kernel: add SwitchRule signal_src

frontends/ast/genrtlil.cc

@@ -627,6 +627,7 @@ struct AST_INTERNAL::ProcessGenerator
 				RTLIL::SwitchRule *sw = new RTLIL::SwitchRule;
 				set_src_attr(sw, ast);
 				sw->signal = ast->children[0]->genWidthRTLIL(width_hint, sign_hint, &subst_rvalue_map.stdmap());
+				sw->signal_src = ast->children[0]->loc_string();
 				current_case->switches.push_back(sw);
 
 				for (auto &attr : ast->attributes) {

kernel/rtlil.h

@@ -2553,7 +2553,7 @@ struct RTLIL::CaseRule : public RTLIL::AttrObject
 	std::vector<RTLIL::SigSpec> compare;
 	std::vector<RTLIL::SyncAction> actions;
 	std::vector<RTLIL::SwitchRule*> switches;
-	Const compare_src;
+	RTLIL::Const compare_src;
 
 	~CaseRule();
 
@@ -2567,6 +2567,7 @@ struct RTLIL::CaseRule : public RTLIL::AttrObject
 struct RTLIL::SwitchRule : public RTLIL::AttrObject
 {
 	RTLIL::SigSpec signal;
+	RTLIL::Const signal_src;
 	std::vector<RTLIL::CaseRule*> cases;
 
 	~SwitchRule();