Pregrow buffer to reduce allocs on building cookie string.
We calc cookie name value and domain size (most distributed by value) and
add 110 extra characters allows to write most cookie attributes
without additional allocations in most cases.

name              old time/op    new time/op    delta
CookieString-4      1.65µs ± 3%    1.27µs ± 2%  -23.01%  (p=0.008 n=5+5)
ReadSetCookies-4    5.78µs ± 4%    5.67µs ± 3%     ~     (p=0.310 n=5+5)
ReadCookies-4       7.12µs ± 4%    7.04µs ± 3%     ~     (p=0.690 n=5+5)

name              old alloc/op   new alloc/op   delta
CookieString-4        360B ± 0%      144B ± 0%  -60.00%  (p=0.008 n=5+5)
ReadSetCookies-4      976B ± 0%      976B ± 0%     ~     (all equal)
ReadCookies-4       2.17kB ± 0%    2.17kB ± 0%     ~     (all equal)

name              old allocs/op  new allocs/op  delta
CookieString-4        5.00 ± 0%      1.00 ± 0%  -80.00%  (p=0.008 n=5+5)
ReadSetCookies-4      15.0 ± 0%      15.0 ± 0%     ~     (all equal)
ReadCookies-4         16.0 ± 0%      16.0 ± 0%     ~     (all equal)

Change-Id: I50defac954a135b785b3551342b00878429b3d7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/163017Reviewed-by: Volker Dobler <dr.volker.dobler@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

New test case designed to mimic the code in issue 30908, which
features duplicate but non-indentical DWARF abstract subprogram DIEs.

Updates #30908.

Change-Id: Iacb4b53e6a988e46c801cdac236cef883c553f8f
Reviewed-on: https://go-review.googlesource.com/c/go/+/168957
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

For "rundir" tests, allow users to add in linker flags as well as
compiler flags, e.g.

// rundir -m -ldflags -w

The directive above will pass "-m" to the compiler on each package compilation
and "-w" to the linker for the final link.

In addition, if "-P" is specified with 'rundir', then for each compile
pass in "-p <X>" to set the packagepath explicitly, which is closer to
how the compiler is run by 'go build'.

Change-Id: I04720011a89d1bd8dcb4f2ccb4af1d74f6a01da1
Reviewed-on: https://go-review.googlesource.com/c/go/+/168977Reviewed-by: Cherry Zhang <cherryyz@google.com>

When generating DWARF inline info records, the post-SSA code looks
through the original "pre-inline" dcl list for the function so as to
handle situations where formal params are promoted or optimized away.
This code was not properly handling the case where an output parameter
was promoted to the heap -- in this case the param node is converted
in place from class PPARAMOUT to class PAUTOHEAP. This caused
inconsistencies later on, since the variable entry in the abstract
subprogram DIE wound up as a local and not an output parameter.

Fixes #30908.

Change-Id: Ia70b89f0cf7f9b16246d95df17ad6e307228b8c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/168818Reviewed-by: Cherry Zhang <cherryyz@google.com>

go_js_wasm_exec was returning with code 0 if WebAssembly.instantiate
failed. This made failing tests show as passed.

Change-Id: Icfb2f42e9f1c3c70ca4a130a61a63cb305edff32
Reviewed-on: https://go-review.googlesource.com/c/go/+/168885
Run-TryBot: Richard Musiol <neelance@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Some WebAssembly runtimes (e.g. Node.js) fail to load a wasm binary if
it has more than 100000 data segments. Do not skip zero regions any more
if the limit was reached.

Change-Id: I14c4c2aba142d1d2b887bce6d03b8c1c1746c5ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/168884
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: I7a438409748f0f9d6517a7ea1cdee6512ce3ca8a
Reviewed-on: https://go-review.googlesource.com/c/go/+/161678
Run-TryBot: Rob Pike <r@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

The Go 1.12 introduced Writer() method for logger objects, but
it was not exposed as log package function for standard logger.
This commit adds such Writer() function.

Change-Id: Ia81b1524839fe05c152ecb5eaef047a076349fea
GitHub-Last-Rev: dc152ea641dd928178dbd921e2d0f6361661a0d6
GitHub-Pull-Request: golang/go#31009
Reviewed-on: https://go-review.googlesource.com/c/go/+/168920
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Most chars in URLs are lowercase, so check that first.

Performance change:

String-4               7.62µs ± 1%    7.27µs ± 3%  -4.61%  (p=0.008 n=5+5)
QueryEscape/#00-4      92.6ns ± 3%    90.3ns ± 1%  -2.48%  (p=0.016 n=5+5)
QueryEscape/#01-4       515ns ± 4%     510ns ± 2%    ~     (p=0.683 n=5+5)
QueryEscape/#02-4       375ns ± 1%     343ns ± 1%  -8.52%  (p=0.008 n=5+5)
QueryEscape/#03-4       758ns ± 1%     699ns ± 1%  -7.83%  (p=0.008 n=5+5)
QueryEscape/#04-4      6.06µs ± 1%    5.74µs ± 1%  -5.38%  (p=0.008 n=5+5)
PathEscape/#00-4        140ns ± 1%     135ns ± 2%  -3.85%  (p=0.008 n=5+5)
PathEscape/#01-4        511ns ± 3%     507ns ± 3%    ~     (p=0.587 n=5+5)
PathEscape/#02-4        372ns ± 1%     342ns ± 2%  -8.22%  (p=0.008 n=5+5)
PathEscape/#03-4        747ns ± 1%     685ns ± 1%  -8.30%  (p=0.008 n=5+5)
PathEscape/#04-4       5.94µs ± 1%    5.64µs ± 3%  -4.98%  (p=0.008 n=5+5)
QueryUnescape/#00-4     111ns ± 4%     110ns ± 2%    ~     (p=0.952 n=5+5)
QueryUnescape/#01-4     390ns ± 0%     391ns ± 2%    ~     (p=0.714 n=5+5)
QueryUnescape/#02-4     297ns ± 5%     295ns ± 3%    ~     (p=0.524 n=5+5)
QueryUnescape/#03-4     543ns ± 3%     556ns ± 2%  +2.39%  (p=0.032 n=5+5)
QueryUnescape/#04-4    3.23µs ± 3%    3.22µs ± 2%    ~     (p=1.000 n=5+5)
PathUnescape/#00-4      111ns ± 1%     110ns ± 3%    ~     (p=0.881 n=5+5)
PathUnescape/#01-4      389ns ± 2%     386ns ± 2%    ~     (p=0.444 n=5+5)
PathUnescape/#02-4      297ns ± 1%     295ns ± 3%    ~     (p=0.738 n=5+5)
PathUnescape/#03-4      557ns ± 3%     553ns ± 2%    ~     (p=0.810 n=5+5)
PathUnescape/#04-4     2.94µs ± 2%    2.97µs ± 2%    ~     (p=0.222 n=5+5)

Change-Id: I7e6d64cd5f8f5218cb40f52f0015168a8674aabb
Reviewed-on: https://go-review.googlesource.com/c/go/+/168883Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

TestScript executes PowerShell. And PowerShell appears to require
WINDIR environment variable to exists on windows-arm.

So keep WINDIR environment variable when running PowerShell.

Fixes #30711

Change-Id: I14dde6614347325a8f3caf994ea8ab05294450a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/168859
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

lexSpace consumed all spaces, even if the last one was part of a right
delimiter like " -}}". Thus, "3  -}}" wouldn't lex as "3" and a right
delimiter, but as "3", "-", and "}}".

To fix that, make lexSpace stop if it encounters a right delimiter.

Fixes #30948.

Change-Id: I80a5546e5809e54f6823e2bf3a57a7e8808329be
Reviewed-on: https://go-review.googlesource.com/c/go/+/168457Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

This change adds the environment variable GOWASM, which is a comma
separated list of experimental WebAssembly features that the compiled
WebAssembly binary is allowed to use. The default is to use no
experimental features. Initially there are no features avaiable.

