Fixes GC bug.

3 files changed, 16 insertions, 1 deletions

diff --git a/src/gc/sms.c b/src/gc/sms.c
index 6261dc1..a2ab18e 100644
--- a/src/gc/sms.c
+++ b/src/gc/sms.c
@@ -95,7 +95,7 @@ static void gc_mark(const struct value initial_value) {
   // - A black object has its mark bit set, but is not pointed to by obj, nor is
   //   it in the prev linked list.
   struct object *prev = NULL;
-  while (obj) {
+  for (;;) {
     // INVARIANT: obj points to a white object that we're about to make gray.
     // Since it's white, none of its fields should have the tag TAG_GC_INTERNAL,
     // so it shouldn't have a saved tag either.
@@ -199,6 +199,7 @@ static void gc_sweep(void) {
   while ((header = *head)) {
     if ((*head)->mark) {
       (*head)->mark = false;
+      (*head)->saved_tag = 0;
       head = &header->next;
     } else {
       *head = header->next;
diff --git a/src/util.c b/src/util.c
index b512296..ba03ed9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -11,6 +11,15 @@ noreturn void assume__failed(const char *file, int line, const char *expr) {
   panic_end();
 }
 
+void debugf__impl(const char *file, int line, const char *fmt, ...) {
+  fprintf(stderr, "%s:%d: ", file, line);
+  va_list ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+  fprintf(stderr, "\n");
+}
+
 noreturn void todo__impl(const char *file, int line, const char *fmt, ...) {
   panic_begin();
   printf("%s:%d: TODO: ", file, line);
diff --git a/src/util.h b/src/util.h
index 4384fcd..b4e1916 100644
--- a/src/util.h
+++ b/src/util.h
@@ -23,6 +23,11 @@ static inline void assume__impl(bool cond, const char *file, int line,
 
 #define assume(COND) assume__impl(COND, __FILE__, __LINE__, #COND)
 
+__attribute__((format(printf, 3, 4))) void
+debugf__impl(const char *file, int line, const char *fmt, ...);
+
+#define debugf(...) debugf__impl(__FILE__, __LINE__, __VA_ARGS__)
+
 __attribute__((format(printf, 3, 4))) noreturn void
 todo__impl(const char *file, int line, const char *fmt, ...);