Mesa (main): panfrost: Add zsa->zs_always_passes flag

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Module: Mesa
Branch: main
Commit: 2454531de49848bbeb5913043d09f5ce18c533f9
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2454531de49848bbeb5913043d09f5ce18c533f9

Author: Alyssa Rosenzweig <alyssa at collabora.com>
Date:   Tue Jul 12 17:14:31 2022 -0400

panfrost: Add zsa->zs_always_passes flag

If we know ahead-of-time that depth/stencil testing will always pass, it's
better to use weak_early than force_early. However, if depth/stencil testing
could fail (discarding pixels), we'd rather use force_early. Determine which
case we're in at CSO create time.

Signed-off-by: Alyssa Rosenzweig <alyssa at collabora.com>
Cc: mesa-stable
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17428>

---

 src/gallium/drivers/panfrost/pan_cmdstream.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/gallium/drivers/panfrost/pan_cmdstream.c b/src/gallium/drivers/panfrost/pan_cmdstream.c
index 258e6f7c3c3..ce5d9ac93e1 100644
--- a/src/gallium/drivers/panfrost/pan_cmdstream.c
+++ b/src/gallium/drivers/panfrost/pan_cmdstream.c
@@ -65,6 +65,11 @@ struct panfrost_zsa_state {
         /* Is any depth, stencil, or alpha testing enabled? */
         bool enabled;
 
+        /* Does the depth and stencil tests always pass? This ignores write
+         * masks, we are only interested in whether pixels may be killed.
+         */
+        bool zs_always_passes;
+
 #if PAN_ARCH <= 7
         /* Prepacked words from the RSD */
         struct mali_multisample_misc_packed rsd_depth;
@@ -4362,6 +4367,21 @@ pan_pipe_to_stencil(const struct pipe_stencil_state *in,
 }
 #endif
 
+static bool
+pipe_zs_always_passes(const struct pipe_depth_stencil_alpha_state *zsa)
+{
+        if (zsa->depth_enabled && zsa->depth_func != PIPE_FUNC_ALWAYS)
+                return false;
+
+        if (zsa->stencil[0].enabled && zsa->stencil[0].func != PIPE_FUNC_ALWAYS)
+                return false;
+
+        if (zsa->stencil[1].enabled && zsa->stencil[1].func != PIPE_FUNC_ALWAYS)
+                return false;
+
+        return true;
+}
+
 static void *
 panfrost_create_depth_stencil_state(struct pipe_context *pipe,
                                     const struct pipe_depth_stencil_alpha_state *zsa)
@@ -4428,6 +4448,8 @@ panfrost_create_depth_stencil_state(struct pipe_context *pipe,
         so->enabled = zsa->stencil[0].enabled ||
                 (zsa->depth_enabled && zsa->depth_func != PIPE_FUNC_ALWAYS);
 
+        so->zs_always_passes = pipe_zs_always_passes(zsa);
+
         /* TODO: Bounds test should be easy */
         assert(!zsa->depth_bounds_test);