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-rw-r--r--src/compiler/nir/nir.h1
-rw-r--r--src/compiler/nir/nir_lower_system_values.c49
2 files changed, 49 insertions, 1 deletions
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index b0cff50eaf2..1dd605010f6 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2178,6 +2178,7 @@ typedef struct nir_shader_compiler_options {
bool lower_helper_invocation;
bool lower_cs_local_index_from_id;
+ bool lower_cs_local_id_from_index;
bool lower_device_index_to_zero;
diff --git a/src/compiler/nir/nir_lower_system_values.c b/src/compiler/nir/nir_lower_system_values.c
index fbc40573579..08a9e8be44a 100644
--- a/src/compiler/nir/nir_lower_system_values.c
+++ b/src/compiler/nir/nir_lower_system_values.c
@@ -51,6 +51,45 @@ build_local_group_size(nir_builder *b)
return local_size;
}
+static nir_ssa_def *
+build_local_invocation_id(nir_builder *b)
+{
+ if (b->shader->options->lower_cs_local_id_from_index) {
+ /* We lower gl_LocalInvocationID from gl_LocalInvocationIndex based
+ * on this formula:
+ *
+ * gl_LocalInvocationID.x =
+ * gl_LocalInvocationIndex % gl_WorkGroupSize.x;
+ * gl_LocalInvocationID.y =
+ * (gl_LocalInvocationIndex / gl_WorkGroupSize.x) %
+ * gl_WorkGroupSize.y;
+ * gl_LocalInvocationID.z =
+ * (gl_LocalInvocationIndex /
+ * (gl_WorkGroupSize.x * gl_WorkGroupSize.y)) %
+ * gl_WorkGroupSize.z;
+ *
+ * However, the final % gl_WorkGroupSize.z does nothing unless we
+ * accidentally end up with a gl_LocalInvocationIndex that is too
+ * large so it can safely be omitted.
+ */
+ nir_ssa_def *local_index = nir_load_local_invocation_index(b);
+ nir_ssa_def *local_size = build_local_group_size(b);
+
+ nir_ssa_def *id_x, *id_y, *id_z;
+ id_x = nir_umod(b, local_index,
+ nir_channel(b, local_size, 0));
+ id_y = nir_umod(b, nir_udiv(b, local_index,
+ nir_channel(b, local_size, 0)),
+ nir_channel(b, local_size, 1));
+ id_z = nir_udiv(b, local_index,
+ nir_imul(b, nir_channel(b, local_size, 0),
+ nir_channel(b, local_size, 1)));
+ return nir_vec3(b, id_x, id_y, id_z);
+ } else {
+ return nir_load_local_invocation_id(b);
+ }
+}
+
static bool
convert_block(nir_block *block, nir_builder *b)
{
@@ -91,7 +130,7 @@ convert_block(nir_block *block, nir_builder *b)
*/
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);
+ nir_ssa_def *local_id = build_local_invocation_id(b);
sysval = nir_iadd(b, nir_imul(b, group_id, group_size), local_id);
break;
@@ -126,6 +165,14 @@ convert_block(nir_block *block, nir_builder *b)
break;
}
+ case SYSTEM_VALUE_LOCAL_INVOCATION_ID:
+ /* If lower_cs_local_id_from_index is true, then we derive the local
+ * index from the local id.
+ */
+ if (b->shader->options->lower_cs_local_id_from_index)
+ sysval = build_local_invocation_id(b);
+ break;
+
case SYSTEM_VALUE_LOCAL_GROUP_SIZE: {
sysval = build_local_group_size(b);
break;