_uses(instr);
+      exec_node_insert_node_before(&cursor.instr->node, &instr->node);
+      break;
+   case nir_cursor_after_instr:
+      /* Inserting instructions after a jump is illegal. */
+      assert(cursor.instr->type != nir_instr_type_jump);
+
+      /* Only allow inserting jumps at the end of the block. */
+      if (instr->type == nir_instr_type_jump)
+         assert(cursor.instr == nir_block_last_instr(cursor.instr->block));
+
+      instr->block = cursor.instr->block;
+      add_defs_uses(instr);
+      exec_node_insert_after(&cursor.instr->node, &instr->node);
+      break;
+   }
+
+   if (instr->type == nir_instr_type_jump)
+      nir_handle_add_jump(instr->block);
+}
+
+void
 nir_instr_insert_before(nir_instr *instr, nir_instr *before)
 {
-   assert(before->type != nir_instr_type_jump);
-   before->block = instr->block;
-   add_defs_uses(before);
-   exec_node_insert_node_before(&instr->node, &before->node);
+   nir_instr_insert(nir_before_instr(instr), before);
 }
 
 void
 nir_instr_insert_after(nir_instr *instr, nir_instr *after)
 {
-   assert(instr->type != nir_instr_type_jump);
-
-   if (after->type == nir_instr_type_jump) {
-      assert(instr == nir_block_last_instr(instr->block));
-   }
-
-   after->block = instr->block;
-   add_defs_uses(after);
-   exec_node_insert_after(&instr->node, &after->node);
-
-   if (after->type == nir_instr_type_jump)
-      nir_handle_add_jump(after->block);
+   nir_instr_insert(nir_after_instr(instr), after);
 }
 
 void
 nir_instr_insert_before_block(nir_block *block, nir_instr *before)
 {
-   if (before->type == nir_instr_type_jump)
-      assert(exec_list_is_empty(&block->instr_list));
-
-   before->block = block;
-   add_defs_uses(before);
-   exec_list_push_head(&block->instr_list, &before->node);
-
-   if (before->type == nir_instr_type_jump)
-      nir_handle_add_jump(block);
+   nir_instr_insert(nir_before_block(block), before);
 }
 
 void
 nir_instr_insert_after_block(nir_block *block, nir_instr *after)
 {
-   nir_instr *last = nir_block_last_instr(block);
-   assert(last == NULL || last->type != nir_instr_type_jump);
-   (void) last;
-
-   after->block = block;
-   add_defs_uses(after);
-   exec_list_push_tail(&block->instr_list, &after->node);
-
-   if (after->type == nir_instr_type_jump)
-      nir_handle_add_jump(block);
+   nir_instr_insert(nir_after_block(block), after);
 }
 
 void
 nir_instr_insert_before_cf(nir_cf_node *node, nir_instr *before)
 {
-   if (node->type == nir_cf_node_block) {
-      nir_instr_insert_before_block(nir_cf_node_as_block(node), before);
-   } else {
-      nir_cf_node *prev = nir_cf_node_prev(node);
-      assert(prev->type == nir_cf_node_block);
-      nir_block *prev_block = nir_cf_node_as_block(prev);
-
-      nir_instr_insert_before_block(prev_block, before);
-   }
+   nir_instr_insert(nir_before_cf_node(node), before);
 }
 
 void
 nir_instr_insert_after_cf(nir_cf_node *node, nir_instr *after)
 {
-   if (node->type == nir_cf_node_block) {
-      nir_instr_insert_after_block(nir_cf_node_as_block(node), after);
-   } else {
-      nir_cf_node *next = nir_cf_node_next(node);
-      assert(next->type == nir_cf_node_block);
-      nir_block *next_block = nir_cf_node_as_block(next);
-
-      nir_instr_insert_before_block(next_block, after);
-   }
+   nir_instr_insert(nir_after_cf_node(node), after);
 }
 
 void
 nir_instr_insert_before_cf_list(struct exec_list *list, nir_instr *before)
 {
-   nir_cf_node *first_node = exec_node_data(nir_cf_node,
-                                            exec_list_get_head(list), node);
-   nir_instr_insert_before_cf(first_node, before);
+   nir_instr_insert(nir_before_cf_list(list), before);
 }
 
 void
 nir_instr_insert_after_cf_list(struct exec_list *list, nir_instr *after)
 {
-   nir_cf_node *last_node = exec_node_data(nir_cf_node,
-                                           exec_list_get_tail(list), node);
-   nir_instr_insert_after_cf(last_node, after);
+   nir_instr_insert(nir_after_cf_list(list), after);
 }
 
 static bool
diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 65e4daf..ac01c86 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1641,6 +1641,13 @@ nir_after_cf_list(struct exec_list *cf_list)
    return nir_after_cf_node(last_node);
 }
 
+/**
+ * Insert a NIR instruction at the given cursor.
+ *
+ * Note: This does not update the cursor.
+ */
+void nir_instr_insert(nir_cursor cursor, nir_instr *instr);
+
 void nir_instr_insert_before(nir_instr *instr, nir_instr *before);
 void nir_instr_insert_after(nir_instr *instr, nir_instr *after);
 
-- 
2.5.0