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Ilya Tocar 25813f9f91 cmd/compile/internal/ssa: tweak branchelim cost model on amd64 
Currently branchelim is too aggressive in converting branches to
conditinal movs. On most x86 cpus resulting cmov* are more expensive than
most simple instructions, because they have a latency of 2, instead of 1,
So by teaching branchelim to limit number of CondSelects and consider possible
need to recalculate flags, we can archive huge speed-ups (fix big regressions).
In package strings:

ToUpper/#00-6                              10.9ns ± 1%  11.8ns ± 1%   +8.29%  (p=0.000 n=10+10)
ToUpper/ONLYUPPER-6                        27.9ns ± 0%  27.8ns ± 1%     ~     (p=0.106 n=9+10)
ToUpper/abc-6                              90.3ns ± 2%  90.3ns ± 1%     ~     (p=0.956 n=10+10)
ToUpper/AbC123-6                            110ns ± 1%   113ns ± 2%   +3.19%  (p=0.000 n=10+10)
ToUpper/azAZ09_-6                           109ns ± 2%   110ns ± 1%     ~     (p=0.174 n=10+10)
ToUpper/longStrinGwitHmixofsmaLLandcAps-6   228ns ± 1%   233ns ± 2%   +2.11%  (p=0.000 n=10+10)
ToUpper/longɐstringɐwithɐnonasciiⱯchars-6   907ns ± 1%   709ns ± 2%  -21.85%  (p=0.000 n=10+10)
ToUpper/ɐɐɐɐɐ-6                             793ns ± 2%   562ns ± 2%  -29.06%  (p=0.000 n=10+10)

In fmt:

SprintfQuoteString-6   272ns ± 2%   195ns ± 4%  -28.39%  (p=0.000 n=10+10)

And in archive/zip:

CompressedZipGarbage-6       4.00ms ± 0%    4.03ms ± 0%   +0.71%  (p=0.000 n=10+10)
Zip64Test-6                  27.5ms ± 1%    24.2ms ± 0%  -12.01%  (p=0.000 n=10+10)
Zip64TestSizes/4096-6        10.4µs ±12%    10.7µs ± 8%     ~     (p=0.068 n=10+8)
Zip64TestSizes/1048576-6     79.0µs ± 3%    70.2µs ± 2%  -11.14%  (p=0.000 n=10+10)
Zip64TestSizes/67108864-6    4.64ms ± 1%    4.11ms ± 1%  -11.43%  (p=0.000 n=10+10)

As far as I can tell, no cases with significant gain from cmov have regressed.

On go1 it looks like most changes are unrelated, but I've verified that
TimeFormat really switched from cmov to branch in a hot spot.
Fill results below:

name                     old time/op    new time/op    delta
BinaryTree17-6              4.42s ± 1%     4.44s ± 1%    ~     (p=0.075 n=10+10)
Fannkuch11-6                4.23s ± 0%     4.18s ± 0%  -1.16%  (p=0.000 n=8+10)
FmtFprintfEmpty-6          67.5ns ± 2%    67.5ns ± 0%    ~     (p=0.950 n=10+7)
FmtFprintfString-6          117ns ± 2%     119ns ± 1%  +1.07%  (p=0.045 n=9+10)
FmtFprintfInt-6             122ns ± 0%     123ns ± 2%    ~     (p=0.825 n=8+10)
FmtFprintfIntInt-6          188ns ± 1%     187ns ± 1%  -0.85%  (p=0.001 n=10+10)
FmtFprintfPrefixedInt-6     223ns ± 1%     226ns ± 1%  +1.40%  (p=0.000 n=9+10)
FmtFprintfFloat-6           380ns ± 1%     379ns ± 0%    ~     (p=0.350 n=9+7)
FmtManyArgs-6               784ns ± 0%     790ns ± 1%  +0.81%  (p=0.000 n=10+9)
GobDecode-6                10.7ms ± 1%    10.8ms ± 0%  +0.68%  (p=0.000 n=10+10)
GobEncode-6                8.95ms ± 0%    8.94ms ± 0%    ~     (p=0.436 n=10+10)
Gzip-6                      378ms ± 0%     378ms ± 0%    ~     (p=0.696 n=8+10)
Gunzip-6                   60.5ms ± 0%    60.9ms ± 0%  +0.73%  (p=0.000 n=8+10)
HTTPClientServer-6          109µs ± 3%     111µs ± 2%  +2.53%  (p=0.000 n=10+10)
JSONEncode-6               20.2ms ± 0%    20.2ms ± 0%    ~     (p=0.382 n=8+8)
JSONDecode-6               85.9ms ± 1%    84.5ms ± 0%  -1.59%  (p=0.000 n=10+8)
Mandelbrot200-6            6.89ms ± 0%    6.85ms ± 1%  -0.49%  (p=0.000 n=9+10)
GoParse-6                  5.49ms ± 0%    5.40ms ± 0%  -1.63%  (p=0.000 n=8+10)
RegexpMatchEasy0_32-6       126ns ± 1%     129ns ± 1%  +2.14%  (p=0.000 n=10+10)
RegexpMatchEasy0_1K-6       320ns ± 1%     317ns ± 2%    ~     (p=0.089 n=10+10)
RegexpMatchEasy1_32-6       119ns ± 2%     121ns ± 4%    ~     (p=0.591 n=10+10)
RegexpMatchEasy1_1K-6       544ns ± 1%     541ns ± 0%  -0.67%  (p=0.020 n=8+8)
RegexpMatchMedium_32-6      184ns ± 1%     184ns ± 1%    ~     (p=0.360 n=10+10)
RegexpMatchMedium_1K-6     57.7µs ± 2%    58.3µs ± 1%  +1.12%  (p=0.022 n=10+10)
RegexpMatchHard_32-6       2.72µs ± 5%    2.70µs ± 0%    ~     (p=0.166 n=10+8)
RegexpMatchHard_1K-6       80.2µs ± 0%    81.0µs ± 0%  +1.01%  (p=0.000 n=8+10)
Revcomp-6                   607ms ± 0%     601ms ± 2%  -1.00%  (p=0.006 n=8+10)
Template-6                 93.1ms ± 1%    92.6ms ± 0%  -0.56%  (p=0.000 n=9+9)
TimeParse-6                 472ns ± 0%     470ns ± 0%  -0.28%  (p=0.001 n=9+9)
TimeFormat-6                546ns ± 0%     511ns ± 0%  -6.41%  (p=0.001 n=7+7)
[Geo mean]                 76.4µs         76.3µs       -0.12%

