Add test to check that struct type in reflectlite is mirror of reflect.
Note that the test does not check the field types, only check for number
of fields and field name are the same.

Updates #34486

Change-Id: Id5f9b26d35faec97863dd1fe7e5eab37d4913181
Reviewed-on: https://go-review.googlesource.com/c/go/+/199280
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Add a Reset method to blocks that allows us to reduce the amount of
code we generate for block rewrite rules.

Thanks to Cherry for suggesting a similar fix to this in CL 196557.

Compilebench result:

name                      old time/op       new time/op       delta
Template                        211ms ± 1%        211ms ± 1%   -0.30%  (p=0.028 n=19+20)
Unicode                        83.7ms ± 3%       83.0ms ± 2%   -0.79%  (p=0.029 n=18+19)
GoTypes                         757ms ± 1%        755ms ± 1%   -0.31%  (p=0.034 n=19+19)
Compiler                        3.51s ± 1%        3.50s ± 1%   -0.20%  (p=0.013 n=18+18)
SSA                             11.7s ± 1%        11.7s ± 1%   -0.38%  (p=0.000 n=19+19)
Flate                           131ms ± 1%        130ms ± 1%   -0.32%  (p=0.024 n=18+18)
GoParser                        162ms ± 1%        162ms ± 1%     ~     (p=0.059 n=20+18)
Reflect                         471ms ± 0%        470ms ± 0%   -0.24%  (p=0.045 n=20+17)
Tar                             187ms ± 1%        186ms ± 1%     ~     (p=0.157 n=20+20)
XML                             255ms ± 1%        255ms ± 1%     ~     (p=0.461 n=19+20)
LinkCompiler                    754ms ± 2%        755ms ± 2%     ~     (p=0.919 n=17+17)
ExternalLinkCompiler            2.82s ±16%        2.37s ±10%  -15.94%  (p=0.000 n=20+20)
LinkWithoutDebugCompiler        439ms ± 4%        442ms ± 6%     ~     (p=0.461 n=18+19)
StdCmd                          25.8s ± 2%        25.5s ± 1%   -0.95%  (p=0.000 n=20+20)

name                      old user-time/op  new user-time/op  delta
Template                        240ms ± 8%        238ms ± 7%     ~     (p=0.301 n=20+20)
Unicode                         107ms ±18%        104ms ±13%     ~     (p=0.149 n=20+20)
GoTypes                         883ms ± 3%        888ms ± 2%     ~     (p=0.211 n=20+20)
Compiler                        4.22s ± 1%        4.20s ± 1%     ~     (p=0.077 n=20+18)
SSA                             14.1s ± 1%        14.1s ± 2%     ~     (p=0.192 n=20+20)
Flate                           145ms ±10%        148ms ± 5%     ~     (p=0.126 n=20+18)
GoParser                        186ms ± 7%        186ms ± 7%     ~     (p=0.779 n=20+20)
Reflect                         538ms ± 3%        541ms ± 3%     ~     (p=0.192 n=20+20)
Tar                             218ms ± 4%        217ms ± 6%     ~     (p=0.835 n=19+20)
XML                             298ms ± 5%        298ms ± 5%     ~     (p=0.749 n=19+20)
LinkCompiler                    818ms ± 5%        825ms ± 8%     ~     (p=0.461 n=20+20)
ExternalLinkCompiler            1.55s ± 4%        1.53s ± 5%     ~     (p=0.063 n=20+18)
LinkWithoutDebugCompiler        460ms ±12%        460ms ± 7%     ~     (p=0.925 n=20+20)

name                      old object-bytes  new object-bytes  delta
Template                        554kB ± 0%        554kB ± 0%     ~     (all equal)
Unicode                         215kB ± 0%        215kB ± 0%     ~     (all equal)
GoTypes                        2.01MB ± 0%       2.01MB ± 0%     ~     (all equal)
Compiler                       7.97MB ± 0%       7.97MB ± 0%   +0.00%  (p=0.000 n=20+20)
SSA                            26.8MB ± 0%       26.9MB ± 0%   +0.27%  (p=0.000 n=20+20)
Flate                           340kB ± 0%        340kB ± 0%     ~     (all equal)
GoParser                        434kB ± 0%        434kB ± 0%     ~     (all equal)
Reflect                        1.34MB ± 0%       1.34MB ± 0%     ~     (all equal)
Tar                             480kB ± 0%        480kB ± 0%     ~     (all equal)
XML                             622kB ± 0%        622kB ± 0%     ~     (all equal)

