If slice cap is not set, it will be equal to slice len. So
isSmallMakeSlice only needs to check whether slice cap is constant.
While at it, also add test to make sure panicmakeslicecap is called
when make slice contains invalid non-constant len.
For this benchmark:
func BenchmarkMakeSliceNonConstantLen(b *testing.B) {
len := 1
for i := 0; i < b.N; i++ {
s := make([]int, len, 2)
_ = s
}
}
Result compare with parent:
name old time/op new time/op delta
MakeSliceNonConstantLen-12 18.4ns ± 1% 0.2ns ± 2% -98.66% (p=0.008 n=5+5)
Fixes#37975
Change-Id: I4bc926361bc2ffeab4cfaa888ef0a30cbc3b80e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/226278
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
In CL 187657, I refactored constant conversion logic without realizing
that conversions between int/float and complex types are allowed for
constants (assuming the constant values are representable by the
destination type), but are never allowed for non-constant expressions.
This CL expands convertop to take an extra srcConstant parameter to
indicate whether the source expression is a constant; and if so, to
allow any numeric-to-numeric conversion. (Conversions of values that
cannot be represented in the destination type are rejected by
evconst.)
Fixes#38117.
Change-Id: Id7077d749a14c8fd910be38da170fa5254819f2b
Reviewed-on: https://go-review.googlesource.com/c/go/+/226197
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Make sure we write the entire address range we are asked to write,
with no holes between the blocks or at the end.
Should fix NetBSD build.
Change-Id: I13b1f551377cbc4bcde3650417ac95cba62ff807
Reviewed-on: https://go-review.googlesource.com/c/go/+/226617
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
URLs in GOPROXY may now be separated with commas (,) or pipes (|). If
a request to a proxy fails with any error (including connection errors
and timeouts) and the proxy URL is followed by a pipe, the go command
will try the request with the next proxy in the list. If the proxy is
followed by a comma, the go command will only try the next proxy if
the error a 404 or 410 HTTP response.
The go command will determine how to connect to the checksum database
using the same logic. Before accessing the checksum database, the go
command sends a request to <proxyURL>/sumdb/<sumdb-name>/supported.
If a proxy responds with 404 or 410, or if any other error occurs and
the proxy URL in GOPROXY is followed by a pipe, the go command will
try the request with the next proxy. If all proxies respond with 404
or 410 or are configured to fall back on errors, the go command will
connect to the checksum database directly.
This CL does not change the default value or meaning of GOPROXY.
Fixes#37367
Change-Id: I35dd218823fe8cb9383e9ac7bbfec2cc8a358748
Reviewed-on: https://go-review.googlesource.com/c/go/+/226460
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
For reasons unknown, SIGUSR1 appears to be blocked at process start
for tests on the android-arm-corellium and android-arm64-corellium
builders. (This has been observed before, too: see CL 203957.)
Make the test resilient to blocked signals by always calling Notify
and waiting for potential signal delivery after sending any signal
that is not known to be unblocked.
Also remove the initial SIGWINCH signal from testCancel. The behavior
of an unhandled SIGWINCH is already tested in TestStop, so we don't
need to re-test that same case: waiting for an unhandled signal takes
a comparatively long time (because we necessarily don't know when it
has been delivered), so this redundancy makes the overall test binary
needlessly slow, especially since it is called from both TestReset and
TestIgnore.
Since each signal is always unblocked while we have a notification
channel registered for it, we don't need to modify any other tests:
TestStop and testCancel are the only functions that send signals
without a registered channel.
Fixes#38165
Updates #33174
Updates #15661
Change-Id: I215880894e954b62166024085050d34323431b63
Reviewed-on: https://go-review.googlesource.com/c/go/+/226461
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In CL 223019, I reduced the short timeout in the testLayers helper to
be even shorter than it was. That exposed a racy (time-dependent)
select later in the function, which failed in one of the slower
builders (android-386-emu).
Also streamline the test to make it easier to test with a very high -count flag:
- Run tests that sleep for shortDuration in parallel to reduce latency.
- Use shorter durations in examples to reduce test running time.
- Avoid mutating global state (in package math/rand) in testLayers.
After this change (but not before it),
'go test -run=TestLayersTimeout -count=100000 context' passes on my workstation.
