StructField.ByteSize is almost always unset; document that Type.Size()
is the place to look.

The dwarf package doesn't spend much effort teaching you DWARF, so I
don't know what level of handholding is appropriate. Still, no harm in a
little comment.

Closes #21093

Change-Id: I0ed8cad2fa18e10a47d264ff16c176d603d6033c
Reviewed-on: https://go-review.googlesource.com/71671
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Fixes #21800

Change-Id: I6c61d3543f28e9951b2a219b3c7298077b38f29e
Reviewed-on: https://go-review.googlesource.com/66210
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

This adds a whitelisted subset of compiler flags to the DW_AT_producer
DWARF attribute of each package compilation unit DIE. This is common
practice in DWARF and can help debuggers determine the quality of the
produced debugging information.

Fixes #22168.

Change-Id: I1b994ef2262aa9b88b68eb6e883695d1103acc58
Reviewed-on: https://go-review.googlesource.com/71430Reviewed-by: Ian Lance Taylor <iant@golang.org>

Currently mmap returns an unsafe.Pointer that encodes OS errors as
values less than 4096. In practice this is okay, but it borders on
being really unsafe: for example, the value has to be checked
immediately after return and if stack copying were ever to observe
such a value, it would panic. It's also not remotely idiomatic.

Fix this by making mmap return a separate pointer value and error,
like a normal Go function.

Updates #22218.

Change-Id: Iefd965095ffc82cc91118872753a5d39d785c3a6
Reviewed-on: https://go-review.googlesource.com/71270
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Set DW_AT_variable_parameter on DW_TAG_formal_parameters that are
actually return values. variable_parameter is supposed to indicate inout
parameters, but Go doesn't really have those, and DWARF doesn't have
explicit support for multiple return values. This seems to be the best
compromise, especially since the implementation of the two is very
similar -- both are stack slots.

Fixes #21100

Change-Id: Icebabc92b7b397e0aa00a7237478cce84ad1a670
Reviewed-on: https://go-review.googlesource.com/71670
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Updates http2 to x/net/http2 git rev 1087133bc4a for:

  http2: reject DATA frame before HEADERS frame
  https://golang.org/cl/56770

  http2: respect peer's SETTINGS_MAX_HEADER_LIST_SIZE in ClientConn
  https://golang.org/cl/29243

  http2: reset client stream after processing response headers
  https://golang.org/cl/70510

Also updated TestRequestLimit_h2 as the behavior changed slightly due
to https://golang.org/cl/29243.

Fixes #13959
Fixes #20521
Fixes #21466

Change-Id: Iac659694f3a48b8bd485546a4f96a932e3056026
Reviewed-on: https://go-review.googlesource.com/71611
Run-TryBot: Tom Bergan <tombergan@google.com>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes Darwin 386 build. It turns out that the Darwin pthread_create
function saves the SSE registers, and therefore requires an aligned stack.
This worked before https://golang.org/cl/70530 because the stack sizes
were chosen to leave the stack aligned.

Change-Id: I911a9e8dcde4e41e595d5ef9b9a1ca733e154de6
Reviewed-on: https://go-review.googlesource.com/71432Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Fixes #13265.

Change-Id: I792eb4ee26bef8a56e279e23f9802cb39019e0d0
Reviewed-on: https://go-review.googlesource.com/34929Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #22292

Change-Id: I016e5f2b8624a6ebaf11a693a0f6d94d7b0d3f92
Reviewed-on: https://go-review.googlesource.com/71550Reviewed-by: Daniel Theophanes <kardianos@gmail.com>

More generally I'm concerned about these tests using
$GOROOT/src/cmd/go as scratch space, especially
combined wtih tg.parallel() - it's easy to believe some other
test might inadvertently also try to write x.exe about the
same time. This CL only solves the "didn't clean up x.exe"
problem and leaves for another day the "probably shouldn't
write to cmd/go at all" problem.

Fixes #22266.

Change-Id: I651534d70e2d360138e0373fb4a316081872550b
Reviewed-on: https://go-review.googlesource.com/71410
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Nowhere in the spec did we mention the import path for package
unsafe. Now we do.

Fixes #22308.

Change-Id: Ifd42c873188e898c597cdee4284e7a9d234a9282
Reviewed-on: https://go-review.googlesource.com/71373Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I9d723e49bf2cabf97a09e29e46fd2c426845fd1d
Reviewed-on: https://go-review.googlesource.com/71470Reviewed-by: Ian Lance Taylor <iant@golang.org>

This reverts commit 897080d5.

Reason for revert: Fails to fix all the locking issues.

Updates #21117

Change-Id: I6fc9cb7897244d6e1af78c089a2bf383258ec049
Reviewed-on: https://go-review.googlesource.com/71450Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixed an error that occurred in atomic mode. cover adds a global
variable declaration that forces sync/atomic to be used. fixDirectives
was confused by this declaration since it has an invalid
position. These declarations are now skipped.

