For code like the following (where x escapes):

   x := []int{1}

We're currently generating a nil check.  The line above is really 3 operations:

	t := new([1]int)
	t[0] = 1
	x := t[:]

We remove the nil check for t[0] = 1, but not for t[:].

Our current nil check removal rule is too strict about the possible
memory arguments of the nil check. Unlike zeroing or storing to the
result of runtime.newobject, the nilness of runtime.newobject is
always false, even after other stores have happened in the meantime.

Change-Id: I95fad4e3a59c27effdb37c43ea215e18f30b1e5f
Reviewed-on: https://go-review.googlesource.com/58711
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Change-Id: I6e9b5caeca842b6bf72afefb31f5140608b86d20
Reviewed-on: https://go-review.googlesource.com/58530
Run-TryBot: Francesc Campoy Flores <campoy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

In writelines the linker uses various auxiliary information about a
function to create its line table entries. (It also does some unrelated
stuff, but never mind.) There's no reason to do this for non-Go
functions, so it bails out if the symbol has no FuncInfo.

However, it does so *after* it looks up (and implicitly creates!) the
go.info symbol for the function, which doesn't make sense and risks
creating duplicate symbols for static C functions. Move the check up so
that it doesn't do that.

Since non-Go functions can't reference Go types, there shouldn't be any
relocations to type info DIEs that need to be built, so there should be
no harm not doing that.

I wanted to change the Lookup to an ROLookup but that broke the
shared-mode tests with an inscrutable error.

No test. It seems too specific to worry about, but if someone disagrees
I can figure something out.

Fixes #21566

Change-Id: I61f03b7c504a3bf1c4245a8811795b6303469e91
Reviewed-on: https://go-review.googlesource.com/58630Reviewed-by: Ian Lance Taylor <iant@golang.org>

Pre-emptive. Go 1.9 is expected to be released in August.

Change-Id: I0f58c012c4110bf490022dc2c1d69c0988d73bfa
Reviewed-on: https://go-review.googlesource.com/52351Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I97075f24319a4b96cbeb9e3ff2e7b2056ff59e32
Reviewed-on: https://go-review.googlesource.com/58651Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This eliminates a nil check of b while evaluating b.tophash,
which is in the inner loop of many hot map functions.
It also makes the code a bit clearer.

Also remove some gotos in favor of labeled breaks.

On non-x86 architectures, this change introduces a pointless reg-reg move,
although the cause is well-understood (#21572).

Change-Id: Ib7ee58b59ea5463b92e1590c8b8f5c0ef87d410a
Reviewed-on: https://go-review.googlesource.com/58372
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Otherwise the default computation in symalign kicked in, setting the
alignment to be too high. This didn't matter with GNU ld, which put
each loadable note into a separate PT_NOTE segment, but it did matter
with gold which accumulated them all into a single PT_NOTE segment,
respecting the requested alignment. In the single PT_NOTE segment
generated by gold, the incorrect section alignment made the notes
unreadable.

Fixes #21564

Change-Id: I15eb408bb04a2566c9fdfb6828e14188d9ef2280
Reviewed-on: https://go-review.googlesource.com/58290Reviewed-by: Russ Cox <rsc@golang.org>

This is a crude compiler pass to eliminate stores to auto variables
that are only ever written to.

Eliminates an unnecessary store to x from the following code:

func f() int {
	var x := 1
	return *(&x)
}

Fixes #19765.

Change-Id: If2c63a8ae67b8c590b6e0cc98a9610939a3eeffa
Reviewed-on: https://go-review.googlesource.com/38746
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This prevents unnecessary reg-reg moves during pointer arithmetic.

This change reduces the size of the full hello world binary by 0.4%.

Updates #21572

Change-Id: Ia0427021e5c94545a0dbd83a6801815806e5b12d
Reviewed-on: https://go-review.googlesource.com/58371
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: Icfe24d5660666093f3e645f82d30b7687c8077be
Reviewed-on: https://go-review.googlesource.com/58370
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>

On 386 the below code triggered an infinite loop in growslice:
x = make([]byte, 1<<30-1, 1<<30-1)
x = append(x, x...)

Check for overflow when calculating the new slice capacity
and set the new capacity to the requested capacity when an overflow
is detected to avoid an infinite loop.

No automatic test added due to requiring to allocate 1GB of memory
on a 32bit plaform before use of append is able to trigger the
overflow check.

Fixes #21441

Change-Id: Ia871cc9f88479dacf2c7044531b233f83d2fcedf
Reviewed-on: https://go-review.googlesource.com/57950
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

Currently all package tests are executed once
with Parallel tests executed in parallel.
Then this process is repeated count*cpu times.
Tests are not parallelized over count*cpu.
Parallelizing over cpu is not possible as
GOMAXPROCS is a global setting. But it is
possible for count.

