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Russ Cox 92dba0d278 cmd/internal/gc: use hardware instruction for math.Sqrt (amd64/arm)
I first prototyped this change in Sept 2011, and I discarded it
because it made no difference in the obvious benchmark loop.
It still makes no difference in the obvious benchmark loop,
but in a less obvious one, doing some extra computation
around the calls to Sqrt, not making the call does have a
significant effect.

benchmark                 old ns/op     new ns/op     delta
BenchmarkSqrt             4.56          4.57          +0.22%
BenchmarkSqrtIndirect     4.56          4.56          +0.00%
BenchmarkSqrtGo           69.4          69.4          +0.00%
BenchmarkSqrtPrime        4417          3647          -17.43%

This is a warmup for using hardware expansions for some
calls to 1-line assembly routines in the runtime (for example getg).

Change-Id: Ie66be23f8c09d0f7dc4ddd7ca8a93cfce28f55a4
Reviewed-on: https://go-review.googlesource.com/8356
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-03 16:13:36 +00:00
api api: update next.txt 2015-03-03 00:35:53 +00:00
doc doc/go1.5: add Stats to database/sql 2015-04-01 23:34:55 +00:00
lib/time remove the obsolete lib/codereview. 2014-12-08 07:51:54 +00:00
misc misc/ios: retry loop to handle builder flakiness 2015-03-30 18:11:07 +00:00
src cmd/internal/gc: use hardware instruction for math.Sqrt (amd64/arm) 2015-04-03 16:13:36 +00:00
test cmd/internal/gc: use big.Float to represent Mpflt bits 2015-04-02 22:49:47 +00:00
.gitattributes .gitattributes: prevent all magic line ending changes 2014-12-12 23:14:54 +00:00
.gitignore .gitignore: ignore ARM64 build products 2015-03-16 18:44:22 +00:00
AUTHORS A+C: add another email address for Emil Hessman 2014-11-12 10:01:23 -08:00
CONTRIBUTING.md doc: direct people to the mailing list 2015-01-18 21:27:07 +00:00
CONTRIBUTORS C: add Nick Cooper (Google CLA). 2014-11-14 17:03:17 +11:00
favicon.ico godoc: update favicon 2012-10-11 17:02:36 +11:00
LICENSE doc: update licensing text one more time 2012-03-27 15:09:13 +11:00
PATENTS
README.md doc: fix broken link in README 2015-02-19 05:50:57 +00:00
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