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43 lines
1.6 KiB
43 lines
1.6 KiB
4 months ago
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/**
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* Not necessarily optimal... but it produces correct results (at least for int)
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* If we're lucky, LLVM will recognize the pattern and produce rotate
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* instructions:
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* http://llvm.1065342.n5.nabble.com/rotate-td47679.html
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*
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* Eventually, someone should feel free to implement an llvm-specific version
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*/
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_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE rotate(__CLC_GENTYPE x, __CLC_GENTYPE n){
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//Try to avoid extra work if someone's spinning the value through multiple
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//full rotations
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n = n % (__CLC_GENTYPE)__CLC_GENSIZE;
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#ifdef __CLC_SCALAR
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if (n > 0){
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return (x << n) | (((__CLC_U_GENTYPE)x) >> (__CLC_GENSIZE - n));
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} else if (n == 0){
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return x;
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} else {
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return ( (((__CLC_U_GENTYPE)x) >> -n) | (x << (__CLC_GENSIZE + n)) );
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}
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#else
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//XXX: There's a lot of __builtin_astype calls to cast everything to
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// unsigned ... This should be improved so that if __CLC_GENTYPE==__CLC_U_GENTYPE, no
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// casts are required.
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__CLC_U_GENTYPE x_1 = __builtin_astype(x, __CLC_U_GENTYPE);
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//XXX: Is (__CLC_U_GENTYPE >> S__CLC_GENTYPE) | (__CLC_U_GENTYPE << S__CLC_GENTYPE) legal?
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// If so, then combine the amt and shifts into a single set of statements
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__CLC_U_GENTYPE amt;
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amt = (n < (__CLC_GENTYPE)0 ? __builtin_astype((__CLC_GENTYPE)0-n, __CLC_U_GENTYPE) : (__CLC_U_GENTYPE)0);
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x_1 = (x_1 >> amt) | (x_1 << ((__CLC_U_GENTYPE)__CLC_GENSIZE - amt));
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amt = (n < (__CLC_GENTYPE)0 ? (__CLC_U_GENTYPE)0 : __builtin_astype(n, __CLC_U_GENTYPE));
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x_1 = (x_1 << amt) | (x_1 >> ((__CLC_U_GENTYPE)__CLC_GENSIZE - amt));
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return __builtin_astype(x_1, __CLC_GENTYPE);
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#endif
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}
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