when replacing an if with its condition (when it has no body), we must drop it

6 files changed, 78 insertions, 1 deletions

diff --git a/src/passes/Vacuum.cpp b/src/passes/Vacuum.cpp
index 150593713..89ef7359e 100644
--- a/src/passes/Vacuum.cpp
+++ b/src/passes/Vacuum.cpp
@@ -190,7 +190,7 @@ struct Vacuum : public WalkerPass<ExpressionStackWalker<Vacuum, Visitor<Vacuum>>
       // no else
       if (curr->ifTrue->is<Nop>()) {
         // no nothing
-        replaceCurrent(curr->condition);
+        replaceCurrent(Builder(*getModule()).makeDrop(curr->condition));
       }
     }
   }
diff --git a/test/unit.asm.js b/test/unit.asm.js
index b4c10b1d2..8f0812e29 100644
--- a/test/unit.asm.js
+++ b/test/unit.asm.js
@@ -308,6 +308,17 @@ function asm(global, env, buffer) {
    } while(0);
   }
 
+  function ifChainEmpty(label) {
+    label = label | 0;
+    if ((label|0) == 4) {
+      return 0;
+    }
+    else if ((label|0) == 7) {
+      // unreachable;
+    }
+    return 0;
+  }
+
   function z() {
   }
   function w() {
diff --git a/test/unit.fromasm b/test/unit.fromasm
index cecbeef22..bc5281ed5 100644
--- a/test/unit.fromasm
+++ b/test/unit.fromasm
@@ -558,4 +558,16 @@
       )
     )
   )
+  (func $ifChainEmpty (param $0 i32) (result i32)
+    (if
+      (i32.eq
+        (get_local $0)
+        (i32.const 4)
+      )
+      (return
+        (i32.const 0)
+      )
+    )
+    (i32.const 0)
+  )
 )
diff --git a/test/unit.fromasm.imprecise b/test/unit.fromasm.imprecise
index ba1af7916..945d6cc8e 100644
--- a/test/unit.fromasm.imprecise
+++ b/test/unit.fromasm.imprecise
@@ -540,4 +540,16 @@
       )
     )
   )
+  (func $ifChainEmpty (param $0 i32) (result i32)
+    (if
+      (i32.eq
+        (get_local $0)
+        (i32.const 4)
+      )
+      (return
+        (i32.const 0)
+      )
+    )
+    (i32.const 0)
+  )
 )
diff --git a/test/unit.fromasm.imprecise.no-opts b/test/unit.fromasm.imprecise.no-opts
index 0c02680da..f06912d08 100644
--- a/test/unit.fromasm.imprecise.no-opts
+++ b/test/unit.fromasm.imprecise.no-opts
@@ -932,6 +932,27 @@
       (nop)
     )
   )
+  (func $ifChainEmpty (param $label i32) (result i32)
+    (if
+      (i32.eq
+        (get_local $label)
+        (i32.const 4)
+      )
+      (return
+        (i32.const 0)
+      )
+      (if
+        (i32.eq
+          (get_local $label)
+          (i32.const 7)
+        )
+        (nop)
+      )
+    )
+    (return
+      (i32.const 0)
+    )
+  )
   (func $z
     (nop)
   )
diff --git a/test/unit.fromasm.no-opts b/test/unit.fromasm.no-opts
index fbbc6e7ff..222e0fa65 100644
--- a/test/unit.fromasm.no-opts
+++ b/test/unit.fromasm.no-opts
@@ -938,6 +938,27 @@
       (nop)
     )
   )
+  (func $ifChainEmpty (param $label i32) (result i32)
+    (if
+      (i32.eq
+        (get_local $label)
+        (i32.const 4)
+      )
+      (return
+        (i32.const 0)
+      )
+      (if
+        (i32.eq
+          (get_local $label)
+          (i32.const 7)
+        )
+        (nop)
+      )
+    )
+    (return
+      (i32.const 0)
+    )
+  )
   (func $z
     (nop)
   )