From 282369b5430287c2397eb9e3cdd859ad12fa3937 Mon Sep 17 00:00:00 2001
From: Alon Zakai <alonzakai@gmail.com>
Date: Wed, 7 Sep 2016 15:59:58 -0700
Subject: autodrop if body if no else

---
 src/ast_utils.h | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'src/ast_utils.h')

diff --git a/src/ast_utils.h b/src/ast_utils.h
index f7a486332..5deaa6a2c 100644
--- a/src/ast_utils.h
+++ b/src/ast_utils.h
@@ -832,6 +832,13 @@ struct AutoDrop : public WalkerPass<ExpressionStackWalker<AutoDrop, Visitor<Auto
     curr->finalize(); // we may have changed our type
   }
 
+  void visitIf(If* curr) {
+    // if without else does not return a value, so the body must be dropped if it is concrete
+    if (!curr->ifFalse && isConcreteWasmType(curr->ifTrue->type)) {
+      curr->ifTrue = Builder(*getModule()).makeDrop(curr->ifTrue);
+    }
+  }
+
   void visitFunction(Function* curr) {
     if (curr->result == none && isConcreteWasmType(curr->body->type)) {
       curr->body = Builder(*getModule()).makeDrop(curr->body);
-- 
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