Fixes #22309

Change-Id: I84f5fec13ef847fca35ad49f7704fb93b60503e0
Reviewed-on: https://go-review.googlesource.com/71351
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Simplifies the switch statement in the isZeroValue function by merging
the case branches.

Change-Id: I5b27939b62808dadac0cef632567b17e0e2b9a1d
Reviewed-on: https://go-review.googlesource.com/71390
Run-TryBot: Gabriel Aszalos <gabriel.aszalos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

When an opening "{" of a block is missing and after advancing we
find a closing "}", it's likely better to assume the end of the
block. Fixed and removed TODO.

Change-Id: I20c9b4ecca798933a7cd4cbf21185bd4ca04f5f7
Reviewed-on: https://go-review.googlesource.com/71291Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Change-Id: I2c2571b33603f0fd0ba5a79400da7b845d246b8c
Reviewed-on: https://go-review.googlesource.com/71290Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Current suffix check is based on instruction, which is not very
accurate. For example, "MOVW.S R1, R2" is valid, but
"MOVW.S $0xaaaaaaaa, R1" and "MOVW.P CPSR, R9" are not.

This patch fixes the above kinds of issues by checking suffix
based on []optab. And also more test cases are added.

fixes #20509

Change-Id: Ibad91be72c78eefa719412a83b4d44370d2202a8
Reviewed-on: https://go-review.googlesource.com/70910
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

CL 46037 and CL 46038 implemented termination of
locked OS threads when the goroutine exits.

However, this behavior leads to crashes of Go programs
using runtime.LockOSThread on Plan 9. This is notably
the case of the os/exec and net packages.

This change disables termination of locked OS threads
on Plan 9.

Updates #22227.

Change-Id: If9fa241bff1c0b68e7e9e321e06e5203b3923212
Reviewed-on: https://go-review.googlesource.com/71230Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

CL 46033 added a "template thread" mechanism to
allow creation of thread with a known-good state
from a thread of unknown state.

However, we are experiencing issues on Plan 9
with programs using the os/exec and net package.
These package are relying on runtime.LockOSThread.

Updates #22227.

Change-Id: I85b71580a41df9fe8b24bd8623c064b6773288b0
Reviewed-on: https://go-review.googlesource.com/70231
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Optimize arm64 CALLFN wrapper with LDP/STP instructions.
This provides a significant speedup for big argument copy.
Benchmark results for reflect:

name                      old time/op    new time/op     delta
Call-8                      79.0ns ± 4%     73.6ns ± 4%    -6.78%  (p=0.000 n=10+10)
CallArgCopy/size=128-8      80.5ns ± 0%     60.3ns ± 0%   -25.06%  (p=0.000 n=10+9)
CallArgCopy/size=256-8       119ns ± 2%       67ns ± 1%   -43.59%  (p=0.000 n=8+10)
CallArgCopy/size=1024-8      524ns ± 1%       99ns ± 1%   -81.03%  (p=0.000 n=10+10)
CallArgCopy/size=4096-8      837ns ± 0%      231ns ± 1%   -72.42%  (p=0.000 n=9+9)
CallArgCopy/size=65536-8    13.6µs ± 6%      3.1µs ± 1%   -77.38%  (p=0.000 n=10+10)
PtrTo-8                     12.9ns ± 0%     13.1ns ± 3%    +1.86%  (p=0.000 n=10+10)
FieldByName1-8              28.7ns ± 2%     28.6ns ± 2%      ~     (p=0.408 n=9+10)
FieldByName2-8               928ns ± 4%      946ns ± 8%      ~     (p=0.326 n=9+10)
FieldByName3-8              5.35µs ± 5%     5.32µs ± 5%      ~     (p=0.755 n=10+10)
InterfaceBig-8              2.57ns ± 0%     2.57ns ± 0%      ~     (all equal)
InterfaceSmall-8            2.57ns ± 0%     2.57ns ± 0%      ~     (all equal)
New-8                       9.09ns ± 1%     8.83ns ± 1%    -2.81%  (p=0.000 n=10+9)

name                      old alloc/op   new alloc/op    delta
Call-8                       0.00B           0.00B           ~     (all equal)

name                      old allocs/op  new allocs/op   delta
Call-8                        0.00            0.00           ~     (all equal)

name                      old speed      new speed       delta
CallArgCopy/size=128-8    1.59GB/s ± 0%   2.12GB/s ± 1%   +33.46%  (p=0.000 n=10+9)
CallArgCopy/size=256-8    2.14GB/s ± 2%   3.81GB/s ± 1%   +78.02%  (p=0.000 n=8+10)
CallArgCopy/size=1024-8   1.95GB/s ± 1%  10.30GB/s ± 0%  +427.99%  (p=0.000 n=10+9)
CallArgCopy/size=4096-8   4.89GB/s ± 0%  17.69GB/s ± 1%  +261.87%  (p=0.000 n=9+9)
CallArgCopy/size=65536-8  4.84GB/s ± 6%  21.36GB/s ± 1%  +341.67%  (p=0.000 n=10+10)

Change-Id: I775d88b30c43cb2eda1d0612ac15e6d283e70beb
Reviewed-on: https://go-review.googlesource.com/70570Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Unify the 386 entry point code as much as possible.