name                      old export-bytes  new export-bytes  delta
Template                       20.4kB ± 0%       20.4kB ± 0%     ~     (all equal)
Unicode                        8.21kB ± 0%       8.21kB ± 0%     ~     (all equal)
GoTypes                        36.6kB ± 0%       36.6kB ± 0%     ~     (all equal)
Compiler                        115kB ± 0%        115kB ± 0%   +0.08%  (p=0.000 n=20+20)
SSA                             141kB ± 0%        141kB ± 0%   +0.07%  (p=0.000 n=20+20)
Flate                          5.11kB ± 0%       5.11kB ± 0%     ~     (all equal)
GoParser                       8.93kB ± 0%       8.93kB ± 0%     ~     (all equal)
Reflect                        11.8kB ± 0%       11.8kB ± 0%     ~     (all equal)
Tar                            10.9kB ± 0%       10.9kB ± 0%     ~     (all equal)
XML                            17.4kB ± 0%       17.4kB ± 0%     ~     (all equal)

name                      old text-bytes    new text-bytes    delta
HelloSize                       742kB ± 0%        742kB ± 0%     ~     (all equal)
CmdGoSize                      10.7MB ± 0%       10.7MB ± 0%     ~     (all equal)

name                      old data-bytes    new data-bytes    delta
HelloSize                      10.7kB ± 0%       10.7kB ± 0%     ~     (all equal)
CmdGoSize                       312kB ± 0%        312kB ± 0%     ~     (all equal)

name                      old bss-bytes     new bss-bytes     delta
HelloSize                       122kB ± 0%        122kB ± 0%     ~     (all equal)
CmdGoSize                       146kB ± 0%        146kB ± 0%     ~     (all equal)

name                      old exe-bytes     new exe-bytes     delta
HelloSize                      1.10MB ± 0%       1.10MB ± 0%     ~     (all equal)
CmdGoSize                      14.9MB ± 0%       14.9MB ± 0%     ~     (all equal)

Change-Id: Ic89a8e62423b3d9fd9391159e0663acf450803b5
Reviewed-on: https://go-review.googlesource.com/c/go/+/198419
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

CL 197938 actually fixes those regression on Darwin as syscalls
are no longer labeled as always blocking and consume a thread.

Fixes #33953
Fixes #32326

Change-Id: I82c98516c23cd36f762bc5433d7b71ea8939a0ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/199477
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

Fixes #31590

Change-Id: I7fd6dcc5c34496776439ff0295f18b5fb5cb538a
Reviewed-on: https://go-review.googlesource.com/c/go/+/199141Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

CL 191198 updated runtime rtype and mapType without adopting the changes
to reflectlite, causing mismatch between them.

This CL updates those changes to reflectlite.

Fixes #34486

Change-Id: I2bb043673d997f97bb0b12c4ad471474803b2160
Reviewed-on: https://go-review.googlesource.com/c/go/+/197559
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Updates #34486

Change-Id: Iec9a5d120013aaa287eccf2999b3f2b831be070e
Reviewed-on: https://go-review.googlesource.com/c/go/+/197558Reviewed-by: Ian Lance Taylor <iant@golang.org>

TestScripts/mod_get_svn would stop with the following prompt if the real
user didn't have vcs-test.golang.org in their known_hosts file:

	The authenticity of host 'vcs-test.golang.org (35.184.38.56)' can't be established.
	ECDSA key fingerprint is SHA256:[...]
	Are you sure you want to continue connecting (yes/no/[fingerprint])?

This was bad because it relied on the user's real ssh known_hosts file.
Worse even, if the user didn't expert or notice the prompt, it could
hang a 'go test' run for quite a while.

Work around that by forcing svn to not use ssh at all. Other potentially
better approaches were tried, but none worked on svn 1.12.2 with openssh
8.0p1.

