v is pretty generic. Subsequent changes will make this function
more complicated, so rename it now, independently, for easier review.
v is the control value for the block (or its underlying phi);
call it ctl.
Passes toolstash-check.
Updates #37608
Change-Id: I3fbae3344f1c95aff0a69c1e4f61ef637a54774e
Reviewed-on: https://go-review.googlesource.com/c/go/+/222917
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit extends the -spectre flag to cmd/asm and adds
a new Spectre mitigation mode "ret", which enables the use
of retpolines.
Retpolines prevent speculation about the target of an indirect
jump or call and are described in more detail here:
https://support.google.com/faqs/answer/7625886
Change-Id: I4f2cb982fa94e44d91e49bd98974fd125619c93a
Reviewed-on: https://go-review.googlesource.com/c/go/+/222661
Reviewed-by: Keith Randall <khr@golang.org>
This commit adds a new cmd/compile flag -spectre,
which accepts a comma-separated list of possible
Spectre mitigations to apply, or the empty string (none),
or "all". The only known mitigation right now is "index",
which uses conditional moves to ensure that x86-64 CPUs
do not speculate past index bounds checks.
Speculating past index bounds checks may be problematic
on systems running privileged servers that accept requests
from untrusted users who can execute their own programs
on the same machine. (And some more constraints that
make it even more unlikely in practice.)
The cases this protects against are analogous to the ones
Microsoft explains in the "Array out of bounds load/store feeding ..."
sections here:
https://docs.microsoft.com/en-us/cpp/security/developer-guidance-speculative-execution?view=vs-2019#array-out-of-bounds-load-feeding-an-indirect-branch
Change-Id: Ib7532d7e12466b17e04c4e2075c2a456dc98f610
Reviewed-on: https://go-review.googlesource.com/c/go/+/222660
Reviewed-by: Keith Randall <khr@golang.org>
Function declarations with blank ("_") names do not introduce a binding,
and therefore cannot be referenced or executed (in fact, they do not
make it into the final compiled binary at all). As such, counters
defined while annotating their bodies will always be zero.
These types of functions are commonly used to create compile-time
checks (e.g., stringer) which are not expected to be executed.
Skip over these functions when annotating a file, preventing the unused
counters from being generated and appearing as uncovered lines in
coverage reports.
Fixes#36264
Change-Id: I6b516cf43c430a6248d68d5f483a3902253fbdab
Reviewed-on: https://go-review.googlesource.com/c/go/+/223117
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This test requires subversion to run, but does not check to see if it's
available before running as it does for git.
Call testenv.MustHaveExecPath to check beforehand to allow the test to
be skipped if the svn binary does not exist.
Change-Id: I16ae104621b221fc6e96f6c7dcd71bf406caa0c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/223082
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This does some clean up of the ppc64 opcodes to remove names
from the opcode list that don't actually assemble. At one time
names were added to this list to represent opcode "classes" to
organize other opcodes that have the same set of operand
combinations. Since this is not documented, it is confusing as
to which opcodes can be used in an asm file and which can't, and
which opcodes should be supported in the disassembler. It is
clearer for the user if the list of Go opcodes are all opcodes
that can be assembled with names that match the ppc64 opcode
where possible.
I found this when trying to use Go opcode XXLAND in an asm file
which seems like it should map to ppc64 xxland but when used it
gets this error:
go tool asm test_xxland.s
asm: bad r/r, r/r/r or r/r/r/r opcode XXLAND
asm: assembly failed
This change removes the opcodes that are only used for opcode
"classes" and fixes the case statement where they are referenced.
This also fixes XXLAND and XXPERM which are opcodes that should
assemble to their corresponding ppc64 opcode but do not.
Change-Id: I52300db6b22f7f8b3dd3491c3f35a384b943352c
Reviewed-on: https://go-review.googlesource.com/c/go/+/223138
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The timerproc function has been removed.
Fixes#37774
Change-Id: Ice5e1d8fec91cd6ee7f032e0d21e8315a26bc6a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/222783
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
Update error messages for pointer alignment checks and pointer
arithmetic checks so that each type of error has a unique error
message.
Fixes#37488
Change-Id: Ida2c2fa3f041a3307d665879a463f9e8f2c1fd03
Reviewed-on: https://go-review.googlesource.com/c/go/+/223037
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The cleantimers can run for a while in some unlikely cases.
If the GC is trying to preempt the G, it is forced to wait as the
G is holding timersLock. To avoid introducing a GC delay,
return from cleantimers if the G has a preemption request.
