nir: Add new SPIR-V ballot intrinsics and lowering

Someone can make the lowering optional later if they want something
different for their hardware.

Reviewed-by: Lionel Landwerlin <[email protected]>
Reviewed-by: Samuel Iglesias Gonsálvez <[email protected]>
Reviewed-by: Iago Toral Quiroga <[email protected]>

2 files changed, 22 insertions, 0 deletions

diff --git a/src/compiler/nir/nir_intrinsics.h b/src/compiler/nir/nir_intrinsics.h
index 1a816b46792..46f67a908ed 100644
--- a/src/compiler/nir/nir_intrinsics.h
+++ b/src/compiler/nir/nir_intrinsics.h
@@ -106,6 +106,18 @@ INTRINSIC(ballot, 1, ARR(1), true, 0, 0, 0, xx, xx, xx, NIR_INTRINSIC_CAN_ELIMIN
 INTRINSIC(read_invocation, 2, ARR(0, 1), true, 0, 0, 0, xx, xx, xx, NIR_INTRINSIC_CAN_ELIMINATE)
 INTRINSIC(read_first_invocation, 1, ARR(0), true, 0, 0, 0, xx, xx, xx, NIR_INTRINSIC_CAN_ELIMINATE)
 
+/** Additional SPIR-V ballot intrinsics
+ *
+ * These correspond to the SPIR-V opcodes
+ *
+ *    OpGroupUniformElect
+ *    OpSubgroupFirstInvocationKHR
+ */
+INTRINSIC(elect, 0, ARR(0), true, 1, 0, 0, xx, xx, xx,
+          NIR_INTRINSIC_CAN_ELIMINATE)
+INTRINSIC(first_invocation, 0, ARR(0), true, 1, 0, 0, xx, xx, xx,
+          NIR_INTRINSIC_CAN_ELIMINATE)
+
 /*
  * Memory barrier with semantics analogous to the compute shader
  * groupMemoryBarrier(), memoryBarrierAtomicCounter(), memoryBarrierBuffer(),
diff --git a/src/compiler/nir/nir_lower_subgroups.c b/src/compiler/nir/nir_lower_subgroups.c
index acc6ed9a36e..e45a7d723ac 100644
--- a/src/compiler/nir/nir_lower_subgroups.c
+++ b/src/compiler/nir/nir_lower_subgroups.c
@@ -244,6 +244,16 @@ lower_subgroups_intrin(nir_builder *b, nir_intrinsic_instr *intrin,
       return nir_bit_count(b, nir_iand(b, int_val, mask));
    }
 
+   case nir_intrinsic_elect: {
+      nir_intrinsic_instr *first =
+         nir_intrinsic_instr_create(b->shader,
+                                    nir_intrinsic_first_invocation);
+      nir_ssa_dest_init(&first->instr, &first->dest, 1, 32, NULL);
+      nir_builder_instr_insert(b, &first->instr);
+
+      return nir_ieq(b, nir_load_subgroup_invocation(b), &first->dest.ssa);
+   }
+
    default:
       break;
    }