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| author | Richard Henderson | 2016-11-21 12:06:26 +0100 |
|---|---|---|
| committer | Richard Henderson | 2017-01-10 17:48:57 +0100 |
| commit | 250a87d5561a7212fe43357b084f69992eced75a (patch) | |
| tree | bdcddaa4f0827557266d48049b943b7c29146f07 | |
| parent | target-ppc: Use ctpop helper (diff) | |
| download | qemu-250a87d5561a7212fe43357b084f69992eced75a.tar.gz qemu-250a87d5561a7212fe43357b084f69992eced75a.tar.xz qemu-250a87d5561a7212fe43357b084f69992eced75a.zip | |
target-s390x: Avoid a loop for popcnt
Signed-off-by: Richard Henderson <rth@twiddle.net>
| -rw-r--r-- | target/s390x/int_helper.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/target/s390x/int_helper.c b/target/s390x/int_helper.c index 5bc470bdc7..f26f36a904 100644 --- a/target/s390x/int_helper.c +++ b/target/s390x/int_helper.c @@ -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; } |