add tests

Author: tianleiwu

onnxruntime/core/common/safeint.h

@@ -63,23 +63,21 @@ template <typename R, typename T, typename U, typename... Rest>
 
   // SafeMultiply(T, U, T&) requires the first argument and result to share
   // the same type. Cast the first operand to R so the result is directly in R.
-  R result{};
-  if constexpr (std::is_same_v<R, T>) {
-    result = a;
-  } else {
-    if (!SafeCast(a, result)) {
-      SafeIntDefaultExceptionHandler::SafeIntOnOverflow();
-    }
+  R cast_a{};
+  if (!SafeCast(a, cast_a)) {
+    SafeIntDefaultExceptionHandler::SafeIntOnOverflow();
   }
 
-  if (!SafeMultiply(result, b, result)) {
+  R result{};
+  if (!SafeMultiply(cast_a, b, result)) {
     SafeIntDefaultExceptionHandler::SafeIntOnOverflow();
   }
 
   if constexpr (sizeof...(rest) > 0) {
     return SafeMul<R>(result, rest...);
+  } else {
+    return result;
   }
-  return result;
 }
 
 }  // namespace onnxruntime

onnxruntime/test/common/safeint_test.cc

@@ -0,0 +1,38 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+#include "core/common/safeint.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+
+#include "gtest/gtest.h"
+
+namespace onnxruntime::test {
+
+static_assert(is_supported_integer_v<int>);
+static_assert(is_supported_integer_v<uint8_t>);
+static_assert(!is_supported_integer_v<bool>);
+
+TEST(SafeIntTest, SafeMulMultipliesOperands) {
+  EXPECT_EQ(SafeMul<size_t>(size_t{2}, 3U), size_t{6});
+  EXPECT_EQ(SafeMul<int>(-2, 3, 4), -24);
+}
+
+TEST(SafeIntTest, SafeMulHandlesSameVariableOperands) {
+  const int value = 7;
+  EXPECT_EQ(SafeMul<int>(value, value), 49);
+}
+
+#ifndef ORT_NO_EXCEPTIONS
+TEST(SafeIntTest, SafeMulThrowsOnInitialCastOverflow) {
+  EXPECT_THROW((SafeMul<uint32_t>(-1, 2)), OnnxRuntimeException);
+}
+
+TEST(SafeIntTest, SafeMulThrowsOnMultiplyOverflow) {
+  EXPECT_THROW((SafeMul<int>(std::numeric_limits<int>::max(), 2)), OnnxRuntimeException);
+}
+#endif
+
+}  // namespace onnxruntime::test