From a6347d0cc65a22f6f0b0a89dad0bde85ecafcdb1 Mon Sep 17 00:00:00 2001
From: skanehira <sho19921005@gmail.com>
Date: Sat, 22 Jul 2023 18:56:47 +0900
Subject: [PATCH] fix: hang up when in loop

---
 src/execution/op.rs      | 4 +++-
 src/execution/runtime.rs | 7 ++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/execution/op.rs b/src/execution/op.rs
index 4b4a46d..abbc1d5 100644
--- a/src/execution/op.rs
+++ b/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)?
diff --git a/src/execution/runtime.rs b/src/execution/runtime.rs
index 693924c..c407a3d 100644
--- a/src/execution/runtime.rs
+++ b/src/execution/runtime.rs
@@ -370,7 +370,7 @@ 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() {
@@ -378,6 +378,11 @@ impl Runtime {
                         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,