Not recording the address being taken was causing
the liveness analysis not to preserve x in the absence
of direct references to x, which in turn was making the
net test fail with GOGC=0.

In addition to the test, this fixes a bug wherein
        GOGC=0 go test -short net
crashed if liveness analysis was in use (like at tip, not like Go 1.2).

TBR=ken2
CC=golang-codereviews
https://golang.org/cl/64470043

This problem was discovered by reading the code.
I have not seen it in practice, nor do I have any ideas
on how to trigger it reliably in a test. But it's still worth
fixing.

TBR=ken2
CC=golang-codereviews
https://golang.org/cl/64370046

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/64380043

The VARDEF placement must be before the initialization
but after any final use. If you have something like s = ... using s ...
the rhs must be evaluated, then the VARDEF, then the lhs
assigned.

There is a large comment in pgen.c on gvardef explaining
this in more detail.

This CL also includes Ian's suggestions from earlier CLs,
namely commenting the use of mode in link.h and fixing
the precedence of the ~r check in dcl.c.

This CL enables the check that if liveness analysis decides
a variable is live on entry to the function, that variable must
be a function parameter (not a result, and not a local variable).
If this check fails, it indicates a bug in the liveness analysis or
in the generated code being analyzed.

The race detector generates invalid code for append(x, y...).
The code declares a temporary t and then uses cap(t) before
initializing t. The new liveness check catches this bug and
stops the compiler from writing out the buggy code.
Consequently, this CL disables the race detector tests in
run.bash until the race detector bug can be fixed
(golang.org/issue/7334).

Except for the race detector bug, the liveness analysis check
does not detect any problems (this CL and the previous CLs
fixed all the detected problems).

The net test still fails with GOGC=0 but the rest of the tests
now pass or time out (because GOGC=0 is so slow).

TBR=iant
CC=golang-codereviews
https://golang.org/cl/64170043

The existing tests issue4463.go and issue4654.go had failures at
typechecking and did not test walking the AST.

Fixes #7272.

LGTM=khr
R=khr, rsc, iant
CC=golang-codereviews
https://golang.org/cl/60550044

Catch the error instead and return it to the user. Before this fix,
the template package panicked. Now you get:
        template: bug11:1:14: executing "bug11" at <.PS>: dereference of nil pointer of type *string
Extended example at http://play.golang.org/p/uP6pCW3qKT

Fixes #7333.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/64150043

The branchtags method was removed but we should've
been using branchmap all along.

http://selenic.com/hg/rev/4274eda143cb

LGTM=franciscossouza, r
R=golang-codereviews, franciscossouza, r
CC=golang-codereviews
https://golang.org/cl/57500045

These should never be found in a bzip2 file but it does appear that
there's a buggy encoder that is producing them. Since the official
bzip2 handles this case, this change makes the Go code do likewise.

With this change, the code produces the same output as the official
bzip2 code on the invalid example given in the bug.

Fixes #7279.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/64010043

Rfork is not splitting the stack when creating a new thread,
so the parent and child are executing on the same stack.
However, if the parent returns and keeps executing before
the child can read the arguments from the parent stack,
the child will not see the right arguments. The solution
is to load the needed pieces from the parent stack into
register before INT $64.

Thanks to Russ Cox for the explanation.

LGTM=rsc
R=rsc
CC=ality, golang-codereviews
https://golang.org/cl/64140043

Fixes #7329

LGTM=gri
R=gri, bradfitz, mtj
CC=golang-codereviews
https://golang.org/cl/63710043

A previous CL added support for cross compiling with cgo, but
missed the GOOS check in cmd/go. Remove it.

Update #4714

LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/57210046

Changing the PC confuses gdb, because execution does not
continue where gdb expects it.  Not changing the PC has the
potential to confuse a stack dump, but when running under gdb
it seems better to confuse a stack dump than to confuse gdb.

Fixes #6776.

LGTM=rsc
R=golang-codereviews, dvyukov, rsc
CC=golang-codereviews
https://golang.org/cl/49580044

A configuration like the following:

7: tun6rd: <NOARP,UP,LOWER_UP> mtu 1280
        link/sit 10.11.12.13 brd 0.0.0.0
        inet 1.2.3.4/24 scope global tun6rd
        inet6 2014:1001:a0b:c0d::1/32 scope global
        inet6 ::10.11.12.13/128 scope global
9: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1496
        link/ppp
        inet 192.168.101.234 peer 192.168.102.234/32 scope global ppp0
        inet 10.20.30.40/24 scope global ppp0
        inet6 2014:1002::1/64 scope global
11: tun0@NONE: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1480
        link/ipip 192.168.202.34 peer 192.168.202.69
        inet 192.168.10.1/24 scope global tunnel0
        inet6 2014:1003::1/64 scope global

will be handled like below.

