diff -r 000000000000 -r 6474c204b198 mfbt/tests/TestCeilingFloor.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mfbt/tests/TestCeilingFloor.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/MathAlgorithms.h"
+
+using mozilla::CeilingLog2;
+using mozilla::FloorLog2;
+using mozilla::RoundUpPow2;
+
+static void
+TestCeiling()
+{
+  for (uint32_t i = 0; i <= 1; i++)
+    MOZ_RELEASE_ASSERT(CeilingLog2(i) == 0);
+
+  for (uint32_t i = 2; i <= 2; i++)
+    MOZ_RELEASE_ASSERT(CeilingLog2(i) == 1);
+
+  for (uint32_t i = 3; i <= 4; i++)
+    MOZ_RELEASE_ASSERT(CeilingLog2(i) == 2);
+
+  for (uint32_t i = 5; i <= 8; i++)
+    MOZ_RELEASE_ASSERT(CeilingLog2(i) == 3);
+
+  for (uint32_t i = 9; i <= 16; i++)
+    MOZ_RELEASE_ASSERT(CeilingLog2(i) == 4);
+}
+
+static void
+TestFloor()
+{
+  for (uint32_t i = 0; i <= 1; i++)
+    MOZ_RELEASE_ASSERT(FloorLog2(i) == 0);
+
+  for (uint32_t i = 2; i <= 3; i++)
+    MOZ_RELEASE_ASSERT(FloorLog2(i) == 1);
+
+  for (uint32_t i = 4; i <= 7; i++)
+    MOZ_RELEASE_ASSERT(FloorLog2(i) == 2);
+
+  for (uint32_t i = 8; i <= 15; i++)
+    MOZ_RELEASE_ASSERT(FloorLog2(i) == 3);
+
+  for (uint32_t i = 16; i <= 31; i++)
+    MOZ_RELEASE_ASSERT(FloorLog2(i) == 4);
+}
+
+static void
+TestRoundUpPow2()
+{
+  MOZ_RELEASE_ASSERT(RoundUpPow2(0) == 1);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(1) == 1);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(2) == 2);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(3) == 4);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(4) == 4);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(5) == 8);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(6) == 8);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(7) == 8);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(8) == 8);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(9) == 16);
+
+  MOZ_RELEASE_ASSERT(RoundUpPow2(15) == 16);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(16) == 16);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(17) == 32);
+
+  MOZ_RELEASE_ASSERT(RoundUpPow2(31) == 32);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(32) == 32);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(33) == 64);
+
+  size_t MaxPow2 = size_t(1) << (sizeof(size_t) * CHAR_BIT - 1);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2 - 1) == MaxPow2);
+  MOZ_RELEASE_ASSERT(RoundUpPow2(MaxPow2) == MaxPow2);
+  // not valid to round up when past the max power of two
+}
+
+int main()
+{
+  TestCeiling();
+  TestFloor();
+
+  TestRoundUpPow2();
+  return 0;
+}