Parallelize over count.

Brings down testing of my package with -count=100
form 10s to 0.3s.

Change-Id: I76d8322adeb8c5c6e70b99af690291fd69d6402a
Reviewed-on: https://go-review.googlesource.com/44830
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This slightly improves the generated code on x86 architectures,
including on many hot paths.

It is a no-op on other architectures.

Change-Id: I86336fd846bc5805a27bbec572e8c73dcbd0d567
Reviewed-on: https://go-review.googlesource.com/57411
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This is necessary when you aren't actively changing the runtime. Oops.

Also, run the tests on the builders, to avoid silent failures (#17472).

Change-Id: I1fc03790cdbddddb07026a772137a79919dcaac7
Reviewed-on: https://go-review.googlesource.com/58050
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

The Reader and Writer are now at feature parity,
meaning that everything that can be parsed by the Reader,
can also be composed by the Writer.

This position enables us to support selection of the format
in a backwards compatible way, since it ensures that everything
that can be read can also be round-trip written.

As such, we add the following new API:
    type Format int
            const FormatUnknown Format = 0 ...
    type Header struct { ...; Format Format }

The new Header.Format field is populated by the Reader on the
best guess on what the format is. Note that the Reader is very liberal
in what it permits, so a hybrid TAR file using aspects of multiple
formats can still be decoded, but will be reported as FormatUnknown.

Even though Reader has full support for V7 and basic support for STAR,
it will still report those formats as unknown (and the constants for
those formats are not even exported). The reasons for this is because
the Writer has no support for V7 or STAR. Leaving it as unknown allows
the Writer to choose a format usually USTAR or GNU that can encode
the equivalent Header.

When writing, the Header.allowedFormats will take the Format field
into consideration if it is a known format.

Fixes #18710

Change-Id: I00980c475d067c6969d3414e1ff0224fdd89cd49
Reviewed-on: https://go-review.googlesource.com/58230
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Fixes #19520

Change-Id: Ib0a1f0f2429172d2781c9b6fbd21f9cb8da1b8ed
Reviewed-on: https://go-review.googlesource.com/43295
Run-TryBot: Francesc Campoy Flores <campoy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

Existing code in encoding/xml packages contains code which breaks
various linter rules (comments, constant and variable naming, variable
shadowing, etc).

Fixes #21578

Change-Id: Id4bd9a9be6d5728ce88fb6efe33030ef943c078c
Reviewed-on: https://go-review.googlesource.com/58210Reviewed-by: Sam Whited <sam@samwhited.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Sam Whited <sam@samwhited.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The method Method expects index to be an index of exported fields,
but, before this change, the index used by MethodByName could
take into account unexported fields if those happened sort
before the exported one.

Fixes #21177

Change-Id: I90bb64a47b23e2e43fdd2b8a1e0a2c9a8a63ded2
Reviewed-on: https://go-review.googlesource.com/51810Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This CL is the second step (of two; part1 is CL/56771) for adding
sparse file support to the Writer.

There are no new identifiers exported in this CL, but this does make
use of Header.SparseHoles added in part1. If the Typeflag is set to
TypeGNUSparse or len(SparseHoles) > 0, then the Writer will emit an
sparse file, where the holes must be written by the user as zeros.

If TypeGNUSparse is set, then the output file must use the GNU format.
Otherwise, it must use the PAX format (with GNU-defined PAX keys).

A future CL may export Reader.Discard and Writer.FillZeros,
but those methods are currently unexported, and only used by the
tests for efficiency reasons.
Calling Discard or FillZeros on a hole 10GiB in size does take
time, even if it is essentially a memcopy.

Updates #13548

Change-Id: Id586d9178c227c0577f796f731ae2cbb72355601
Reviewed-on: https://go-review.googlesource.com/57212Reviewed-by: Ian Lance Taylor <iant@golang.org>

Run "cmd/go terminal test" after standard library tests.
Run "testing race detector" before cgo tests, not in the middle of them.

Fixes #21524

Change-Id: I32964ec6377dd070242138ec452bd8ab1821dcc5
Reviewed-on: https://go-review.googlesource.com/57230
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Joe Tsai <joetsai@google.com>

For those tests there won't be enough permissions in containers.
I decided to go this way instead of just skipping os.IsPermission errors because
many of those tests were specifically written to check false positive permission
errors.