Fixes#38161
Change-Id: Iaf4abe7ac308b2100d8828267cda9f4f8ae4be82
Reviewed-on: https://go-review.googlesource.com/c/go/+/226457
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Per RFC 8017, reject signatures which are not the same length as the RSA
modulus. This matches the behavior of SignPKCS1v15 which properly left pads
the signatures it generates to the size of the modulus.
Fixes#21896
Change-Id: I2c42a0b24cf7fff158ece604b6f0c521a856d932
GitHub-Last-Rev: 6040f79906
GitHub-Pull-Request: golang/go#38140
Reviewed-on: https://go-review.googlesource.com/c/go/+/226203
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This reverts CL 212767.
Reason for revert: new test is persistently failing on freebsd-arm64-dmgk builder.
Change-Id: Ifd1227628e0e747688ddb4dc580170b2a103a89e
Reviewed-on: https://go-review.googlesource.com/c/go/+/226597
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Now concurrent relocsym may access symbols attributes
concurrently, causing data race when using the race detector. I
think it is still safe as we read/write on different bits, and
not write the same symbol's attributes from multiple goroutines,
so it will always reads the right value regardless whether the
write happens before or after, as long as the memory model is not
so insane.
Use atomic accesses to appease the race detector. It doesn't seem
to cost much, at least on x86.
Change-Id: I2bfc3755ee59c87ed237d508f29d6172fa976392
Reviewed-on: https://go-review.googlesource.com/c/go/+/226368
Reviewed-by: Austin Clements <austin@google.com>
Implement various branch pseudo-instructions for riscv64. These make it easier
to read/write assembly and will also make it easier for the compiler to generate
optimised code.
Change-Id: Ic31a7748c0e1495522ebecf34b440842b8d12c04
Reviewed-on: https://go-review.googlesource.com/c/go/+/226397
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Use explicit names for the error code returned by pollReset
and pollWait, rather than just 0, 1, 2, 3.
Change-Id: I0ab12cae57693deab7cca9cdd2fadd597e23a956
Reviewed-on: https://go-review.googlesource.com/c/go/+/226537
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Recently, the gVisor project needs an instruction's address
with 128 bytes alignment and a function's start address with
2K bytes alignment to fit the architecture requirement for
interrupt table.
This patch allows aligning the address of an instruction to be
aligned to a specific value (2^n and not higher than 2048) and
the address of a function to be 2048 bytes.
The main changes include:
1. Adds ALIGN2048 flag to align a function's address with
2048 bytes.
e.g. "TEXT ·Add(SB),NOSPLIT|ALIGN2048" indicates that the
address of Add function should be aligned to 2048 bytes.
2. Adds a new element in the FuncInfo structure defined in
cmd/internal/obj/link.go file to record the alignment
information.
3. Adds a new element in the Func structure defined in
cmd/internal/goobj/read.go file to read the alignment
information.
4. Because go introduces a new object file format, also add
a new element in the FuncInfo structure defined in
cmd/internal/goobj2/funcinfo.go to record the alignment
information.
5. Adds the assembler support to align an intruction's offset
with a specific value (2^n and not higher than 2048).
e.g. "PCALIGN $256" indicates that the next instruction should
be aligned to 256 bytes.
This CL also adds a test.
Change-Id: I31cfa6fb5bc35dee2c44bf65913e90cddfcb492a
Reviewed-on: https://go-review.googlesource.com/c/go/+/212767
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In CL 226138, I updated TestStop to have more uniform behavior for its signals.
However, that test seems to always fail for SIGUSR1 on the Android ARM builders.
I'm not sure what's special about Android for this particular case,
but let's skip the test to unbreak the builders while I investigate.
For #38165
Updates #33174
Change-Id: I35a70346cd9757a92acd505a020bf95e6871405c
Reviewed-on: https://go-review.googlesource.com/c/go/+/226458
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We support disassembly on both ARM and ARM64. Tests are only
enabled on one or the other. This CL enables both.
Change-Id: If89d78b975c241c2b14f72b714dcdc771b4b382c
Reviewed-on: https://go-review.googlesource.com/c/go/+/226459
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Introduces a parallel OutBuf implementation, and POC on amd64. Due to
some of the weird behaviors I saw on MacOS (SIGBUS while calling msync),
I will wait for feedback to port to other architectures.
On my mac, sped up Asmb by ~78% for cmd/compile (below). Will likely
have an appreciable speedup on kubelet benchmark.
Asmb 39.1ms ±11% 8.5ms ±10% -78.17% (p=0.000 n=10+9)
TotalTime 596ms ± 2% 577ms ± 8% -3.07% (p=0.034 n=8+10)
Change-Id: Id2a2577c3f4da155d8dccc862897f43b941877ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/223742
Run-TryBot: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
zeroUpper32Bits wasn't checking for shift-extension ops. This would not
check shifts that were marking as bounded by prove (normally, shifts
are wrapped in a sequence that ends with an ANDL, and zeroUpper32Bits
would see the ANDL).
This produces no changes on generated output right now, but will be
important once CL196679 lands because many shifts will be marked
as bounded, and lower will stop generating the masking code sequence
around them.
Change-Id: Iaea94acc5b60bb9a5021c9fb7e4a1e2e5244435e
Reviewed-on: https://go-review.googlesource.com/c/go/+/226338
Reviewed-by: Keith Randall <khr@golang.org>
Reorganize the linker phase ordering so that addexport() runs before
loadlibfull. In previous CLs addexport() was changed to use loader
APIs but then copy back its work into sym.Symbol, so this change
removes the copying/shim code in question.
Change-Id: I17314a90007909e6242ee00e26393f3e4a02cf25
Reviewed-on: https://go-review.googlesource.com/c/go/+/226362
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
CL 181857 broke the translation of certain C types using cmd/cgo -godefs
because it stores each typedef, array and qualified type with their
parent type name in the translation cache.
Fix this by only considering the parent type for typedefs of anonymous
structs which is the only case where types might become ambiguous.
Updates #31891Fixes#37479Fixes#37621
Change-Id: I301a749ec89585789cb0d213593bb8b7341beb88
Reviewed-on: https://go-review.googlesource.com/c/go/+/226341
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Add some new loader.Sym equivalents to the archSyms struct so that we
can run setArchSyms earlier in the pipeline, and add a "mode" to
setArchSyms to control whether it should create loader.Sym symbols or
their *sym.Symbol equivalents.
These change needed for a subsequent patch in which addexport() is run
earlier as well
Change-Id: I0475c9388c39f13e045dd4aa9c90eaec42624810
Reviewed-on: https://go-review.googlesource.com/c/go/+/226361
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Add support for migrating over the symbol Dynid property
when converting loader.Sym symbols to sym.Symbol.
Change-Id: Icc3b91b4adcae6f2ede7d915bb674cc206025217
Reviewed-on: https://go-review.googlesource.com/c/go/+/226360
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Use a uniform function (named “quiesce”) to wait for possible signals
in a way that gives the kernel many opportunities to deliver them.
Simplify channel usage and concurrency in stress tests.
Use (*testing.T).Deadline instead of parsing the deadline in TestMain.
In TestStop, sleep forever in a loop if we expect the test to die from
a signal. That should reduce the flakiness of TestNohup, since
TestStop will no longer spuriously pass when run as a subprocess of
TestNohup.
Since independent signals should not interfere, run the different
signals in TestStop in parallel when testing in short mode.
Since TestNohup runs TestStop as a subprocess, and TestStop needs to
wait many times for signals to quiesce, run its test subprocesses
concurrently and in short mode — reducing the latency of that test by
more than a factor of 2.
The above two changes reduce the running time of TestNohup on my
workstation to ~345ms, making it possible to run much larger counts of
the test in the same amount of wall time. If the test remains flaky
after this CL, we can spend all or part of that latency improvement on
a longer settle time.
Updates #33174
Change-Id: I09206f213d8c1888b50bf974f965221a5d482419
Reviewed-on: https://go-review.googlesource.com/c/go/+/226138
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Make sure we don't use the rewrite ptr + (c + x) -> c + (ptr + x), as
that may create an ephemeral out-of-bounds pointer.
I have not seen an actual bug caused by this yet, but we've seen
them in the 386 port so I'm fixing this issue for amd64 as well.
