/** * 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 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 }