[runtime] Emit the necessary left shift anding in the LambdaCompiler

We were observing dtest-006.exe test failing on armhf. This test
checks that a right shift with a negative shift amount and a
dynamic base is shifted by the right amount.

We were failing it because we were excluding the step that we
do in regular code generation, which is to do a binary and of the shift
amount so it behaves like we are shifting by the original shift
amount modulo 32. The C# spec defines left shift like so.

This commit adds that to the LambdaCompiler.

1 files changed, 6 insertions, 0 deletions

diff --git a/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Compiler/LambdaCompiler.Binary.cs b/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Compiler/LambdaCompiler.Binary.cs
index a089b81222d..3c9ec62326e 100644
--- a/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Compiler/LambdaCompiler.Binary.cs
+++ b/mcs/class/dlr/Runtime/Microsoft.Scripting.Core/Compiler/LambdaCompiler.Binary.cs
@@ -275,6 +275,12 @@ namespace System.Linq.Expressions.Compiler {
                     if (rightType != typeof(int)) {
                         throw ContractUtils.Unreachable;
                     }
+                    // Note: If this code is made to handle unsigned
+                    // rightType types, emit the following when rightType:
+                    // is unsigned
+                    //_ilg.EmitInt(0x3f);
+                    _ilg.EmitInt(0x1f);
+                    _ilg.Emit(OpCodes.And);
                     _ilg.Emit(OpCodes.Shl);
                     break;
                 case ExpressionType.RightShift: