Phi splitting sometimes leads to a phi with only a single predecessor.
This must be replaced with a copy to maintain a valid SSA form.

Fixes #14857

Change-Id: I5ab2423fb6c85a061928e3206b02185ea8c79cd7
Reviewed-on: https://go-review.googlesource.com/20826Reviewed-by: Keith Randall <khr@golang.org>

API not exposed yet.

Change-Id: Iaba0adc0fa1ae8075e6b56796f99ee8db9177a78
Reviewed-on: https://go-review.googlesource.com/18896Reviewed-by: Russ Cox <rsc@golang.org>

API is not exposed yet.

Change-Id: I729360ef2be1d8ea683ca93cdb1763897cc8657c
Reviewed-on: https://go-review.googlesource.com/18895Reviewed-by: Russ Cox <rsc@golang.org>

testing.go:
- run method will evolve into the Run method.
- added level field in common

benchmark.go:
- benchContext will be central to distinguish handling of benchmarks
  between normal Run methods and ones called from within Benchmark
  function.
- expandCPU will evolve into the processing hook for Run methods
  called within normal processing.
- runBench will evolve into the Run method.

Change-Id: I1816f9985d5ba94deb0ad062302ea9aee0bb5338
Reviewed-on: https://go-review.googlesource.com/18894Reviewed-by: Russ Cox <rsc@golang.org>

The biggest change is that each test is now responsible for managing
the starting and stopping of its parallel subtests.

The "Main" test could be run as a tRunner as well. This shows that
the introduction of subtests is merely a generalization of and
consistent with the current semantics.

Change-Id: Ibf8388c08f85d4b2c0df69c069326762ed36a72e
Reviewed-on: https://go-review.googlesource.com/18893Reviewed-by: Russ Cox <rsc@golang.org>

There's nothing guaranteeing that the *Regexp isn't in active use,
and so copying the sync.Mutex value is invalid.

Updates #14839.

Change-Id: Iddf52bf69df1b563377922399f64a571f76b95dd
Reviewed-on: https://go-review.googlesource.com/20841Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>

This seems to help the problem reported in #14606; this
change seems to produce about a 4% improvement (mostly
for the 128-8192 shards).

Fixes #14789.

Change-Id: I1bd52c82d4ca81d9d5e9ab371fdfc860d7e8af50
Reviewed-on: https://go-review.googlesource.com/20660
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Improve the test by also translating " " to "_".

Fixes #14671.

Change-Id: Ie5997934b93c7663d7b8432244fad47bb5d3ffbe
Reviewed-on: https://go-review.googlesource.com/20714Reviewed-by: Ian Lance Taylor <iant@golang.org>

This is intended to help debug compiler problems that pop
up in the bootstrap phase of make.bash.  GO_GCFLAGS does not
normally apply there.  Options-for-all phases is intended
to allow crude tracing (and full timing) by turning on timing
for all phases, not just one.

Phase names can also be specified using a regular expression,
for example
BOOT_GO_GCFLAGS=-d='ssa/~^.*scc$/off' \
GO_GCFLAGS='-d=ssa/~^.*scc$/off' ./make.bash

I just added this because it was the fastest way to get
me to a place where I could easily debug the compiler.

Change-Id: I0781f3e7c19651ae7452fa25c2d54c9a245ef62d
Reviewed-on: https://go-review.googlesource.com/20775Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ic40449b2e4b4f18cbe5b5d4c3d51ea7b05ac674d
Reviewed-on: https://go-review.googlesource.com/20823
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This change makes unexposed methods start with lowercase letters for
avoiding unnecessary confusion because the net package uses many
embedding structures and intrefaces for controlling exposure of APIs.

Note that this change leaves DNS-related methods as they are.

Change-Id: I253758d1659175c5d0af6b2efcd30ce83f46543d
Reviewed-on: https://go-review.googlesource.com/20784
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: Ic5f62a7d0a5c090da69213d1d0187af0ea48e358
Reviewed-on: https://go-review.googlesource.com/20820Reviewed-by: Rob Pike <r@golang.org>

The critical phase did not correctly maintain the use count
when two predecessors of a new critical block transmit the
same value.

Change-Id: Iba802c98ebb84e36a410721ec32c867140efb6d4
Reviewed-on: https://go-review.googlesource.com/20822Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

* This the simplest solution I could came up with
that doesn't required changing the compiler.
* The bound checks become constants now
so they are removed during opt phase.

Updates #14808

Change-Id: If32c33d7ec08bb400321b465015d152f0a5d3001
Reviewed-on: https://go-review.googlesource.com/20654Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I3c6035559288cfdc33857216f50241b81932c8a4
Reviewed-on: https://go-review.googlesource.com/20811
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Make sure we don't generate write barriers in runtime
code that is marked to forbid write barriers.

Implement the optimization that if we're writing a sliced
slice back to the location it came from, we don't need a
write barrier.

Fixes #14784

Change-Id: I04b6a3b2ac303c19817e932a36a3b006de103aaa
Reviewed-on: https://go-review.googlesource.com/20791Reviewed-by: Austin Clements <austin@google.com>

Reduces size of archives in pkg/linux_amd64 by 1.4MB (3.2%),
slightly improving link time.

name       old s/op   new s/op   delta
LinkCmdGo  0.52 ± 3%  0.51 ± 2%  -0.65%  (p=0.000 n=98+99)

Change-Id: I7e265f4d4dd08967c5c5d55c1045e533466bbbec
Reviewed-on: https://go-review.googlesource.com/20802
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I32fd5c36f055fdb1dfe56524085676aa4111089a
Reviewed-on: https://go-review.googlesource.com/20830Reviewed-by: David Chase <drchase@google.com>

Boolean expressions involving t.Thistuple were converted to use
t.Recv(), because it's a bit clearer and will hopefully reveal cases
where we could remove redundant calls to t.Recv() (in followup CLs).

The other cases were all converted to use t.Recvs().NumFields(),
t.Params().NumFields(), or t.Results().NumFields().

Change-Id: I4df91762e7dc4b2ddae35995f8dd604a52c09b09
Reviewed-on: https://go-review.googlesource.com/20796Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>

We never need a type hash for a method type, so skip trying to
overwrite Thistuple.

Change-Id: I8de6480ba5fd321dfa134facf7661461d298840e
Reviewed-on: https://go-review.googlesource.com/20795Reviewed-by: Russ Cox <rsc@golang.org>

This is an automated rewrite of all the calls of the form:

    for f, it := IterFields(t); f != nil; f = it.Next() { ... }

Followup CLs will work on cleaning up the remaining cases.

Change-Id: Ic1005ad45ae0b50c63e815e34e507e2d2644ba1a
Reviewed-on: https://go-review.googlesource.com/20794Reviewed-by: David Crawshaw <crawshaw@golang.org>

Analogous to the Nodes type used as a more space efficient []*Node
representation.

Passes toolstash -cmp.

Change-Id: I8341e45304777d6e4200bd36dadc935b07ccf3ff
Reviewed-on: https://go-review.googlesource.com/20793Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I85c0bcf02842cc32dbc9bfdcea27efe871173574
Reviewed-on: https://go-review.googlesource.com/20774Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The compiler doesn't care about the runtime's sudog type. Stop
constructing it.

Change-Id: If1885fe30b2e215a08d17662eab5ea6d81fe58ab
Reviewed-on: https://go-review.googlesource.com/20797
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

For every string constant the compiler was creating 2 Sym's and 2
Node's.  It would never refer to them again, but would keep them alive
in gostringpkg.  This changes the code to just use obj.LSym's instead.

When compiling x/tools/go/types, this yields about a 15% reduction in
the number of calls to newname and a 3% reduction in the total number of
Node objects.  Unfortunately I couldn't see any change in compile time,
but reducing memory usage is desirable anyhow.

Passes toolstash -cmp.

Change-Id: I24f1cb1e6cff0a3afba4ca66f7166874917a036b
Reviewed-on: https://go-review.googlesource.com/20792Reviewed-by: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This should probably be considered "experimental" at this stage, but
what it needs is feedback from adventurous adopters.  I think the data
structure used for describing escape reasons might be extendable to
allow a cleanup of the underlying algorithms, which suffers from
insufficiently separated concerns (the graph does not deal well with
escape level adjustments, so it is augmented by a second custom-walk
portion of the "flood" phase. It would be better to put it all,
including level adjustments, in a single graph structure, and then
simply flood the graph.

Tweaked to avoid allocations in the no-logging case.

Modified run.go to ignore lines with leading "#" in the output (since
it can never match a line), and in -update_errors to ignore leading
tabs in output lines and to normalize embedded filenames.

Currently requires -m -m because otherwise the noise/update
burden for the other escape tests is considerable.

There is a partial test.  Existing escape analysis tests seem to
cover all except the panic case and what looks like it might be
unreachable code in escape analysis.

Fixes #10526.

