Added documentation that explains special cases for vendored packages
in the standard library and provides instructions for updating vendor
directories.
Fixes#31806
Change-Id: Ib697ed18eae28023ab0bfb9f4d250992c393571d
Reviewed-on: https://go-review.googlesource.com/c/go/+/174999
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Renaming the method makes clear, both to readers and to vet,
that this method is not the implementation of io.Seeker:
it cannot fail.
Working toward making the tree vet-safe instead of having
so many exceptions in cmd/vet/all/whitelist.
For #31916.
Change-Id: I3e6ad7264cb0121b4b76935450cccb71d533e96b
Reviewed-on: https://go-review.googlesource.com/c/go/+/176108
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This change makes it so that during scavenging we split spans when the
span we have next for scavenging is larger than the amount of work we
have left to do.
The purpose of this change is to improve the worst-case behavior of the
scavenger: currently, if the scavenger only has a little bit of work to
do but sees a very large free span, it will scavenge the whole thing,
spending a lot of time to get way ahead of the scavenge pacing for no
reason.
With this change the scavenger should follow the pacing more closely,
but may still over-scavenge by up to a physical huge page since the
splitting behavior avoids breaking up huge pages in free spans.
This change is also the culmination of the scavenging improvements, so
we also include benchmark results for this series (starting from
"runtime: merge all treaps into one implementation" until this patch).
This patch stack results in average and peak RSS reductions (up to 11%
and 7% respectively) for some benchmarks, with mostly minimal
performance degredation (3-4% for some benchmarks, ~0% geomean). Each of
these benchmarks was executed with GODEBUG=madvdontneed=1 on Linux; the
performance degredation is even smaller when MADV_FREE may be used, but
the impact on RSS is much harder to measure. Applications that generally
maintain a steady heap size for the most part show no change in
application performance.
These benchmarks are taken from an experimental benchmarking suite
representing a variety of open-source Go packages, the raw results may
be found here:
https://perf.golang.org/search?q=upload:20190509.1
For #30333.
Change-Id: I618a48534d2d6ce5f656bb66825e3c383ab1ffba
Reviewed-on: https://go-review.googlesource.com/c/go/+/175797
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This change adds a background scavenging goroutine whose pacing is
determined when the heap goal changes. The scavenger is paced to use
at most 1% of the mutator's time for most systems. Furthermore, the
scavenger's pacing is computed based on the estimated number of
scavengable huge pages to take advantage of optimizations provided by
the OS.
The purpose of this scavenger is to deal with a shrinking heap: if the
heap goal is falling over time, the scavenger should kick in and start
returning free pages from the heap to the OS.
Also, now that we have a pacing system, the credit system used by
scavengeLocked has become redundant. Replace it with a mechanism which
only scavenges on the allocation path if it makes sense to do so with
respect to the new pacing system.
Fixes#30333.
Change-Id: I6203f8dc84affb26c3ab04528889dd9663530edc
Reviewed-on: https://go-review.googlesource.com/c/go/+/142960
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change removes the periodic scavenger which goes over every span
in the heap and scavenges it if it hasn't been used for 5 minutes. It
should no longer be necessary if we have background scavenging
(follow-up).
For #30333.
Change-Id: Ic3a1a4e85409dc25719ba4593a3b60273a4c71e0
Reviewed-on: https://go-review.googlesource.com/c/go/+/143157
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Fixes build - I did not understand that vetall was
effectively pinned to a vet version by cmd/go.mod.
Change-Id: I56bfd8f62eadacc97cad0ed48e41a178bbc18b8f
Reviewed-on: https://go-review.googlesource.com/c/go/+/176179
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When targeting iOS, change the format (DWARF "form") of the call line
attribute for inlined subroutine DIEs, to work around an apparent bug
in /usr/bin/symbols on Darwin.
[Just for posterity: there is nothing wrong with using DW_FORM_udata
for the call_line attribute form; this is perfectly legal DWARF (and
is in fact recommended by the standard relative to data4, which is
less descriptive and often takes more space). The form switch is there
just to make the Apple tools happy.]
Updates #31459.
