delta/go-git.git/src/runtime/internal/sys, branch dev.debug

cmd/compile: intrinsics for math/bits.TrailingZerosX

2017-03-16T02:44:16+00:00

Implement math/bits.TrailingZerosX using intrinsics.

Generally reorganize the intrinsic spec a bit.
The instrinsics data structure is now built at init time.
This will make doing the other functions in math/bits easier.

Update sys.CtzX to return int instead of uint{64,32} so it
matches math/bits.TrailingZerosX.

Improve the intrinsics a bit for amd64.  We don't need the CMOV
for <64 bit versions.

Update #18616

Change-Id: Ic1c5339c943f961d830ae56f12674d7b29d4ff39
Reviewed-on: https://go-review.googlesource.com/38155
Run-TryBot: Keith Randall 
TryBot-Result: Gobot Gobot 
Reviewed-by: Robert Griesemer

cmd/internal/sys, runtime/internal/sys: gofmt

2016-11-07T22:13:18+00:00

Change-Id: Ice8f3b42194852f7ee8f00f004e80014d1ea119b
Reviewed-on: https://go-review.googlesource.com/32875
Reviewed-by: Brad Fitzpatrick

runtime/internal/sys: add arch defs for GOARCH=mips{,le}

2016-11-03T23:28:28+00:00

Change-Id: I6288f1fca1ae4c64b3907af700811ee842053020
Reviewed-on: https://go-review.googlesource.com/31472
Reviewed-by: Ian Lance Taylor

runtime: don't hard-code physical page size

2016-09-06T21:05:53+00:00

Now that the runtime fetches the true physical page size from the OS,
make the physical page size used by heap growth a variable instead of
a constant. This isn't used in any performance-critical paths, so it
shouldn't be an issue.

sys.PhysPageSize is also renamed to sys.DefaultPhysPageSize to make it
clear that it's not necessarily the true page size. There are no uses
of this constant any more, but we'll keep it around for now.

Updates #12480 and #10180.

Change-Id: I6c23b9df860db309c38c8287a703c53817754f03
Reviewed-on: https://go-review.googlesource.com/25022
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Rick Hudson

runtime: assume 64kB physical pages on ARM

2016-09-06T21:05:47+00:00

Currently we assume the physical page size on ARM is 4kB. While this
is usually true, the architecture also supports 16kB and 64kB physical
pages, and Linux (and possibly other OSes) can be configured to use
these larger page sizes.

With Go 1.6, such a configuration could potentially run, but generally
resulted in memory corruption or random panics. With current master,
this configuration will cause the runtime to panic during init on
Linux when it checks the true physical page size (and will still cause
corruption or panics on other OSes).

However, the assumed physical page size only has to be a multiple of
the true physical page size, the scavenger can now deal with large
physical page sizes, and the rest of the runtime can deal with a
larger assumed physical page size than the true size. Hence, there's
little disadvantage to conservatively setting the assumed physical
page size to 64kB on ARM.

This may result in some extra memory use, since we can only return
memory at multiples of the assumed physical page size. However, it is
a simple change that should make Go run on systems configured for
larger page sizes. The following commits will make the runtime query
the actual physical page size from the OS, but this is a simple step
there.

Updates #12480.

Change-Id: I851829595bc9e0c76235c847a7b5f62ad82b5302
Reviewed-on: https://go-review.googlesource.com/25021
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Minux Ma

runtime: insufficient padding in the `p` structure

2016-08-29T23:22:51+00:00

The current padding in the 'p' struct is hardcoded at 64 bytes. It should be the
cache line size. On ppc64x, the current value is only okay because sys.CacheLineSize
is wrong at 64 bytes. This change fixes that by making the padding equal to the
cache line size. It also fixes the cache line size for ppc64/ppc64le to 128 bytes.

Fixes #16477

Change-Id: Ib7ec5195685116eb11ba312a064f41920373d4a3
Reviewed-on: https://go-review.googlesource.com/25370
Reviewed-by: Lynn Boger 
Reviewed-by: Minux Ma 
Run-TryBot: Michael Munday 
TryBot-Result: Gobot Gobot

cmd/compile: clean up ctz ops

2016-08-23T23:45:12+00:00

Now that we have ops that can return 2 results, have BSF return a result
and flags.  We can then get rid of the redundant comparison and use CMOV
instead of CMOVconst ops.

Get rid of a bunch of the ops we don't use.  Ctz{8,16}, plus all the Clzs,
and CMOVNEs.  I don't think we'll ever use them, and they would be easy
to add back if needed.

Change-Id: I8858a1d017903474ea7e4002fc76a6a86e7bd487
Reviewed-on: https://go-review.googlesource.com/27630
Run-TryBot: Keith Randall 
TryBot-Result: Gobot Gobot 
Reviewed-by: David Chase

runtime/internal/sys: implement Ctz and Bswap in assembly for 386

2016-06-30T19:35:44+00:00

Ctz is a hot-spot in the Go 1.7 memory manager. In SSA it's
implemented as an intrinsic that compiles to a few instructions, but
on the old backend (all architectures other than amd64), it's
implemented as a fairly complex Go function. As a result, switching to
bitmap-based allocation was a significant hit to allocation-heavy
workloads like BinaryTree17 on non-SSA platforms.

