ONAME, OLITERAL, and OTYPE nodes can be shared between functions.
In a concurrent backend, such nodes might be walked concurrently
with being read in other functions.
Arrange for them to be unmodified by walk.

This is a follow-up to CL 38609.

Passes toolstash-check.

Updates #15756

Change-Id: I03ff1d2c0ad81dafac3fd55caa218939cf7c0565
Reviewed-on: https://go-review.googlesource.com/38655
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Updates #15756

Change-Id: Id8d65ca9a3f1a7f9ea43e26cdd5e7d3befef8ba0
Reviewed-on: https://go-review.googlesource.com/38593
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Concurrent compilation requires providing an
explicit position and curfn to temp.
This implementation of tempAt temporarily
continues to use the globals lineno and Curfn,
so as not to collide with mdempsky's
work for #19683 eliminating the Curfn dependency
from func nod.

Updates #15756
Updates #19683

Change-Id: Ib3149ca4b0740e9f6eea44babc6f34cdd63028a9
Reviewed-on: https://go-review.googlesource.com/38592
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

If go doesn't have permission to run strace, this test hangs while
waiting for strace to run. Instead try invoking strace with
Run() first - on fail skip and report error, otherwise run
the test normally using strace.

Also fix link to open mips64 issue in same test.

Fixes #9711

Change-Id: Ibbc5fbb143ea6d0f8b6cfdca4b385ef4c8960b3d
Reviewed-on: https://go-review.googlesource.com/38633Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The type switch in walkexpr is giant.
Shrink it a little by coalescing identical cases
and removing some vertical whitespace.

No functional changes.

Passes toolstash-check.

Change-Id: I7f7efb4faae1f8657dfafac04585172f99d8b37d
Reviewed-on: https://go-review.googlesource.com/38652
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Sym.Fsym is used only to avoid adding duplicate
entries to funcsyms, but that is easily
accomplished by detecting the first lookup
vs subsequent lookups of the func sym name.

This avoids creating an unnecessary ONAME node
during funcsym, which eliminates a dependency
in the backend on Curfn and lineno.

It also makes the code a lot simpler and clearer.

Updates #15756

Passes toolstash-check -all.
No compiler performance changes.
funcsymname does generate garbage via string
concatenation, but it is not called very much,
and this CL also eliminates allocation of several
Nodes and Names.

Change-Id: I7116c78fa39d975b7bd2c65a1d228749cf0dd46b
Reviewed-on: https://go-review.googlesource.com/38605Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Passes toolstash-check -all.

Change-Id: Ib9f969e5ecc1537b7eab186dc4fd504a50f800f2
Reviewed-on: https://go-review.googlesource.com/38586
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
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Clean up code that does interface equality. Avoid doing checks
in efaceeq/ifaceeq that we already did before calling those routines.

No noticeable performance changes for existing benchmarks.

name            old time/op  new time/op  delta
EfaceCmpDiff-8   604ns ± 1%   553ns ± 1%  -8.41%  (p=0.000 n=9+10)

Fixes #18618

Change-Id: I3bd46db82b96494873045bc3300c56400bc582eb
Reviewed-on: https://go-review.googlesource.com/38606
Run-TryBot: Keith Randall <khr@golang.org>
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Reviewed-by: David Chase <drchase@google.com>

Change-Id: Icf69862554d0121ec24e3c162d5c48630a03b99a
Reviewed-on: https://go-review.googlesource.com/38583Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I9885606801b9c8fcb62c16d0856025c4e83e658b
Reviewed-on: https://go-review.googlesource.com/38650
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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In the future, walk will probably run concurrently
with SSA construction. It is possible for walk
to be walking a function node that is referred
to by another function undergoing SSA construction.
In that case, this particular assignment to n.Type
is race-y.

This assignment is also not necessary;
evconst does not change the type of n.
Both arguments to evconst must have the same type,
and at the end of evconst, n is replaced with n.Left.

Remove the assignment, and add a check to ensure
that its removal remains correct.

Updates #15756

Change-Id: Id95faaff42d5abd76be56445d1d3e285775de8bf
Reviewed-on: https://go-review.googlesource.com/38609
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Avoid construction of incorrect syntax trees in presence of errors.

For #19663.

Change-Id: I43025a3cf0fe02cae9a57e8bb9489b5f628c3fd7
Reviewed-on: https://go-review.googlesource.com/38604
Run-TryBot: Robert Griesemer <gri@golang.org>
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The improvementis achieved in encoding/gob/decode.go decodeMap by
allocate keyInstr and elemInstr only once and pass it to
decodeIntoValue, instead of allocating a new instance on every loop
cycle.

name                     old time/op  new time/op  delta
DecodeComplex128Slice-8  64.2µs ±10%  62.2µs ± 8%     ~     (p=0.686 n=4+4)
DecodeFloat64Slice-8     37.1µs ± 3%  36.5µs ± 5%     ~     (p=0.343 n=4+4)
DecodeInt32Slice-8       33.7µs ± 3%  32.7µs ± 4%     ~     (p=0.200 n=4+4)
DecodeStringSlice-8      59.7µs ± 5%  57.3µs ± 1%     ~     (p=0.114 n=4+4)
DecodeInterfaceSlice-8    543µs ± 7%   497µs ± 3%     ~     (p=0.057 n=4+4)
DecodeMap-8              3.78ms ± 8%  2.66ms ± 2%  -29.69%  (p=0.029 n=4+4)

Updates #19525

Change-Id: Iec5fa4530de76f0a70da5de8a129a567b4aa096e
Reviewed-on: https://go-review.googlesource.com/38317Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
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This change strips the port in mux.Handler before attempting to
match handlers and adds a test for a request with port.

CONNECT requests continue to use the original path and port.

Fixes #10463

Change-Id: Iff3a2ca2b7f1d884eca05a7262ad6b7dffbcc30f
Reviewed-on: https://go-review.googlesource.com/38194Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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The section on map literals mentions constant map keys but doesn't say
what happens for equal non-constant map keys - that is covered in the
section on evaluation order. Added respective link for clarity.

Fixes #19689.

Change-Id: If9a5368ba02e8250d4bb0a1d60d0de26a1f37bbb
Reviewed-on: https://go-review.googlesource.com/38598Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Simple phi insertion already had a heuristic to check
for dead blocks, namely having no predecessors.
When we stopped generating code for dead blocks,
we eliminated some values contained in more subtle
dead blocks, which confused phi insertion.
Compensate by beefing up the reachability check.

Fixes #19678

Change-Id: I0081e4a46f7ce2f69b131a34a0553874a0cb373e
Reviewed-on: https://go-review.googlesource.com/38602
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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CL 37499 allows inlining more functions by ignoring dead code.
However, that dead code can contain non-exportable constructs.
Teach the exporter not to export dead code.

Fixes #19679 

Change-Id: Idb1d3794053514544b6f1035d29262aa6683e1e7
Reviewed-on: https://go-review.googlesource.com/38601
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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Reviewed-by: Robert Griesemer <gri@golang.org>

Fixes #19687

Change-Id: I2e4769b4ec5812506df4ac5dc6bc6a7c5774ecb0
Reviewed-on: https://go-review.googlesource.com/38600
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Almost never happens in practice.
The compiler will generate reasonable code anyway,
since assignments involving [0]T never do any work.

Fixes #19696
Fixes #19671

Change-Id: I350d2e0c5bb326c4789c74a046ab0486b2cee49c
Reviewed-on: https://go-review.googlesource.com/38599
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TryBot-Result: Gobot Gobot <gobot@golang.org>

Updates #15756

Change-Id: I860dd45cae9d851c7844654621bbc99efe7c7f03
Reviewed-on: https://go-review.googlesource.com/38591
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

The darwin linker for ARM does not allow PC-relative relocation
of external symbol in text section. Work around it by accessing
it indirectly: putting its address in a global variable (which is
not external), and accessing through that variable.

Fixes #19684.

Change-Id: I41361bbb281b5dbdda0d100ae49d32c69ed85a81
Reviewed-on: https://go-review.googlesource.com/38596
Run-TryBot: Cherry Zhang <cherryyz@google.com>
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Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Elias Naur <elias.naur@gmail.com>

Custom logic from request.go has been removed.

Created by running: “go run gen.go -core” from x/text
at fc7fa097411d30e6708badff276c4c164425590c.

Fixes golang/go#17268

Change-Id: Ie440d6ae30288352283d303e5126e5837f11bece
Reviewed-on: https://go-review.googlesource.com/37111
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
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We already handle n << (uint64(c)&63).
This change also handles n << (uint8(c)&63)
where the SSA compiler promotes the counter to 32 bits.

Fixes #19681

Change-Id: I9327d64a994286aa0dbf76eb995578880be6923a
Reviewed-on: https://go-review.googlesource.com/38550
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
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Reviewed-by: Keith Randall <khr@golang.org>

Fixes #18069
Also added a test in: cmd/asm/internal/asm/testdata/arm64.s

Change-Id: Iee400bda4f30503ea3c1dc5bb8301568f19c92d1
Signed-off-by: Wei Xiao <wei.xiao@arm.com>
Reviewed-on: https://go-review.googlesource.com/33594
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Updates #15756

Change-Id: I5ad87ef44b8ee48e1294820e0b1ab0ec07c480eb
Reviewed-on: https://go-review.googlesource.com/38590
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Pass around the imported package explicitly instead of relying
on a global variable.

Unfortunately we still need a global variable to communicate to
the typechecker that we're in an import, but the semantic load
is significantly reduced as it's just a bool, set/reset in a
couple of places only.

Change-Id: I4ebeae4064eb76ca0c4e2a15e4ca53813f005c29
Reviewed-on: https://go-review.googlesource.com/38595
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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First step towards removing global var importpkg.

