[libc] Use a wrapper for rand instead of calling std::rand in fma tests.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D94198

libc/test/src/math/FmaTest.h

@@ -13,8 +13,7 @@
 #include "utils/FPUtil/TestHelpers.h"
 #include "utils/MPFRWrapper/MPFRUtils.h"
 #include "utils/UnitTest/Test.h"
-
-#include <random>
+#include "utils/testutils/RandUtils.h"
 
 namespace mpfr = __llvm_libc::testing::mpfr;
 
@@ -32,8 +31,9 @@ private:
 
   UIntType getRandomBitPattern() {
     UIntType bits{0};
-    for (size_t i = 0; i < sizeof(UIntType) / 2; ++i) {
-      bits = (bits << 2) + static_cast<uint16_t>(std::rand());
+    for (UIntType i = 0; i < sizeof(UIntType) / 2; ++i) {
+      bits =
+          (bits << 2) + static_cast<uint16_t>(__llvm_libc::testutils::rand());
     }
     return bits;
   }

libc/utils/testutils/CMakeLists.txt

@@ -5,6 +5,8 @@ endif()
 
 add_llvm_library(
   libc_test_utils
+  RandUtils.cpp
+  RandUtils.h
   StreamWrapper.cpp
   StreamWrapper.h
   ${EFFile}

libc/utils/testutils/RandUtils.cpp

@@ -0,0 +1,19 @@
+//===-- RandUtils.cpp -----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "RandUtils.h"
+
+#include <cstdlib>
+
+namespace __llvm_libc {
+namespace testutils {
+
+int rand() { return std::rand(); }
+
+} // namespace testutils
+} // namespace __llvm_libc

libc/utils/testutils/RandUtils.h

@@ -0,0 +1,16 @@
+//===-- RandUtils.h ---------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+namespace __llvm_libc {
+namespace testutils {
+
+// Wrapper for std::rand.
+int rand();
+
+} // namespace testutils
+} // namespace __llvm_libc