* It does very simple bounds checking elimination. E.g.
removes the second check in for i := range a { a[i]++; a[i++]; }
* Improves on the following redundant expression:
return a6 || (a6 || (a6 || a4)) || (a6 || (a4 || a6 || (false || a6)))
* Linear in the number of block edges.

I patched in CL 12960 that does bounds, nil and constant propagation
to make sure this CL is not just redundant. Size of pkg/tool/linux_amd64/*
(excluding compile which is affected by this change):

With IsInBounds and IsSliceInBounds
-this -12960 92285080
+this -12960 91947416
-this +12960 91978976
+this +12960 91923088

Gain is ~110% of 12960.

Without IsInBounds and IsSliceInBounds (older run)
-this -12960 95515512
+this -12960 95492536
-this +12960 95216920
+this +12960 95204440

Shaves 22k on its own.

* Can we handle IsInBounds better with this? In
for i := range a { a[i]++; } the bounds checking at a[i]
is not eliminated.

Change-Id: I98957427399145fb33693173fd4d5a8d71c7cc20
Reviewed-on: https://go-review.googlesource.com/19710Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Add the max arg length to opcodes and use it in zcse.  Doesn't affect
speed, but allows better checking in checkFunc and removes the need
to keep a list of zero arg opcodes up to date.

Change-Id: I157c6587154604119720ec6228b767b6e52bb5c7
Reviewed-on: https://go-review.googlesource.com/19994Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

plive doesn't like the fact that we put JMPs right
after CALL ops to select{send,recv}.

Fixes SSA -N build.

Change-Id: I9b3c9e5293196094fd5a6206dd2f99784951f7a9
Reviewed-on: https://go-review.googlesource.com/19982
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

non-SSA backends are all over the map as to whether nil checks
get removed or not.  amd64, 386, 386/387, arm are all subtly different.
Remove these extra checks for now, they are in nilptr3_ssa.go so they
won't get lost.

Change-Id: I2e0051f488fb2cb7278c6fdd44cb9d68b5778345
Reviewed-on: https://go-review.googlesource.com/19961Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Just like we do for integer loads/stores.

Update #14511

Change-Id: Ic6ca6b54301438a5701ea5fb0be755451cb24d45
Reviewed-on: https://go-review.googlesource.com/19923Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>

Our stack frame sizes look pretty good now.  Lower the stack
guard from 1024 to 720.
Tip is currently using 720.
We could go lower (to 640 at least) except PPC doesn't like that.

Change-Id: Ie5f96c0e822435638223f1e8a2bd1a1eed68e6aa
Reviewed-on: https://go-review.googlesource.com/19922
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

The -d compiler flag can also specify ssa phase and flag,
for example -d=ssa/generic_cse/time,ssa/generic_cse/stats

Spaces in the phase names can be specified with an
underscore.  Flags currently parsed (not necessarily
recognized by the phases yet) are:

   on, off, mem, time, debug, stats, and test

On, off and time are handled in the harness,
debug, stats, and test are interpreted by the phase itself.

The pass is now attached to the Func being compiled, and a
new method logStats(key, ...value) on *Func to encourage a
semi-standardized format for that output.  Output fields
are separated by tabs to ease digestion by awk and
spreadsheets.  For example,
	if f.pass.stats > 0 {
		f.logStat("CSE REWRITES", rewrites)
	}

Change-Id: I16db2b5af64c50ca9a47efeb51d961147a903abc
Reviewed-on: https://go-review.googlesource.com/19885Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

Found looking at mapaccess1_faststr.

runtime.throw never returns.
Do x+y+c with an LEA.

Change-Id: I27ea6669324242a6302397cbdc73230891d97591
Reviewed-on: https://go-review.googlesource.com/19911
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Forgot the obvious case.  Allows us to remove the load in:

func f(p *int, x int) int {
	*p = x + 5
	return *p
}

Change-Id: I93686d8240bab3a1d166b88e224cf71e3d947aef
Reviewed-on: https://go-review.googlesource.com/19905
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The @ directive used to read the target block after some value
structure had already changed.  I don't think it was ever really
a bug, but it's confusing.

