br_if returns its value

4 files changed, 18 insertions, 8 deletions

diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index fa8ab2f6c..15482de25 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -146,11 +146,10 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs, Visitor<R
       // if without an else. try to reduce   if (condition) br  =>  br_if (condition)
       Break* br = curr->ifTrue->dynCast<Break>();
       if (br && !br->condition) { // TODO: if there is a condition, join them
-        // if the br has a value, then if => br_if means we always execute the value, and also the order is value,condition vs condition,value
         if (canTurnIfIntoBrIf(curr->condition, br->value)) {
           br->condition = curr->condition;
           br->finalize();
-          replaceCurrent(br);
+          replaceCurrent(Builder(*getModule()).dropIfConcretelyTyped(br));
           anotherCycle = true;
         }
       }
@@ -407,18 +406,18 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs, Visitor<R
           auto* ifTrueBreak = iff->ifTrue->dynCast<Break>();
           if (ifTrueBreak && !ifTrueBreak->condition && canTurnIfIntoBrIf(iff->condition, ifTrueBreak->value)) {
             // we are an if-else where the ifTrue is a break without a condition, so we can do this
-            list[i] = ifTrueBreak;
             ifTrueBreak->condition = iff->condition;
             ifTrueBreak->finalize();
+            list[i] = Builder(*getModule()).dropIfConcretelyTyped(ifTrueBreak);
             ExpressionManipulator::spliceIntoBlock(curr, i + 1, iff->ifFalse);
             continue;
           }
           // otherwise, perhaps we can flip the if
           auto* ifFalseBreak = iff->ifFalse->dynCast<Break>();
           if (ifFalseBreak && !ifFalseBreak->condition && canTurnIfIntoBrIf(iff->condition, ifFalseBreak->value)) {
-            list[i] = ifFalseBreak;
             ifFalseBreak->condition = Builder(*getModule()).makeUnary(EqZInt32, iff->condition);
             ifFalseBreak->finalize();
+            list[i] = Builder(*getModule()).dropIfConcretelyTyped(ifFalseBreak);
             ExpressionManipulator::spliceIntoBlock(curr, i + 1, iff->ifTrue);
             continue;
           }
diff --git a/src/wasm-builder.h b/src/wasm-builder.h
index f9b2e73f6..546d72391 100644
--- a/src/wasm-builder.h
+++ b/src/wasm-builder.h
@@ -339,6 +339,12 @@ public:
     input->finalize();
     return ret;
   }
+
+  // Drop an expression if it has a concrete type
+  Expression* dropIfConcretelyTyped(Expression* curr) {
+    if (!isConcreteWasmType(curr->type)) return curr;
+    return makeDrop(curr);
+  }
 };
 
 } // namespace wasm
diff --git a/src/wasm-interpreter.h b/src/wasm-interpreter.h
index 292d6a521..5d4e7d7b4 100644
--- a/src/wasm-interpreter.h
+++ b/src/wasm-interpreter.h
@@ -155,18 +155,19 @@ public:
   Flow visitBreak(Break *curr) {
     NOTE_ENTER("Break");
     bool condition = true;
-    Flow flow(curr->name);
+    Flow flow;
     if (curr->value) {
       flow = visit(curr->value);
       if (flow.breaking()) return flow;
-      flow.breakTo = curr->name;
     }
     if (curr->condition) {
       Flow conditionFlow = visit(curr->condition);
       if (conditionFlow.breaking()) return conditionFlow;
       condition = conditionFlow.value.getInteger() != 0;
+      if (!condition) return flow;
     }
-    return condition ? flow : Flow();
+    flow.breakTo = curr->name;
+    return flow;
   }
   Flow visitSwitch(Switch *curr) {
     NOTE_ENTER("Switch");
diff --git a/src/wasm.h b/src/wasm.h
index 4d5cf4d70..1bce0bac9 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -1027,7 +1027,11 @@ public:
 
   void finalize() {
     if (condition) {
-      type = none;
+      if (value) {
+        type = value->type;
+      } else {
+        type = none;
+      }
     } else {
       type = unreachable;
     }