Add flag to report GC collections

src/kuroko.c

@@ -742,7 +742,7 @@ int main(int argc, char * argv[]) {
 	int flags = 0;
 	int moduleAsMain = 0;
 	int opt;
-	while ((opt = getopt(argc, argv, "+c:C:dgm:rstTMSV-:")) != -1) {
+	while ((opt = getopt(argc, argv, "+c:C:dgGm:rstTMSV-:")) != -1) {
 		switch (opt) {
 			case 'c':
 				return runString(argv, flags, optarg);
@@ -754,6 +754,9 @@ int main(int argc, char * argv[]) {
 				/* Always garbage collect during an allocation. */
 				flags |= KRK_GLOBAL_ENABLE_STRESS_GC;
 				break;
+			case 'G':
+				flags |= KRK_GLOBAL_REPORT_GC_COLLECTS;
+				break;
 			case 's':
 				/* Print debug information during compilation. */
 				flags |= KRK_THREAD_ENABLE_SCAN_TRACING;
@@ -793,6 +796,7 @@ int main(int argc, char * argv[]) {
 						"Interpreter options:\n"
 						" -d          Debug output from the bytecode compiler.\n"
 						" -g          Collect garbage on every allocation.\n"
+						" -G          Report GC collections.\n"
 						" -m mod      Run a module as a script.\n"
 						" -r          Disable complex line editing in the REPL.\n"
 						" -s          Debug output from the scanner/tokenizer.\n"

src/kuroko/vm.h

@@ -237,6 +237,7 @@ typedef struct KrkVM {
 #define KRK_GLOBAL_GC_PAUSED           (1 << 9)
 #define KRK_GLOBAL_CLEAN_OUTPUT        (1 << 10)
 #define KRK_GLOBAL_CALLGRIND           (1 << 11)
+#define KRK_GLOBAL_REPORT_GC_COLLECTS  (1 << 12)
 
 #ifdef ENABLE_THREADING
 #  define threadLocal __thread

src/memory.c

@@ -297,6 +297,9 @@ size_t krk_collectGarbage(void) {
 	tableRemoveWhite(&vm.strings);
 	size_t out = sweep();
 	vm.nextGC = vm.bytesAllocated * 2;
+	if (vm.globalFlags & KRK_GLOBAL_REPORT_GC_COLLECTS) {
+		fprintf(stderr, "[gc] collected %llu, next collection at %llu\n", (unsigned long long)out, (unsigned long long)vm.nextGC);
+	}
 	return out;
 }