34 lines
788 B
C
34 lines
788 B
C
/* { dg-do compile } */
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/* { dg-options "-O2" } */
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static const unsigned long long magic = 0x03f08c5392f756cdULL;
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static const char table[64] = {
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0, 1, 12, 2, 13, 22, 17, 3,
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14, 33, 23, 36, 18, 58, 28, 4,
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62, 15, 34, 26, 24, 48, 50, 37,
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19, 55, 59, 52, 29, 44, 39, 5,
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63, 11, 21, 16, 32, 35, 57, 27,
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61, 25, 47, 49, 54, 51, 43, 38,
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10, 20, 31, 56, 60, 46, 53, 42,
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9, 30, 45, 41, 8, 40, 7, 6,
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};
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static inline int ctz1 (unsigned long long b)
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{
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unsigned long long lsb = b & -b;
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return table[(lsb * magic) >> 58];
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}
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void f (unsigned long long x, int *p)
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{
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if (x != 0)
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{
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int a = ctz1 (x);
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*p = a | p[a];
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}
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}
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/* { dg-final { scan-assembler-times "rbit\t" 1 } } */
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/* { dg-final { scan-assembler-times "clz\t" 1 } } */
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