For unknown reasons, this hit 386 particularly hard. We can regain a
lot of the lost performance by implementing Ctz in assembly on the
386. This isn't as good as an intrinsic, since it still generates a
function call and prevents useful inlining, but it's much better than
the pure Go implementation:

name                      old time/op    new time/op    delta
BinaryTree17-12              3.59s ± 1%     3.06s ± 1%  -14.74%  (p=0.000 n=19+20)
Fannkuch11-12                3.72s ± 1%     3.64s ± 1%   -2.09%  (p=0.000 n=17+19)
FmtFprintfEmpty-12          52.3ns ± 3%    52.3ns ± 3%     ~     (p=0.829 n=20+19)
FmtFprintfString-12          156ns ± 1%     148ns ± 3%   -5.20%  (p=0.000 n=18+19)
FmtFprintfInt-12             137ns ± 1%     136ns ± 1%   -0.56%  (p=0.000 n=19+13)
FmtFprintfIntInt-12          227ns ± 2%     225ns ± 2%   -0.93%  (p=0.000 n=19+17)
FmtFprintfPrefixedInt-12     210ns ± 1%     208ns ± 1%   -0.91%  (p=0.000 n=19+17)
FmtFprintfFloat-12           375ns ± 1%     371ns ± 1%   -1.06%  (p=0.000 n=19+18)
FmtManyArgs-12               995ns ± 2%     978ns ± 1%   -1.63%  (p=0.000 n=17+17)
GobDecode-12                9.33ms ± 1%    9.19ms ± 0%   -1.59%  (p=0.000 n=20+17)
GobEncode-12                7.73ms ± 1%    7.73ms ± 1%     ~     (p=0.771 n=19+20)
Gzip-12                      375ms ± 1%     374ms ± 1%     ~     (p=0.141 n=20+18)
Gunzip-12                   61.8ms ± 1%    61.8ms ± 1%     ~     (p=0.602 n=20+20)
HTTPClientServer-12         87.7µs ± 2%    86.9µs ± 3%   -0.87%  (p=0.024 n=19+20)
JSONEncode-12               20.2ms ± 1%    20.4ms ± 0%   +0.53%  (p=0.000 n=18+19)
JSONDecode-12               65.3ms ± 0%    65.4ms ± 1%     ~     (p=0.385 n=16+19)
Mandelbrot200-12            4.11ms ± 1%    4.12ms ± 0%   +0.29%  (p=0.020 n=19+19)
GoParse-12                  3.75ms ± 1%    3.61ms ± 2%   -3.90%  (p=0.000 n=20+20)
RegexpMatchEasy0_32-12       104ns ± 0%     103ns ± 0%   -0.96%  (p=0.000 n=13+16)
RegexpMatchEasy0_1K-12       805ns ± 1%     803ns ± 1%     ~     (p=0.189 n=18+18)
RegexpMatchEasy1_32-12       111ns ± 0%     111ns ± 3%     ~     (p=1.000 n=14+19)
RegexpMatchEasy1_1K-12      1.00µs ± 1%    1.00µs ± 1%   +0.50%  (p=0.003 n=19+19)
RegexpMatchMedium_32-12      133ns ± 2%     133ns ± 2%     ~     (p=0.218 n=20+20)
RegexpMatchMedium_1K-12     41.2µs ± 1%    42.2µs ± 1%   +2.52%  (p=0.000 n=18+16)
RegexpMatchHard_32-12       2.35µs ± 1%    2.38µs ± 1%   +1.53%  (p=0.000 n=18+18)
RegexpMatchHard_1K-12       70.9µs ± 2%    72.0µs ± 1%   +1.42%  (p=0.000 n=19+17)
Revcomp-12                   1.06s ± 0%     1.05s ± 0%   -1.36%  (p=0.000 n=20+18)
Template-12                 86.2ms ± 1%    84.6ms ± 0%   -1.89%  (p=0.000 n=20+18)
TimeParse-12                 425ns ± 2%     428ns ± 1%   +0.77%  (p=0.000 n=18+19)
TimeFormat-12                517ns ± 1%     519ns ± 1%   +0.43%  (p=0.001 n=20+19)
[Geo mean]                  74.3µs         73.5µs        -1.05%

Prior to this commit, BinaryTree17-12 on 386 was 33% slower than at
the go1.6 tag. With this commit, it's 13% slower.

On arm and arm64, BinaryTree17-12 is only ~5% slower than it was at
go1.6. It may be worth implementing Ctz for them as well.

I consider this change low risk, since the functions it replaces are
simple, very well specified, and well tested.

For #16117.

Change-Id: Ic39d851d5aca91330134596effd2dab9689ba066
Reviewed-on: https://go-review.googlesource.com/24640
Reviewed-by: Rick Hudson 
Reviewed-by: Keith Randall 
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot

runtime/internal/sys: better fallback algorithms for intrinsics

2016-04-14T21:09:03+00:00

Use deBruijn sequences to count low-order zeros.
Reorg bswap to not use &^, it takes another instruction on x86.

Change-Id: I4a5ed9fd16ee6a279d88c067e8a2ba11de821156
Reviewed-on: https://go-review.googlesource.com/22084
Reviewed-by: David Chase

runtime: remove remaining references to TheChar

2016-04-11T04:32:07+00:00

After mdempsky's recent changes, these are the only references to
"TheChar" left in the Go tree. Without the context, and without
knowing the history, this is confusing.

Also rename sys.TheGoos and sys.TheGoarch to sys.GOOS
and sys.GOARCH.

Also change the heap dump format to include sys.GOARCH
rather than TheChar, which is no longer a concept.

Updates #15169 (changes heapdump format)

Change-Id: I3e99eeeae00ed55d7d01e6ed503d958c6e931dca
Reviewed-on: https://go-review.googlesource.com/21647
Reviewed-by: Matthew Dempsky