Check for unreachable in `Select::finalize(Type)` (#6389)

Previously selects finalized with explicit types would never be marked
unreachable, even when they should have been.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 374a97e19..7147f2c3d 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -760,7 +760,15 @@ void Binary::finalize() {
   }
 }
 
-void Select::finalize(Type type_) { type = type_; }
+void Select::finalize(Type type_) {
+  assert(ifTrue && ifFalse);
+  if (ifTrue->type == Type::unreachable || ifFalse->type == Type::unreachable ||
+      condition->type == Type::unreachable) {
+    type = Type::unreachable;
+  } else {
+    type = type_;
+  }
+}
 
 void Select::finalize() {
   assert(ifTrue && ifFalse);