//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

/**
 * Not necessarily optimal... but it produces correct results (at least for int)
 * If we're lucky, LLVM will recognize the pattern and produce rotate
 * instructions:
 * http://llvm.1065342.n5.nabble.com/rotate-td47679.html
 *
 * Eventually, someone should feel free to implement an llvm-specific version
 */

_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE __spirv_ocl_rotate(__CLC_GENTYPE x,
                                                        __CLC_GENTYPE n) {
  // Try to avoid extra work if someone's spinning the value through multiple
  // full rotations
  n = n % (__CLC_GENTYPE)__CLC_GENSIZE;

#ifdef __CLC_SCALAR
  if (n > 0) {
    return (x << n) | (((__CLC_U_GENTYPE)x) >> (__CLC_GENSIZE - n));
  } else if (n == 0) {
    return x;
  } else {
    return ((((__CLC_U_GENTYPE)x) >> -n) | (x << (__CLC_GENSIZE + n)));
  }
#else
  // XXX: There's a lot of __builtin_astype calls to cast everything to
  //      unsigned ... This should be improved so that if
  //      __CLC_GENTYPE==__CLC_U_GENTYPE, no casts are required.

  __CLC_U_GENTYPE x_1 = __builtin_astype(x, __CLC_U_GENTYPE);

  // XXX: Is (__CLC_U_GENTYPE >> S__CLC_GENTYPE) | (__CLC_U_GENTYPE <<
  // S__CLC_GENTYPE) legal?
  //      If so, then combine the amt and shifts into a single set of statements

  __CLC_U_GENTYPE amt;
  amt = (n < (__CLC_GENTYPE)0
             ? __builtin_astype((__CLC_GENTYPE)0 - n, __CLC_U_GENTYPE)
             : (__CLC_U_GENTYPE)0);
  x_1 = (x_1 >> amt) | (x_1 << ((__CLC_U_GENTYPE)__CLC_GENSIZE - amt));

  amt = (n < (__CLC_GENTYPE)0 ? (__CLC_U_GENTYPE)0
                              : __builtin_astype(n, __CLC_U_GENTYPE));
  x_1 = (x_1 << amt) | (x_1 >> ((__CLC_U_GENTYPE)__CLC_GENSIZE - amt));

  return __builtin_astype(x_1, __CLC_GENTYPE);
#endif
}