Fixes #33883.

Change-Id: I2f925fa892f2fa53c77d86b0034141162517ee69
Reviewed-on: https://go-review.googlesource.com/c/go/+/199142
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #24715

Change-Id: Ie7cdac346fb024858441bfd4028bf09adab3c9d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/198545
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates #24715

Change-Id: If5d9591a820f6e921e69e722d46bf91d2ae738cb
Reviewed-on: https://go-review.googlesource.com/c/go/+/198543
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

syscall, internal/syscall/windows, internal/syscall/windows/registry: make go generate use new golang.org/x/sys/windows/mkwinsyscall

Updates #34388

Change-Id: I327a1c1557c47fa6c113c7a1a507a8e7355f9d1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/199277
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>

When translating C types, cache the in-progress type under its parent
names, so that anonymous structs can also be translated for multiple
typedefs, without clashing.

Standalone types are not affected by this change.

Also updated the test for issue 9026 because the C struct name
generation algorithm has changed.

Fixes #31891

Change-Id: I00cc64852a2617ce33da13f74caec886af05b9f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/181857
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Icb1c3eb30147180ba5949a25c65b48307b14c1ca
GitHub-Last-Rev: 937ae8641321139b9165ce7d57abeac5a67dc24d
GitHub-Pull-Request: golang/go#34704
Reviewed-on: https://go-review.googlesource.com/c/go/+/199157
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

add preceding "+" for a line that is certainly a statement,
and "_" for a line this is certainly not a statement.

Change-Id: I831435dbc2302f25db1320b99d3513fe61fe1fa2
Reviewed-on: https://go-review.googlesource.com/c/go/+/198737
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

Two changes, one to cause the back end to not number ITab operations
(these tend to disappear and are also followed by something more robust)
and to explicitly unmark (as statements) all but the first bit of
the code generated to implement a type switch.

Change-Id: I9f7bf7cbf7ccc5d7eda57f7fb080e600eb312eb0
Reviewed-on: https://go-review.googlesource.com/c/go/+/198739
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

Calls are code-generated in an alternate path that inherits
its positions from values, not from *SSAGenState.  The
default position on *SSAGenState was marked as not-a-statement,
but this was not applied to the value itself, leading to
spurious "is statement" marks in the output (convention:
after code generation in the compiler, everything is either
definitely a statement or definitely not a statement, nothing
is in the undetermined state).

This CL causes a 35 statement regression in ssa/stmtlines_test.
This is down from the earlier 150 because of all the other
CLs preceding this one that deal with the root causes of the
missing lines (repeated lines on nested calls hid missing lines).

This also removes some line repeats from ssa/debug_test.

Change-Id: Ie9a507bd5447e906b35bbd098e3295211df2ae01
Reviewed-on: https://go-review.googlesource.com/c/go/+/188018
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

This was a cause of some statements being lost.

Change-Id: I81c95dcf3df6ed8a03b7578a27f9b21d33b3cf39
Reviewed-on: https://go-review.googlesource.com/c/go/+/198484
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

We replace the existing file with a thin wrapper around its target so
that we don't break anybody's workflow.

Updates #34388

Change-Id: I0d00371c483cb78f4be18fe987df33c79cd40f05
Reviewed-on: https://go-review.googlesource.com/c/go/+/198977
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This page has moved to x/website in https://golang.org/cl/197638.

Updates golang/go#33637
Updates golang/go#29206

Change-Id: I4f5f7822a2bf540a3911470548d38ccc7a66b74c
Reviewed-on: https://go-review.googlesource.com/c/go/+/199117
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Jean de Klerk <deklerk@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

This reduces the number of missing-statement lines.

Change-Id: Iefa56c2a253220d17d8b53210c8c6af78ee68756
Reviewed-on: https://go-review.googlesource.com/c/go/+/198483
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

Fixes #34697

Change-Id: Iedfa3d46d558510f3bd1fdf9466cd974793d9ecd
Reviewed-on: https://go-review.googlesource.com/c/go/+/199017
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

This is being moved to x/website in https://golang.org/cl/199058.

Updates golang/go#33637
Updates golang/go#29206

Change-Id: I5c58b784fcdd212d7a003cd0f4085059f33a47c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/199057Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

This reverts CL 183841.

