panfrost: Add helper to determine if we are capturing

That is, is the varying setup for xfb *and* is there a buffer for it?

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5423>

diff --git a/src/gallium/drivers/panfrost/pan_cmdstream.c b/src/gallium/drivers/panfrost/pan_cmdstream.c
index 6480733a2b53699425579c67fa7451d86137c3e0..1b2e632cf1b971e8c9516038e98e18991e701282 100644 (file)
--- a/src/gallium/drivers/panfrost/pan_cmdstream.c
+++ b/src/gallium/drivers/panfrost/pan_cmdstream.c
@@ -1929,6 +1929,21 @@ pan_emit_vary_xfb(unsigned present,
         return meta;
 }
 
+/* Determine if we should capture a varying for XFB. This requires actually
+ * having a buffer for it. If we don't capture it, we'll fallback to a general
+ * varying path (linked or unlinked, possibly discarding the write) */
+
+static bool
+panfrost_xfb_captured(struct panfrost_shader_state *xfb,
+                unsigned loc, unsigned max_xfb)
+{
+        if (!(xfb->so_mask & (1ll << loc)))
+                return false;
+
+        struct pipe_stream_output *o = pan_get_so(&xfb->stream_output, loc);
+        return o->output_buffer < max_xfb;
+}
+
 void
 panfrost_emit_varying_descriptor(struct panfrost_batch *batch,
                                  unsigned vertex_count,