Add timing stats for IdString garbage collection

kernel/driver.cc

@@ -709,6 +709,8 @@ int main(int argc, char **argv)
 				total_ns += it.second->runtime_ns + 1;
 				timedat.insert(make_tuple(it.second->runtime_ns + 1, it.second->call_counter, it.first));
 			}
+		timedat.insert(make_tuple(RTLIL::OwningIdString::garbage_collection_ns() + 1,
+				RTLIL::OwningIdString::garbage_collection_count(), "id_gc"));
 
 		if (timing_details)
 		{

kernel/register.cc

@@ -129,6 +129,11 @@ void Pass::post_execute(Pass::pre_post_exec_state_t state)
 	int64_t time_ns = PerformanceTimer::query() - state.begin_ns;
 	runtime_ns += time_ns;
 	current_pass = state.parent_pass;
+	subtract_from_current_runtime_ns(time_ns);
+}
+
+void Pass::subtract_from_current_runtime_ns(int64_t time_ns)
+{
 	if (current_pass)
 		current_pass->runtime_ns -= time_ns;
 }

kernel/register.h

@@ -95,6 +95,8 @@ struct Pass
 	bool experimental_flag = false;
 	bool internal_flag = false;
 
+	static void subtract_from_current_runtime_ns(int64_t time_ns);
+
 	void experimental() {
 		experimental_flag = true;
 	}

kernel/rtlil.cc

@@ -243,8 +243,12 @@ struct IdStringCollector {
 	std::unordered_set<int> live;
 };
 
+int64_t RTLIL::OwningIdString::gc_ns;
+int RTLIL::OwningIdString::gc_count;
+
 void RTLIL::OwningIdString::collect_garbage()
 {
+	int64_t start = PerformanceTimer::query();
 #ifndef YOSYS_NO_IDS_REFCNT
 	IdStringCollector collector;
 	for (auto &[idx, design] : *RTLIL::Design::get_all_designs()) {
@@ -288,6 +292,10 @@ void RTLIL::OwningIdString::collect_garbage()
 		it = global_autoidx_id_prefix_storage_.erase(it);
 	}
 #endif
+	int64_t time_ns = PerformanceTimer::query() - start;
+	Pass::subtract_from_current_runtime_ns(time_ns);
+	gc_ns += time_ns;
+	++gc_count;
 }
 
 dict<std::string, std::string> RTLIL::constpad;

kernel/rtlil.h

@@ -578,6 +578,8 @@ struct RTLIL::OwningIdString : public RTLIL::IdString {
 
 	// Collect all non-owning references.
 	static void collect_garbage();
+	static int64_t garbage_collection_ns() { return gc_ns; }
+	static int garbage_collection_count() { return gc_count; }
 
 	// Used by the ID() macro to create an IdString with no destructor whose string will
 	// never be released. If ID() creates a closure-static `OwningIdString` then
@@ -589,6 +591,9 @@ struct RTLIL::OwningIdString : public RTLIL::IdString {
 		return result;
 	}
 private:
+	static int64_t gc_ns;
+	static int gc_count;
+
 	void get_reference()
 	{
 		get_reference(index_);