It might fail like this:

(Foo x y) -> @v.Args[0].Block (Bar y (Baz ...))

v.Op = Bar
v.Args[0] = y
v.Args[1] = v.Args[0].Block.NewValue(Baz, ...)

That new value is allocated in the block of y, not the
block of x.

Anyway, read the destination block first so this
potential bug can't happen.

Change-Id: Ie41d2fc349b35cefaa319fa9327808bcb781b4e2
Reviewed-on: https://go-review.googlesource.com/19900
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

Remove the stuff that's already done.

Change-Id: I3b4fc827240d45dd051dc36897883532d8900a0c
Reviewed-on: https://go-review.googlesource.com/19906Reviewed-by: David Chase <drchase@google.com>

In regalloc, make LoadReg instructions use the line number
of their *use*, not their *source*.  This reduces the
tendency of debugger stepping to "jump around" the program.

Change-Id: I59e2eeac4dca9168d8af3a93effbc5bdacac2881
Reviewed-on: https://go-review.googlesource.com/19836
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Construct better initial partitions by recursively comparing values and
their arguments.  This saves one second on compile of arithConst_ssa.go
(4.3s to 3.3s) and shows a 3-5% increase with compilebench.

name       old time/op     new time/op     delta
Template       266ms ± 3%      253ms ± 4%  -5.08%          (p=0.032 n=5+5)
GoTypes        927ms ± 3%      885ms ± 2%  -4.55%          (p=0.016 n=5+5)
Compiler       3.91s ± 3%      3.73s ± 2%  -4.49%          (p=0.008 n=5+5)
MakeBash       31.6s ± 1%      30.5s ± 3%  -3.51%          (p=0.016 n=5+5)

Change-Id: I6ede31ff459131ccfed69531acfbd06b19837700
Reviewed-on: https://go-review.googlesource.com/19838Reviewed-by: David Chase <drchase@google.com>

Helps keep line numbers around for debugging, particularly
for break and continue statements (which often compile
down to nothing).

Update #14379

Change-Id: I6ea06aa887b0450d9ba4f11e319e5c263f5a98ba
Reviewed-on: https://go-review.googlesource.com/19848Reviewed-by: David Chase <drchase@google.com>

Saves about 2k for binaries in pkg/tool/linux_amd64.
Also useful when opt runs after cse (as in 12960) which reorders
arguments for commutative operations such as Add64.

Change-Id: I49ad53afa53db9736bd35c425f4fb35fb511fd63
Reviewed-on: https://go-review.googlesource.com/19827
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Semi-regular merge from tip to dev.ssa.

Change-Id: If7d2269f267bcbc0ecd3a483d349951044470e3f

name                        old time/op  new time/op  delta
DecodeValidASCII-4          94.7ns ± 1%  87.4ns ± 1%  -7.71%  (p=0.000 n=10+9)
DecodeValidJapaneseChars-4  91.0ns ± 2%  84.8ns ± 0%  -6.77%  (p=0.000 n=9+10)
DecodeRune-4                16.5ns ± 0%  16.6ns ± 2%    ~     (p=0.108 n=9+10)

For #6957

Change-Id: I618c15c2a42ef7ec6a5cd163b7c3f1a65ca4ad01
Reviewed-on: https://go-review.googlesource.com/19826Reviewed-by: Rob Pike <r@golang.org>

This reverts commit f28bbb77.

Change-Id: I82fb81dcff3ddcaefef72949f1ef3a41bcd22301
Reviewed-on: https://go-review.googlesource.com/19849
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

The previous Happy Eyeballs implementation would intentionally leak
connections, because dialTCP could not be reliably terminated upon
losing the race.

Now that dialTCP supports cancelation (plan9 excluded), dialParallel can
wait for responses from both the primary and fallback racers, strictly
before returning control to the caller.

In dial_test.go, we no longer need Sleep to avoid leaks.
Also, fix a typo in the Benchmark IPv4 address.

