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target-s390x: Avoid a loop for popcnt

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Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2016-11-21 12:06:26 +01:00
parent 7977000220
commit 250a87d556
1 changed files with 6 additions and 9 deletions
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15
target/s390x/int_helper.c
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@ -137,14 +137,11 @@ uint64_t HELPER(cvd)(int32_t reg)
return dec;
}
uint64_t HELPER(popcnt)(uint64_t r2)
uint64_t HELPER(popcnt)(uint64_t val)
{
uint64_t ret = 0;
int i;
for (i = 0; i < 64; i += 8) {
uint64_t t = ctpop32((r2 >> i) & 0xff);
ret |= t << i;
}
return ret;
/* Note that we don't fold past bytes. */
val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL);
val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
val = (val + (val >> 4)) & 0x0f0f0f0f0f0f0f0fULL;
return val;
}