Fix PostWalker traversal of push instruction (#2419)

PostWalker traversal should visit its value.

3 files changed, 23 insertions, 0 deletions

diff --git a/src/wasm-traversal.h b/src/wasm-traversal.h
index 8f4fb5922..16fe87af1 100644
--- a/src/wasm-traversal.h
+++ b/src/wasm-traversal.h
@@ -1075,6 +1075,7 @@ struct PostWalker : public Walker<SubType, VisitorType> {
       }
       case Expression::Id::PushId: {
         self->pushTask(SubType::doVisitPush, currp);
+        self->pushTask(SubType::scan, &curr->cast<Push>()->value);
         break;
       }
       case Expression::Id::PopId: {
diff --git a/test/passes/dce_all-features.txt b/test/passes/dce_all-features.txt
index f9e1b70a4..109f759c2 100644
--- a/test/passes/dce_all-features.txt
+++ b/test/passes/dce_all-features.txt
@@ -532,3 +532,14 @@
   )
  )
 )
+(module
+ (type $FUNCSIG$v (func))
+ (func $foo (; 0 ;) (type $FUNCSIG$v)
+  (nop)
+ )
+ (func $push_unreachable (; 1 ;) (type $FUNCSIG$v)
+  (push
+   (unreachable)
+  )
+ )
+)
diff --git a/test/passes/dce_all-features.wast b/test/passes/dce_all-features.wast
index c6fe0d5d0..cfdc58bbb 100644
--- a/test/passes/dce_all-features.wast
+++ b/test/passes/dce_all-features.wast
@@ -768,3 +768,14 @@
     (call $foo) ;; should be dce'd
   )
 )
+
+;; Push-pop
+(module
+  (func $foo)
+  (func $push_unreachable
+    (push
+      (unreachable)
+    )
+    (call $foo) ;; should be dce'd
+  )
+)