From 9250fb9f0e4f14aeb86c54eeea20dab5d43ee4ea Mon Sep 17 00:00:00 2001
From: Jason Ekstrand <jason@jlekstrand.net>
Date: Wed, 22 Jan 2020 14:26:24 -0600
Subject: [PATCH] anv: Insert holes for non-existant XFB varyings

Thanks to optimizations, it's possible for varyings to get deleted but
still leave the variable there for nir_gather_xfb_info to find.  If we
get into this case, insert a hole.

Fixes: 36ee2fd61c8 "anv: Implement the basic form of..."
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3520>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3520>
(cherry picked from commit 993f866d2e31c06462b49d760debf64d14e54a68)
---
 .pick_status.json                |  2 +-
 src/intel/vulkan/genX_pipeline.c | 22 +++++++++++++++++-----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index a67055e3802..eeceddea077 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -211,7 +211,7 @@
         "description": "anv: Insert holes for non-existant XFB varyings",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "36ee2fd61c8f943be1d1e2b0354f7a121ffef28f"
     },
diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 0964ef5c604..ea2e38834e8 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -1415,11 +1415,23 @@ emit_3dstate_streamout(struct anv_pipeline *pipeline,
          next_offset[buffer] = output->offset +
                                __builtin_popcount(component_mask) * 4;
 
-         so_decl[stream][decls[stream]++] = (struct GENX(SO_DECL)) {
-            .OutputBufferSlot = buffer,
-            .RegisterIndex = vue_map->varying_to_slot[varying],
-            .ComponentMask = component_mask,
-         };
+         const int slot = vue_map->varying_to_slot[varying];
+         if (slot < 0) {
+            /* This can happen if the shader never writes to the varying.
+             * Insert a hole instead of actual varying data.
+             */
+            so_decl[stream][decls[stream]++] = (struct GENX(SO_DECL)) {
+               .HoleFlag = true,
+               .OutputBufferSlot = buffer,
+               .ComponentMask = component_mask,
+            };
+         } else {
+            so_decl[stream][decls[stream]++] = (struct GENX(SO_DECL)) {
+               .OutputBufferSlot = buffer,
+               .RegisterIndex = slot,
+               .ComponentMask = component_mask,
+            };
+         }
       }
 
       int max_decls = 0;