Added a workaround for undefined behavior.

src/compiler/instruction.cc

Index: src/compiler/instruction.cc
diff --git a/src/compiler/instruction.cc b/src/compiler/instruction.cc
index d85ae07954eae0856e03600c32284fe11a3bf936..1e8cad3b0275c4c294c25aca295adb46d90a8d30 100644
--- a/src/compiler/instruction.cc
+++ b/src/compiler/instruction.cc
@@ -337,6 +337,9 @@ std::ostream& operator<<(std::ostream& os,
 }
 
 
+Constant::Constant(int32_t v) : type_(kInt32), value_(v) {}
+
+
 std::ostream& operator<<(std::ostream& os, const Constant& constant) {
   switch (constant.type()) {
     case Constant::kInt32: