The global encbuf helped avoid allocations.
It is incompatible with a concurrent backend.
To avoid a performance regression while removing it,
introduce two optimizations.
First, re-use a buffer in dwarf.PutFunc.
Second, avoid a buffer entirely when the int
being encoded fits in seven bits, which is about 75%
of the time.

Passes toolstash-check.

Updates #15756


name       old alloc/op    new alloc/op    delta
Template      40.6MB ± 0%     40.6MB ± 0%  -0.08%  (p=0.001 n=8+9)
Unicode       29.9MB ± 0%     29.9MB ± 0%    ~     (p=0.068 n=8+10)
GoTypes        116MB ± 0%      116MB ± 0%  +0.05%  (p=0.043 n=10+9)
SSA            864MB ± 0%      864MB ± 0%  +0.01%  (p=0.010 n=10+9)
Flate         25.8MB ± 0%     25.8MB ± 0%    ~     (p=0.353 n=10+10)
GoParser      32.2MB ± 0%     32.2MB ± 0%    ~     (p=0.353 n=10+10)
Reflect       80.2MB ± 0%     80.2MB ± 0%    ~     (p=0.165 n=10+10)
Tar           27.0MB ± 0%     26.9MB ± 0%    ~     (p=0.143 n=10+10)
XML           42.8MB ± 0%     42.8MB ± 0%    ~     (p=0.400 n=10+9)

name       old allocs/op   new allocs/op   delta
Template        398k ± 0%       397k ± 0%  -0.20%  (p=0.002 n=8+9)
Unicode         320k ± 0%       321k ± 1%    ~     (p=0.122 n=8+10)
GoTypes        1.16M ± 0%      1.17M ± 0%    ~     (p=0.053 n=10+9)
SSA            7.65M ± 0%      7.65M ± 0%    ~     (p=0.122 n=10+8)
Flate           240k ± 1%       240k ± 1%    ~     (p=0.243 n=10+9)
GoParser        322k ± 1%       322k ± 1%    ~     (p=0.481 n=10+10)
Reflect        1.00M ± 0%      1.00M ± 0%    ~     (p=0.211 n=9+10)
Tar             256k ± 0%       255k ± 1%    ~     (p=0.052 n=10+10)
XML             400k ± 1%       400k ± 0%    ~     (p=0.631 n=10+10)


Change-Id: Ia39d9de09232fdbfc9c9cec14587bbf6939c9492
Reviewed-on: https://go-review.googlesource.com/38713
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

If the user created an httptest.Server directly without using a
constructor it won't have the new unexported 'client' field. So don't
assume it's non-nil.

Fixes #19729

Change-Id: Ie92e5da66cf4e7fb8d95f3ad0f4e3987d3ae8b77
Reviewed-on: https://go-review.googlesource.com/38710
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Kevin Burke <kev@inburke.com>

We reused the old C stack check mechanism for the implementation of
//go:systemstack, so when we execute a //go:systemstack function on a
user stack, the system fails by calling morestackc. However,
morestackc's message still talks about "executing C code".

Fix morestackc's message to reflect its modern usage.

Change-Id: I7e70e7980eab761c0520f675d3ce89486496030f
Reviewed-on: https://go-review.googlesource.com/38572
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

On Android, the thread local offset is found by looping through memory
starting at the TLS base address. The search is limited to
PTHREAD_KEYS_MAX, but issue 19472 made it clear that in some cases, the
slot is located further from the TLS base.

The limit is merely a sanity check in case our assumptions about the
thread-local storage layout are wrong, so this CL raises it to 384, which
is enough for the test case in issue 19472.

Fixes #19472

Change-Id: I89d1db3e9739d3a7fff5548ae487a7483c0a278a
Reviewed-on: https://go-review.googlesource.com/38636
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The proto_test tests are failing on NetBSD:

https://build.golang.org/log/a3a577144ac48c6ef8e384ce6a700ad30549fb78

the failures seem similar to previous failures on Android:

https://build.golang.org/log/b5786e0cd6d5941dc37b6a50be5172f6b99e22f0

The Android failures where fixed by CL 37896. This CL is an attempt
to fix the NetBSD failures with a similar fix.

