cranelift: Fix shifts and implement rotates in interpreter (#4519)

* cranelift: Fix shifts and implement rotates in interpreter

* x64: Implement `rotl`/`rotr` for some small type combinations

cranelift/interpreter/src/step.rs

@@ -153,6 +153,20 @@ where
                   right: V|
      -> ValueResult<ControlFlow<V>> { Ok(assign(op(left, right)?)) };
 
+    // Same as `binary_unsigned`, but converts the values to their unsigned form before the
+    // operation and back to signed form afterwards. Since Cranelift types have no notion of
+    // signedness, this enables operations that depend on sign.
+    let binary_unsigned =
+        |op: fn(V, V) -> ValueResult<V>, left: V, right: V| -> ValueResult<ControlFlow<V>> {
+            Ok(assign(
+                op(
+                    left.convert(ValueConversionKind::ToUnsigned)?,
+                    right.convert(ValueConversionKind::ToUnsigned)?,
+                )
+                .and_then(|v| v.convert(ValueConversionKind::ToSigned))?,
+            ))
+        };
+
     // Similar to `binary` but converts select `ValueError`'s into trap `ControlFlow`'s
     let binary_can_trap = |op: fn(V, V) -> ValueResult<V>,
                            left: V,
@@ -690,10 +704,10 @@ where
         Opcode::RotlImm => binary(Value::rotl, arg(0)?, imm_as_ctrl_ty()?)?,
         Opcode::RotrImm => binary(Value::rotr, arg(0)?, imm_as_ctrl_ty()?)?,
         Opcode::Ishl => binary(Value::shl, arg(0)?, arg(1)?)?,
-        Opcode::Ushr => binary(Value::ushr, arg(0)?, arg(1)?)?,
+        Opcode::Ushr => binary_unsigned(Value::ushr, arg(0)?, arg(1)?)?,
         Opcode::Sshr => binary(Value::ishr, arg(0)?, arg(1)?)?,
         Opcode::IshlImm => binary(Value::shl, arg(0)?, imm_as_ctrl_ty()?)?,
-        Opcode::UshrImm => binary(Value::ushr, arg(0)?, imm_as_ctrl_ty()?)?,
+        Opcode::UshrImm => binary_unsigned(Value::ushr, arg(0)?, imm_as_ctrl_ty()?)?,
         Opcode::SshrImm => binary(Value::ishr, arg(0)?, imm_as_ctrl_ty()?)?,
         Opcode::Bitrev => assign(Value::reverse_bits(arg(0)?)?),
         Opcode::Clz => assign(arg(0)?.leading_zeros()?),