Change-Id: I2524fdec54facae48b00b2548e25d9e46fcaf832
Reviewed-on: https://go-review.googlesource.com/18041
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

If a phi has duplicate arguments, then the new block that is constructed
to remove the critical edge can be used for all of the duplicate
arguments.

read-only data = -904 bytes (-0.058308%)
global text (code) = -2240 bytes (-0.060056%)
Total difference -3144 bytes (-0.056218%)

Change-Id: Iee3762744d6a8c9d26cdfa880bb23feb62b03c9c
Reviewed-on: https://go-review.googlesource.com/20746
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Between the enumeration of fdsToClose in the parent and the
closing of fds in the child, it's possible for a file to be
closed in another thread. If that file descriptor is reused
when opening the child-parent status pipe, it will be closed
prematurely in the child and the forkExec gets out of sync.
This has been observed to cause failures in builder tests
when the link step of a build is started before the compile
step has run, with "file does not exist" messages as the
visible symptom.

The simple workaround is to check against closing the pipe.
A more comprehensive solution would be to rewrite the fd
closing code to avoid races, along the lines of the long
ago proposed https://golang.org/cl/57890043 - but meanwhile
this correction will prevent some builder failures.

Change-Id: I4ef5eaea70c21d00f4df0e0847a1c5b2966de7da
Reviewed-on: https://go-review.googlesource.com/20800
Run-TryBot: David du Colombier <0intro@gmail.com>
Reviewed-by: David du Colombier <0intro@gmail.com>

Separate unicode formatting into its own fmt_unicode function.
Remove the fmtUnicode wrapper and the f.unicode and f.uniQuote
flags that are not needed anymore. Remove mangling and restoring
of the precision and sharp flags.

Removes the buffer copy needed for %#U by moving
the character encoding before the number encoding.

Changes the behavior of plus and space flag to have
no effect instead of printing a plus or space before "U+".

Always print at least four digits after "U+"
even if precision is set to less than 4.

Change-Id: If9a0ee79e9eca2c76f06a4e0fdd75d98393899ac
Reviewed-on: https://go-review.googlesource.com/20574
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Keep track of how many uses each Value has.  Each appearance in
Value.Args and in Block.Control counts once.

The number of uses of a value is generically useful to
constrain rewrite rules.  For instance, we might want to
prevent merging index operations into loads if the same
index expression is used lots of times.

But I have one use in particular for which the use count is required.
We must make sure we don't combine ops with loads if the load has
more than one use.  Otherwise, we may split a single load
into multiple loads and that breaks perceived behavior in
the presence of races.  In particular, the load of m.state
in sync/mutex.go:Lock can't be done twice.  (I have a separate
CL which triggers the mutex failure.  This CL has a test which
demonstrates a similar failure.)

Change-Id: Icaafa479239f48632a069d0c3f624e6ebc6b1f0e
Reviewed-on: https://go-review.googlesource.com/20790
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

Spotted while splunking in the compiler with GOGC=off.

name       old time/op     new time/op     delta
Template       407ms ± 5%      402ms ± 6%     ~           (p=0.301 n=20+20)
GoTypes        1.33s ± 2%      1.29s ± 1%   -3.47%        (p=0.000 n=20+20)
Compiler       6.21s ± 1%      5.91s ± 2%   -4.83%        (p=0.000 n=20+20)

name       old alloc/op    new alloc/op    delta
Template      66.8MB ± 0%     63.9MB ± 0%   -4.46%        (p=0.000 n=19+20)
GoTypes        232MB ± 0%      220MB ± 0%   -5.16%        (p=0.000 n=19+17)
Compiler      1.02GB ± 0%     0.97GB ± 0%   -5.81%        (p=0.000 n=20+20)

name       old allocs/op   new allocs/op   delta
Template        789k ± 0%       708k ± 0%  -10.28%        (p=0.000 n=19+20)
GoTypes        2.49M ± 0%      2.20M ± 0%  -11.57%        (p=0.000 n=20+20)
Compiler       10.8M ± 0%       9.4M ± 0%  -12.82%        (p=0.000 n=20+20)

Change-Id: I76615cab912dde10595ca6ab9979ff6c5f1aec49
Reviewed-on: https://go-review.googlesource.com/20782Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

When building shared libraries, all symbols on Allsym are marked reachable.
What I didn't realize was that this includes the ".dup" symbols created when
"dupok" symbols are read from multiple package files. This breaks now because
deadcode makes some assumptions that fail for these ".dup" symbols, but in any
case was a bad idea -- I suspect this change makes libstd.so a bunch smaller,
but creating it was broken before this CL so I can't be sure.

