nir,nak: update comments referencing nir_metadata_preserve

in prep for removing this method.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33722>

src/compiler/nir/nir.h

@@ -3286,8 +3286,7 @@ typedef enum {
     */
    nir_metadata_live_defs = 0x4,
 
-   /** A dummy metadata value to track when a pass forgot to call
-    * nir_metadata_preserve.
+   /** A dummy metadata value to track when a pass forgot to preserve metadata.
     *
     * A pass should always clear this value even if it doesn't make any
     * progress to indicate that it thought about preserving metadata.
@@ -3348,9 +3347,7 @@ typedef enum {
    /** All metadata
     *
     * This includes all nir_metadata flags except not_properly_reset.  Passes
-    * which do not change the shader in any way should call
-    *
-    *    nir_metadata_preserve(impl, nir_metadata_all);
+    * which do not change the shader in any way should use this.
     */
    nir_metadata_all = ~nir_metadata_not_properly_reset,
 } nir_metadata;

src/compiler/nir/nir_metadata.c

@@ -143,7 +143,7 @@ nir_metadata_invalidate(nir_shader *shader)
  * Make sure passes properly invalidate metadata (part 1).
  *
  * Call this before running a pass to set a bogus metadata flag, which will
- * only be preserved if the pass forgets to call nir_metadata_preserve().
+ * only be preserved if the pass forgets to call nir_progress().
  */
 void
 nir_metadata_set_validation_flag(nir_shader *shader)
@@ -158,7 +158,7 @@ nir_metadata_set_validation_flag(nir_shader *shader)
  *
  * Call this after a pass makes progress to verify that the bogus metadata set by
  * the earlier function was properly thrown away.  Note that passes may not call
- * nir_metadata_preserve() if they don't actually make any changes at all.
+ * nir_progress() if they don't actually make any changes at all.
  */
 void
 nir_metadata_check_validation_flag(nir_shader *shader)

src/nouveau/compiler/nak_nir_lower_cf.c

@@ -472,7 +472,7 @@ lower_cf_func(nir_function *func)
    /* Now sort by reverse PDFS and restore SSA
     *
     * Note: Since we created a new nir_function_impl, there is no metadata,
-    * dirty or otherwise, so we have no need to call nir_metadata_preserve().
+    * dirty or otherwise, so we have no need to call nir_progress().
     */
    nir_sort_unstructured_blocks(new_impl);
    nir_repair_ssa_impl(new_impl);