"tun6rd": flags "up", ifindex 7, mtu 1280
        hardware address ""
        interface address "1.2.3.4/24"
        interface address "2014:1001:a0b:c0d::1/32"
        interface address "::a0b:c0d/128"
"ppp0": flags "up|pointtopoint|multicast", ifindex 9, mtu 1496
        hardware address ""
        interface address "192.168.101.234/32"
        interface address "10.20.30.40/24"
        interface address "2014:1002::1/64"
"tun0": flags "up|pointtopoint", ifindex 11, mtu 1480
        hardware address ""
        interface address "192.168.10.1/24"
        interface address "2014:1003::1/64"

Fixes #6433.
Update #4839

LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/57700043

On Linux include/net directory is just to help porting applications
from BSDs and files under net keep less information than include/linux.
Making use of files under include/linux instead of include/net prevents
lack of information.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/63930043

The following checkdead message is false positive:

$ go test -race -c runtime
$ ./runtime.test -test.cpu=2 -test.run=TestSmhasherWindowed -test.v
=== RUN TestSmhasherWindowed-2
checkdead: find g 18 in status 1
SIGABRT: abort
PC=0x42bff1

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews, iant, khr
https://golang.org/cl/59490046

Currently small and large (size>rate) objects are merged into a single entry.
But rate adjusting is required only for small objects.
As a result pprof either incorrectly adjusts large objects
or does not adjust small objects.
With this change objects of different sizes are stored in different buckets.

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/59220049

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63680045

It's implementation detail.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/63690043

When the liveness code doesn't know a function doesn't return
(but the generated code understands that), the liveness analysis
invents a control flow edge that is not really there, which can cause
variables to seem spuriously live. This is particularly bad when the
variables are uninitialized.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63720043

Currently it periodically fails with the following message.
The immediate cause is the wrong base register when obtaining g
in sys_windows_amd64/386.s.
But there are several secondary problems as well.

runtime: unknown pc 0x0 after stack split
panic: invalid memory address or nil pointer dereference
fatal error: panic during malloc
[signal 0xc0000005 code=0x0 addr=0x60 pc=0x42267a]

runtime stack:
runtime.panic(0x7914c0, 0xc862af)
        c:/src/perfer/work/windows-amd64-a15f344a9efa/go/src/pkg/runtime/panic.c:217 +0x2c
runtime: unexpected return pc for runtime.externalthreadhandler called from 0x0

R=rsc, alex.brainman
CC=golang-codereviews
https://golang.org/cl/63310043

The registerization code needs the function to end in a RET,
even if that RET is actually unreachable.

The liveness code needs to avoid such unreachable RETs.
It had a special case for final RET after JMP, but no case
for final RET after UNDEF. Instead of expanding the special
cases, let fixjmp - which already knows what is and is not
reachable definitively - mark the unreachable RET so that
the liveness code can identify it.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63680043

A normal RET is treated as using the return values,
but a tail jump RET does not - it is jumping to the
function that is going to fill in the return values.
If a tail jump RET is recorded as using the return values,
since nothing initializes them they will be marked as
live on entry to the function, which is clearly wrong.

Found and tested by the new code in plive.c that looks
for variables that are incorrectly live on entry.
That code is disabled for now because there are other
cases remaining to be fixed. But once it is enabled,
test/live1.go becomes a real test of this CL.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63570045

Any initialization of a variable by a block copy or block zeroing
or by multiple assignments (componentwise copying or zeroing
of a multiword variable) needs to emit a VARDEF. These cases were not.

Fixes #7205.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63650044

The test added in CL 63630043 fails on 5g and 8g because they
were not emitting the VARDEF instruction when clearing a fat
value by clearing the components. 6g had the call in the right place.

Hooray tests.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63660043

This CL enables the current tree to work with FreeBSD 10-STABLE
on ARM EABI platforms, though there are still a few test fails.

Also updates documentation.

LGTM=iant
R=iant, dave
CC=golang-codereviews
https://golang.org/cl/61060044

TestDNSThreadLimit creates tons of DNS queries and it occasionally
causes an unintentional traffic jam and/or crash of some virtual
machine software, especially its builtin networking stuff.

We can run TestDNSThreadLimit with -dnsflood flag instead.

LGTM=dave, rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/63600043

The "fat" referred to being used for multiword values only.
We're going to use it for non-fat values sometimes too.