Fixes#37779
Change-Id: Id9a567f991e26668e2292eefc39e2edc56efa4e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/223122
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
//line bogo.go:9999999 will cause 'go tool objdump' to crash
unless bogo.go has that many lines. Guard the array index
and return innocuous values (nil, nil) from the file cache.
Fixes#36683
Change-Id: I4a9f8444dc611654d270cc876e8848dfd2f84770
Reviewed-on: https://go-review.googlesource.com/c/go/+/223081
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The previous "invalid pseudo-version: does not match version-control
timestamp" error message used a different timestamp format than the
format used in go.mod and go.sum. For cut-and-paste-ability this patch
makes the two consistent.
Fixes#36974
Change-Id: I21f344ab9898cc584c0bcf4a75d74275a703c650
Reviewed-on: https://go-review.googlesource.com/c/go/+/217437
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
In each test, either set the -n flag to avoid writing build artifacts
to the cache, or set GOCACHE explicitly to point to a clean cache.
Tested manually with 'go test -count=2 cmd/go'.
Fixes#37820
Change-Id: I24403e738b1a10d5fe9dc8d98ef27a76ebe2704a
Reviewed-on: https://go-review.googlesource.com/c/go/+/223140
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
With a clean cache on a laptop
before change
time go run run.go -- . fixedbugs
real 2m10.195s
user 3m16.547s
sys 1m52.939s
Or, before, directly after make.bash (the actual use case we care about)
time go run run.go -- . fixedbugs
real 2m8.704s
user 3m12.327s
sys 1m49.123s
after change
time go run run.go -- . fixedbugs
real 1m38.915s
user 2m38.389s
sys 1m8.490s
Tests, fortunately, still seem to pass.
Latest version of this takes the slow route for cross-compilation, which includes wasm.
Change-Id: Iad19951612defa96c4e9830bce920c5e8733834a
Reviewed-on: https://go-review.googlesource.com/c/go/+/223083
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This was missed in CL 223139. It doesn't seem to affect correctness,
but might be confusing if we need to debug the cache key.
Updates #37804
Change-Id: I979efa68381cf79a7e246581510c90a724be6cd9
Reviewed-on: https://go-review.googlesource.com/c/go/+/223144
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Offered as an alternative to CL 221380, which was more
tutorial than necessary.
Update #37344
Change-Id: Ide673b0b97983c2c2319a9311dc3d0a10567e6c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/223097
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Regenerate symkind_string.go, since it has become a bit out of date.
Change-Id: I57abf67aab8fe4e4a94fb5e45b9bc4c4005cbae3
Reviewed-on: https://go-review.googlesource.com/c/go/+/223079
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
After CL 166983, the guard for OCOMPLEX in evconst is not necessary
anymore.
Passes toolstash-check.
Change-Id: I1d4a9b447bad9ba0289fc7f997febc0e0b4167ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/214837
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
1) Introduced setLit method to uniformly set the scanner state for
literals instead of directly manipulating the scanner fields.
2) Use a local variable 'ok' to track validity of literals instead
of relying on the side-effect of error reporters setting s.bad.
More code but clearer because it is local and explicit.
3) s/litname/baseName/ and use this function uniformly, also for
escapes. Consequently we now report always "hexadecimal" and
not "hex" (in the case of invalid escapes).
4) Added TestDirectives verifying that we get the correct directive
string (even if that string contains '%').
Verified that lines/s parsing performance is unchanged by comparing
go test -run StdLib -fast -skip "syntax/(scanner|scanner_test)\.go"
before and after (no relevant difference).
Change-Id: I143e4648fdaa31d1c365fb794a1cae4bc1c3f5ba
Reviewed-on: https://go-review.googlesource.com/c/go/+/222258
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This fixes observed failures using the following steps to reproduce:
go env -w GO111MODULE=off
go test cmd/internal/moddeps
Fixes#37749
Change-Id: I7761f0b20266ac911ad19a724ba2551beca3f267
Reviewed-on: https://go-review.googlesource.com/c/go/+/222674
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Previously, we extracted module zip files to temporary directories
with random names, then renamed them to their final locations. This
failed with ERROR_ACCESS_DENIED on Windows if any file in the
temporary was open. Antivirus programs did this occasionally. Retrying
the rename did not work (CL 220978).
With this change, we extract module zip files in place. We create a
.partial file alongside the .lock file to indicate a directory is not
fully populated, and we delete this at the end of the process.
Updates #36568
Change-Id: I75c09df879a602841f3459322c021896292b2fdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/221157
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
Currently, we extract module zip files to temporary directories, then
atomically rename them into place. On Windows, this can fail with
ERROR_ACCESS_DENIED if another process (antivirus) has files open
before the rename. In CL 220978, we repeated the rename operation in a
loop over 500 ms, but this didn't solve the problem for everyone.