The load-combining rules needed to be reworked somewhat to still
work without the above broken rule.
Update #37881
Change-Id: I8046d170e89e2035195f261535e34ca7d8aca68a
Reviewed-on: https://go-review.googlesource.com/c/go/+/226437
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This gives some small speedup:
(linking cmd/compile)
Loadlibfull 77.8ms ± 6% 68.6ms ± 5% -11.88% (p=0.008 n=5+5)
Also convert some Relocs.At to At2, which should have been done
earlier.
Change-Id: I2a66aeb5857234c6e645e1b23380149cffc8221f
Reviewed-on: https://go-review.googlesource.com/c/go/+/226363
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This adds support for the -gnu option on Go objdump. When
this option is used, then output will include gnu
assembly in comments alongside the Go assembly.
The objdump test was updated to test this new option.
This option is supported for the arches found in
golang.org/x that provide the GNUsyntax function.
Updates #34372
Change-Id: I9e60e1691526607dda3c857c4564dcef408b8391
Reviewed-on: https://go-review.googlesource.com/c/go/+/225459
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Currently there are a few sanity checks in the page allocator which
should fail immediately but because it's a check for a negative number
on a uint, it's actually dead-code.
If there's a bug in the page allocator which would cause the sanity
check to fail, this could cause memory corruption by returning an
invalid address (more precisely, one might either see a segfault, or
span overlap).
This change fixes these sanity checks to check the correct condition.
Fixes#38130.
Change-Id: Ia19786cece783d39f26df24dec8788833a6a3f21
Reviewed-on: https://go-review.googlesource.com/c/go/+/226297
Reviewed-by: Giovanni Bajo <rasky@develer.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When using the new(old) linker but an old(new) object file is
found, give a better error message.
Change-Id: I94786f1a4b527c15c4f5b00457eab60d215a72a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/225457
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
The type annotation of some trim functions are inconsistent with all
other function signatures of the strings package.
Example:
func TrimRight(s string, cutset string) string
To be:
func TrimRight(s, cutset string) string
Change-Id: I456a33287bfb4ad6a7962e30a6424f209ac320c1
Reviewed-on: https://go-review.googlesource.com/c/go/+/226339
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Previously, details about the underlying fetch error
were not visible in the net/http error text:
net/http: fetch() failed: <object>
When using the message property, they are:
net/http: fetch() failed: Failed to fetch
net/http: fetch() failed: The user aborted a request.
Reference: https://developer.mozilla.org/en-US/docs/Web/API/DOMException/message.
Change-Id: Iecf7c6bac01abb164731a4d5c9af6582c250a1a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/226205
Reviewed-by: Johan Brandhorst <johan.brandhorst@gmail.com>
This addresses comments made by Russ after
https://golang.org/cl/174122 was merged. It addes a test
for the connection validator and renames the interface to just
"Validator".
Change-Id: Iea53e9b250c9be2e86e9b75906e7353e26437c5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/223963
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Add accessor methods to get at the symbol {plt,got} value for
PE symbols. Fix a bug in the loaders SetPlt/SetGot methods.
Change-Id: I975bd6b86122622b206487c8798f8290ecd25a57
Reviewed-on: https://go-review.googlesource.com/c/go/+/225199
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Go build scripts on UNIX (make.bash, all.bash) have not required
GOROOT_BOOTSTRAP since August 2017 (CL 57753). Windows build scripts
have followed suit since CL 96455. Most people building Go will have
a Go toolchain in their PATH and will not need to specify a different
toolchain.
This CL removes the GOROOT_BOOTSTRAP mention from the contribution guide
(it was there for Windows only, but it's not required anymore). The guide
is meant to be light and clear for beginners and is not supposed to be
a reference, so there's not need to keep mentioning GOROOT_BOOTSTRAP.
Also update install-source.html to reflect the current status quo,
where using the PATH is probably the first and most used default, and
GOROOT_BOOTSTRAP is just an option.
Change-Id: Iab453e61b0c749c256aaaf81ea9b2ae58822cb89
Reviewed-on: https://go-review.googlesource.com/c/go/+/224717
Run-TryBot: Giovanni Bajo <rasky@develer.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Instead of calling netpollwakeup, just do the write in netpollBreak.
