message: implement "max" agg_op for stripe store operation
diff: @@ -371,6 +371,17 @@ void Compiler::Visit(const stripe::Store& store) {
  } else {
  throw Error("Invalid addition type: " + to_string(from.type));
  }
  + } else if ("max" == agg_op) {
  + llvm::Value* prev = builder_.CreateLoad(element);
  + llvm::Value* flag = nullptr;
  + if (is_float(from.type)) {
  + flag = builder_.CreateFCmpUGT(prev, value);
  + } else if (is_int(from.type)) {
  + flag = builder_.CreateICmpSGT(prev, value);
  + } else if (is_uint(from.type)) {
  + flag = builder_.CreateICmpUGT(prev, value);
  + }
  + value = builder_.CreateSelect(flag, prev, value);
  } else if ("assign" == agg_op) {
  // fall through to assignment
  } else if (!agg_op.empty()) {
  