A better solution will extract module zip files to their permanent
locations in the cache and will keep a ".partial" marker file,
indicating when a module hasn't been fully extracted (CL 221157).
This approach is not safe if current versions of Go access the module
cache concurrently, since the module directory is detected with a
single os.Stat.
In the interim, this CL makes two changes:
1. Flaky file system operations are repeated over 2000 ms to reduce
the chance of this error occurring.
2. cmd/go will now check for .partial files created by future
versions. If a .partial file is found, it will lock the lock file,
then remove the .partial file and directory if needed.
After some time has passed and Go versions lacking this CL are no
longer supported, we can start extracting module zip files in place.
Updates #36568
Change-Id: I467ee11aa59a90b63cf0e3e761c4fec89d57d3b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/221820
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Also increase the default deadline to 5s, since it empirically
doesn't need to be short and 1s seems to be too slow on some platforms.
Fixes#37795
Change-Id: Ie6bf3916b107401235a1fa8cb0f22c4a98eb2dae
Reviewed-on: https://go-review.googlesource.com/c/go/+/222959
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
CL 213058's "bonus optimization I noticed while working on this"
turns out to be buggy. It would be correct for CMP, but not TEST.
Fix it to use TEST semantics instead.
This was breaking compilation with the upcoming Spectre mode.
Change-Id: If2d4c3798ed182f35f0244febe74e68c61e4c61b
Reviewed-on: https://go-review.googlesource.com/c/go/+/222853
Reviewed-by: Keith Randall <khr@golang.org>
The default is for later flags to override earlier ones,
so if the asmcheck set flags, it lost the important -S=2.
Change-Id: Id538254908d658da2acb55157ac4f6fa44f6a467
Reviewed-on: https://go-review.googlesource.com/c/go/+/222820
Reviewed-by: Keith Randall <khr@golang.org>
This test is flaky, and the cause is suspected to be an OpenBSD kernel bug.
Since there is no obvious workaround on the Go side, skip the test on
builders whose versions are known to be affected.
Fixes#17496
Change-Id: Ifa70061eb429e1d949f0fa8a9e25d177afc5c488
Reviewed-on: https://go-review.googlesource.com/c/go/+/222856
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
This change forces CFGs to take the full width of their column
and allows them to be as tall as necessary.
In my (recent) experience, this makes them far less likely to
be cropped, which makes them much more useful.
On rare occasions, this can lead to gigantic CFGs,
but if you've bothered to explicitly request a CFG,
this is still better than an irrevocably truncated CFG.
Change-Id: I9a649ea57fa3c2792998bb71331a2580e429b36a
Reviewed-on: https://go-review.googlesource.com/c/go/+/222618
Reviewed-by: Cherry Zhang <cherryyz@google.com>
In the open-code defer implementation, we add defer struct entries to the defer
chain on-the-fly at panic time to represent stack frames that contain open-coded
defers. This allows us to process non-open-coded and open-coded defers in the
correct order. Also, we need somewhere to be able to store the 'started' state of
open-coded defers. However, if a recover succeeds, defers will now be processed
inline again (unless another panic happens). Any defer entry representing a frame
with open-coded defers will become stale once we run the corresponding defers
inline and exit the associated stack frame. So, we need to remove all entries for
open-coded defers at recover time.
The current code was only removing the top-most open-coded defer from the defer
chain during recovery. However, with recursive functions that do repeated
panic-recover-repanic, multiple stale entries can accumulate on the chain. So, we
just adjust the loop to process the entire chain. Since this is at panic/recover
case, it is fine to scan through the entire chain (which should usually have few
elements in it, since most defers are open-coded).
The added test fails with a SEGV without the fix, because it tries to run a stale
open-code defer entry (and the stack has changed).
Fixes#37664.
Change-Id: I8e3da5d610b5e607411451b66881dea887f7484d
Reviewed-on: https://go-review.googlesource.com/c/go/+/222420
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Tighten up a testpoint that looks for the compile unit
DW_AT_go_package_name attribute. The linker code that injects this
attribute was accidentally broken on the dev.link branch, but in a way
that wasn't detected by the test (attr was generated, but always with
an empty string). The new test will fail if the attr is an empty
string, or if we can't find the attribute for the runtime package.