Use the same signaling we now use in other netpollBreak instances.
Change-Id: I53a65c22862ecc8484aee91d0e1ffb21a9e62d8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/226199
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Removes two variables:
- days which is unused, and similar usage provided by longDayNames
- months in favour of using longMonthNames
Fixes#36359
Change-Id: I51b6b7408db9359c658462ba73e59ed432f655a6
GitHub-Last-Rev: 778d3ea157
GitHub-Pull-Request: golang/go#36372
Reviewed-on: https://go-review.googlesource.com/c/go/+/213177
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This reverts CL 225618.
This is causing TestNetpollBreak to fail on AIX more often than not.
Change-Id: Ia3c24041ead4b320202f7f5b17a6b286f639a689
Reviewed-on: https://go-review.googlesource.com/c/go/+/226198
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
add dark mode to CFGs in the ssa.html output by targeting individual
parts of each svg and applying dark mode styles to the stroke & fill.
Fixes#37767
Change-Id: Ic867e161c6837c26d9d735ea02bc94fdb56102f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/222877
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Simplify the printing of PackageErrors by pushing and popping packages
from the import stack when creating the error, rather than when printing
the error. In some cases, we don't have the same amount of information
to recreate the exact error, so we'll print the name of the package
the error is for, even when it's redundant. In the case of import cycle
errors, this change results in the addition of the position information
of the error.
This change supercedes CLs 220718 and 217106. It introduces a simpler
way to format errors.
Fixes#36173
Change-Id: Ie27011eb71f82e165ed4f9567bba6890a3849fc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/224660
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
netpollBreak calls netpollwakeup, and netpollwakeup expects the mtxpoll
lock to be held, so that it has exclusive access to pendingUpdates.
Not acquiring the lock was a mistake in CL 171824. Fortunately it
rarely matters in practice.
Change-Id: I32962ec2575c846ef3d6a91a4d821b2ff02d983c
Reviewed-on: https://go-review.googlesource.com/c/go/+/225618
Reviewed-by: Michael Knyszek <mknyszek@google.com>
On linux-386 builders run the TestExtraFiles subprocess under strace,
in hopes of finding out where the unexpected descriptor is coming from.
For #25628
Change-Id: I9a62d6a5192a076525a616ccc71de74bbe7ebd58
Reviewed-on: https://go-review.googlesource.com/c/go/+/225799
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Retrying CL 222782, with a fix that will hopefully stop the random crashing.
The issue with the previous CL is that it does pointer arithmetic
in a way that may briefly generate an out-of-bounds pointer. If an
interrupt happens to occur in that state, the referenced object may
be collected incorrectly.
Suppose there was code that did s[x+c]. The previous CL had a rule
to the effect of ptr + (x + c) -> c + (ptr + x). But ptr+x is not
guaranteed to point to the same object as ptr. In contrast,
ptr+(x+c) is guaranteed to point to the same object as ptr, because
we would have already checked that x+c is in bounds.
For example, strconv.trim used to have this code:
MOVZX -0x1(BX)(DX*1), BP
CMPL $0x30, AL
After CL 222782, it had this code:
LEAL 0(BX)(DX*1), BP
CMPB $0x30, -0x1(BP)
An interrupt between those last two instructions could see BP pointing
outside the backing store of the slice involved.
It's really hard to actually demonstrate a bug. First, you need to
have an interrupt occur at exactly the right time. Then, there must
be no other pointers to the object in question. Since the interrupted
frame will be scanned conservatively, there can't even be a dead
pointer in another register or on the stack. (In the example above,
a bug can't happen because BX still holds the original pointer.)
Then, the object in question needs to be collected (or at least
scanned?) before the interrupted code continues.
This CL needs to handle load combining somewhat differently than CL 222782
because of the new restriction on arithmetic. That's the only real
difference (other than removing the bad rules) from that old CL.
This bug is also present in the amd64 rewrite rules, and we haven't
seen any crashing as a result. I will fix up that code similarly to
this one in a separate CL.
Update #37881
Change-Id: I5f0d584d9bef4696bfe89a61ef0a27c8d507329f
Reviewed-on: https://go-review.googlesource.com/c/go/+/225798
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
