d3d12: report face as integer sysval

src/gallium/drivers/d3d12/d3d12_compiler.cpp

@@ -514,7 +514,7 @@ validate_geometry_shader_variant(struct d3d12_selection_context *sel_ctx)
    if (sel_ctx->fill_mode_lowered != PIPE_POLYGON_MODE_FILL) {
       key.fill_mode = sel_ctx->fill_mode_lowered;
       key.cull_mode = sel_ctx->cull_mode_lowered;
-      key.has_front_face = (fs->initial->info.inputs_read & VARYING_BIT_FACE) ? 1 : 0;
+      key.has_front_face = (fs->initial->info.system_values_read & SYSTEM_BIT_FRONT_FACE) ? 1 : 0;
       if (key.cull_mode != PIPE_FACE_NONE || key.has_front_face)
          key.front_ccw = ctx->gfx_pipeline_state.rast->base.front_ccw ^ (ctx->flip_y < 0);
       key.edge_flag_fix = needs_edge_flag_fix(ctx->initial_api_prim);
@@ -635,7 +635,6 @@ d3d12_fill_shader_key(struct d3d12_selection_context *sel_ctx,
    pipe_shader_type stage = sel->stage;
 
    uint64_t system_generated_in_values =
-         VARYING_BIT_FACE |
          VARYING_BIT_PNTC |
          VARYING_BIT_PRIMITIVE_ID;
 
@@ -821,10 +820,7 @@ select_shader_variant(struct d3d12_selection_context *sel_ctx, d3d12_shader_sele
    }
 
    if (key.fs.remap_front_facing) {
-      nir_foreach_variable(input, &new_nir_variant->inputs) {
-         if (input->data.location == VARYING_SLOT_FACE)
-            input->data.location = VARYING_SLOT_VAR12;
-      }
+      d3d12_forward_front_face(new_nir_variant);
 
       nir_function_impl *impl = nir_shader_get_entrypoint(new_nir_variant);
       nir_shader_gather_info(new_nir_variant, impl);

src/gallium/drivers/d3d12/d3d12_screen.cpp

@@ -256,6 +256,9 @@ d3d12_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT:
       return 1;
 
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
+      return 1;
+
    case PIPE_CAP_ACCELERATED:
       return 1;