Change-Id: I8b065e7eb3486646364d0eaf48a73db6acffbd18
Reviewed-on: https://go-review.googlesource.com/c/go/+/218483
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
AIX, Solaris, and Illumos all appear to implement fcntl deadlock
detection at the granularity of processes. However, we are acquiring
and releasing file locks on individual goroutines running
concurrently: our locking occurs at a much finer granularity. As a
result, these platforms occasionally fail with EDEADLK errors, when
they detect locks that would be _misordered_ in a single-threaded
program but are safely _unordered_ in a multi-threaded context.
To work around the spurious errors, we treat EDEADLK as always
spurious, and retry the failing system call with a bounded exponential
backoff. This approach may introduce substantial latency since we no
longer benefit from kernel-scheduled wakeups in case of collisions,
but high-latency operations seem better than spurious failures.
Updates #33974
Updates #35618Fixes#32817
Change-Id: I58b2c6a0f143bce55d6460fd4ddc3db83577ada7
Reviewed-on: https://go-review.googlesource.com/c/go/+/222277
Reviewed-by: Jay Conrod <jayconrod@google.com>
If typehash (used by reflect) does not match the built-in map's hash,
then problems occur. If a map is built using reflect, and then
assigned to a variable of map type, the hash function can change. That
causes very bad things.
This issue is rare. MapOf consults a cache of all types that occur in
the binary before making a new one. To make a true new map type (with
a hash function derived from typehash) that map type must not occur in
the binary anywhere. But to cause the bug, we need a variable of that
type in order to assign to it. The only way to make that work is to
use a named map type for the variable, so it is distinct from the
unnamed version that MapOf looks for.
Fixes#37716
Change-Id: I3537bfceca8cbfa1af84202f432f3c06953fe0ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/222357
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Due to improved optimisation, we no longer emit SUBW for the write barrier
checks on riscv64, hence remove special handling in markUnsafePoints.
Change-Id: Ia1150c3e11f25e183735e58f8716a511d9e90fb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/222638
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This CL copies IMAGE_FILE_*, IMAGE_SUBSYSTEM_* and
IMAGE_DLLCHARACTERISTICS_* consts from cmd/link/internal/ld package.
The consts are also used in cmd/go and debug/pe tests. So avoid the
duplication.
The consts are defined in
https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
and might be useful to other Go users.
The CL also adds some related consts.
RELNOTE=yes
Change-Id: Iaa868deaffc7c61051f2273397f3e7e101880a5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/222637
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Functions that are exported through cgo will now retain their
parameter names provided that their parameter names use only
ASCII characters.
Fixes#37746
Change-Id: Ia5f643e7d872312e81c224febd1f81ce14425c32
GitHub-Last-Rev: 220959beba
GitHub-Pull-Request: golang/go#37750
Reviewed-on: https://go-review.googlesource.com/c/go/+/222619
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This change re-vendors x/tools to add the ifaceassert and stringintconv
checks to cmd/vet.
Fixes#32479.
Updates #4483.
Change-Id: I6bd30b0a3278592dfab4bd247036404ddaff09e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/221339
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Rewrite string(int) to a string literal with a NUL byte, in preparation for the vet warning.
Updates #32479.
Change-Id: If4b6879334884324df3d566b6b4166ecf501d066
Reviewed-on: https://go-review.googlesource.com/c/go/+/221338
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Use a separate compiler pass to introduce complicated x86 addressing
modes. Loads in the normal architecture rules (for x86 and all other
platforms) can have constant offsets (AuxInt values) and symbols (Aux
values), but no more.
The complex addressing modes (x+y, x+2*y, etc.) are introduced in a
separate pass that combines loads with LEAQx ops.
Organizing rewrites this way simplifies the number of rewrites
required, as there are lots of different rule orderings that have to
be specified to ensure these complex addressing modes are always found
if they are possible.
Update #36468
Change-Id: I5b4bf7b03a1e731d6dfeb9ef19b376175f3b4b44
Reviewed-on: https://go-review.googlesource.com/c/go/+/217097
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Re-vendor x/net/dns/dnsmessage, x/net/route, and github.com/google/pprof
(commit 1ebb73c). The updated dependencies fix the string(int)
conversions, in preparation for the vet warning.
Updates #32479.
Change-Id: I023a4e30415d060f8b403b9943fe911f6d19f2e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/221337
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
CL 212777 added a check to isNonNegative
to return true for unsigned values.
However, the SSA backend isn't type safe
enough for that to be sound.
The other checks in isNonNegative
look only at the pattern of bits.
Remove the type-based check.
Updates #37753
Change-Id: I059d0e86353453133f2a160dce53af299f42e533
Reviewed-on: https://go-review.googlesource.com/c/go/+/222620
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
