fix: hang up when in loop

src/execution/op.rs

@@ -190,7 +190,9 @@ pub fn br(labels: &mut Vec<Label>, stack: &mut Vec<Value>, level: &u32) -> Resul
  .with_context(|| Error::NotFoundLabel(label_index))?;
 
  let pc = if kind == LabelKind::Loop {
- // since it jumps to the beginning of the loop,
+ // NOTE: we still need loop label to jump to the beginning of the loop.
+ labels.drain(label_index + 1..);
+ // NOTE: since it jumps to the beginning of the loop,
  // the stack is unwound without considering the return value.
  stack_unwind(stack, sp, 0)?;
  start.with_context(|| Error::NotFoundStartPc)?

src/execution/runtime.rs

@@ -370,14 +370,19 @@ impl Runtime {
  Instruction::If(block) => {
  let cond: Value = stack.pop1()?;
 
- // cal pc when the if block is end
+ // calc pc when the end of block
  let next_pc = get_end_address(insts, frame.pc)?;
 
  if !cond.is_true() {
  // if the condition is false, skip the if block
  frame.pc = get_else_or_end_address(insts, frame.pc)? as isize;
  }
 
+ // NOTE: if block has no any instruction, just continue
+ if next_pc == frame.pc as usize {
+ continue;
+ }
+
  let label = Label {
  start: None,
  kind: LabelKind::If,