This change simply stops adding these symbols to Allsym, which might make some
of the many iterations over Allsym the linker does a touch quicker, although
that's not the motivation here.

Add a test that no symbols called ".dup" makes it into the runtime shared
library.

Fixes #14841

Change-Id: I65dd6e88d150a770db2d01b75cfe5db5fd4f8d25
Reviewed-on: https://go-review.googlesource.com/20780
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Receiver parameters generally aren't relevant to the function
signature type. In particular:

  1. When checking whether a type's method implements an interface's
     method, we specifically want to ignore the receiver parameters,
     because they'll be different.

  2. When checking interface type equality, interface methods always
     use the same "fakethis" *struct{} type as their receiver.

  3. Finally, method expressions and method values degenerate into
     receiver-less function types.

The only case where we care about receiver types matching is in
addmethod, which is easily handled by adding an extra Eqtype check of
the receiver parameters. Also, added a test for this, since
(surprisingly) there weren't any.

As precedence, go/types.Identical ignores receiver parameters when
comparing go/types.Signature values.

Notably, this allows us to slightly simplify the "implements"
function, which is used for checking whether type/interface t
implements interface iface. Currently, cmd/compile actually works
around Eqtype's receiver parameter checking by creating new throwaway
TFUNC Types without the receiver parameter.

(Worse, the compiler currently only provides APIs to build TFUNC Types
from Nod syntax trees, so building those throwaway types also involves
first building throwaway syntax trees.)

Passes toolstash -cmp.

Change-Id: Ib07289c66feacee284e016bc312e8c5ff674714f
Reviewed-on: https://go-review.googlesource.com/20602Reviewed-by: Robert Griesemer <gri@golang.org>

Follow-up to CL 20674.

Passes toolstash -cmp.

Change-Id: I065fd4cd80d996c1e6566773189401ca4630c1ca
Reviewed-on: https://go-review.googlesource.com/20692
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

We can’t perfectly predict how large the function
will be, but we can make a safe overestimate.
No significant CPU time changes.

name       old alloc/op    new alloc/op    delta
Template      67.7MB ± 0%     67.5MB ± 0%   -0.24%          (p=0.029 n=4+4)
Unicode       43.9MB ± 0%     43.8MB ± 0%   -0.13%          (p=0.029 n=4+4)
GoTypes        244MB ± 0%      244MB ± 0%   -0.28%          (p=0.029 n=4+4)
Compiler      1.05GB ± 0%     1.05GB ± 0%   -0.38%          (p=0.029 n=4+4)

name       old allocs/op   new allocs/op   delta
Template        795k ± 0%       794k ± 0%   -0.14%          (p=0.029 n=4+4)
Unicode         569k ± 0%       569k ± 0%     ~             (p=0.114 n=4+4)
GoTypes        2.59M ± 0%      2.58M ± 0%   -0.11%          (p=0.029 n=4+4)
Compiler       11.0M ± 0%      11.0M ± 0%   -0.09%          (p=0.029 n=4+4)

Passes toolstash -cmp.

Change-Id: I0a92ab04cba7520540ec58fe7189666d0e771454
Reviewed-on: https://go-review.googlesource.com/20771Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>

Passes toolstash -cmp.

Change-Id: I77a415a4e5d8de7eb902fb0866aaf8783259485a
Reviewed-on: https://go-review.googlesource.com/20770Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Add a C.CBytes function to copy a Go byte slice into C memory. This
returns an unsafe.Pointer, since that is what needs to be passed to
C.free, and the data is often opaque bytes anyway.

Fixes #14838

Change-Id: Ic7bc29637eb6f1f5ee409b3898c702a59833a85a
Reviewed-on: https://go-review.googlesource.com/20762Reviewed-by: Ian Lance Taylor <iant@golang.org>

Currently we generate write barriers when the right side of an
assignment is a global function. This doesn't fall into the existing
case of storing an address of a global because we haven't lowered the
function to a pointer yet.

This write barrier is unnecessary, so eliminate it.

Fixes #13901.

Change-Id: Ibc10e00a8803db0fd75224b66ab94c3737842a79
Reviewed-on: https://go-review.googlesource.com/20772
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Passes toolstash -cmp.

Change-Id: Ie11912a16d2cd54500e2f6e84316519b80e7c304
Reviewed-on: https://go-review.googlesource.com/20672Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

c2go translated writing and advancing a pointer using slices.
Switch to something more idiomatic.
It is also more efficient, but not enough to matter.

Change-Id: I67709632ac53253615a35365824ae97bbe5458d5
Reviewed-on: https://go-review.googlesource.com/20767
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>