Mesa (main): nir: Removing uses of SSA defs destroys SSA liveness

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Module: Mesa
Branch: main
Commit: 0ddac113f87ff12c6d251a2cc39e39a3ae784583
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0ddac113f87ff12c6d251a2cc39e39a3ae784583

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Tue Aug  3 10:16:58 2021 -0500

nir: Removing uses of SSA defs destroys SSA liveness

The liveness information will be a superset of real liveness so it's
unlikely something will explode if it tries to use it.  However, it is
out-of-date and should be re-run if someone really wants it.

Reviewed-by: Emma Anholt <emma at anholt.net>
Reviewed-by: Alyssa Rosenzweig <alyssa at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12186>

---

 src/compiler/nir/nir.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 47e4658ceb0..2789080d1df 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -3100,7 +3100,8 @@ typedef enum {
     *   - nir_block::live_out
     *
     * A pass can preserve this metadata type if it never adds or removes any
-    * SSA defs (most passes shouldn't preserve this metadata type).
+    * SSA defs or uses of SSA defs (most passes shouldn't preserve this
+    * metadata type).
     */
    nir_metadata_live_ssa_defs = 0x4,