Change-Id: Iaf362788a8c6684eea4cde8956c0661b694cecc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/174538
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
The vetall builder runs vet straight out of golang.org/x/tools,
so submiting CL 176097 in that repo will break the builder
by making all these whitelist entries stale.
Submiting this CL will fix it, by removing them.
The addition of the gcWriteBarrier declaration in runtime/stubs.go
is necessary because the diagnostic is no longer emitted on arm,
so it must be removed from all.txt. Adding it to runtime is better
than adding it to every-other-goarch.txt.
For #31916.
Change-Id: I432f6049cd3ee5a467add5066c440be8616d9d54
Reviewed-on: https://go-review.googlesource.com/c/go/+/176177
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This seems to deflake the test, and also allows testing
on macOS.
Fixes#31786.
Change-Id: I10bfba46dd4b8e64cb09fdd4dd9d175c1ce1f022
Reviewed-on: https://go-review.googlesource.com/c/go/+/176058
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
In CL 173938, the linker's object file reader was switched over to
selectively create strings backed with read-only mmap'd memory.
In the process a call to r.rd.Offset() was added to readSymName(),
which greatly increased the number of system calls (Offset does a
seek system call).
This patch changes the object file reader so that all reads are done
directly from the mmap'd data if it is present, and adds logic to keep
track of the offset within the rodata consumed so far. Doing this gets
rid of the calls to r.rd.Offset() and the corresponding seek system
calls.
Also as part of this change, hoist the calls to objabi.PathToPrefix
up into the initial setup code for object reading, and store the
result in the reader (since objabi.PathToPrefix was also coming up
as hot in the profile).
Numbers for this change from compilebench:
benchmark old ns/op new ns/op delta
BenchmarkTemplate 172053975 170357597 -0.99%
BenchmarkUnicode 64564850 64333653 -0.36%
BenchmarkGoTypes 627931042 628043673 +0.02%
BenchmarkCompiler 2982468893 2924575043 -1.94%
BenchmarkSSA 9701681721 9799342557 +1.01%
BenchmarkFlate 106847240 107509414 +0.62%
BenchmarkGoParser 132082319 130734905 -1.02%
BenchmarkReflect 386810586 383036621 -0.98%
BenchmarkTar 154360072 152670594 -1.09%
BenchmarkXML 217725693 216858727 -0.40%
BenchmarkLinkCompiler 908813802 734363234 -19.20%
BenchmarkStdCmd 32378532486 31222542974 -3.57%
Fixes#31898.
Change-Id: Ibf253a52ce9213325f42b1c2b20d0410f5c88c3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/176039
Reviewed-by: Cherry Zhang <cherryyz@google.com>
f+0(SB) is a non-standard but acceptable alias for f(SB).
Fixes#30968.
Change-Id: I499ccee4d3ff3ab4e47f75d99407aace858e59aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/174537
Reviewed-by: Austin Clements <austin@google.com>
The most common failure mode of the current std/cmd setup is
going to be people running "go get m@latest" and then not running
"go mod vendor" and being confused about getting the old m.
Diagnose and report what to do.
Also, having done the check, when in the standard library,
switch the go command to -mod=vendor mode.
This avoids some network accesses I saw when running
'go clean -modcache' before doing some work in cmd.
Change-Id: I0ba4a66637b67225a9b97a1c89f26f9015b41673
Reviewed-on: https://go-review.googlesource.com/c/go/+/174528
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
And use it in two internal windows packages, so they don't show up in
"go list std" or binary releases on non-Windows platforms.
Fixes#31920
Change-Id: Iaa292b6015c9d7310dd677c9e296006440ba5e27
Reviewed-on: https://go-review.googlesource.com/c/go/+/175983
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
noteRule is useful when you're trying to debug
a particular rule, or get a general sense for
how often a rule fires overall.
It is less useful if you're trying to figure
out which functions might be useful to benchmark
to ascertain the impact of a newly added rule.
Enter countRule. You use it like noteRule,
except that you get per-function summaries.