No change other than the renaming.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63650043

Was spuriously marking results live on entry to function.

TBR=iant
CC=golang-codereviews
https://golang.org/cl/63640043

Old:
prog.go:9: invalid operation: this[i] (index of type int)
New:
prog.go:9: invalid operation: this[i] (type int does not support indexing)

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/52540043

Before, an unnamed return value turned into an ONAME node n with n->sym
named ~anon%d, and n->orig == n.

A blank-named return value turned into an ONAME node n with n->sym
named ~anon%d but n->orig == the original blank n. Code generation and
printing uses n->orig, so that this node formatted as _.

But some code does not use n->orig. In particular the liveness code does
not know about the n->orig convention and so mishandles blank identifiers.
It is possible to fix but seemed better to avoid the confusion entirely.

Now the first kind of node is named ~r%d and the second ~b%d; both have
n->orig == n, so that it doesn't matter whether code uses n or n->orig.

After this change the ->orig field is only used for other kinds of expressions,
not for ONAME nodes.

This requires distinguishing ~b from ~r names in a few places that care.
It fixes a liveness analysis bug without actually changing the liveness code.

TBR=ken2
CC=golang-codereviews
https://golang.org/cl/63630043

Make the loop nesting depth of &x depend on where x is declared,
not on where the &x appears. The latter is only a conservative
estimate of the former. Being more careful can avoid some
variables escaping, and it is easier to reason about.

It would have avoided issue 7313, although that was still a bug
worth fixing.

Not much effect in the tree: one variable in the whole tree
is saved from a heap allocation (something in x509 parsing).

LGTM=daniel.morsing
R=daniel.morsing
CC=golang-codereviews
https://golang.org/cl/62380043

The methods MoveAfter and MoveBefore of the container/list package did silently corrupt the interal structure of the list if a mark element is used which is not an element of the list.

LGTM=gri
R=golang-codereviews, gobot, gri
CC=golang-codereviews
https://golang.org/cl/60980043

Generated by addca.

R=gobot
CC=golang-codereviews
https://golang.org/cl/63620043

Tweak the ARM assembler to improve its performance.

  * Use TEQ instead of CMP which preserves the carry flag.  This means
    we can avoid saving and restoring CPSR which is very slow.

  * Use conditional instructions to read the value of the carry flag.

  * Use 3 argument ARM instructions to save instructions

  * Improve scheduling for MOVW instructions (LDR)

  * Use RSB constant to save an instruction in bitLen

Results of -test.bench 'VV|VW|VU|WW|Bit' -test.benchtime 3s on Samsung
Exynos5 Chromebook.

There are a few small regressions in the benchmarks which I believe to
be noise, perhaps due to different cacheline alignment.

The changes to bitLen are apparently no faster, however less
instructions means less I-cache usage which is a win. I suspect it
will be a win on older ARM processors.

benchmark                 old ns/op    new ns/op    delta
BenchmarkAddVV_1                 48           14  -70.84%
BenchmarkAddVV_2                 87           17  -80.25%
BenchmarkAddVV_3                126           20  -83.97%
BenchmarkAddVV_4                165           23  -86.00%
BenchmarkAddVV_5                204           26  -87.21%
BenchmarkAddVV_1e1              399           41  -89.72%
BenchmarkAddVV_1e2             3921          315  -91.97%
BenchmarkAddVV_1e3            39085         2972  -92.40%
BenchmarkAddVV_1e4           390330        29623  -92.41%
BenchmarkAddVV_1e5          3935366       343431  -91.27%
BenchmarkAddVW_1                 20           10  -49.04%
BenchmarkAddVW_2                 60           14  -76.53%
BenchmarkAddVW_3                 99           16  -83.38%
BenchmarkAddVW_4                140           18  -86.50%
BenchmarkAddVW_5                179           21  -88.04%
BenchmarkAddVW_1e1              376           33  -91.20%
BenchmarkAddVW_1e2             3933          256  -93.49%
BenchmarkAddVW_1e3            39630         2378  -94.00%
BenchmarkAddVW_1e4           396218        23623  -94.04%
BenchmarkAddVW_1e5          3972901       238403  -94.00%
BenchmarkAddMulVVW_1             11           11   -4.27%
BenchmarkAddMulVVW_2             15           15   +0.00%
BenchmarkAddMulVVW_3             18           19   +4.37%
BenchmarkAddMulVVW_4             21           21   +4.29%
BenchmarkAddMulVVW_5             24           24   -0.82%
BenchmarkAddMulVVW_1e1           40           39   -2.70%
BenchmarkAddMulVVW_1e2          329          326   -0.91%
BenchmarkAddMulVVW_1e3         3200         3098   -3.19%
BenchmarkAddMulVVW_1e4        38457        40013   +4.05%
BenchmarkAddMulVVW_1e5       461880       428580   -7.21%
BenchmarkBitLen0                  5            5   -0.19%
BenchmarkBitLen1                  5            5   +0.00%
BenchmarkBitLen2                  5            5   -0.56%
BenchmarkBitLen3                  5            5   +0.38%
BenchmarkBitLen4                  5            5   +0.19%
BenchmarkBitLen5                  5            5   +0.56%
BenchmarkBitLen8                  5            5   -0.19%
BenchmarkBitLen9                  5            5   -0.56%
BenchmarkBitLen16                 5            5   -0.19%
BenchmarkBitLen17                 5            5   -0.37%
BenchmarkBitLen31                 5            5   -1.30%
BenchmarkBitset                  72           70   -2.49%
BenchmarkBitsetNeg             1584          396  -75.00%
BenchmarkBitsetOrig            1990         1980   -0.50%
BenchmarkBitsetNegOrig         4031         2877  -28.63%

