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| author | Neven Sajko <nsajko@gmail.com> | 2019-04-03 02:01:50 +0000 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2019-04-04 00:26:24 +0000 |
| commit | 964fe4b80ff7a9e5490f11de0e216ae34a019ebc (patch) | |
| tree | 3d0f9d3b55ff53885fdcfc42066216d51613d7d2 /src/math | |
| parent | 4145c5da1f533fafd928769d18d5be60968cb9dc (diff) | |
| download | go-964fe4b80ff7a9e5490f11de0e216ae34a019ebc.tar.xz | |
math/big: simplify shlVU_g and shrVU_g
Rewrote a few lines to be more idiomatic/less assembly-ish.
Benchmarked with `go test -bench Float -tags math_big_pure_go`:
name old time/op new time/op delta
FloatString/100-8 751ns ± 0% 746ns ± 1% -0.71% (p=0.000 n=10+10)
FloatString/1000-8 22.9µs ± 0% 22.9µs ± 0% ~ (p=0.271 n=10+10)
FloatString/10000-8 1.89ms ± 0% 1.89ms ± 0% ~ (p=0.481 n=10+10)
FloatString/100000-8 184ms ± 0% 184ms ± 0% ~ (p=0.094 n=9+9)
FloatAdd/10-8 56.4ns ± 1% 56.5ns ± 0% ~ (p=0.170 n=9+9)
FloatAdd/100-8 59.7ns ± 0% 59.3ns ± 0% -0.70% (p=0.000 n=8+9)
FloatAdd/1000-8 101ns ± 0% 99ns ± 0% -1.89% (p=0.000 n=8+8)
FloatAdd/10000-8 553ns ± 0% 536ns ± 0% -3.00% (p=0.000 n=9+10)
FloatAdd/100000-8 4.94µs ± 0% 4.74µs ± 0% -3.94% (p=0.000 n=9+10)
FloatSub/10-8 50.3ns ± 0% 50.5ns ± 0% +0.52% (p=0.000 n=8+8)
FloatSub/100-8 52.0ns ± 0% 52.2ns ± 1% +0.46% (p=0.012 n=8+10)
FloatSub/1000-8 77.9ns ± 0% 77.3ns ± 0% -0.80% (p=0.000 n=7+8)
FloatSub/10000-8 371ns ± 0% 362ns ± 0% -2.67% (p=0.000 n=10+10)
FloatSub/100000-8 3.20µs ± 0% 3.10µs ± 0% -3.16% (p=0.000 n=10+10)
ParseFloatSmallExp-8 7.84µs ± 0% 7.82µs ± 0% -0.17% (p=0.037 n=9+9)
ParseFloatLargeExp-8 29.3µs ± 1% 29.5µs ± 0% ~ (p=0.059 n=9+8)
FloatSqrt/64-8 516ns ± 0% 519ns ± 0% +0.54% (p=0.000 n=9+9)
FloatSqrt/128-8 1.07µs ± 0% 1.07µs ± 0% ~ (p=0.109 n=8+9)
FloatSqrt/256-8 1.23µs ± 0% 1.23µs ± 0% +0.50% (p=0.000 n=9+9)
FloatSqrt/1000-8 3.43µs ± 0% 3.44µs ± 0% +0.53% (p=0.000 n=9+8)
FloatSqrt/10000-8 40.9µs ± 0% 40.7µs ± 0% -0.39% (p=0.000 n=9+8)
FloatSqrt/100000-8 1.07ms ± 0% 1.07ms ± 0% -0.10% (p=0.017 n=10+9)
FloatSqrt/1000000-8 89.3ms ± 0% 89.2ms ± 0% -0.07% (p=0.015 n=9+8)
Change-Id: Ibf07c6142719d11bc7f329246957d87a9f3ba3d2
GitHub-Last-Rev: 870a041ab7bb9c24be083114f53653a5f4eed611
GitHub-Pull-Request: golang/go#31220
Reviewed-on: https://go-review.googlesource.com/c/go/+/170449
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Diffstat (limited to 'src/math')
| -rw-r--r-- | src/math/big/arith.go | 18 |
1 files changed, 6 insertions, 12 deletions
diff --git a/src/math/big/arith.go b/src/math/big/arith.go index ed51f38836..b0885f261f 100644 --- a/src/math/big/arith.go +++ b/src/math/big/arith.go @@ -160,14 +160,11 @@ func shlVU_g(z, x []Word, s uint) (c Word) { s &= _W - 1 // hint to the compiler that shifts by s don't need guard code ŝ := _W - s ŝ &= _W - 1 // ditto - w1 := x[len(z)-1] - c = w1 >> ŝ + c = x[len(z)-1] >> ŝ for i := len(z) - 1; i > 0; i-- { - w := w1 - w1 = x[i-1] - z[i] = w<<s | w1>>ŝ + z[i] = x[i]<<s | x[i-1]>>ŝ } - z[0] = w1 << s + z[0] = x[0] << s return } @@ -182,14 +179,11 @@ func shrVU_g(z, x []Word, s uint) (c Word) { s &= _W - 1 // hint to the compiler that shifts by s don't need guard code ŝ := _W - s ŝ &= _W - 1 // ditto - w1 := x[0] - c = w1 << ŝ + c = x[0] << ŝ for i := 0; i < len(z)-1; i++ { - w := w1 - w1 = x[i+1] - z[i] = w>>s | w1<<ŝ + z[i] = x[i]>>s | x[i+1]<<ŝ } - z[len(z)-1] = w1 >> s + z[len(z)-1] = x[len(z)-1] >> s return } |