5 files changed, 33 insertions, 10 deletions
diff --git a/src/parser/contexts.h b/src/parser/contexts.h
index bf6c291e7..4147f7bda 100644
--- a/src/parser/contexts.h
+++ b/src/parser/contexts.h
@@ -398,6 +398,12 @@ struct NullInstrParserCtx {
   template<typename TypeT> Result<> makeRefTest(Index, TypeT) { return Ok{}; }
   template<typename TypeT> Result<> makeRefCast(Index, TypeT) { return Ok{}; }
 
+  Result<> makeBrOn(Index, LabelIdxT, BrOnOp) { return Ok{}; }
+
+  template<typename TypeT> Result<> makeBrOn(Index, LabelIdxT, BrOnOp, TypeT) {
+    return Ok{};
+  }
+
   template<typename HeapTypeT> Result<> makeStructNew(Index, HeapTypeT) {
     return Ok{};
   }
@@ -1290,6 +1296,11 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx> {
     return withLoc(pos, irBuilder.makeRefCast(type));
   }
 
+  Result<>
+  makeBrOn(Index pos, Index label, BrOnOp op, Type castType = Type::none) {
+    return withLoc(pos, irBuilder.makeBrOn(label, op, castType));
+  }
+
   Result<> makeStructNew(Index pos, HeapType type) {
     return withLoc(pos, irBuilder.makeStructNew(type));
   }
diff --git a/src/parser/parsers.h b/src/parser/parsers.h
index 6b6bb0aa5..e2fb3732a 100644
--- a/src/parser/parsers.h
+++ b/src/parser/parsers.h
@@ -1315,11 +1315,17 @@ template<typename Ctx> Result<> makeRefCast(Ctx& ctx, Index pos) {
 }
 
 template<typename Ctx> Result<> makeBrOnNull(Ctx& ctx, Index pos, bool onFail) {
-  return ctx.in.err("unimplemented instruction");
+  auto label = labelidx(ctx);
+  CHECK_ERR(label);
+  return ctx.makeBrOn(pos, *label, onFail ? BrOnNonNull : BrOnNull);
 }
 
 template<typename Ctx> Result<> makeBrOnCast(Ctx& ctx, Index pos, bool onFail) {
-  return ctx.in.err("unimplemented instruction");
+  auto label = labelidx(ctx);
+  CHECK_ERR(label);
+  auto type = reftype(ctx);
+  CHECK_ERR(type);
+  return ctx.makeBrOn(pos, *label, onFail ? BrOnCastFail : BrOnCast, *type);
 }
 
 template<typename Ctx>
diff --git a/src/wasm-ir-builder.h b/src/wasm-ir-builder.h
index c0cd7b4a1..64ee0d62e 100644
--- a/src/wasm-ir-builder.h
+++ b/src/wasm-ir-builder.h
@@ -151,7 +151,8 @@ public:
   // [[nodiscard]] Result<> makeCallRef();
   [[nodiscard]] Result<> makeRefTest(Type type);
   [[nodiscard]] Result<> makeRefCast(Type type);
-  // [[nodiscard]] Result<> makeBrOn();
+  [[nodiscard]] Result<>
+  makeBrOn(Index label, BrOnOp op, Type castType = Type::none);
   [[nodiscard]] Result<> makeStructNew(HeapType type);
   [[nodiscard]] Result<> makeStructNewDefault(HeapType type);
   [[nodiscard]] Result<>
diff --git a/src/wasm.h b/src/wasm.h
index 96c9271fe..dbedc05f4 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -1566,6 +1566,7 @@ public:
 
 class BrOn : public SpecificExpression<Expression::BrOnId> {
 public:
+  BrOn() = default;
   BrOn(MixedArena& allocator) {}
 
   BrOnOp op;
diff --git a/src/wasm/wasm-ir-builder.cpp b/src/wasm/wasm-ir-builder.cpp
index c973238e9..cc2bfb433 100644
--- a/src/wasm/wasm-ir-builder.cpp
+++ b/src/wasm/wasm-ir-builder.cpp
@@ -220,18 +220,15 @@ Result<> IRBuilder::visitExpression(Expression* curr) {
 #define DELEGATE_FIELD_CHILD_VECTOR(id, field)                                 \
   WASM_UNREACHABLE("should have called visit" #id " because " #id              \
                    " has child vector " #field);
-#define DELEGATE_FIELD_SCOPE_NAME_USE(id, field)                               \
-  WASM_UNREACHABLE("should have called visit" #id " because " #id              \
-                   " has scope name use " #field);
-#define DELEGATE_FIELD_SCOPE_NAME_USE_VECTOR(id, field)                        \
-  WASM_UNREACHABLE("should have called visit" #id " because " #id              \
-                   " has scope name use vector " #field);
 
 #define DELEGATE_FIELD_INT(id, field)
 #define DELEGATE_FIELD_INT_ARRAY(id, field)
 #define DELEGATE_FIELD_LITERAL(id, field)
 #define DELEGATE_FIELD_NAME(id, field)
 #define DELEGATE_FIELD_NAME_VECTOR(id, field)
+#define DELEGATE_FIELD_SCOPE_NAME_USE(id, field)
+#define DELEGATE_FIELD_SCOPE_NAME_USE_VECTOR(id, field)
+
 #define DELEGATE_FIELD_TYPE(id, field)
 #define DELEGATE_FIELD_HEAPTYPE(id, field)
 #define DELEGATE_FIELD_ADDRESS(id, field)
@@ -933,7 +930,14 @@ Result<> IRBuilder::makeRefCast(Type type) {
   return Ok{};
 }
 
-// Result<> IRBuilder::makeBrOn() {}
+Result<> IRBuilder::makeBrOn(Index label, BrOnOp op, Type castType) {
+  BrOn curr;
+  CHECK_ERR(visitBrOn(&curr));
+  auto name = getLabelName(label);
+  CHECK_ERR(name);
+  push(builder.makeBrOn(op, *name, curr.ref, castType));
+  return Ok{};
+}
 
 Result<> IRBuilder::makeStructNew(HeapType type) {
   StructNew curr(wasm.allocator);