minor changes

fix-vm/src/lib.rs

@@ -422,12 +422,10 @@ impl<C: VmContext> Vm<C> {
         self.fuel -= 1;
 
         let byte = self.ctx.bytecode()[self.pc];
-        if likely_stable::unlikely(!(0..Op::Illegal as u8).contains(&byte)) {
+        if !likely_stable::likely((0..Op::Illegal as u8).contains(&byte)) {
             panic!("unknown opcode: {byte:#04x}")
         }
-        let op = unsafe {
-            std::mem::transmute::<u8, Op>(byte)
-        };
+        let op = unsafe { std::mem::transmute::<u8, Op>(byte) };
         // let Ok(op) = Op::try_from_primitive(self.ctx.bytecode()[self.pc])
         //     .map_err(|err| panic!("unknown opcode: {:#04x}", err.number));
         self.pc += 1;
@@ -1105,7 +1103,7 @@ impl<C: VmContext> Vm<C> {
                 return self.handle_return();
             }
 
-            Illegal => unreachable!()
+            Illegal => unreachable!(),
         }
 
         Action::Continue
@@ -1294,13 +1292,13 @@ impl<C: VmContext> Vm<C> {
     #[inline]
     fn force_tos(&mut self) -> Action {
         loop {
-            let (run, target_depth) = self.arena.mutate_root(|_mc, root| {
+            let (run, target_depth) = self.arena.mutate_root(|mc, root| {
                 let thunk = root.stack.tos_mut().expect("stack underflow");
 
                 let Some(thunk_state) = thunk.as_gc::<Thunk>() else {
                     return (false, 0);
                 };
-                match *thunk_state.borrow() {
+                let ret = match *thunk_state.borrow() {
                     ThunkState::Pending { ip, env, with_env } => {
                         root.frames
                             .push(CallFrame {
@@ -1320,7 +1318,11 @@ impl<C: VmContext> Vm<C> {
                         (false, 0)
                     }
                     ThunkState::Blackhole => todo!("force_tos"),
+                };
+                if ret.0 {
+                    *thunk_state.borrow_mut(mc) = ThunkState::Blackhole;
                 }
+                ret
             });
             if likely_stable::likely(!run) {
                 return Action::Continue;