name                     old speed      new speed      delta
GobDecode-6              71.5MB/s ± 1%  71.1MB/s ± 0%  -0.68%  (p=0.000 n=10+10)
GobEncode-6              85.8MB/s ± 0%  85.8MB/s ± 0%    ~     (p=0.425 n=10+10)
Gzip-6                   51.3MB/s ± 0%  51.3MB/s ± 0%    ~     (p=0.680 n=8+10)
Gunzip-6                  321MB/s ± 0%   318MB/s ± 0%  -0.73%  (p=0.000 n=8+10)
JSONEncode-6             95.9MB/s ± 0%  96.0MB/s ± 0%    ~     (p=0.367 n=8+8)
JSONDecode-6             22.6MB/s ± 1%  22.9MB/s ± 0%  +1.62%  (p=0.000 n=10+8)
GoParse-6                10.6MB/s ± 0%  10.7MB/s ± 0%  +1.64%  (p=0.000 n=8+10)
RegexpMatchEasy0_32-6     252MB/s ± 1%   247MB/s ± 1%  -2.22%  (p=0.000 n=10+10)
RegexpMatchEasy0_1K-6    3.19GB/s ± 1%  3.22GB/s ± 2%    ~     (p=0.105 n=10+10)
RegexpMatchEasy1_32-6     267MB/s ± 2%   264MB/s ± 4%    ~     (p=0.481 n=10+10)
RegexpMatchEasy1_1K-6    1.88GB/s ± 1%  1.89GB/s ± 0%  +0.62%  (p=0.038 n=8+8)
RegexpMatchMedium_32-6   5.41MB/s ± 2%  5.43MB/s ± 0%    ~     (p=0.339 n=10+8)
RegexpMatchMedium_1K-6   17.8MB/s ± 1%  17.6MB/s ± 1%  -1.12%  (p=0.029 n=10+10)
RegexpMatchHard_32-6     11.8MB/s ± 5%  11.8MB/s ± 0%    ~     (p=0.163 n=10+8)
RegexpMatchHard_1K-6     12.8MB/s ± 0%  12.6MB/s ± 0%  -1.06%  (p=0.000 n=7+10)
Revcomp-6                 419MB/s ± 0%   423MB/s ± 2%  +1.02%  (p=0.006 n=8+10)
Template-6               20.9MB/s ± 0%  21.0MB/s ± 0%  +0.53%  (p=0.000 n=8+8)
[Geo mean]               77.0MB/s       77.0MB/s       +0.05%

diff --git a/src/cmd/compile/internal/ssa/branchelim.go b/src/cmd/compile/internal/ssa/branchelim.go

Change-Id: Ibdffa9ea9b4c72668617ce3202ec4a83a1cd59be
Reviewed-on: https://go-review.googlesource.com/107936
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2018-04-25 16:06:54 +00:00
.github github: update Pull Request template 2018-02-21 02:07:46 +00:00
api syscall: introduce Pointer type and use it instead of uintptr 2018-04-18 08:50:42 +00:00
doc doc: update "go get" HTTPS answer to mention .netrc 2018-04-25 02:49:10 +00:00
lib/time all: use HTTPS for iana.org links 2018-02-13 18:36:48 +00:00
misc cmd/cgo: don't use absolute paths in the export header file 2018-04-25 00:36:09 +00:00
src cmd/compile/internal/ssa: tweak branchelim cost model on amd64 2018-04-25 16:06:54 +00:00
test cmd/compile/internal/ssa: fix endless compile loop on AMD64 2018-04-24 16:20:41 +00:00
.gitattributes
.gitignore .gitignore: ignore src/cmd/dist/dist 2017-10-28 21:55:49 +00:00
AUTHORS A+C: update email address 2018-04-14 19:28:37 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS C: add Iskander Sharipov's individual CLA mail 2018-04-16 04:49:46 +00:00
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README.md README: update number of contributors 2018-04-03 22:10:32 +00:00
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