diff --git a/libs/vkd3d-shader/spirv.c b/libs/vkd3d-shader/spirv.c
index 7c25bbad..0d06813b 100644
--- a/libs/vkd3d-shader/spirv.c
+++ b/libs/vkd3d-shader/spirv.c
@@ -1933,40 +1933,11 @@ static const struct vkd3d_spirv_builtin *vkd3d_get_spirv_builtin(enum vkd3d_shad
     return NULL;
 }
 
-static enum vkd3d_component_type vkd3d_component_type_for_register(enum vkd3d_shader_register_type reg_type,
-        enum vkd3d_shader_input_sysval_semantic sysval)
-{
-    const struct vkd3d_spirv_builtin *builtin;
-
-    if ((builtin = vkd3d_get_spirv_builtin(reg_type, sysval)))
-        return builtin->component_type;
-
-    return VKD3D_TYPE_FLOAT;
-}
-
-static unsigned int vkd3d_component_count_for_register(enum vkd3d_shader_register_type reg_type,
-        enum vkd3d_shader_input_sysval_semantic sysval)
-{
-    const struct vkd3d_spirv_builtin *builtin;
-
-    if ((builtin = vkd3d_get_spirv_builtin(reg_type, sysval)))
-        return builtin->component_count;
-
-    return 0;
-}
-
 static void vkd3d_dxbc_compiler_decorate_builtin(struct vkd3d_dxbc_compiler *compiler,
-        uint32_t target_id, enum vkd3d_shader_register_type reg_type,
-        enum vkd3d_shader_input_sysval_semantic sysval)
+        uint32_t target_id, SpvBuiltIn builtin)
 {
     struct vkd3d_spirv_builder *builder = &compiler->spirv_builder;
-    const struct vkd3d_spirv_builtin *builtin_info;
-    SpvBuiltIn builtin;
 
-    if (!(builtin_info = vkd3d_get_spirv_builtin(reg_type, sysval)))
-        return;
-
-    builtin = builtin_info->spirv_builtin;
     if (compiler->shader_type == VKD3D_SHADER_TYPE_PIXEL && builtin == SpvBuiltInPosition)
         builtin = SpvBuiltInFragCoord;
 
@@ -1978,6 +1949,7 @@ static uint32_t vkd3d_dxbc_compiler_emit_input(struct vkd3d_dxbc_compiler *compi
 {
     unsigned int component_idx, component_count, input_component_count;
     struct vkd3d_spirv_builder *builder = &compiler->spirv_builder;
+    const struct vkd3d_spirv_builtin *builtin;
     enum vkd3d_component_type component_type;
     uint32_t val_id = 0, input_id, var_id;
     struct vkd3d_symbol reg_symbol;
@@ -1985,6 +1957,8 @@ static uint32_t vkd3d_dxbc_compiler_emit_input(struct vkd3d_dxbc_compiler *compi
     struct rb_entry *entry = NULL;
     bool use_private_var = false;
 
+    builtin = vkd3d_get_spirv_builtin(dst->reg.type, sysval);
+
     /* vThreadIDInGroupFlattened is declared with no write mask in shader
      * bytecode generated by fxc. */
     if (!dst->write_mask && dst->reg.type == VKD3DSPR_LOCALTHREADINDEX)
@@ -1997,19 +1971,25 @@ static uint32_t vkd3d_dxbc_compiler_emit_input(struct vkd3d_dxbc_compiler *compi
         component_idx = vkd3d_write_mask_get_component_idx(dst->write_mask);
         component_count = vkd3d_write_mask_component_count(dst->write_mask);
     }
-    component_type = vkd3d_component_type_for_register(dst->reg.type, sysval);
-    if (!(input_component_count = vkd3d_component_count_for_register(dst->reg.type, sysval)))
+    if (builtin)
+    {
+        component_type = builtin->component_type;
+        input_component_count = builtin->component_count;
+    }
+    else
+    {
+        component_type = VKD3D_TYPE_FLOAT;
         input_component_count = component_count;
+    }
     assert(component_count <= input_component_count);
 
     storage_class = SpvStorageClassInput;
     input_id = vkd3d_dxbc_compiler_emit_variable(compiler, &builder->global_stream,
             storage_class, component_type, input_component_count);
     vkd3d_spirv_add_iface_variable(builder, input_id);
-    if (dst->reg.type == VKD3DSPR_THREADID || dst->reg.type == VKD3DSPR_LOCALTHREADID
-            || dst->reg.type == VKD3DSPR_LOCALTHREADINDEX || sysval)
+    if (builtin)
     {
-        vkd3d_dxbc_compiler_decorate_builtin(compiler, input_id, dst->reg.type, sysval);
+        vkd3d_dxbc_compiler_decorate_builtin(compiler, input_id, builtin->spirv_builtin);
         if (component_idx)
             FIXME("Unhandled component index %u.\n", component_idx);
     }
@@ -2073,6 +2053,7 @@ static uint32_t vkd3d_dxbc_compiler_emit_output(struct vkd3d_dxbc_compiler *comp
     const struct vkd3d_shader_signature_element *signature_element;
     const struct vkd3d_shader_register *reg = &dst->reg;
     const struct vkd3d_shader_signature *signature;
+    const struct vkd3d_spirv_builtin *builtin;
     enum vkd3d_component_type component_type;
     struct vkd3d_symbol reg_symbol;
     SpvStorageClass storage_class;
@@ -2081,12 +2062,21 @@ static uint32_t vkd3d_dxbc_compiler_emit_output(struct vkd3d_dxbc_compiler *comp
     bool use_private_variable;
     uint32_t id, var_id;
 
+    builtin = vkd3d_get_spirv_builtin(dst->reg.type, sysval);
+
     component_idx = vkd3d_write_mask_get_component_idx(dst->write_mask);
     component_count = vkd3d_write_mask_component_count(dst->write_mask);
-    /* FIXME: Consider output signature when choosing component type for output variable. */
-    component_type = vkd3d_component_type_for_register(reg->type, sysval);
-    if (!(output_component_count = vkd3d_component_count_for_register(reg->type, sysval)))
+    if (builtin)
+    {
+        component_type = builtin->component_type;
+        output_component_count = builtin->component_count;
+    }
+    else
+    {
+        /* FIXME: Consider output signature when choosing component type for output variable. */
+        component_type = VKD3D_TYPE_FLOAT;
         output_component_count = component_count;
+    }
     assert(component_count <= output_component_count);
 
     signature_element = NULL;
@@ -2110,9 +2100,9 @@ static uint32_t vkd3d_dxbc_compiler_emit_output(struct vkd3d_dxbc_compiler *comp
     id = vkd3d_dxbc_compiler_emit_variable(compiler, &builder->global_stream,
             storage_class, component_type, component_count);
     vkd3d_spirv_add_iface_variable(builder, id);
-    if (sysval)
+    if (builtin)
     {
-        vkd3d_dxbc_compiler_decorate_builtin(compiler, id, reg->type, sysval);
+        vkd3d_dxbc_compiler_decorate_builtin(compiler, id, builtin->spirv_builtin);
         if (component_idx)
             FIXME("Unhandled component index %u.\n", component_idx);
     }