intel/compiler: Introduce backend_shader method to propagate IR changes to analysis passes

The invalidate_analysis() method knows what analysis passes there are
in the back-end and calls their invalidate() method to report changes
in the IR.  For the moment it just calls invalidate_live_intervals()
(which will eventually be fully replaced by this function) if anything
changed.

This makes all optimization passes invalidate DEPENDENCY_EVERYTHING,
which is clearly far from ideal -- The dependency classes passed to
invalidate_analysis() will be refined in a future commit.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4012>

src/intel/compiler/brw_shader.cpp

@@ -1245,6 +1245,13 @@ backend_shader::calculate_cfg()
    cfg = new(mem_ctx) cfg_t(&this->instructions);
 }
 
+void
+backend_shader::invalidate_analysis(brw::analysis_dependency_class c)
+{
+   if (c)
+      invalidate_live_intervals();
+}
+
 extern "C" const unsigned *
 brw_compile_tes(const struct brw_compiler *compiler,
                 void *log_data,