merge work/known-bugs: constant-expression precedence, local const in constant expressions, duplicate case labels, unterminated strings, droppable cycles in one collection, js vm exit, docs, actors_demo orderHEADmain

1 files changed, 9 insertions, 5 deletions

diff --git a/src/runtime/rt.zc b/src/runtime/rt.zc
index 149138b..4f96320 100644
--- a/src/runtime/rt.zc
+++ b/src/runtime/rt.zc
@@ -428,7 +428,7 @@ const int F_SHARE = 8;
 // table (dtab), its drop has run (it never runs again), and the collector found it
 // unreachable and runs its drop once the sweep is over.
 const int F_HASDROP = 16, F_DROPPED = 32, F_FINAL = 64, F_CYCLE = 128;	// F_CYCLE: during gc_drops only, a candidate its own contents reach
-int o3_depth, gc_pending;
+int o3_depth, gc_pending, gc_cyc;	// gc_cyc: the last sweep found a cycle with drops to run
 // flags live in these bits; the size class is above them.
 const int F_LOW = 65535;
 int hbump; word[32] freel; int gc_runs, gc_freed, gc_auto = 1;
@@ -1456,7 +1456,7 @@ int o3_leave() {
 // an unreachable value with a drop that hasn't run is kept for one more cycle and
 // flagged F_FINAL, unless another such value reaches it (its parent drops first and
 // it waits for a later collection) and it doesn't reach itself (a cycle drops one
-// value per collection). nothing runs user code here.
+// value per sweep, and gc() repeats the sweep until the cycle is done). nothing runs user code here.
 int gc_drops() {
 	int i, again = 1; word k;
 	while (again) {
@@ -1486,9 +1486,9 @@ int gc_drops() {
 		k = dtab[i * 3];
 		if (k > 1 && (k[-4] & F_FINAL)) {
 			// reached from another candidate: later. one in a cycle has nothing outside it
-			// to drop first, so it drops now (it is marked, so kept), and the rest of the
-			// cycle in later collections, one each, never twice
-			if ((k[-4] & 7) == 1) mark(k); else if (!(k[-4] & F_CYCLE)) k[-4] = k[-4] & ~F_FINAL;
+			// to drop first, so it drops now (it is marked, so kept); gc() then sweeps again
+			// for the rest of the cycle, one each, never twice
+			if ((k[-4] & 7) == 1) mark(k); else if (!(k[-4] & F_CYCLE)) k[-4] = k[-4] & ~F_FINAL; else gc_cyc = 1;
 			k[-4] = k[-4] & ~F_CYCLE;
 		}
 		i++;
@@ -1549,8 +1549,12 @@ unchecked int gc_sweep() {
 unchecked int gc() {
 	int n;
 	if (o3_depth) { gc_pending = 1; return 0; }
+	gc_cyc = 0;
 	n = gc_sweep();
 	if (dcount) gc_finalize();
+	// an unreachable cycle with drops finishes in this collection: each sweep drops one
+	// member (nothing outside the cycle has to go first), and every value drops once
+	while (gc_cyc) { gc_cyc = 0; n = n + gc_sweep(); if (dcount) gc_finalize(); }
 	return n;
 }
 // the number of live heap objects, for tests and leak checks.