[Mesa-dev] [PATCH v2] nir: Handle variables dependent on the local work group size.

[Plamena Manolova]

Lowering shader variables which depend on the local work group
size being available in nir_lower_system_values is only possible
if the local work group size isn't variable, otherwise this should
be handled by the native driver (if it supports
ARB_compute_variable_group_size).

Signed-off-by: Plamena Manolova <plamena.n.manolova at gmail.com>
---
 src/compiler/nir/nir_lower_system_values.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/compiler/nir/nir_lower_system_values.c b/src/compiler/nir/nir_lower_system_values.c
index bde7eb1180..6fdf9f9c51 100644
--- a/src/compiler/nir/nir_lower_system_values.c
+++ b/src/compiler/nir/nir_lower_system_values.c
@@ -77,6 +77,15 @@ convert_block(nir_block *block, nir_builder *b)
           *    "The value of gl_GlobalInvocationID is equal to
           *    gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID"
           */
+
+         /*
+          * If the local work group size is variable we can't lower the global
+          * invocation id here.
+          */
+         if (b->shader->info.cs.local_size_variable) {
+            break;
+         }
+
          nir_ssa_def *group_size = build_local_group_size(b);
          nir_ssa_def *group_id = nir_load_work_group_id(b);
          nir_ssa_def *local_id = nir_load_local_invocation_id(b);
@@ -115,6 +124,11 @@ convert_block(nir_block *block, nir_builder *b)
       }
 
       case SYSTEM_VALUE_LOCAL_GROUP_SIZE: {
+         /* If the local work group size is variable we can't lower it here */
+         if (b->shader->info.cs.local_size_variable) {
+            break;
+         }
+
          sysval = build_local_group_size(b);
          break;
       }
@@ -189,6 +203,14 @@ convert_block(nir_block *block, nir_builder *b)
          break;
 
       case SYSTEM_VALUE_GLOBAL_GROUP_SIZE: {
+         /*
+          * If the local work group size is variable we can't lower the global
+          * group size here.
+          */
+         if (b->shader->info.cs.local_size_variable) {
+            break;
+         }
+
          nir_ssa_def *group_size = build_local_group_size(b);
          nir_ssa_def *num_work_groups = nir_load_num_work_groups(b);
          sysval = nir_imul(b, group_size, num_work_groups);
-- 
2.11.0