Fix rotate_left and rotate_right with 128bit shift amount

Fixes rust-lang#1114

Author: bjorn3

example/std_example.rs

@@ -84,6 +84,7 @@ fn main() {
     assert_eq!(houndred_i128 as f64, 100.0);
     assert_eq!(houndred_f32 as i128, 100);
     assert_eq!(houndred_f64 as i128, 100);
+    assert_eq!(1u128.rotate_left(2), 4);
 
     // Test signed 128bit comparing
     let max = usize::MAX as i128;

src/intrinsics/mod.rs

@@ -632,11 +632,21 @@ pub(crate) fn codegen_intrinsic_call<'tcx>(
         };
         rotate_left, <T>(v x, v y) {
             let layout = fx.layout_of(T);
+            let y = if fx.bcx.func.dfg.value_type(y) == types::I128 {
+                fx.bcx.ins().ireduce(types::I64, y)
+            } else {
+                y
+            };
             let res = fx.bcx.ins().rotl(x, y);
             ret.write_cvalue(fx, CValue::by_val(res, layout));
         };
         rotate_right, <T>(v x, v y) {
             let layout = fx.layout_of(T);
+            let y = if fx.bcx.func.dfg.value_type(y) == types::I128 {
+                fx.bcx.ins().ireduce(types::I64, y)
+            } else {
+                y
+            };
             let res = fx.bcx.ins().rotr(x, y);
             ret.write_cvalue(fx, CValue::by_val(res, layout));
         };