[PATCH vkd3d v7 6/6] vkd3d-shader/hlsl: Handle loops in copy propagation.

[Giovanni Mascellani]

Signed-off-by: Giovanni Mascellani <gmascellani at codeweavers.com>
---
 libs/vkd3d-shader/hlsl_codegen.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/libs/vkd3d-shader/hlsl_codegen.c b/libs/vkd3d-shader/hlsl_codegen.c
index 86d82965..1178134d 100644
--- a/libs/vkd3d-shader/hlsl_codegen.c
+++ b/libs/vkd3d-shader/hlsl_codegen.c
@@ -266,7 +266,15 @@ static void replace_node(struct hlsl_ir_node *old, struct hlsl_ir_node *new)
  * "else") can inherit the variable state available just before the
  * conditional block. After the conditional block, all variables that
  * might have been written in either branch must be invalidated,
- * because we don't know which branch has executed. */
+ * because we don't know which branch has executed.
+ *
+ * When entering a loop block, we can inherit the variable state
+ * available just before the loop block, except that all variables
+ * that are written in the body must be invalidated (because at the
+ * beginning of each execution of the body we don't know whether the
+ * body has already executed or not). The same is valid after the loop
+ * block, because we don't know whether the body has executed at all
+ * or not. */
 
 struct copy_propagation_value
 {
@@ -561,6 +569,22 @@ end:
     return progress;
 }
 
+static bool copy_propagation_process_loop(struct hlsl_ctx *ctx, struct hlsl_ir_loop *loop,
+        struct copy_propagation_state *state)
+{
+    bool progress = false;
+
+    copy_propagation_invalidate_from_block(ctx, state, &loop->body);
+    if (!copy_propagation_duplicate(ctx, state))
+        return progress;
+
+    progress |= copy_propagation_transform_block(ctx, &loop->body, state);
+
+    copy_propagation_pop(state);
+
+    return progress;
+}
+
 static bool copy_propagation_transform_block(struct hlsl_ctx *ctx, struct hlsl_block *block,
         struct copy_propagation_state *state)
 {
@@ -584,7 +608,7 @@ static bool copy_propagation_transform_block(struct hlsl_ctx *ctx, struct hlsl_b
                 return progress;
 
             case HLSL_IR_LOOP:
-                FIXME("Copy propagation doesn't support loops yet, leaving.\n");
+                progress |= copy_propagation_process_loop(ctx, hlsl_ir_loop(instr), state);
                 return progress;
 
             default:
-- 
2.33.1