Change-Id: Ifdda7c295e5720a7ff2da9baea17f03f190d48fa
Reviewed-on: https://go-review.googlesource.com/38594
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Go uses CommandLineToArgV from shell32.dll to parse command
line parameters. But shell32.dll is slow to load. Implement
Windows command line parsing in Go. This should make starting
Go programs faster.

I can see these speed ups for runtime.BenchmarkRunningGoProgram

on my Windows 7 amd64:
name                old time/op  new time/op  delta
RunningGoProgram-2  11.2ms ± 1%  10.4ms ± 2%  -6.63%  (p=0.000 n=9+10)

on my Windows XP 386:
name                old time/op  new time/op  delta
RunningGoProgram-2  19.0ms ± 3%  12.1ms ± 1%  -36.20%  (p=0.000 n=10+10)

on @egonelbre Windows 10 amd64:
name                old time/op  new time/op  delta
RunningGoProgram-8  17.0ms ± 1%  15.3ms ± 2%  -9.71%  (p=0.000 n=10+10)

This CL is based on CL 22932 by John Starks.

Fixes #15588.

Change-Id: Ib14be0206544d0d4492ca1f0d91fac968be52241
Reviewed-on: https://go-review.googlesource.com/37915Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
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Collapse funcHeader into funcDecl.
Initialize pragmas earlier.
Move empty / non-empty body errors closer to fun.Body handling.
Switch some yyerror to yyerrorl.

Change-Id: I71fb7a3c0b77d656af560e4d88da894ba6183826
Reviewed-on: https://go-review.googlesource.com/38475Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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Change-Id: I5daeb8f00044c86bb10510afbc6886898e61ba15
Reviewed-on: https://go-review.googlesource.com/38570
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Change-Id: I21e3abcfd1859f933f55fe875476dec07e43b038
Reviewed-on: https://go-review.googlesource.com/38466
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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When a map or slice is used as a return type create an empty value
rather than a nil value.

Fixes #19588

Change-Id: I577fd74956172329745d614ac37d4db8f737efb8
Reviewed-on: https://go-review.googlesource.com/38474
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Verified that BenchmarkBitLen time went down from 2.25 ns/op to 0.65 ns/op
an a 2.3 GHz Intel Core i7, before removing that benchmark (now covered by
math/bits benchmarks).

Change-Id: I3890bb7d1889e95b9a94bd68f0bdf06f1885adeb
Reviewed-on: https://go-review.googlesource.com/38464
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This reverts commit b1b4f671.

Reason for revert: Broke the build.

Change-Id: I5c99779896e39137c93c77d016ce683c872a69d7
Reviewed-on: https://go-review.googlesource.com/38532Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

It is currently possible in the compiler to create a struct type,
calculate the widths of types that depend on it,
and then alter the struct type.

transformclosure has local protection against this.
Protect against it at a deeper level.

This is preparation to call dowidth automatically,
rather than explicitly.

Change-Id: Ic1578ca014610197cfe54a9f4d044d122a7217e8
Reviewed-on: https://go-review.googlesource.com/38469
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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Change-Id: I9e52a2c52b754568412d719b415f91a998d247fe
Reviewed-on: https://go-review.googlesource.com/38467
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: If5eabd622700a6b82dc4961ae9174c9d907eedb7
Reviewed-on: https://go-review.googlesource.com/38465
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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In livenessepilogue, if we save liveness information for instructions
before updating liveout, we can avoid an extra bitvector temporary and
some extra copying around.

Passes toolstash-check -all.

Change-Id: I10d5803167ef3eba2e9e95094adc7e3d33929cc7
Reviewed-on: https://go-review.googlesource.com/38408Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

In some newer Linux distros, systemd forces
all mount namespaces to be shared, starting
at /. This disables the CLONE_NEWNS
flag in unshare(2) and clone(2).
While this problem is most commonly seen
on systems with systemd, it can happen anywhere,
due to how Linux namespaces now work.

Hence, to create a private mount namespace,
it is not sufficient to just set
CLONE_NEWS; you have to call mount(2) to change
the behavior of namespaces, i.e.
mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL)

This is tested and working and we can now correctly
start child process with private namespaces on Linux
distros that use systemd.

The new test works correctly on Ubuntu 16.04.2 LTS.
It fails if I comment out the new Mount, and
succeeds otherwise. In each case it correctly
cleans up after itself.

Fixes #19661

Change-Id: I52240b59628e3772b529d9bbef7166606b0c157d
Reviewed-on: https://go-review.googlesource.com/38471Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
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A -0 constant is the same as 0. Use explicit negative zero
for float64 -0.0. Also, fix two test cases that were wrong.

Fixes #19673.

Change-Id: Ic09775f29d9bc2ee7814172e59c4a693441ea730
Reviewed-on: https://go-review.googlesource.com/38463
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>