More information about feature proposals can be found at
https://github.com/WebAssembly/proposals

Change-Id: I4c8dc534c99ecff8bb075dded0186ca8f8decaef
Reviewed-on: https://go-review.googlesource.com/c/go/+/168881
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This change optimizes the blocks in the wasm binary by generating the
entryPointLoop only if it is used and adding an unwindExit block to
be able to use the short BrIf instruction for unwinding the stack.
These changes were suggested by the wasm-opt tool and reduce the
wasm binary size of "hello world" by 1.5%.

Change-Id: Ie52db2fa2d9b8482f9a78b7c189231750811fe97
Reviewed-on: https://go-review.googlesource.com/c/go/+/167937
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

This CL implements MADD&MSUB, which are mips32r2 instructions.

Change-Id: I06fe51573569baf3b71536336b34b95ccd24750b
Reviewed-on: https://go-review.googlesource.com/c/go/+/167680
Run-TryBot: Ben Shi <powerman1st@163.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

CL 166717 changed the way ns/op benchmark results were printed and
inadvertently rounded all ns/op results down to an integer, even if
they were small enough to print with digits after the decimal place.
For example, prior to this change, we got output like

    BenchmarkFast-8       380491575	 3.12 ns/op

CL 166717 changed this to

    BenchmarkFast-8       380491575      3.00 ns/op

This had the further side-effect that ns/op values between 0 and 1
would not be printed at all because they would be rounded down to 0.

This CL fixes this by always recomputing the float64 value of ns/op
instead of using the int64 truncation from BenchmarkResult.NsPerOp.

Fixes #30997. Fixes #31005.

Change-Id: I21f73b9d5cc5ad41e7ff535675d07ca00051ecd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/168937Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

This change is a re-apply of the reverted CL 140863 with changes to
address issue #30821. Specifically, path.Split continues to be used
to split the '/'-separated import path, rather than filepath.Split.

Document the algorithm for how the default executable name is determined
in DefaultExecName.

Rename a variable returned from os.Stat from bs to fi for consistency.

CL 140863 factored out the logic to determine the default executable
name from the Package.load method into a DefaultExecName function,
and started using it in more places to avoid having to re-implement
the logic everywhere it's needed. Most previous callers already computed
the default executable name based on the import path. The load.Package
method, before CL 140863, was the exception, in that it used the p.Dir
value in GOPATH mode instead. There was a NOTE(rsc) comment that it
should be equivalent to use import path, but it was too late in Go 1.11
cycle to risk implementing that change.

This is part 1, a more conservative change for backporting to Go 1.12.2,
and it keeps the original behavior of splitting on p.Dir in GOPATH mode.
Part 2 will address the NOTE(rsc) comment and modify behavior in
Package.load to always use DefaultExecName which splits the import path
rather than directory. It is intended to be included in Go 1.13.

Fixes #27283 (again)
Updates #26869
Fixes #30821

Change-Id: Ib1ebb95acba7c85c24e3a55c40cdf48405af34f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/167503Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

This reverts CL 140863 (commit bf94fc3a).

Reason for revert: There was a potential problem spotted in the original
fix, which resulted in it being rolled back from release-branch.go1.12
and not included in Go 1.12.1 release. We intend to improve the fix and
include it in Go 1.12.2 instead. To make the fix easier to backport,
revert this change before re-applying the improved fix (next commit).

Change-Id: If6c785f58482d2531b5927c5ea7002f548c21c7c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168402Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

Introduce a new linker command line option "-strictdups", which
enables sanity checking of "ok to duplicate" symbols, especially
DWARF info symbols. Acceptable values are 0 (no checking) 1 (issue
warnings) and 2 (issue a fatal error checks fail).

Currently if we read a DWARF symbol (such as "go.info.PKG.FUNCTION")
from one object file, and then encounter the same symbol later on
while reading another object file, we simply discard the second one
and move on with the link, since the two should in theory be
identical.

If as a result of a compiler bug we wind up with symbols that are not
identical, this tends to (silently) result in incorrect DWARF
generation, which may or may not be discovered depending on who is
consuming the DWARF and what's being done with it.