Sample output:
# runtime
(*mspan).sweep: idx1=1
evacuate_faststr: idx1=1
evacuate_fast32: idx1=1
evacuate: idx1=2
evacuate_fast64: idx1=1
sweepone: idx1=1
purgecachedstats: idx1=1
mProf_Free: idx1=1
This suggests that the map benchmarks
might be good to run for this added rule.
Change-Id: Id471c3231f1736165f2020f6979ff01c29677808
Reviewed-on: https://go-review.googlesource.com/c/go/+/167088
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
compilebench depends on the legacy heap profile format to read the
allocation stats of build tools. We're adding a benchmark for the
linker to compilebench, so we need the linker to emit the heap profile
in the legacy format.
This is the linker equivalent of CL 35484, which did this for the
compiler.
Change-Id: I16ad60c4f0fd80b4b6d608a5677ebe04e1fb5e5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/176057
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When running go build with the flag -mod=readonly, it fails the build if
go.sum files requires updating. This ensures that CI/CD systems get a
complete go.sum file so that they'd never hit a notary,
assuming the CI/CD system passes the above flag.
I am not familiar with the entire codebase but I assume goSum.dirty
will always be true if go.sum has any missing lines.
Fixes#30667
Change-Id: I767d3b594055d8c10048f4c68e6687c94bb0545c
Reviewed-on: https://go-review.googlesource.com/c/go/+/166237
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In IDE-like applications (and also in tests), there is often a need to
type-check an expression as if it appeared at a particular position in
the source code of an already typed-checked package.
Eval was added to address this need, but did so only partially,
stopping short of exposing a type-annotated expression tree. This
makes it impossible to resolve an expression such as new(T).x and
discover what Object x refers to. CheckExpr exposes that generality.
Eval is now implemented in terms of CheckExpr.
This change includes a test that demonstrates the object resolution
functionality just described.
Historical context:
- https://go-review.googlesource.com/c/tools/+/10800
- https://codereview.appspot.com/10748044/
Change-Id: I715ba934b9fc0c9ceb61270e20c5f91f4eff20c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/144677
Run-TryBot: Alan Donovan <adonovan@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Currently we say that a negative index means no match,
but we don't say how "no match" is expressed when 'Index'
is not present. Say how it is expressed.
Change-Id: I82b6c9038557ac49852ac03642afc0bc545bb4a2
Reviewed-on: https://go-review.googlesource.com/c/go/+/175677
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The compiler output shown in the doc is now quite old
(most of the changes happened in Go 1.5).
Update it to be more like what users will actually see.
Also explain how to get literal machine code again.
Prompted by #30968.
Change-Id: I0ce139c3fe299ccc43e85b6aca81c6e0aac1a2df
Reviewed-on: https://go-review.googlesource.com/c/go/+/175757
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Gccgo's implementation of direct interface types has bugs that
causes reflect Call of method from Type.Method fail. CL 175837
and CL 175798 fix the bug. This CL adds a test.
Change-Id: I4e5f2cb96304c1ac7be04ca6d2851bac52b8eb24
Reviewed-on: https://go-review.googlesource.com/c/go/+/175880
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The PNG decode path attempts to handle paletted images that refer to
non-existent palette indicies. This PR fixes a corner case were images
that have exactly 255 palette colors and an IDAT chunk that references
palette index 255 produce an invalid image such that invoking At on
the pixel(s) in question causes an index out of range panic.
Fixes#31830
Change-Id: I34c44d9de5b9d76fe8c45c04e866fbc7f51f2a9c
Reviewed-on: https://go-review.googlesource.com/c/go/+/175397
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
For the case where the addresses of parameter z and x of the function
shlVU overlap and the address of z is greater than x, x (input value)
can be polluted during the calculation when the high words of x are
overlapped with the low words of z (output value).
Fixes#31084
Change-Id: I9bb0266a1d7856b8faa9a9b1975d6f57dece0479
Reviewed-on: https://go-review.googlesource.com/c/go/+/169780
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This change is a simple work-around to avoid a compiler crash
and provide a reasonable error message. A future change should
fix the root cause for this problem.
Fixes#23823.
