Mesa (master): radeonsi: fix applying the NGG minimum vertex count requirement

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Module: Mesa
Branch: master
Commit: 64c741ffb7aa0ae40c4302bc065fef0192123c6a
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=64c741ffb7aa0ae40c4302bc065fef0192123c6a

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Thu Jul 30 08:19:48 2020 -0400

radeonsi: fix applying the NGG minimum vertex count requirement

The code applied the restriction too late, which could overflow LDS size,
which started happening more often after the minimum vertex count was
increased for Sienna.

Incorporate the clamping into the previous code for rounding up the counts.
Now the LDS size can never overflow, but it may use vector lanes less
efficiently (max_gsprims can be decreased more), which will be addressed
in the next commit.

Fixes: 4ecc39e1aa1 ("radeonsi/gfx10: NGG geometry shader PM4 and upload")

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6137>

---

 src/gallium/drivers/radeonsi/gfx10_shader_ngg.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c b/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
index ee242da7ed1..0797f9cdb3a 100644
--- a/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
+++ b/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
@@ -2022,6 +2022,8 @@ retry_select_mode:
             max_esverts =
                MIN2(max_esverts, (max_lds_size - max_gsprims * gsprim_lds_size) / esvert_lds_size);
          max_esverts = MIN2(max_esverts, max_gsprims * max_verts_per_prim);
+         /* Hardware restriction: minimum value of max_esverts */
+         max_esverts = MAX2(max_esverts, min_esverts - 1 + max_verts_per_prim);
 
          max_gsprims = align(max_gsprims, wavesize);
          max_gsprims = MIN2(max_gsprims, max_gsprims_base);
@@ -2031,10 +2033,13 @@ retry_select_mode:
          clamp_gsprims_to_esverts(&max_gsprims, max_esverts, min_verts_per_prim, use_adjacency);
          assert(max_esverts >= max_verts_per_prim && max_gsprims >= 1);
       } while (orig_max_esverts != max_esverts || orig_max_gsprims != max_gsprims);
-   }
 
-   /* Hardware restriction: minimum value of max_esverts */
-   max_esverts = MAX2(max_esverts, min_esverts - 1 + max_verts_per_prim);
+      /* Verify the restriction. */
+      assert(max_esverts >= min_esverts - 1 + max_verts_per_prim);
+   } else {
+      /* Hardware restriction: minimum value of max_esverts */
+      max_esverts = MAX2(max_esverts, min_esverts - 1 + max_verts_per_prim);
+   }
 
    unsigned max_out_vertices =
       max_vert_out_per_gs_instance