When this option is turned on, at the point where a duplicate
symbol is detected in the object file reader, we check to make sure
that the length/contents of the symbol are the same as the previously
read symbol, and print a descriptive warning (or error) if not.

For the time being this can be used for one-off testing to find
problems; at some point it would be nice if we can enable it by
default.

Updates #30908.

Change-Id: I64c4e07c326b4572db674ff17c93307e2eec607c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168410
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

A lot of the naked for loops begin like:

	for {
		v := b.Control
		if v.Op != OpConstBool {
			break
		}
		...
		return true
	}

Instead, write them out in a more compact and readable way:

	for v.Op == OpConstBool {
		...
		return true
	}

This requires the addition of two bytes.Buffer writers, as this helps us
make a decision based on future pieces of generated code. This probably
makes rulegen slightly slower, but that's not noticeable; the code
generation still takes ~3.5s on my laptop, excluding build time.

The "v := b.Control" declaration can be moved to the top of each
function. Even though the rules can modify b.Control when firing, they
also make the function return, so v can't be used again.

While at it, remove three unnecessary lines from the top of each
rewriteBlock func.

In total, this results in ~4k lines removed from the generated code, and
a slight improvement in readability.

Change-Id: I317e4c6a4842c64df506f4513375475fad2aeec5
Reviewed-on: https://go-review.googlesource.com/c/go/+/167399
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This change implements the following functions on js/wasm:
- os.Chown
- os.Fchown
- os.Lchown
- syscall.Getuid
- syscall.Getgid
- syscall.Geteuid
- syscall.Getegid
- syscall.Getgroups
- syscall.Getpid
- syscall.Getppid
- syscall.Umask

Change-Id: Icdb0fafc02c9df6e9e3573542f8499c3464dc671
Reviewed-on: https://go-review.googlesource.com/c/go/+/154157
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This CL deals with the additional comments of CL 159017.

Change-Id: I4ad3c60c834646d58dc0c544c741b92bfe83fb8b
Reviewed-on: https://go-review.googlesource.com/c/go/+/168857Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I4f8d0178e780b86d1f551b367e2ddac3789be5aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/168880
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I939518462c931ba9feb125b2f299ef0706b124ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/168879
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Enable pattern lib.a/shared.so.X in cgo_import_dynamic as on AIX,
archive files (.a) often have shared objects (.so) inside them.

Change-Id: I21096c75eb7fbcc7064b0b832bfa8ed862142051
Reviewed-on: https://go-review.googlesource.com/c/go/+/168877
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Ia78ea589cc6d58ff22f7d519399c06c5308419dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/168878Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>

Add a Fuzz function to package png, under the gofuzz build
tag. This function is based on the png/png.go code, from
github.com/dvyukov/go-fuzz-corpus, modified to use direct
comparison of image bounds rather than reflect.DeepEqual.

Updates #30979
Updates #19109

Change-Id: Idb86e7ded0c2d78e6cadbeda84c7b1f35b8c579c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168558Reviewed-by: thepudds <thepudds1460@gmail.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>

Change-Id: I64e05a1f768cb57194506021bb7fdca0ad19bf1c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168461
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This disrupts code instrumentation tools like go-fuzz.

Change-Id: I524f31316975096ca5e3b1203a82e91ed1b6097e
Reviewed-on: https://go-review.googlesource.com/c/go/+/168801
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

This change optimizes the data section in the wasm binary by
omitting blocks of zeroes and instead emitting data segments
with offsets skipping the zeroes.

This optimization is inspired by the memory-packing pass of the
wasm-opt tool and reduces the wasm binary size of "hello world" by 14%.

Change-Id: Iba3043df05bf6aab4745c5f8015c0337fc218aff
Reviewed-on: https://go-review.googlesource.com/c/go/+/167801
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

When gif.Encode is given an "m image.Image" argument that isn't an
*image.Paletted, it creates a temporary *image.Paletted (called pm) that
is intended to be a copy of this image, only with fewer colors.