Change-Id: Ifc80d9f4d35e063c378e54d5cd8d1cf4c0d2ec6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/175518
Reviewed-by: Ian Lance Taylor <iant@golang.org>
I assume this was for debugging purposes.
Updates #31624
Change-Id: Ie158fde0574c9bbbd9d1b684f51af5681974aff7
Reviewed-on: https://go-review.googlesource.com/c/go/+/175449
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Followup to CL 157961 and CL 158457.
Finish the list of operators and punctuation
that disable semicolon insertion at end-of-line
The reported case was "(" but "." was also missing.
Fixes#31017.
Change-Id: I0c06443f38dc8250c62e3aadd104abfa0e3be074
Reviewed-on: https://go-review.googlesource.com/c/go/+/174524
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The crypto/tls and crypto/x509 APIs leak PublicKey and PrivateKey types,
so in order to add support for Ed25519 certificates we need the ed25519
package in the stdlib.
It's also a primitive that's reasonable to use directly in applications,
as it is a modern, safe and fast signing algorithm, for which there
aren't higher level APIs. (The nacl/sign API is limiting in that it
repeats the message.)
A few docs changes will come in a follow-up, and a CL will land on
golang.org/x/crypto/ed25519 to make it a type alias wrapper on Go 1.13+.
Updates #25355
Change-Id: I057f20cc7d1aca2b95c29ce73eb03c3b237e413f
Reviewed-on: https://go-review.googlesource.com/c/go/+/174945
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
Even with 10 shards on builders, it still takes about ~2.5 minutes per
shard (and getting slower all the time as the test/ directory grows).
I'm currently experimenting with massively sharding out testing on
Cloud Run (each dist test & normal TestFoo func all running in
parallel), and in such a setup, 2.5 minutes is an eternity. I'd like
to increase that dist test's sharding from 10 to more like 1,000.
Updates golang/go#31834
Change-Id: I8b02989727793b5b5b2013d67e1eb01ef4786e28
Reviewed-on: https://go-review.googlesource.com/c/go/+/175297
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Most changes are removing redundant declaration of type when direct
instantiating value of map or slice, e.g. []T{T{}} become []T{{}}.
Small changes are removing the high order of subslice if its value
is the length of slice itself, e.g. T[:len(T)] become T[:].
The following file is excluded due to incompatibility with go1.4,
- src/cmd/compile/internal/gc/ssa.go
Change-Id: Id3abb09401795ce1e6da591a89749cba8502fb26
Reviewed-on: https://go-review.googlesource.com/c/go/+/166437
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Before this CL we used to panic with "nil pointer dereference" because
the value we're calling assignTo on is the zero Value. Provide a better
error message.
Fixes#28748
Change-Id: I7dd4c9e30b599863664d91e78cc45878d8b0052e
Reviewed-on: https://go-review.googlesource.com/c/go/+/175440
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This change adds a new sysHugePage function to provide the equivalent of
Linux's madvise(MADV_HUGEPAGE) support to the runtime. It then uses
sysHugePage to mark a newly-coalesced free span as backable by huge
pages to make the freeHugePages approximation a bit more accurate.
The problem being solved here is that if a large free span is composed
of many small spans which were coalesced together, then there's a chance
that they have had madvise(MADV_NOHUGEPAGE) called on them at some point,
which makes freeHugePages less accurate.
For #30333.
Change-Id: Idd4b02567619fc8d45647d9abd18da42f96f0522
Reviewed-on: https://go-review.googlesource.com/c/go/+/173338
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Now that the treap is first-fit, we can make a nice optimization.
Mainly, since we know that span splitting doesn't modify the relative
position of a span in a treap, we can actually modify a span in-place
on the treap. The only caveat is that we need to update the relevant
metadata.
To enable this optimization, this change introduces a mutate method on
the iterator which takes a callback that is passed the iterator's span.
The method records some properties of the span before it calls into the
callback and then uses those records to see what changed and update
treap metadata appropriately.
Change-Id: I74f7d2ee172800828434ba0194d3d78d3942acf2
Reviewed-on: https://go-review.googlesource.com/c/go/+/174879
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This change tracks the number of potential free and unscavenged huge
pages which will be used to inform the rate at which scavenging should
occur.