The main function could not be unified because on Windows 386 it is
called _main. Putting main in asm_386.s caused multiple definition
errors when using the external linker.

Add the _lib entry point to various operating systems.  A future CL
will enable c-archive/c-shared mode for those targets.

Fix _rt0_386_windows_lib_go--it was passing arguments as though it
were amd64.

Change-Id: Ic73f1c95cdbcbea87f633f4a29bbc218a5db4f58
Reviewed-on: https://go-review.googlesource.com/70530
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Also fix 64-bit DWARF to read a 64-bit abbrev offset in the
compilation unit.

Change-Id: Idc22e59ffb354d58e9973b62fdbd342acf695859
Reviewed-on: https://go-review.googlesource.com/71171Reviewed-by: Austin Clements <austin@google.com>

- checking for the correct closing token leads to slightly better
  behavior for some randomly bogus programs
- removed `switch` in favor of an `if` statement

Follow-up on https://go-review.googlesource.com/c/go/+/71250.

Change-Id: I47f6c47b43baf790907f55ed97a947661687a9db
Reviewed-on: https://go-review.googlesource.com/71252Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Adds the two range control actions "break" and "continue". They act the
same as the Go keywords break and continue, but are simplified in that
only the innermost range statement can be broken out of or continued.

Fixes #20531

Change-Id: I4412b3bbfd4dadb0ab74ae718e308c1ac7a0a1e9
Reviewed-on: https://go-review.googlesource.com/66410Reviewed-by: Rob Pike <r@golang.org>

Fine-tune skipping of tokens after missing closing parentheses in lists.

Fixes #22164.

Change-Id: I575d86e21048cd40340a2c08399e8b0deec337cf
Reviewed-on: https://go-review.googlesource.com/71250
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Previously, cover printed directives (//go: comments) near the top of
the file unless they were in doc comments. However, directives
frequently apply to specific definitions, and they are not written in
doc comments to prevent godoc from printing them. Moving all
directives to the top of the file affected semantics of tests.

With this change, directives are kept together with the following
top-level declarations. Only directives that occur after all top-level
declarations are moved.

Fixes #22022

Change-Id: Ic5c61c4d3969996e4ed5abccba0989163789254c
Reviewed-on: https://go-review.googlesource.com/69630
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

name                   old time/op  new time/op  delta
ModSqrt224_3Mod4-4      153µs ± 2%   154µs ± 1%   ~     (p=0.548 n=5+5)
ModSqrt5430_3Mod4-4     776ms ± 2%   791ms ± 2%   ~     (p=0.222 n=5+5)

Fixes #22265

Change-Id: If233542716e04341990a45a1c2b7118da6d233f7
Reviewed-on: https://go-review.googlesource.com/70832
Run-TryBot: Filippo Valsorda <hi@filippo.io>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Use TEXT pseudo-instruction to adjust SP instead of a SUB instruction
so that the assembler knows how to fill in the pcsp table and the frame
description entry correctly.

Updates #21569

Change-Id: I436c840b2af99bbb3042ecd38a7d7c1ab4d7372a
Reviewed-on: https://go-review.googlesource.com/70937
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The code was commented out by https://golang.org/cl/13234050 in 2013.
Let's just remove it.

Change-Id: I46ae1f07386719e991458e782d236214c40bdce1
Reviewed-on: https://go-review.googlesource.com/70770
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Use them to replace if/else chains with at least three comparisons,
where the code becomes clearly simpler.

Passes toolstash -cmp on std cmd.

Change-Id: Ic98aa3905944ddcab5aef5f9d9ba376853263d94
Reviewed-on: https://go-review.googlesource.com/70934
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

The write barrier insertion has moved to the SSA backend's
writebarrier pass. There is still needwritebarrier function
left in the frontend. This function is used in two places:

- fncall, which is called in ascompatet, which is called in
  walking OAS2FUNC. For OAS2FUNC, in order pass we've already
  created temporaries, and there is no write barrier for the
  assignments of these temporaries.

- updateHasCall, which updates the HasCall flag of a node. the
  HasCall flag is then used in
  - fncall, mentioned above.
  - ascompatet. As mentioned above, this is an assignment to
    a temporary, no write barrier.
  - reorder1, which is always called with a list produced by
    ascompatte, which is a list of assignments to stack, which
    have no write barrier.
  - vmatch1, which is called in oaslit with r.Op as OSTRUCTLIT,
    OARRAYLIT, OSLICELIT, or OMAPLIT. There is no write barrier
    in those literals.

