private static Hasher BuildDynamicHasher(Type declaringType, IReadOnlyCollection <FieldInfo> fieldInfos)
{
return(DynamicMethod <Hasher> .New(il =>
{
// Declare the local variable to store the target instance
il.DeclareLocal(declaringType);
// Load the argument (the object instance)
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Castclass, declaringType);
il.Emit(OpCodes.Stloc_0);
// Unroll the member access
MethodInfo
validateDelegateInfo = typeof(ShaderHashCodeProvider).GetMethod(nameof(ValidateDelegate), BindingFlags.NonPublic | BindingFlags.Static),
getMethodInfo = typeof(Delegate).GetProperty(nameof(Delegate.Method)).GetMethod,
getHashCodeInfo = typeof(object).GetMethod(nameof(GetHashCode));
foreach (FieldInfo fieldInfo in fieldInfos)
{
Label label = il.DefineLabel();
// if (fieldInfo.GetValue(obj) != null) {
il.Emit(OpCodes.Ldloc_0);
il.Emit(OpCodes.Ldfld, fieldInfo);
il.Emit(OpCodes.Brfalse_S, label);
// if (ValidateDelegate(field)) {
il.Emit(OpCodes.Ldloc_0);
il.Emit(OpCodes.Ldfld, fieldInfo);
il.EmitCall(OpCodes.Call, validateDelegateInfo, null);
il.Emit(OpCodes.Brfalse_S, label);
// hash = hash * 17 + field.Method.GetHashCode();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldc_I4_S, (byte)17);
il.Emit(OpCodes.Mul);
il.Emit(OpCodes.Ldloc_0);
il.Emit(OpCodes.Ldfld, fieldInfo);
il.EmitCall(OpCodes.Callvirt, getMethodInfo, null);
il.EmitCall(OpCodes.Callvirt, getHashCodeInfo, null);
il.Emit(OpCodes.Add);
il.Emit(OpCodes.Starg_S, (byte)0);
il.MarkLabel(label);
}
// Return the computed hash
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ret);
}));
}
public void TestSquare()
{
Square square = DynamicMethod <Square> .New(il =>
{
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Dup);
il.Emit(OpCodes.Mul);
il.Emit(OpCodes.Ret);
});
int result = square(2); // result = 2 * 2
Assert.IsTrue(result == 4);
}
