3 files changed, 24 insertions, 5 deletions
diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index f0db1eee6..d2b7c944f 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -173,6 +173,11 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
     auto* iff = (*currp)->dynCast<If>();
 
     if (iff) {
+      if (iff->condition->type == unreachable) {
+        // avoid all the branching, we never reach it anyhow
+        *currp = iff->condition;
+        return;
+      }
       self->pushTask(doVisitIf, currp);
       if (iff->ifFalse) {
       // we need to join up if-else control flow, and clear after the condition
diff --git a/test/passes/remove-unused-brs.txt b/test/passes/remove-unused-brs.txt
index 5cc900abd..599459c57 100644
--- a/test/passes/remove-unused-brs.txt
+++ b/test/passes/remove-unused-brs.txt
@@ -1062,12 +1062,13 @@
  )
  (func $unreachable-if-that-could-be-a-br_if (type $7) (result i64)
   (loop $label$3
-   (if
-    (unreachable)
-    (f64.const 1)
-    (br $label$3)
-   )
+   (unreachable)
    (i64.const 1)
   )
  )
+ (func $nop-br-might-update-type (type $1)
+  (block $label$39
+   (unreachable)
+  )
+ )
 )
diff --git a/test/passes/remove-unused-brs.wast b/test/passes/remove-unused-brs.wast
index ecf70b758..32c4ece6a 100644
--- a/test/passes/remove-unused-brs.wast
+++ b/test/passes/remove-unused-brs.wast
@@ -953,5 +953,18 @@
     (i64.const 1)
    )
   )
+  (func $nop-br-might-update-type
+   (block $label$39
+    (if
+     (unreachable)
+     (if (result i32)
+      (i32.const 1)
+      (br $label$39) ;; if we nop this, then the parent type must change
+      (i32.const 0)
+     )
+     (i32.const 0)
+    )
+   )
+  )
 )