Fixes #21379

Change-Id: Ie25e1d6d47f85bb6b570352638440f3ac1e18e03
Reviewed-on: https://go-review.googlesource.com/58170Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The current code treats floating-point constant as integer
and does not treat fcmp/fcmpe as the comparison instrucitons
that requires special handling.

The fix corrects the type of immediate arguments and adds fcmp/fcmpe
in the special handing.

Uncomment the fcmp/fcmpe cases.

Fixes #21567
Change-Id: I6782520e2770f6ce70270b667dd5e68f71e2d5ad
Reviewed-on: https://go-review.googlesource.com/57852
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

This will prevent any ptrace calls from getting trace output from the runtime
itself setting up after fork.

Fixes #21428.

Change-Id: I9d835bd5a8f404394eb6237679f2111a72e5bc17
Reviewed-on: https://go-review.googlesource.com/55811
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Avelino <t@avelino.xxx>

When deleting entries from a map, only clear the key and value
if they contain pointers. And use memclrHasPointers to do so.

While we're here, specialize key clearing in mapdelete_faststr,
and fix another missed usage of add in mapdelete.

Benchmarking impeded by #21546.

Change-Id: I3f6f924f738d6b899b722d6438e9e63f52359b84
Reviewed-on: https://go-review.googlesource.com/57630
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Move the tophash checks after the equality/length checks.

For fast32/fast64, since we've done a full equality check already,
just check whether tophash is empty instead of checking tophash.
This is cheaper and allows us to skip calculating tophash.

These changes are modeled on the changes in CL 57590,
which were polished based on benchmarking.
Benchmarking directly is impeded by #21546.

Change-Id: I0e17163028e34720310d1bf8f95c5ef42d223e00
Reviewed-on: https://go-review.googlesource.com/57611
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

This better matches the style of the rest of the runtime.

Change-Id: I6abb755df50eb3d9086678629c0d184177e1981f
Reviewed-on: https://go-review.googlesource.com/57610
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>

While we're here, check string length before checking b.tophash.

name                     old time/op  new time/op  delta
MapStringKeysEight_16-8  11.4ns ±10%   7.0ns ± 2%  -38.27%  (p=0.000 n=29+28)
MapStringKeysEight_32-8  10.9ns ± 2%   6.3ns ± 3%  -41.89%  (p=0.000 n=26+30)
MapStringKeysEight_64-8  10.8ns ± 3%   6.3ns ± 2%  -41.52%  (p=0.000 n=28+27)
MapStringKeysEight_1M-8  10.9ns ± 4%   6.3ns ± 2%  -41.91%  (p=0.000 n=29+29)
IntMap-8                 7.05ns ± 4%  6.77ns ± 3%   -3.94%  (p=0.000 n=29+30)


Change-Id: I0f3dc3301bdf550e4ac5250e1e64e7f2a0ffb269
Reviewed-on: https://go-review.googlesource.com/57590
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

During rebase of golang.org/cl/55152 the bucket argument
which was removed in golang.org/cl/56290 from makemap
was not removed from the argument list of makemap64.

This did lead to "pointer in unallocated span" errors
on 32bit platforms since the compiler did only generate
calls to makemap64 without the bucket argument.

Fixes #21568

Change-Id: Ia964a3c285837cd901297f4e16e40402148f8c1c
Reviewed-on: https://go-review.googlesource.com/57990Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Using the wonderful https://github.com/client9/misspell tool.

Change-Id: Icdbc75a5559854f4a7a61b5271bcc7e3f99a1a24
Reviewed-on: https://go-review.googlesource.com/57851Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The intent is to allow more aggressive refactoring
in the runtime without silent performance changes.

The test would be useful for many functions.
I've seeded it with the runtime functions tophash and add;
it will grow organically (or wither!) from here.

Updates #21536 and #17566

Change-Id: Ib26d9cfd395e7a8844150224da0856add7bedc42
Reviewed-on: https://go-review.googlesource.com/57410Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ib6d94f185dd43568cf97ef267dd51a09f43a402f
Reviewed-on: https://go-review.googlesource.com/51391Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I71b24dd0293dd1e26a5c799161a7f9af48fb3c7d
Reviewed-on: https://go-review.googlesource.com/57295
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

mkcall is used to construct calls to builtin functions.

Instead of silently ignoring any additional arguments to mkcall
abort compilation with an error.

This protects against accidentally supplying too many arguments to mkcall
when compiler changes are made.

Change appendslice and copyany to construct calls to
slicestringcopy and slicecopy explicitly instead of
relying on the old behavior as a feature.

Change-Id: I3cfe815a57d454a129e3c08aac824f6107779a42
Reviewed-on: https://go-review.googlesource.com/57770
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Where possible generate calls to runtime makemap with int hint argument
during compile time instead of makemap with int64 hint argument.

