Address review feedback for #1014 (#1016)

* address review feedback for #1014

1 files changed, 44 insertions, 0 deletions

diff --git a/src/ast/branch-utils.h b/src/ast/branch-utils.h
new file mode 100644
index 000000000..a54b8151f
--- /dev/null
+++ b/src/ast/branch-utils.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_ast_branch_h
+#define wasm_ast_branch_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+namespace BranchUtils {
+
+// branches not actually taken (e.g. (br $out (unreachable)))
+// are trivially ignored in our type system
+
+inline bool isBranchTaken(Break* br) {
+  return !(br->value     && br->value->type     == unreachable) &&
+         !(br->condition && br->condition->type == unreachable);
+}
+
+inline bool isBranchTaken(Switch* sw) {
+  return !(sw->value && sw->value->type     == unreachable) &&
+                        sw->condition->type != unreachable;
+}
+
+} // namespace BranchUtils
+
+} // namespace wasm
+
+#endif // wasm_ast_branch_h
+