For #30333.
Change-Id: I47663e5ffb64cac44ffa10db158486783f707479
Reviewed-on: https://go-review.googlesource.com/c/go/+/170860
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change adds two new treap iteration types: one for large
unscavenged spans (contain at least one huge page) and one for small
unscavenged spans. This allows us to scavenge the huge spans first by
first iterating over the large ones, then the small ones.
Also, since we now depend on physHugePageSize being a power of two,
ensure that that's the case when it's retrieved from the OS.
For #30333.
Change-Id: I51662740205ad5e4905404a0856f5f2b2d2a5680
Reviewed-on: https://go-review.googlesource.com/c/go/+/174399
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change introduces a treapIterFilter type which represents the
power set of states described by a treapIterType.
This change then adds a treapIterFilter field to each treap node
indicating the types of spans that live in that subtree. The field is
maintained via the same mechanism used to maintain maxPages. This allows
pred, succ, start, and end to be judicious about which subtrees it will
visit, ensuring that iteration avoids traversing irrelevant territory.
Without this change, repeated scavenging attempts can end up being N^2
as the scavenger walks over what it already scavenged before finding new
spans available for scavenging.
Finally, this change also only scavenges a span once it is removed from
the treap. There was always an invariant that spans owned by the treap
may not be mutated in-place, but with this change violating that
invariant can cause issues with scavenging.
For #30333.
Change-Id: I8040b997e21c94a8d3d9c8c6accfe23cebe0c3d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/174878
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This change modifies the treap implementation to support holding all
spans in a single treap, instead of keeping them all in separate treaps.
This improves ergonomics for nearly all treap-related callsites.
With that said, iteration is now more expensive, but it never occurs on
the fast path, only on scavenging-related paths.
This change opens up the opportunity for further optimizations, such as
splitting spans without treap removal (taking treap removal off the span
allocator's critical path) as well as improvements to treap iteration
(building linked lists for each iteration type and managing them on
insert/removal, since those operations should be less frequent).
For #30333.
Change-Id: I3dac97afd3682a37fda09ae8656a770e1369d0a9
Reviewed-on: https://go-review.googlesource.com/c/go/+/174398
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Currently, when the compiler emits a symbol name in the object
file, it uses "". for the package path of the package being
compiled. This is then expanded in the linker to the actual
package path.
With CL 173938, it does not need an allocation if the symbol name
does not need expansion. In many cases, the compiler actually
knows the package path (through the -p flag), so we could just
write it out in compile time, without fixing it up in the linker.
This reduces allocations in the linker.
In case that the package path is not known (compiler's -p flag is
missing, or the object file is generated by the assembler), the
linker still does the expansion.
This reduces ~100MB allocations (~10% inuse_space) in linking
k8s.io/kubernetes/cmd/kube-apiserver on Linux/AMD64.
Also makes the linker a little faster: linking cmd/go on
Linux/AMD64:
Real 1.13 ± 1% 1.11 ± 1% -2.13% (p=0.000 n=10+10)
User 1.17 ± 3% 1.14 ± 5% -3.14% (p=0.003 n=10+10)
Sys 0.34 ±15% 0.34 ±15% ~ (p=0.986 n=10+10)
The caveat is that the object files get slightly bigger. On
Linux/AMD64, runtime.a gets 2.1% bigger, cmd/compile/internal/ssa
(which has a longer import path) gets 2.8% bigger.
This reveals that when building an unnamed plugin (e.g.
go build -buildmode=plugin x.go), the go command passes different
package paths to the compiler and to the linker. Before this CL
there seems nothing obviously broken, but given that the compiler
already emits the package's import path in various places (e.g.
debug info), I guess it is possible that this leads to some
unexpected behavior. Now that the compiler writes the package
path in more places, this disagreement actually leads to
unresolved symbols. Adjust the go command to use the same package
path for both compiling and linking.
Change-Id: I19f08981f51db577871c906e08d9e0fd588a2dd8
Reviewed-on: https://go-review.googlesource.com/c/go/+/174657
Reviewed-by: Austin Clements <austin@google.com>
