delta/go-git.git/src/runtime/string_test.go, branch dev.boringcrypto

runtime: revert signal stack mlocking

2020-08-13T02:17:17+00:00

Go 1.14 included a (rather awful) workaround for a Linux kernel bug
that corrupted vector registers on x86 CPUs during signal delivery
(https://bugzilla.kernel.org/show_bug.cgi?id=205663). This bug was
introduced in Linux 5.2 and fixed in 5.3.15, 5.4.2 and all 5.5 and
later kernels. The fix was also back-ported by major distros. This
workaround was necessary, but had unfortunate downsides, including
causing Go programs to exceed the mlock ulimit in many configurations
(#37436).

We're reasonably confident that by the Go 1.16 release, the number of
systems running affected kernels will be vanishingly small. Hence,
this CL removes this workaround.

This effectively reverts CLs 209597 (version parser), 209899 (mlock
top of signal stack), 210299 (better failure message), 223121 (soft
mlock failure handling), and 244059 (special-case patched Ubuntu
kernels). The one thing we keep is the osArchInit function. It's empty
everywhere now, but is a reasonable hook to have.

Updates #35326, #35777 (the original register corruption bugs).
Updates #40184 (request to revert in 1.15).
Fixes #35979.

Change-Id: Ie213270837095576f1f3ef46bf3de187dc486c50
Reviewed-on: https://go-review.googlesource.com/c/go/+/246200
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

all: avoid string(i) where i has type int

2020-02-26T04:38:19+00:00

Instead use string(r) where r has type rune.

This is in preparation for a vet warning for string(i).

Updates #32479

Change-Id: Ic205269bba1bd41723950219ecfb67ce17a7aa79
Reviewed-on: https://go-review.googlesource.com/c/go/+/220844
Run-TryBot: Ian Lance Taylor 
TryBot-Result: Gobot Gobot 
Reviewed-by: Akhil Indurti 
Reviewed-by: Brad Fitzpatrick 
Reviewed-by: Toshihiro Shiino

runtime: add a simple version number parser

2019-12-05T01:48:12+00:00

This will be used to parse the Linux kernel versions, but this code is
generic and can be tested on its own.

For #35777.

Change-Id: If1df48d07250e5855dde45bc9d57c66f777b9fb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/209597
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Brad Fitzpatrick

strings: declare IndexByte as noescape

2018-10-30T20:03:54+00:00

This lets []byte->string conversions which are used as arguments to
strings.IndexByte and friends have their backing store allocated on
the stack.

It only prevents allocation when the string is small enough (32
bytes), so it isn't perfect. But reusing the []byte backing store
directly requires a bunch more compiler analysis (see #2205 and
related issues).

Fixes #25864.

Change-Id: Ie52430422196e3c91e5529d6e56a8435ced1fc4c
Reviewed-on: https://go-review.googlesource.com/c/146018
Reviewed-by: Brad Fitzpatrick

cmd/compile: optimize len([]rune(string))

2018-05-06T05:31:01+00:00

Adds a new runtime function to count runes in a string.
Modifies the compiler to detect the pattern len([]rune(string))
and replaces it with the new rune counting runtime function.

RuneCount/lenruneslice/ASCII                  27.8ns ± 2%  14.5ns ± 3%  -47.70%  (p=0.000 n=10+10)
RuneCount/lenruneslice/Japanese                126ns ± 2%    60ns ± 2%  -52.03%  (p=0.000 n=10+10)
RuneCount/lenruneslice/MixedLength             104ns ± 2%    50ns ± 1%  -51.71%  (p=0.000 n=10+9)

Fixes #24923

Change-Id: Ie9c7e7391a4e2cca675c5cdcc1e5ce7d523948b9
Reviewed-on: https://go-review.googlesource.com/108985
Run-TryBot: Martin Möhrmann 
TryBot-Result: Gobot Gobot 
Reviewed-by: Josh Bleecher Snyder

runtime: simplify range expressions in tests

2018-03-12T19:58:42+00:00

Generated by running gofmt -s on the files in question.

Change-Id: If6578b150e1bfced8657196d2af01f5d36879f93
Reviewed-on: https://go-review.googlesource.com/100135
Run-TryBot: Tobias Klauser 
TryBot-Result: Gobot Gobot 
Reviewed-by: Ian Lance Taylor

runtime: add slicebytetostring benchmark

2017-03-05T05:14:08+00:00

Change-Id: I666d2c6ea8d0b54a71260809d1a2573b122865b2
Reviewed-on: https://go-review.googlesource.com/37790
Run-TryBot: Josh Bleecher Snyder 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

runtime: improve atoi implementation

2016-11-01T14:04:39+00:00

- Adds overflow checks
- Adds parsing of negative integers
- Adds boolean return value to signal parsing errors
- Adds atoi32 for parsing of integers that fit in an int32
- Adds tests

Handling of errors to provide error messages
at the call sites is left to future CLs.

Updates #17718

Change-Id: I3cacd0ab1230b9efc5404c68edae7304d39bcbc0
Reviewed-on: https://go-review.googlesource.com/32390
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Brad Fitzpatrick

runtime: speed up non-ASCII rune decoding

2016-10-17T11:25:22+00:00

Copies utf8 constants and EncodeRune implementation from unicode/utf8.

Adds a new decoderune implementation that is used by the compiler
in code generated for ranging over strings. It does not handle
ASCII runes since these are handled directly before calls to decoderune.

The DecodeRuneInString implementation from unicode/utf8 is not used
since it uses a lookup table that would increase the use of cpu caches.

Adds more tests that check decoding of valid and invalid utf8 sequences.

name                              old time/op  new time/op  delta
RuneIterate/range2/ASCII-4        7.45ns ± 2%  7.45ns ± 1%     ~     (p=0.634 n=16+16)
RuneIterate/range2/Japanese-4     53.5ns ± 1%  49.2ns ± 2%   -8.03%  (p=0.000 n=20+20)
RuneIterate/range2/MixedLength-4  46.3ns ± 1%  41.0ns ± 2%  -11.57%  (p=0.000 n=20+20)

new:
"".decoderune t=1 size=423 args=0x28 locals=0x0
old:
"".charntorune t=1 size=666 args=0x28 locals=0x0

Change-Id: I1df1fdb385bb9ea5e5e71b8818ea2bf5ce62de52
Reviewed-on: https://go-review.googlesource.com/28490
Run-TryBot: Martin Möhrmann 
TryBot-Result: Gobot Gobot 
Reviewed-by: Brad Fitzpatrick

cmd/compile: intrinsify slicebytetostringtmp when not instrumenting

2016-09-14T21:58:14+00:00

when not instrumenting:
- Intrinsify uses of slicebytetostringtmp within the runtime package
  in the ssa backend.
- Pass OARRAYBYTESTRTMP nodes to the compiler backends for lowering
  instead of generating calls to slicebytetostringtmp.

name                    old time/op  new time/op  delta
ConcatStringAndBytes-4  27.9ns ± 2%  24.7ns ± 2%  -11.52%  (p=0.000 n=43+43)

Fixes #17044

Change-Id: I51ce9c3b93284ce526edd0234f094e98580faf2d
Reviewed-on: https://go-review.googlesource.com/29017
Run-TryBot: Martin Möhrmann 
TryBot-Result: Gobot Gobot 
Reviewed-by: Keith Randall