removePredecessor can change which blocks are live.
However, it cannot remove dead blocks from the function's
slice of blocks because removePredecessor may have been
called from within a function doing a walk of the blocks.

CL 11879 did not handle this correctly and broke the build.

To fix this, mark the block as dead but leave its actual
removal for a deadcode pass. Blocks that are dead must have
no successors, predecessors, values, or control values,
so they will generally be ignored by other passes.
To be safe, we add a deadcode pass after the opt pass,
which is the only other pass that calls removePredecessor.

Two alternatives that I considered and discarded:

(1) Make all call sites aware of the fact that removePrecessor
might make arbitrary changes to the list of blocks. This
will needlessly complicate callers.

(2) Handle the things that can go wrong in practice when
we encounter a dead-but-not-removed block. CL 11930 takes
this approach (and the tests are stolen from that CL).
However, this is just patching over the problem.

Change-Id: Icf0687b0a8148ce5e96b2988b668804411b05bd8
Reviewed-on: https://go-review.googlesource.com/12004Reviewed-by: Todd Neal <todd@tneal.org>
Reviewed-by: Michael Matloob <michaelmatloob@gmail.com>

Reduces 'go run run.go 64bit.go' from 23s to 8s on my machine.

Change-Id: Ie5b642d0abb56e8eb3899d69472bc88a85a1c985
Reviewed-on: https://go-review.googlesource.com/12023Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This is a prerequisite for implementing break and continue;
blocks ending in break or continue need to have
the increment block as a successor.

While we're here, implement for loops with no condition.

Change-Id: I85d8ba020628d805bfd0bd583dfd16e1be6f6fae
Reviewed-on: https://go-review.googlesource.com/11941Reviewed-by: Keith Randall <khr@golang.org>

This change has some tests verifying functionality and an assortment of
benchmarks of various block lists. It modifies NewBlock to allocate in
contiguous blocks improving the performance of intersect() for extremely
large graphs by 30-40%.

benchmark                           old ns/op      new ns/op     delta
BenchmarkDominatorsLinear-8         1185619        901154        -23.99%
BenchmarkDominatorsFwdBack-8        1302138        863537        -33.68%
BenchmarkDominatorsManyPred-8       404670521      247450911     -38.85%
BenchmarkDominatorsMaxPred-8        455809002      471675119     +3.48%
BenchmarkDominatorsMaxPredVal-8     819315864      468257300     -42.85%

BenchmarkNilCheckDeep1-8            766            706           -7.83%
BenchmarkNilCheckDeep10-8           2553           2209          -13.47%
BenchmarkNilCheckDeep100-8          58606          57545         -1.81%
BenchmarkNilCheckDeep1000-8         7753012        8025750       +3.52%
BenchmarkNilCheckDeep10000-8        1224165946     789995184     -35.47%

Change-Id: Id3d6bc9cb1138e8177934441073ac7873ddf7ade
Reviewed-on: https://go-review.googlesource.com/11716Reviewed-by: Keith Randall <khr@golang.org>

The removal of if false { ... } blocks in the opt
pass exposed that removePredecessor needed
to do more cleaning, on pain of failing later
consistency checks.

Change-Id: I45d4ff7e1f7f1486fdd99f867867ce6ea006a288
Reviewed-on: https://go-review.googlesource.com/11879Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: Ie23b13142fd820d7071a348a8370175e58b76d64
Reviewed-on: https://go-review.googlesource.com/11878Reviewed-by: Keith Randall <khr@golang.org>

Loops such as

func f(c chan int) int {
	for x := range c {
		return x
	}
	return 0
}

don't loop. Remove the assumption that they must.

Partly fixes the build.

Change-Id: I766cebeec8e36d14512bea26f54c06c8eaf95e23
Reviewed-on: https://go-review.googlesource.com/11876Reviewed-by: Keith Randall <khr@golang.org>

There is clearly work to do to fix labels and gotos.
The compiler currently hangs on ken/label.go.

For the moment, stop the bleeding.

Fixes the build.

Change-Id: Ib68360d583cf53e1a8ca4acff50644b570382728
Reviewed-on: https://go-review.googlesource.com/11877Reviewed-by: Keith Randall <khr@golang.org>

Partly fixes the build, by punting.
Other things have broken in the meantime.

Change-Id: I1e2b8310057cbbbd9ffc501ef51e744690e00726
Reviewed-on: https://go-review.googlesource.com/11875Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I4e4200b0fa847a1ff8a8b7d1e318bbc1c5e26b5b
Reviewed-on: https://go-review.googlesource.com/11874Reviewed-by: Keith Randall <khr@golang.org>

Doesn't fix the build entirely, but does make it get to the race
detector tests.