This eliminates converting the hint argument for calls to makemap with
int64 hint argument for platforms where int64 values do not fit into
an argument of type int.

A similar optimization for makeslice was introduced in CL
golang.org/cl/27851.

386:
name         old time/op    new time/op    delta
NewEmptyMap    53.5ns ± 5%    41.9ns ± 5%  -21.56%  (p=0.000 n=10+10)
NewSmallMap     182ns ± 1%     165ns ± 1%   -8.92%  (p=0.000 n=10+10)

Change-Id: Ibd2b4c57b36f171b173bf7a0602b3a59771e6e44
Reviewed-on: https://go-review.googlesource.com/55142Reviewed-by: Keith Randall <khr@golang.org>

golang.org/cl/36941 enabled loading of all trusted certs on darwin
for the non-cgo execSecurityRoots.

The corresponding cgo version golang.org/cl/36942 for systemRootsPool
has not been merged yet.

This tests fails reliably on some darwin systems:
--- FAIL: TestSystemRoots (1.28s)
        root_darwin_test.go:31:     cgo sys roots: 353.552363ms
        root_darwin_test.go:32: non-cgo sys roots: 921.85297ms
        root_darwin_test.go:44: got 169 roots
        root_darwin_test.go:44: got 455 roots
        root_darwin_test.go:73: insufficient overlap between cgo and non-cgo roots; want at least 227, have 168
FAIL
FAIL    crypto/x509     2.445s

Updates #16532
Updates #21416

Change-Id: I52c2c847651fb3621fdb6ab858ebe8e28894c201
Reviewed-on: https://go-review.googlesource.com/57830
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

This change adds to the code-generation harness in asm_test.go support
for the use of a '$' placeholder name for test functions.

A few of uninformative function names are also changed to use the
placeholder, to confirm that the change works as expected.

Fixes #21500

Change-Id: Iba168bd85efc9822253305d003b06682cf8a6c5c
Reviewed-on: https://go-review.googlesource.com/57292
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I24374accf48d43edf4bf27ea6ba2245ddca558ad
Reviewed-on: https://go-review.googlesource.com/50910Reviewed-by: Giovanni Bajo <rasky@develer.com>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Some debuggers use the declaration line to avoid showing variables
before they're declared. Emit them for local variables and function
parameters.

DW_AT_decl_file would be nice too, but since its value is an index
into a table built by the linker, that's dramatically harder. In
practice, with inlining disabled it's safe to assume that all a
function's variables are declared in the same file, so this should still
be pretty useful.

Change-Id: I8105818c8940cd71bc5473ec98797cce2f3f9872
Reviewed-on: https://go-review.googlesource.com/44350Reviewed-by: David Chase <drchase@google.com>

eqstring is only called for strings with equal lengths.
Instead of pushing a pointer and length for each argument string
on the stack we can omit pushing one of the lengths on the stack.

Changing eqstrings signature to eqstring(*uint8, *uint8, int) bool
to implement the above optimization would make it very similar to the
existing memequal(*any, *any, uintptr) bool function.

Since string lengths are positive we can avoid code redundancy and
use memequal instead of using eqstring with an optimized signature.

go command binary size reduced by 4128 bytes on amd64.

name                          old time/op    new time/op    delta
CompareStringEqual              6.03ns ± 1%    5.71ns ± 1%   -5.23%  (p=0.000 n=19+18)
CompareStringIdentical          2.88ns ± 1%    3.22ns ± 7%  +11.86%  (p=0.000 n=20+20)
CompareStringSameLength         4.31ns ± 1%    4.01ns ± 1%   -7.17%  (p=0.000 n=19+19)
CompareStringDifferentLength    0.29ns ± 2%    0.29ns ± 2%     ~     (p=1.000 n=20+20)
CompareStringBigUnaligned       64.3µs ± 2%    64.1µs ± 3%     ~     (p=0.164 n=20+19)
CompareStringBig                61.9µs ± 1%    61.6µs ± 2%   -0.46%  (p=0.033 n=20+19)

Change-Id: Ice15f3b937c981f0d3bc8479a9ea0d10658ac8df
Reviewed-on: https://go-review.googlesource.com/53650
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

If an error was already printed during LHS conversion step, we don't reprint
the "cannot convert" error.

In particular, this prevents `_ = int("1")` (and all similar casts) from
resulting in multiple identical error messages being printed.

Fixes #20812.

Change-Id: If6e52c59eab438599d641ecf6f110ebafca740a9
Reviewed-on: https://go-review.googlesource.com/46912Reviewed-by: Robert Griesemer <gri@golang.org>