make stack use checker not have stupid performance penalty

src/asar/asar.h

@@ -60,6 +60,7 @@ virtual_file_error asar_get_last_io_error();
 extern volatile int recursioncount;
 extern int pass;
 
+void reset_stack_use_check();
 bool have_enough_stack_left();
 
 class recurseblock {

src/asar/assembleblock.cpp

@@ -747,6 +747,10 @@ void initstuff()
 	initmathcore();
 
 	callstack.reset();
+#if !defined(_WIN32) && defined(NO_USE_THREADS)
+#else
+	reset_stack_use_check();
+#endif
 }
 
 int get_freespace_pin_target(int target_id) {

src/asar/platform/generic/thread-helpers-pthread.h

@@ -57,17 +57,18 @@ bool run_as_thread(functor&& callback) {
 }
 
 #ifndef NO_USE_THREADS
-bool have_enough_stack_left() {
+void* stack_start = nullptr;
+size_t stack_size = 0;
+void reset_stack_use_check() {
 	pthread_attr_t attrs;
-	void *stack_start;
-	size_t stack_size;
-
 	pthread_getattr_np(pthread_self(), &attrs);
 	pthread_attr_getstack(&attrs, &stack_start, &stack_size);
 	pthread_attr_destroy(&attrs);
-
+}
+bool have_enough_stack_left() {
 	// using a random local as a rough estimate for current top-of-stack
-	size_t stack_left = (char*)&stack_size - (char*)stack_start;
+	char stackvar;
+	size_t stack_left = &stackvar - (char*)stack_start;
 	return stack_left >= 32768;
 }
 #endif

src/asar/platform/windows/thread-helpers-win32.h

@@ -83,11 +83,15 @@ bool run_as_thread(functor&& callback) {
 	return wrapper.result;
 }
 
-bool have_enough_stack_left() {
+char* stack_bottom;
+void reset_stack_use_check() {
 	MEMORY_BASIC_INFORMATION mbi;
 	char stackvar;
 	VirtualQuery(&stackvar, &mbi, sizeof(mbi));
-	char* stack_bottom = (char*)mbi.AllocationBase;
+	stack_bottom = (char*)mbi.AllocationBase;
+}
+bool have_enough_stack_left() {
+	char stackvar;
 	return (&stackvar - stack_bottom) >= 32768;
 }
 #endif