Fixes #34533

Reason for revert: Introduced a significant performance regression for repos with many incompatible-version tags.

Change-Id: I75d7fd76e6e1a0902b114b00167b38439e0f8221
Reviewed-on: https://go-review.googlesource.com/c/go/+/198699
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Passed toolstash-check.

Updates #21738
Fixes #21934

Change-Id: I59f0b2c9890146565ff913b04aeeeff7dc7a4499
Reviewed-on: https://go-review.googlesource.com/c/go/+/197561
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

RELNOTE=yes

Fixes #28362

Change-Id: I43813c0c17bbe6c4cbb4d1f121518c434b3f5aa8
Reviewed-on: https://go-review.googlesource.com/c/go/+/174329Reviewed-by: Filippo Valsorda <filippo@golang.org>

This was a cause of some statements being lost.

Change-Id: Ia4805c2dafd7a880d485a678a48427de8930d57e
Reviewed-on: https://go-review.googlesource.com/c/go/+/198482
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

In the local package build process, when -o is pointing to an existing folder, the object
the filename is generated from files listed on the command line like when the -o is
not pointing to a folder instead of using the `importPath` that is going to be `command-line-arguments`

Fixes #34535

Change-Id: I09a7609c17a2ccdd83da32f01247c0ef473dea1e
GitHub-Last-Rev: b3224226a3914aa2573e47a6daff9fd5a48ca225
GitHub-Pull-Request: golang/go#34562
Reviewed-on: https://go-review.googlesource.com/c/go/+/197544
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

Change-Id: I2d6b73ae7447e4bdeffcdac90f7422a9280666e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/198678
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Statement markers on rematerializable values were getting lost in
register allocation.  This checks for that case (rematerializable
input and using value share line number, but mark is on the input)
and preserves the mark.

When combined with other CLs in this series, this CL reduces the
"nostmt" count (a line appears in the assembly, but no statement
marker) for cmd/go from 413 to 277.  The rematerialized input is
usually a LEAQ (on AMD64).

The cause is "complicated"; for example, a NilCheck originally has the
statement mark (a good thing, if the NilCheck  remains) but the
NilCheck is removed and the mark floats to a Block end, then to a
SliceMake.  The SliceMake decomposes and goes dead without preserving
its marker (its component values are elided in other rewrites and may
target inputs with different line numbers), but before deadcode
removes it from the graph it moves the mark to an input, which at that
time happens to be a LocalAddr. This eventually transforms to a LEAQ.

Change-Id: Iff91fc2a934357fb59ec46ac87b4a9b1057d9160
Reviewed-on: https://go-review.googlesource.com/c/go/+/198480
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

OpPhi nodes tend to disappear or get rearranged,
and cause statement marks to vanish.

Change-Id: I2f5a222903b7fcd0d1a72e8f6d7e156036b23f30
Reviewed-on: https://go-review.googlesource.com/c/go/+/198481
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

According to spec, the hash must be truncated, but crypto/dsa
does not do it. We can't fix it in crypto/dsa, because it would break
verification of previously generated signatures.
In crypto/x509 however, go can't generate DSA certs, only verify them,
so the fix here should be safe.

Fixes #22017

Change-Id: Iee7e20a5d76f45da8901a7ca686063639092949f
GitHub-Last-Rev: 8041cde8d25d3a336b81d86bd52bff5039568246
GitHub-Pull-Request: golang/go#34630
Reviewed-on: https://go-review.googlesource.com/c/go/+/198138Reviewed-by: Filippo Valsorda <filippo@golang.org>

'GOFLAGS=-mod=vendor' currently causes 'go get' to always fail unless
the '-mod' flag is explicitly overwritten. Moreover, as of CL 198319
we plan to set -mod=vendor by default if a vendor directory is
present, so all users with vendor directories will be affected — not
just those who set 'GOFLAGS' explicitly.

Similarly, an explicit '-mod=readonly' argument to 'go get' is
currently ignored as a special case, but the fact that it is ignored
(rather than rejected) can be very surprising.

Rather than adding more special cases, we should remove the '-mod'
flag from 'go get' entirely.

