i965: Implement nir_intrinsic_shader_clock

v2:
 - Add a few const qualifiers for good measure.
 - Drop unneeded retype()s (Matt)
 - Convert timestamp to SIMD8/16, as fs_visitor::get_timestamp() returns
SIMD4 (Connor)

v3:
 - Remove unneeded temporary + MOV (Connor)

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>

src/mesa/drivers/dri/i965/brw_fs_nir.cpp

@@ -1332,6 +1332,15 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
       break;
    }
 
+   case nir_intrinsic_shader_clock: {
+      /* We cannot do anything if there is an event, so ignore it for now */
+      fs_reg shader_clock = get_timestamp(bld);
+      const fs_reg srcs[] = { shader_clock.set_smear(0), shader_clock.set_smear(1) };
+
+      bld.LOAD_PAYLOAD(dest, srcs, ARRAY_SIZE(srcs), 0);
+      break;
+   }
+
    case nir_intrinsic_image_size: {
       /* Get the referenced image variable and type. */
       const nir_variable *var = instr->variables[0]->var;

src/mesa/drivers/dri/i965/brw_vec4_nir.cpp

@@ -808,6 +808,16 @@ vec4_visitor::nir_emit_intrinsic(nir_intrinsic_instr *instr)
       break;
    }
 
+   case nir_intrinsic_shader_clock: {
+      /* We cannot do anything if there is an event, so ignore it for now */
+      const src_reg shader_clock = get_timestamp();
+      const enum brw_reg_type type = brw_type_for_base_type(glsl_type::uvec2_type);
+
+      dest = get_nir_dest(instr->dest, type);
+      emit(MOV(dest, shader_clock));
+      break;
+   }
+
    default:
       unreachable("Unknown intrinsic");
    }