glsl: Add helperInvocationEXT() builtin

From EXT_demote_to_helper_invocation, implemented with the existing
nir_intrinsic_is_helper_invocation.

Such builtin is necessary when using `demote` because we can't
redefine the value of gl_HelperInvocation (since it is an input
variable).

Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/compiler/glsl/glsl_to_nir.cpp b/src/compiler/glsl/glsl_to_nir.cpp
index 883cfb57601..2238bf68044 100644
--- a/src/compiler/glsl/glsl_to_nir.cpp
+++ b/src/compiler/glsl/glsl_to_nir.cpp
@@ -1166,6 +1166,9 @@ nir_visitor::visit(ir_call *ir)
       case ir_intrinsic_read_first_invocation:
          op = nir_intrinsic_read_first_invocation;
          break;
+      case ir_intrinsic_helper_invocation:
+         op = nir_intrinsic_is_helper_invocation;
+         break;
       default:
          unreachable("not reached");
       }
@@ -1641,6 +1644,12 @@ nir_visitor::visit(ir_call *ir)
          nir_builder_instr_insert(&b, &instr->instr);
          break;
       }
+      case nir_intrinsic_is_helper_invocation: {
+         nir_ssa_dest_init(&instr->instr, &instr->dest, 1, 1, NULL);
+         instr->num_components = 1;
+         nir_builder_instr_insert(&b, &instr->instr);
+         break;
+      }
       default:
          unreachable("not reached");
       }