Mesa (main): radeonsi: restructure si_get_vs_vgpr_comp_cnt for readability

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Module: Mesa
Branch: main
Commit: 786678a017c5b488bd36fade440d9f5308c3d23c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=786678a017c5b488bd36fade440d9f5308c3d23c

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Tue May 11 00:40:39 2021 -0400

radeonsi: restructure si_get_vs_vgpr_comp_cnt for readability

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11102>

---

 src/gallium/drivers/radeonsi/si_state_shaders.c | 34 +++++++++++++++----------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_state_shaders.c b/src/gallium/drivers/radeonsi/si_state_shaders.c
index 44dad0c897c..2a1799f17d4 100644
--- a/src/gallium/drivers/radeonsi/si_state_shaders.c
+++ b/src/gallium/drivers/radeonsi/si_state_shaders.c
@@ -509,22 +509,30 @@ static unsigned si_get_vs_vgpr_comp_cnt(struct si_screen *sscreen, struct si_sha
    assert(shader->selector->info.stage == MESA_SHADER_VERTEX ||
           (shader->previous_stage_sel && shader->previous_stage_sel->info.stage == MESA_SHADER_VERTEX));
 
-   /* GFX6-9 LS    (VertexID, RelAutoindex,                InstanceID / StepRate0(==1), ...).
-    * GFX6-9 ES,VS (VertexID, InstanceID / StepRate0(==1), VSPrimID,                    ...)
-    * GFX10  LS    (VertexID, RelAutoindex,                UserVGPR1,                   InstanceID).
-    * GFX10  ES,VS (VertexID, UserVGPR0,                   UserVGPR1 or VSPrimID,       UserVGPR2 or
-    * InstanceID)
+   /* GFX6-9   LS    (VertexID, RelAutoIndex,           InstanceID / StepRate0, InstanceID)
+    * GFX6-9   ES,VS (VertexID, InstanceID / StepRate0, VSPrimID,               InstanceID)
+    * GFX10    LS    (VertexID, RelAutoIndex,           UserVGPR1,              UserVGPR2 or InstanceID)
+    * GFX10    ES,VS (VertexID, UserVGPR1,              UserVGPR2 or VSPrimID,  UserVGPR3 or InstanceID)
     */
    bool is_ls = shader->selector->info.stage == MESA_SHADER_TESS_CTRL || shader->key.as_ls;
+   unsigned max = 0;
 
-   if (sscreen->info.chip_class >= GFX10 && shader->info.uses_instanceid)
-      return 3;
-   else if ((is_ls && shader->info.uses_instanceid) || legacy_vs_prim_id)
-      return 2;
-   else if (is_ls || shader->info.uses_instanceid)
-      return 1;
-   else
-      return 0;
+   if (shader->info.uses_instanceid) {
+      if (sscreen->info.chip_class >= GFX10)
+         max = MAX2(max, 3);
+      else if (is_ls)
+         max = MAX2(max, 2); /* use (InstanceID / StepRate0) because StepRate0 == 1 */
+      else
+         max = MAX2(max, 1); /* use (InstanceID / StepRate0) because StepRate0 == 1 */
+   }
+
+   if (legacy_vs_prim_id)
+      max = MAX2(max, 2); /* VSPrimID */
+
+   if (is_ls)
+      max = MAX2(max, 1); /* RelAutoIndex */
+
+   return max;
 }
 
 static void si_shader_ls(struct si_screen *sscreen, struct si_shader *shader)