Change-Id: I3834afa5b32303ca226e6a31f0f321f66fef9a3f
Reviewed-on: https://go-review.googlesource.com/38637Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Follow-up to CL 38668.

Passes toolstash-check -all.

Change-Id: I78a62509c610b5184b5e7ef2c4aa146fc8038840
Reviewed-on: https://go-review.googlesource.com/38670
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

Follow-up to CL 38446.

Passes toolstash-check -all.

Change-Id: I04cadc058cbaa5f396136502c574e5a395a33276
Reviewed-on: https://go-review.googlesource.com/38669
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

These fields are used to encode a single instruction.
Add them to AsmBuf, which is also per-instruction,
and which is not global.

Updates #15756

Change-Id: I0e5ea22ffa641b07291e27de6e2ff23b6dc534bd
Reviewed-on: https://go-review.googlesource.com/38668
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Thread it through as an argument instead of using a global.

Passes toolstash-check -all.

Updates #15756

Change-Id: Ia8c6ce09b43dbb2e6c7d889ded8dbaeb5366048d
Reviewed-on: https://go-review.googlesource.com/38667
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Empirically, p == ctxt.Curp here.
A scan of (the thousands of lines of) asm6.go
shows no clear opportunity for them to diverge.

Passes toolstash-check -all.

Updates #15756

Change-Id: I9f5ee9585a850fbe24be3b851d8fdc2c966c65ce
Reviewed-on: https://go-review.googlesource.com/38665
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

We don't need them any more since #15837 was fixed.

Fixes #19718

Change-Id: I13e46c62b321b2c9265f44c977b63bfb23163ca2
Reviewed-on: https://go-review.googlesource.com/38664
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

The x86 assembler requires a buffer to build
variable-length instructions.
It used to be an obj.Link field.
That doesn't play nicely with concurrent assembly.
Move the AsmBuf type to the x86 package,
where it belongs anyway,
and make it a local variable.

Passes toolstash-check -all.
No compiler performance impact.

Updates #15756

Change-Id: I8014e52145380bfd378ee374a0c971ee5bada917
Reviewed-on: https://go-review.googlesource.com/38663
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Prior to this CL, instinit was called as needed.
This does not work well in a concurrent backend.
Initialization is very cheap; do it on startup instead.

Passes toolstash-check -all.
No compiler performance impact.

Updates #15756

Change-Id: Ifa5e82e8abf4504435e1b28766f5703a0555f42d
Reviewed-on: https://go-review.googlesource.com/38662
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Ensure that we have a test for when the compiler
encounters a type switch on a non-interface value.

Change-Id: Icb222f986894d0190e1241ca65396b4950e7d14f
Reviewed-on: https://go-review.googlesource.com/38661Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Now that we have consistent use of xOrNil parse methods, we don't
need a special missing_statement singleton to distinguish between
missing actually statements and other errors (which have returned
nil before).

For #19663.

Change-Id: I8364f1441bdf8dd966bcd6d8219b2a42d6b88abd
Reviewed-on: https://go-review.googlesource.com/38656
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

- parser creates sensible nodes in case of syntax errors instead of nil
- a new BadExpr node is used in places where we can't do better
- fixed error message for incorrect type switch guard
- minor cleanups

Fixes #19663.

Change-Id: I028394c6db9cba7371f0e417ebf93f594659786a
Reviewed-on: https://go-review.googlesource.com/38653
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
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>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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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Reviewed-by: Keith Randall <khr@golang.org>

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>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Fixes #19687

Change-Id: I2e4769b4ec5812506df4ac5dc6bc6a7c5774ecb0
Reviewed-on: https://go-review.googlesource.com/38600
Run-TryBot: Keith Randall <khr@golang.org>
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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
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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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>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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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>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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>