Therefore, the needwritebarrier function is unnecessary. This
CL removes it.

Passes "toolstash -cmp" on std cmd.

Updates #17583.

Change-Id: I4b87ba8363d6583e4282a9e607a9ec8ce3ab124a
Reviewed-on: https://go-review.googlesource.com/43640
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

On ARM, STREX does not permit the same register used as both the
source and the destination. Reject the bad instruction.

The assembler also accepted special cases
	STREX R0, (R1)	as STREX R0, (R1), R0
	STREX (R1), R0	as STREX R0, (R1), R0
both are illegal. Remove this special case as well.

For STREXD, check that the destination is not source, and not
source+1. Also check that the source register is even numbered,
as required by the architecture's manual.

Fixes #22268.

Change-Id: I6bfde86ae692d8f1d35bd0bd7aac0f8a11ce8e22
Reviewed-on: https://go-review.googlesource.com/71190
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

In golang.org/cl/61130, I removed the need for setting Xoffset on
OXCASE Nodes, but missed this assignment.

Passes toolstash-check.

Change-Id: I90ab05add14981b89ee18e73e1cdf2f13e9f9934
Reviewed-on: https://go-review.googlesource.com/66934
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

If the client sends a request with a custom Host header and receives
a relative redirect in response, the second request should use the
same Host header as the first request. However, if the response is
an abolute redirect, the Host header should not be preserved. See
further discussion on the issue tracker.

Fixes #22233

Change-Id: I8796e2fbc1c89b3445e651f739d5d0c82e727c14
Reviewed-on: https://go-review.googlesource.com/70792Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Instead of repeating the same list parsing pattern for parenthesized
of braced comma or semicolon-separated lists, introduce a single list
parsing function that can be parametrized and which takes a closure
to parse list elements.

This ensures the same error handling and recovery logic is used across
all lists and simplifies the code.

No semantic change.

Change-Id: Ia738d354d6c2e0c3d84a5f1c7269a6eb95685edc
Reviewed-on: https://go-review.googlesource.com/70492Reviewed-by: Matthew Dempsky <mdempsky@google.com>

No semantic change. Move functionality not related to argument
out of the argument parsing function, and thus match parameter
parsing. Also, use a better function name.

Change-Id: Ic550875251d64e6fe1ebf91c11d33a9e4aec9fdd
Reviewed-on: https://go-review.googlesource.com/70491Reviewed-by: Matthew Dempsky <mdempsky@google.com>

These changes affect the parser only when the internal trace
constant is set.

- factored our printing code used for tracing
- streamlined advance function and added trace output

The parser's trace output now more clearly prints what tokens
are skipped and which is the next token in case of an error.

Example trace:

    4: . . . . . . . . . . call (
    4: . . . . . . . . . . . expr (
    4: . . . . . . . . . . . . unaryExpr (
    4: . . . . . . . . . . . . . pexpr (
    4: . . . . . . . . . . . . . . operand name (
    4: . . . . . . . . . . . . . . )
    4: . . . . . . . . . . . . . . call (
    4: . . . . . . . . . . . . . . )
    4: . . . . . . . . . . . . . )
    4: . . . . . . . . . . . . )
    4: . . . . . . . . . . . )
    4: . . . . . . . . . . . syntax error: expecting comma or )
    4: . . . . . . . . . . . skip ;
    6: . . . . . . . . . . . skip name
    6: . . . . . . . . . . . skip :=
    6: . . . . . . . . . . . skip literal
    6: . . . . . . . . . . . skip ;
    7: . . . . . . . . . . . skip }
    7: . . . . . . . . . . . skip ;
    9: . . . . . . . . . . . skip func
    9: . . . . . . . . . . . skip name
    9: . . . . . . . . . . . skip (
    9: . . . . . . . . . . . next )
    9: . . . . . . . . . . )

For #22164.

Change-Id: I4a233696b1f989ee3287472172afaf92cf424565
Reviewed-on: https://go-review.googlesource.com/70490Reviewed-by: Matthew Dempsky <mdempsky@google.com>

STREX does not permit using the same register for the value to store
and the place where the result is returned. Also the code was wrong
anyhow if the first store failed.

Fixes #22248

Change-Id: I96013497410058514ffcb771c76c86faa1ec559b
Reviewed-on: https://go-review.googlesource.com/70911
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Change-Id: I50389752dcbf5d058ce11256a414be7955cdb77f
Reviewed-on: https://go-review.googlesource.com/71070
Run-TryBot: Tom Bergan <tombergan@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tom Bergan <tombergan@google.com>