benchmark                  old MB/s     new MB/s  speedup
BenchmarkAddVV_1             657.71      2251.28    3.42x
BenchmarkAddVV_2             730.65      3700.37    5.06x
BenchmarkAddVV_3             757.29      4754.30    6.28x
BenchmarkAddVV_4             772.95      5541.58    7.17x
BenchmarkAddVV_5             781.30      6125.59    7.84x
BenchmarkAddVV_1e1           800.33      7814.14    9.76x
BenchmarkAddVV_1e2           815.98     10129.62   12.41x
BenchmarkAddVV_1e3           818.73     10767.07   13.15x
BenchmarkAddVV_1e4           819.82     10802.12   13.18x
BenchmarkAddVV_1e5           813.14      9317.73   11.46x
BenchmarkAddVW_1            1539.56      3006.13    1.95x
BenchmarkAddVW_2            1057.66      4502.20    4.26x
BenchmarkAddVW_3             960.67      5797.65    6.04x
BenchmarkAddVW_4             913.19      6776.86    7.42x
BenchmarkAddVW_5             891.72      7467.82    8.37x
BenchmarkAddVW_1e1           850.12      9681.85   11.39x
BenchmarkAddVW_1e2           813.48     12494.27   15.36x
BenchmarkAddVW_1e3           807.45     13451.80   16.66x
BenchmarkAddVW_1e4           807.64     13545.64   16.77x
BenchmarkAddVW_1e5           805.46     13422.64   16.66x
BenchmarkAddMulVVW_1        2727.29      2847.66    1.04x
BenchmarkAddMulVVW_2        4162.30      4158.69    1.00x
BenchmarkAddMulVVW_3        5236.91      5015.98    0.96x
BenchmarkAddMulVVW_4        6090.27      5837.52    0.96x
BenchmarkAddMulVVW_5        6549.86      6598.60    1.01x
BenchmarkAddMulVVW_1e1      7850.72      8068.00    1.03x
BenchmarkAddMulVVW_1e2      9724.38      9794.40    1.01x
BenchmarkAddMulVVW_1e3      9997.18     10328.58    1.03x
BenchmarkAddMulVVW_1e4      8320.88      7997.39    0.96x
BenchmarkAddMulVVW_1e5      6928.20      7466.50    1.08x

LGTM=gri
R=golang-codereviews, dave, gri
CC=golang-codereviews
https://golang.org/cl/61290043

4 KB is a bit too small in some situations (e.g. panic during a
template execution), and ends up with an unhelpfully-truncated trace.
64 KB should be much more likely to capture the useful information.
There's not a garbage generation issue, since this code should only
be triggered when there's something seriously wrong with the program.

LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://golang.org/cl/63520043

Fixes #6850.

LGTM=agl
R=golang-codereviews, agl
CC=golang-codereviews
https://golang.org/cl/60500046

for example, we now rewrite *_Ctype_int to *C.int.
Fixes #6781.

LGTM=iant
R=golang-codereviews, rsc, iant
CC=golang-codereviews
https://golang.org/cl/36860043

Missed this suggestion in CL 57680046.

LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/63390043

In file included from src/lib9/utf/utfecpy.c:17:0:
src/lib9/utf/utfdef.h:28:0: error: "nil" redefined [-Werror]
In file included from src/lib9/utf/utfrrune.c:17:0:
src/lib9/utf/utfdef.h:28:0: error: "nil" redefined [-Werror]

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/63410043

This change depends on CL 57170052.

LGTM=rsc
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/60840049