Fixes #30345
Fixes #32502
Updates #33848

Change-Id: Iecd3233ca3ef580ca3a66bd5e6ee8d86d4cbd8a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/198438
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

CL 188317 introduced a compiler crash during dwarf generation which
was reported as Issue #34520. After CL 188217, the issue appears to be
fixed. Add a testcase to avoid future regressions.

Fixes #34520

Change-Id: I73544a9e9baf8dbfb85c19eb6d202beea05affb6
Reviewed-on: https://go-review.googlesource.com/c/go/+/198546
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Passing ambiguous patterns, ending in `.go`, to `go list` results in them
being interpreted as Go files despite potentially being package references.
This can then result in errors on other package references.

The parsing logic is modified to check for a locally present file
corresponding to any pattern ending in `.go`. If no such file is present
the pattern is considered to be a package reference.

We're also adding a variety of non-regression tests that fail with the
original parsing code but passes after applying the fix.

Fixes #32483
Fixes #34653

Change-Id: I073871da0dfc5641a359643f95ac14608fdca09b
GitHub-Last-Rev: 5abc200103ffc122df05422d79cf30c3ba0ee646
GitHub-Pull-Request: golang/go#34663
Reviewed-on: https://go-review.googlesource.com/c/go/+/198459
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

The existing text was hard to parse.
Shorten the sentences and simplify the text.

Change-Id: Ic16f486925090ea303c04e70969e5a4b27a60896
Reviewed-on: https://go-review.googlesource.com/c/go/+/198758Reviewed-by: Ian Lance Taylor <iant@golang.org>

Nilcheck would move statements from NilCheck values to others that
turned out were already dead, which leads to lost statements.  Better
to eliminate the dead code first.

One "error" is removed from test/prove.go because the code is
actually dead, and the additional deadcode pass removes it before
prove can run.

Change-Id: If75926ca1acbb59c7ab9c8ef14d60a02a0a94f8b
Reviewed-on: https://go-review.googlesource.com/c/go/+/198479
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

The earlier code was picking nodes that were "poor choices" and
thus sometimes losing statements altogether.

Change-Id: Ibe5ed800ffbd3c926c0ab1bc10c77d72d3042e45
Reviewed-on: https://go-review.googlesource.com/c/go/+/198478
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

Aggregate-making nodes that are later decomposed
are poor choices for statements, because the decomposition
phase turns them into multiple sub-values, some of which may be
dead.  Better to look elsewhere for a statement mark.

Change-Id: Ibd9584138ab3d1384548686896a28580a2e43f54
Reviewed-on: https://go-review.googlesource.com/c/go/+/198477
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

The previous version used the position of the switch statement,
which makes for potentially jumpy stepping and introduces a large
number of statements repeating the line (tricky for inserting
breaks).  It also shared a single OBREAK node and this was not
really a syntax "tree".

This improves both the nostmt test (by 6 lines) and
reduces the total badness score from dwarf-goodness (by about 200).

Change-Id: I1f71b231a26f152bdb6ce9bc8f95828bb222f665
Reviewed-on: https://go-review.googlesource.com/c/go/+/188218
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

1) An empty block is treated as not-a-statement unless its line differs
from at least one of its predecessors (it might make sense to
rearrange branches in predecessors, but that is a different issue).

2) When iterating forward to choose a "good" place for a statement,
actually check that the chosen place is in fact good.

3) Refactor same line and same file into methods on XPos and Pos.

This reduces the failure rate of ssa/stmtlines_test by 7-ish lines.
(And interacts favorably with later debugging CLs.)

Change-Id: Idb7cca7068f6fc9fbfdbe25bc0da15bcfc7b9d4a
Reviewed-on: https://go-review.googlesource.com/c/go/+/188217
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>

Makes it easier to run

    go build -a -gcflags=-d=export std |& grep ^BenchmarkExportSize

and get useful output for feeding into benchstat.

Change-Id: I2b52e8f5ff33b7ccb6c25b18e464513344bd9ad9
Reviewed-on: https://go-review.googlesource.com/c/go/+/198698Reviewed-by: Robert Griesemer <gri@golang.org>