qemu/host-utils.h: Reduce the operation count in the fallback ctpop

Backports commit 7bdcecb7b2d79c292d1256f7d6cf0f1da50d381f from qemu
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Richard Henderson 2018-03-01 18:35:49 -05:00 committed by Lioncash
parent 8a62878523
commit 5ca8ac1aeb
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@ -330,7 +330,7 @@ static inline int ctpop8(uint8_t val)
#else #else
val = (val & 0x55) + ((val >> 1) & 0x55); val = (val & 0x55) + ((val >> 1) & 0x55);
val = (val & 0x33) + ((val >> 2) & 0x33); val = (val & 0x33) + ((val >> 2) & 0x33);
val = (val & 0x0f) + ((val >> 4) & 0x0f); val = (val + (val >> 4)) & 0x0f;
return val; return val;
#endif #endif
@ -347,8 +347,8 @@ static inline int ctpop16(uint16_t val)
#else #else
val = (val & 0x5555) + ((val >> 1) & 0x5555); val = (val & 0x5555) + ((val >> 1) & 0x5555);
val = (val & 0x3333) + ((val >> 2) & 0x3333); val = (val & 0x3333) + ((val >> 2) & 0x3333);
val = (val & 0x0f0f) + ((val >> 4) & 0x0f0f); val = (val + (val >> 4)) & 0x0f0f;
val = (val & 0x00ff) + ((val >> 8) & 0x00ff); val = (val + (val >> 8)) & 0x00ff;
return val; return val;
#endif #endif
@ -365,9 +365,8 @@ static inline int ctpop32(uint32_t val)
#else #else
val = (val & 0x55555555) + ((val >> 1) & 0x55555555); val = (val & 0x55555555) + ((val >> 1) & 0x55555555);
val = (val & 0x33333333) + ((val >> 2) & 0x33333333); val = (val & 0x33333333) + ((val >> 2) & 0x33333333);
val = (val & 0x0f0f0f0f) + ((val >> 4) & 0x0f0f0f0f); val = (val + (val >> 4)) & 0x0f0f0f0f;
val = (val & 0x00ff00ff) + ((val >> 8) & 0x00ff00ff); val = (val * 0x01010101) >> 24;
val = (val & 0x0000ffff) + ((val >> 16) & 0x0000ffff);
return val; return val;
#endif #endif
@ -384,10 +383,8 @@ static inline int ctpop64(uint64_t val)
#else #else
val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL); val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL);
val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL); val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >> 4) & 0x0f0f0f0f0f0f0f0fULL); val = (val + (val >> 4)) & 0x0f0f0f0f0f0f0f0fULL;
val = (val & 0x00ff00ff00ff00ffULL) + ((val >> 8) & 0x00ff00ff00ff00ffULL); val = (val * 0x0101010101010101ULL) >> 56;
val = (val & 0x0000ffff0000ffffULL) + ((val >> 16) & 0x0000ffff0000ffffULL);
val = (val & 0x00000000ffffffffULL) + ((val >> 32) & 0x00000000ffffffffULL);
return (int)val; return (int)val;
#endif #endif