That creation process, and specifically the opts.Drawer.Draw call that
does the copy, incorrectly assumed that m.Bounds().Min is the zero point
(0, 0). This commit fixes that.

Fixes #30887

Change-Id: Ie03bddec359e2dcc52f18451049452105514e179
Reviewed-on: https://go-review.googlesource.com/c/go/+/168418
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

It is possible that a "volatile" value (one that can be clobbered
by preparing args of a call) to be used in multiple write barrier
calls. We used to copy the volatile value right before each call.
But this doesn't work if the value is used the second time, after
the first call where it is already clobbered. Copy it before
emitting any call.

Fixes #30977.

Change-Id: Iedcc91ad848d5ded547bf37a8359c125d32e994c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168677
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Noticed by Ingo Oeser in his review of CL 168321.

Change-Id: I2f39db675a7c22b395062a11903657a9d0d1956d
Reviewed-on: https://go-review.googlesource.com/c/go/+/168560
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The Import function was moved from modfetch/repo.go to modload/import.go
in vgo CL 122880, and its semantics have changed in vgo CL 123095 to do
more than just searching for a module. Both of these changes were ported
to cmd/go in CL 123576.

Delete the mention of the old Import function from the modfetch/repo.go
comment, since what it refers to does not exist anymore.

Change-Id: I6dc6984128152cf9611d30fbc4e6418e91a7641f
Reviewed-on: https://go-review.googlesource.com/c/go/+/166597Reviewed-by: Jay Conrod <jayconrod@google.com>

New release, it broke again the longtest builder. Align the expected
data with the current release.

Making these tests independent of external repositories is #28856.

This fixes the longtest builder.

Updates #28856

Change-Id: I32d2f3325af828d26ab417a5e986e3aeefa1a897
Reviewed-on: https://go-review.googlesource.com/c/go/+/168561
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I7e921b7b4665ff76dc8bae493b2a49318690770b
Reviewed-on: https://go-review.googlesource.com/c/go/+/168637
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The iOS exec wrapper copies the environment variables to the binary
running on the device. However, some variables such as HOME, TMPDIR and
GOCACHE refer to directories that might not be valid on the device.

The wrapper already ignores HOME and TMPDIR, but after GO111MODULE
was flipped to on for the standard library, cmd/go tests started
failing without a valid and writable GOCACHE.

It took a while to reproduce because go test does not set an explicit
GOCACHE but cmd/dist test does.

Fixes #30914

Change-Id: If186cddc5cfd7ad39a0b3eb95f9c64a7d53a27e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/168557
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Android devices don't have git available, so many go tool commands
that fetch dependencies fail. Builders already have a GOPROXY
available, so pass that along to the device environment.

Updates #30885

Change-Id: Id0d2338932f0cd7de4d95d9e0ca9b79d29336ffe
Reviewed-on: https://go-review.googlesource.com/c/go/+/168118
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The initial implementation is intentionally simple.
Let's see how far it gets us.

Fixes #30638

Change-Id: I240afae2b401744ab2ff2a69952c4eb0fd3feb56
Reviewed-on: https://go-review.googlesource.com/c/go/+/168518
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

While we're here, move the test from dwarf_test.go to link_test.go;
it doesn't have anything to do with DWARF.

Should fix the macOS builders with only the Xcode command line tools
installed.

Change-Id: Iaaba1b589f4d778705f7b627f78c2b12388e2b3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/168462
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

To build for watchOS and tvOS the Apple toolchain requires a Mach-O
load command that matches the platform for all object files in a build.
The go.o object file produced by the Go linker contains no such command.

The loader commands are mutually exclusive so we need to pick the
right one. Fortunately, cgo must be enabled for watchOS and tvOS to
be useful, so we can copy the first loader command we find in the object
files produced by the host compiler.

Add a test that builds a small program for tvOS to test both this CL
and the previous CL that added bitcode support.

Updates #22395

Change-Id: I7a47d19be9d80f0459dc358c600cddd9f236c444
Reviewed-on: https://go-review.googlesource.com/c/go/+/168321
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>