Change-Id: Ie986d52374936855b7ee975dc68742306527eb15
Reviewed-on: https://go-review.googlesource.com/11835Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

These additional checks were useful in
tracking down the broken build (CL 11238).

This CL does not fix the build, sadly.

Change-Id: I34de3bed223f450aaa97c1cadaba2e4e5850050b
Reviewed-on: https://go-review.googlesource.com/11681Reviewed-by: Keith Randall <khr@golang.org>

This will make it possible for us to start implementing interfaces
and other stack allocated types which are more than one machine word.

Change-Id: I52b187a791cf1919cb70ed6dabdc9f57b317ea83
Reviewed-on: https://go-review.googlesource.com/11631Reviewed-by: Keith Randall <khr@golang.org>

Forgot to add this in the tip merge.

Change-Id: I0e5a2681133f4ae7a7c360ae2c2d71d46420c693
Reviewed-on: https://go-review.googlesource.com/11793Reviewed-by: Keith Randall <khr@golang.org>

Semi-regular merge from tip into ssa branch.

Change-Id: I9cbe23f566410496d4ceb97c1435e2df7f2b56ec

Everything in the library but crypto and net.

Change-Id: I89b21b9621e6d338fa1891da0eabba5d7d2fe349
Reviewed-on: https://go-review.googlesource.com/11820Reviewed-by: Russ Cox <rsc@golang.org>

Adding a mutex was easier than documenting it, and is consistent with
gob.

Fixes #9847

Change-Id: Ifa94c17e7c11643add81b35431ef840b794d78b1
Reviewed-on: https://go-review.googlesource.com/11682Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

See RFC 7230.

Thanks to Régis Leroy for the report.

Change-Id: Ic1779bc2180900430d4d7a4938cac04ed73c304c
Reviewed-on: https://go-review.googlesource.com/11810Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #11475

Change-Id: Ibaedbb732bb1b9f062bd5af7b866ec4758c724a7
Reviewed-on: https://go-review.googlesource.com/11770Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

The optional Qualifier function determines what prefix to attach to
package-level names, enabling clients to qualify packages in different
ways, for example, using only the package name instead of its complete
path, or using the locally appropriate name for package given a set of
(possibly renaming) imports.

Prior to this change, clients wanting this behavior had to copy
hundreds of lines of complex printing logic.

Fun fact: (*types.Package).Path and (*types.Package).Name are valid
Qualifier functions.

We provide the RelativeTo helper function to create Qualifiers so that
the old behavior remains a one-liner.

Fixes golang/go#11133

This CL is a copy of https://go-review.googlesource.com/#/c/11692/
to the golang.org/x/tools repository.

Change-Id: I26d0f3644d077a26bfe350989f9c545f018eefbf
Reviewed-on: https://go-review.googlesource.com/11790Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>

We can't address more than this on amd64 anyway.

Fixes #9862.

Change-Id: Ifb1abae558e2e1ee2dc953a76995f3f08c60b1df
Reviewed-on: https://go-review.googlesource.com/11715Reviewed-by: Austin Clements <austin@google.com>

Compiling a simple file containing a slice of 100,000 strings,
the size of the resulting binary dropped from 5,896,224 bytes
to 3,495,968 bytes, which is the expected 2,400,000 bytes,
give or take.

Fixes #7384.

Change-Id: I3e551b5a1395b523a41b33518d81a1bf28da0906
Reviewed-on: https://go-review.googlesource.com/11698Reviewed-by: Austin Clements <austin@google.com>

Fixes #7561 correctly.
Fixes #9137.

Change-Id: I7f27e199d7101b785a7645f789e8fe41a405a86f
Reviewed-on: https://go-review.googlesource.com/11713Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

This was originally done in https://codereview.appspot.com/5690059
(Feb 2012) to deal with bad response headers coming back from webcams,
but it presents a potential security problem with HTTP request
smuggling for request headers containing "Content Length" instead of
"Content-Length".

Part of overall HTTP hardening for request smuggling. See RFC 7230.

Thanks to Régis Leroy for the report.

Change-Id: I92b17fb637c9171c5774ea1437979ae2c17ca88a
Reviewed-on: https://go-review.googlesource.com/11772Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

If you have more than 10 procs, then currently they are sorted alphabetically as
0, 10, 11, ..., 19, 2, 20, ...
Assign explicit order to procs so that they are sorted numerically.

