cmov shim (used for Math.Min/Max)

src/mscorlib/shared/System.Private.CoreLib.Shared.projitems

@@ -395,6 +395,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\IsVolatile.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\IteratorStateMachineAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\ITuple.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\JitHelpers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\LoadHint.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\MethodCodeType.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Runtime\CompilerServices\MethodImplAttribute.cs" />

src/mscorlib/shared/System/Math.cs

@@ -480,7 +480,7 @@ public static short Max(short val1, short val2)
         [NonVersionable]
         public static int Max(int val1, int val2)
         {
-            return (val1 >= val2) ? val1 : val2;
+            return JitHelpers.ConditionalSelect((val1 >= val2), val1, val2);
         }
 
         [NonVersionable]
@@ -568,7 +568,7 @@ public static short Min(short val1, short val2)
         [NonVersionable]
         public static int Min(int val1, int val2)
         {
-            return (val1 <= val2) ? val1 : val2;
+            return JitHelpers.ConditionalSelect((val1 <= val2), val1, val2);
         }
 
         [NonVersionable]

src/mscorlib/shared/System/Runtime/CompilerServices/JitHelpers.cs

@@ -0,0 +1,29 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Internal.Runtime.CompilerServices;
+
+namespace System.Runtime.CompilerServices
+{
+    internal static partial class JitHelpers
+    {
+        // From https://software.intel.com/sites/default/files/managed/9e/bc/64-ia-32-architectures-optimization-manual.pdf
+        // Example 3.2. We're taking advantage of the fact that bools are passed by value as 32-bit integers,
+        // so we'll blit it directly into a 1 or a 0 without a jump.
+        // Codegen will emit a movzx, but on Ivy Bridge (and later) the CPU itself elides the instruction.
+
+        // 'valueIfTrue' and 'valueIfFalse' really should be compile-time constants for maximum throughput.
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int ConditionalSelect(bool condition, int valueIfTrue, int valueIfFalse)
+        {
+            return ((-Unsafe.As<bool, int>(ref condition)) & (valueIfTrue - valueIfFalse)) + valueIfFalse;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint ConditionalSelect(bool condition, uint valueIfTrue, uint valueIfFalse)
+        {
+            return (uint)(((-Unsafe.As<bool, int>(ref condition)) & ((int)valueIfTrue - (int)valueIfFalse)) + (int)valueIfFalse);
+        }
+    }
+}

src/mscorlib/src/System/Runtime/CompilerServices/jithelpers.cs

@@ -67,7 +67,7 @@ internal class ArrayPinningHelper
         public byte m_arrayData;
     }
 
-    internal static class JitHelpers
+    internal static partial class JitHelpers
     {
         // The special dll name to be used for DllImport of QCalls
         internal const string QCall = "QCall";