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Paul E. Murphy 756841bffa internal/bytealg: optimize Count/CountString for PPC64/Power10
Power10 adds a handful of new instructions which make this
noticeably quicker for smaller values.

Likewise, since the vector loop requires 32B to enter,
unroll it once to count 32B per iteration. This
improvement benefits all PPC64 cpus.

On Power10 comparing a binary built with GOPPC64=power8

CountSingle/10     8.99ns ± 0%    5.55ns ± 3%   -38.24%
CountSingle/16     7.55ns ± 0%    5.56ns ± 3%   -26.37%
CountSingle/17     7.45ns ± 0%    5.25ns ± 0%   -29.52%
CountSingle/31     18.4ns ± 0%     6.2ns ± 0%   -66.41%
CountSingle/32     6.17ns ± 0%    5.04ns ± 0%   -18.37%
CountSingle/33     7.13ns ± 0%    5.99ns ± 0%   -15.94%
CountSingle/4K      198ns ± 0%     115ns ± 0%   -42.08%
CountSingle/4M      190µs ± 0%     109µs ± 0%   -42.49%
CountSingle/64M    3.28ms ± 0%    2.08ms ± 0%   -36.53%

Furthermore, comparing the new tail implementation on
GOPPC64=power8 with GOPPC64=power10:

CountSingle/10     5.55ns ± 3%    4.52ns ± 1%  -18.66%
CountSingle/16     5.56ns ± 3%    4.80ns ± 0%  -13.65%
CountSingle/17     5.25ns ± 0%    4.79ns ± 0%   -8.78%
CountSingle/31     6.17ns ± 0%    4.82ns ± 0%  -21.79%
CountSingle/32     5.04ns ± 0%    5.09ns ± 6%   +1.01%
CountSingle/33     5.99ns ± 0%    5.42ns ± 2%   -9.54%

Change-Id: I62d80be3b5d706e1abbb4bec7d6278a939a5eed4
Reviewed-on: https://go-review.googlesource.com/c/go/+/512695
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Paul Murphy <murp@ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
2023-08-14 20:30:44 +00:00
.github .github: fix templates with multiple labels 2023-07-31 18:28:27 +00:00
api slices: add Concat 2023-08-08 14:31:39 +00:00
doc net/http: disallow empty Content-Length header 2023-08-11 22:04:35 +00:00
lib/time lib/time: update to 2023c/2023c 2023-05-03 20:14:11 +00:00
misc misc/wasm: switch default WASI runtime 2023-07-26 14:30:35 +00:00
src internal/bytealg: optimize Count/CountString for PPC64/Power10 2023-08-14 20:30:44 +00:00
test cmd/compile: make backingArrayPtrLen to return typecheck-ed nodes 2023-08-09 19:30:45 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore internal/platform,cmd/dist: export the list of supported platforms 2023-06-22 19:44:52 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00
CONTRIBUTING.md doc: normalize proposal-process links 2023-03-29 22:00:27 +00:00
go.env cmd/go: additional doc-inspired tests and bug fixes 2023-06-06 19:18:46 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README.md README: update from CC-BY-3.0 to CC-BY-4.0 2022-11-02 20:14:56 +00:00
SECURITY.md SECURITY.md: replace golang.org with go.dev 2022-04-26 19:59:47 +00:00

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