Change-Id: I6d978d2cd439aa2fcbcf147842a643f9073eef75
Reviewed-on: https://go-review.googlesource.com/11750Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

Fixes #9758

Change-Id: I3089ec06cddd74b547d8b10834d7478a04b02069
Reviewed-on: https://go-review.googlesource.com/11701Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

RawPath is a hint to the desired encoding of Path.
It is ignored when it is not a valid encoding of Path,
such as when Path has been changed but RawPath has not.
It is not ignored but also not useful when it matches
the url package's natural choice of encoding.
In this latter case, set it to the empty string.
This should help drive home the point that clients
cannot in general depend on it being present and
that they should use the EncodedPath method instead.

This also reduces the impact of the change on tests,
especially tests that use reflect.DeepEqual on parsed URLs.

Change-Id: I437c51a33b85439a31c307caf1436118508ea196
Reviewed-on: https://go-review.googlesource.com/11760Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Iacb84421215ca80c7add2818118b2af1a650fd58
Reviewed-on: https://go-review.googlesource.com/11639Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

When an xmlns="..." attribute was explicitly generated,
it was being ignored because the name space on the
attribute was assumed to have been explicitly set (to the empty
name space) and it's not possible to have an element in the
empty name space when there is a non-empty name space set.

We fix this by recording when a default name space has been
explicitly set and setting the name space of the element to that
so printer.defineNS can do its work correctly.

We do not attempt to add our own xmlns="..." attribute
when one is explicitly set.

We also add tests for EncodeElement, as that's the only way
to attain coverage of some of the changed behaviour.
Some other test coverage is also increased, although
more work remains to be done in this area.

This change was jointly developed with Martin Hilton (mhilton on github).

Fixes #11431.

Change-Id: I7b85e06eea5b18b2c15ec16dcbd92a8e1d6a9a4e
Reviewed-on: https://go-review.googlesource.com/11635Reviewed-by: Russ Cox <rsc@golang.org>

Fixes #11438

Change-Id: Iedd31918aa5187fc3fdaed71c8dad82075559084
Reviewed-on: https://go-review.googlesource.com/11667Reviewed-by: Rob Pike <r@golang.org>

The spec says this is invalid, but it matches giflib's behavior.

Fixes #9856 (together with https://go-review.googlesource.com/11661).

Change-Id: I05701f62a9e5e724a2d85c6b87ae4111e537146b
Reviewed-on: https://go-review.googlesource.com/11663Reviewed-by: Rob Pike <r@golang.org>

This is needed by issue #9856.

Change-Id: Idad570a7e55ad903aab55372d390bc746c4e19cf
Reviewed-on: https://go-review.googlesource.com/11661Reviewed-by: Rob Pike <r@golang.org>

Fixes #11426

Change-Id: I77368b0e852149ed4533e139cc43887508ac7f78
Reviewed-on: https://go-review.googlesource.com/11662Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>

This allows for "race free" cancellation, in the sense discussed in
issue #11013: in contrast to Transport.CancelRequest, the cancellation
will not be lost if the user cancels before the request is put into the
transport's internal map.

Fixes #11013.

Change-Id: I0b5e7181231bdd65d900e343f764b4d1d7c422cd
Reviewed-on: https://go-review.googlesource.com/11601
Run-TryBot: David Symonds <dsymonds@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

For #11326 (but not a fix).

Change-Id: Ic51814f5cd7357427c3fd990a5522775d05e7987
Reviewed-on: https://go-review.googlesource.com/11673Reviewed-by: Robert Griesemer <gri@golang.org>

I think this has the same meaning as before,
but the text is tighter, and it makes some people happy.

Fixes #10182.

Change-Id: I7ee1eae4bcd6ee4a5898ea948648939e6bde5f01
Reviewed-on: https://go-review.googlesource.com/11674Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

This behavior is not what we might have designed from the start,
but it has been present since Go 1. Rather than make a visible
behavioral change that might cause programs to work differently
in Go ≤1.4 vs Go ≥1.5, document what SkipDir on a non-directory
has always meant. If code doesn't want this meaning, it is easy
enough not to return SkipDir on non-directories.

Fixes #10533.

Change-Id: Ic0612f032044bc7c69bf62583a02037e4b47530b
Reviewed-on: https://go-review.googlesource.com/11690Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Fixes #9621.

Change-Id: Ib9c6001378364af899f57fd4b89fb23af2042923
Reviewed-on: https://go-review.googlesource.com/11694Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>

Change-Id: I5791639e71874ce13fac836a0c6014e20ee7417e
Reviewed-on: https://go-review.googlesource.com/11664Reviewed-by: Russ Cox <rsc@golang.org>

Also: make (*Scope).Innermost work for Package scopes.

This change is identical to http://go-review.googlesource.com/#/c/11691/,
except for minor changes required by the use of testImporter.

Change-Id: Id07e66f78987f7242c2e642dfd6ee613676e10e5
Reviewed-on: https://go-review.googlesource.com/11714Reviewed-by: Robert Griesemer <gri@golang.org>