only look at the |signed| field of loads if it is relevant (#1235)

1 files changed, 40 insertions, 0 deletions

diff --git a/src/ast/load-utils.h b/src/ast/load-utils.h
new file mode 100644
index 000000000..d5817ff51
--- /dev/null
+++ b/src/ast/load-utils.h
@@ -0,0 +1,40 @@
+/*
+ * 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_load_h
+#define wasm_ast_load_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+namespace LoadUtils {
+
+// checks if the sign of a load matters, which is when an integer
+// load is of fewer bytes than the size of the type (so we must
+// fill in bits either signed or unsigned wise)
+inline bool isSignRelevant(Load* load) {
+  auto type = load->type;
+  if (load->type == unreachable) return false;
+  return !isWasmTypeFloat(type) && load->bytes < getWasmTypeSize(type);
+}
+
+} // namespace LoadUtils
+
+} // namespace wasm
+
+#endif // wasm_ast_load_h
+