Updates #11225
Fixes #14279

Change-Id: Ibf3fe5c7ac2f7a438c1ab2cdb57032beb8bc27b5
Reviewed-on: https://go-review.googlesource.com/19390Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The () parentheses grouped wrongly. Removed them completely in
favor of separate 2- and 3-index slice alternatives which is
clearer.

Fixes #14477.

Change-Id: I0b7521ac912130d9ea8740b8793b3b88e2609418
Reviewed-on: https://go-review.googlesource.com/19853Reviewed-by: Ian Lance Taylor <iant@golang.org>

While investigating the differences between 19710 (remove
tautological controls) and 12960 (bounds and nil propagation)
I observed that part of the wins of 19710 come from missed
opportunities for deadcode elimination due to phis.
See for example runtime.stackcacherelease. 19710 happens much
later than 12960 and has more chances to eliminate bounds.

Size of pkg/tool/linux_amd64/* excluding compile:

-this -12960 95882248
+this -12960 95880120
-this +12960 95581512
+this +12960 95555224

This change saves about 25k.

Change-Id: Id2f4e55fc92b71595842ce493c3ed527d424fe0e
Reviewed-on: https://go-review.googlesource.com/19728Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Makes godoc 10KB smaller.
For #6853.

Change-Id: Id54bd8c82cb2a1ba11d2d724e3107f73024b19d9
Reviewed-on: https://go-review.googlesource.com/19696
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Found running go vet on the package. It barks that
	regexp/backtrack.go:257: unreachable code
	regexp/backtrack.go:302: unreachable code

For #11041

Change-Id: I0f5ba0d6183108fba3d144991b826273db0ffb09
Reviewed-on: https://go-review.googlesource.com/19824Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Current code does not print any response headers from httputil.DumpResponse().

   PUT /miniocloud/new-file HTTP/1.1
   Host: s3.amazonaws.com
   User-Agent: Go-http-client/1.1
   Content-Length: 11
   Accept-Encoding: gzip

   HTTP/1.1 200 OK

With this fix we get an appropriate output for httputil.DumpResponse().

   PUT /miniocloud/new-file HTTP/1.1
   Host: s3.amazonaws.com
   User-Agent: Go-http-client/1.1
   Content-Length: 11
   Accept-Encoding: gzip

   HTTP/1.1 200 OK
   Content-Length: 0
   Date: Thu, 14 Jan 2016 03:04:42 GMT
   Etag: "3e25960a79dbc69b674cd4ec67a72c62"
   Server: AmazonS3
   X-Amz-Id-2: qnXyH6sknlovV0Myy3emFAXTNtI/sQIcu1ZXNq/6wd17K32tQ7WNGB1qb3nzCpW2DhfeZ/MbWfw=
   X-Amz-Request-Id: 8422EACB0CC492BD

Fixes #13942

Change-Id: Ida063cc3524a96170d8a837893f7c9f49b6cf98e
Reviewed-on: https://go-review.googlesource.com/18624Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I6035941df8b0de6aeaf6c05df7257bcf6e9191fe
Reviewed-on: https://go-review.googlesource.com/19320Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

For #6957

Change-Id: Ic497c12f33efc933e9fe81f6cd1b2a0a01abbabf
Reviewed-on: https://go-review.googlesource.com/19820
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

util.go was originally added in golang.org/cl/4851, and later moved to
its current location in golang.org/cl/10287.

Change-Id: I10b4941d42ae1ff2e78990c497c1347bbbae4e3d
Reviewed-on: https://go-review.googlesource.com/19851Reviewed-by: David Crawshaw <crawshaw@golang.org>

Change-Id: Ib413b0cb16405965455d7764a8c4a22bf431389b
Reviewed-on: https://go-review.googlesource.com/19850
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

The upper bits of 8/16/32 bit constants are undefined.  We need to
truncate in order to prevent x86.oclass misidentifying the size of the
constant.

Fixes #14389

Change-Id: I3e5ff79cd904376572a93f489ba7e152a5cb6e60
Reviewed-on: https://go-review.googlesource.com/19740Reviewed-by: Keith Randall <khr@golang.org>

Pass lexer around so state is accessible and dependency is explicit.
In the process remove EOF -> '\n' conversion that has to be corrected
for when reporting errors.

Change-Id: If95564b70e7484dedc1f5348e585cd19acbc1243
Reviewed-on: https://go-review.googlesource.com/19819
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Fixes #14475.

Change-Id: I1b5b0a9793a417572ec55f313185d03ad5ae9d01
Reviewed-on: https://go-review.googlesource.com/19846Reviewed-by: Robert Griesemer <gri@golang.org>

Loads of stores from the same pointer with compatible types
can be replaced with a copy.

Change-Id: I514b3ed8e5b6a9c432946880eac67a51b1607932
Reviewed-on: https://go-review.googlesource.com/19743
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

They do the same thing, except memequal also has the short-circuit
check if the two pointers are equal.

A) We might as well always do the short-circuit check, it is only 2 instructions.
B) The extra function call (memequal->memeq) is expensive.

benchmark                 old ns/op     new ns/op     delta
BenchmarkArrayEqual-8     8.56          5.31          -37.97%

No noticeable affect on the former memeq user (maps).

Fixes #14302

Change-Id: I85d1ada59ed11e64dd6c54667f79d32cc5f81948
Reviewed-on: https://go-review.googlesource.com/19843
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

A comment existed referencing RC4 coming before AES because of it's
vulnerability to the Lucky 13 attack. This clarifies that the Lucky 13 attack
only effects AES-CBC, and not AES-GCM.

Fixes #14474

Change-Id: Idcb07b5e0cdb0f9257cf75abea60129ba495b5f5
Reviewed-on: https://go-review.googlesource.com/19845Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The structure of the code meant that an embedded field was never
checked for export status. We need to check the name of the type,
which is either of type T or type *T, and T might be unexported.

Fixes #14356.

Change-Id: I56f468e9b8ae67e9ed7509ed0b91d860507baed2
Reviewed-on: https://go-review.googlesource.com/19701Reviewed-by: Robert Griesemer <gri@golang.org>

It's not needed on other OSes.

Change-Id: Ia6b13510585392a7062374806527d33876beba2a
Reviewed-on: https://go-review.googlesource.com/19818
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I7414d2fab18ae6e7e7c50f8697ec64d38290f409
Reviewed-on: https://go-review.googlesource.com/19817
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Cuts 20k off cmd/go and 32k off golang.org/x/tools/cmd/godoc, approx 0.15% each.

For #6853 and #9930

Change-Id: Ic510b76b80a9153b1ede7b3533d2dbc16caa5c63
Reviewed-on: https://go-review.googlesource.com/19768
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

When visiting the AST to add counters, there are special cases in which
the code calls cuts the walking short by returning nil. In some cases
certain nodes are ignored, e.g. Init and Cond inside IfStmt.

The fix is to explicitly walk all the children nodes (not only
Body and Else) when cutting the current walk. Similar approach
was taken with SwitchStmt and TypeSwitchStmt.

While the existing test code doesn't handle different counters in the
same line, the generated HTML report does it correctly (because it takes
column into account).

The previous behavior caused lines in function literals to not be
tracked when those literals were inside Init or Cond of an IfStmt for
example.

Fixes #14039.

Change-Id: Iad591363330843ad833bd79a0388d709c8d0c8aa
Reviewed-on: https://go-review.googlesource.com/19775Reviewed-by: Rob Pike <r@golang.org>

These files were not added to the repo. They contain conversion
routines and corresponding tests not used by the compiler and
thus are technically not needed.

However, future changes to math/big (and corresponding updates
of this vendored version) may require these files to exist.
Add them to avoid unnecessary confusion.

Change-Id: Ie390fb54f499463b2bba2fdc084967539afbeeb3
Reviewed-on: https://go-review.googlesource.com/19730Reviewed-by: Alan Donovan <adonovan@google.com>