Also improve missing GC mark diagnostics.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/169450043

Add missing write barrier when initializing state
for newly created goroutine. Add write barrier for
same slot when preempting a goroutine.

Disable write barrier during goroutine death,
because dopanic does pointer writes.

With concurrent mark enabled (not in this CL), all.bash passed once.
The second time, TestGoexitCrash-2 failed.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/167610043

Also rewrite some casp that don't use real pointers
to use casuintptr instead.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/166440044

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/174820043

To turn concurrent gc on alter the if false in func gogc
currently at line 489 in malloc.go

LGTM=rsc
R=rsc
CC=golang-codereviews, rlh
https://golang.org/cl/172190043

This got lost in the change that added the writebarrierfat variants.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/165510043

Now each C printf, Go print, or Go println is guaranteed
not to be interleaved with other calls of those functions.
This should help when debugging concurrent failures.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/169120043

We still don't know why this is happening.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/169990043

- Some sequencing issues with stopping the first gc_m round
at the right place to set up correctly for the second round.

- atomicxor8 is not idempotent; avoid xor.

- Maintain BitsDead type bits correctly; see long comment added.

- Enable checkmark phase by default for now.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/171090043

TBR=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/168860046

This adds an independent mark phase to the GC that can be used to
verify the the default concurrent mark phase has found all reachable
objects. It uses the upper 2 bits of the boundary nibble to encode
the mark leaving the lower bits to encode the boundary and the
normal mark bit.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/167130043

This CL implements the many multiword write barriers by calling
writebarrierptr, so that only writebarrierptr needs the actual barrier.
In lieu of an actual barrier, writebarrierptr checks that the value
being copied is not a small non-zero integer. This is enough to
shake out bugs where the barrier is being called when it should not
(for non-pointer values). It also found a few tests in sync/atomic
that were being too clever.

This CL adds a write barrier for the memory moved during the
builtin copy function, which I forgot when inserting barriers for Go 1.4.

This CL re-enables some write barriers that were disabled for Go 1.4.
Those were disabled because it is possible to change the generated
code so that they are unnecessary most of the time, but we have not
changed the generated code yet. For safety they must be enabled.

None of this is terribly efficient. We are aiming for correct first.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/168770043

The goal here is to get the big-endian fixes so that
in some upcoming code movement for write barriers
I don't make them unmergeable.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/166890043

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/170730043

Still passes on amd64.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/165110043

Stupid mistake in previous CL.

TBR=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/166880043

TBR=iant
CC=golang-codereviews
https://golang.org/cl/164180043

TBR=austin
CC=golang-codereviews
https://golang.org/cl/167820043

TBR=austin
CC=golang-codereviews
https://golang.org/cl/162420043

Fixes #8803.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/169720043

Fixes #9006.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/167800043

It now echoes what strconv.FormatFloat says.

Fixes #9012.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/169730043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/160660046

Fixes #8861.
Fixes #8911.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/165780043

Fixes #8588.

LGTM=austin
R=austin
CC=golang-codereviews, khr
https://golang.org/cl/159700044

goprintf is a printf-like print for Go.
It is used in the code generated by 'defer print(...)' and 'go print(...)'.

Normally print(1, 2, 3) turns into

        printint(1)
        printint(2)
        printint(3)

but defer and go need a single function call to give the runtime;
they give the runtime something like goprintf("%d%d%d", 1, 2, 3).

Variadic functions like goprintf cannot be described in the new
type information world, so we have to replace it.

Replace with a custom function, so that defer print(1, 2, 3) turns
into

        defer func(a1, a2, a3 int) {
                print(a1, a2, a3)
        }(1, 2, 3)

(and then the print becomes three different printints as usual).

Fixes #8614.

LGTM=austin
R=austin
CC=golang-codereviews, r
https://golang.org/cl/159700043

I removed support for jumping between functions years ago,
as part of doing the instruction layout for each function separately.

Given that, it makes sense to treat labels as function-scoped.
This lets each function have its own 'loop' label, for example.

Makes the assembly much cleaner and removes the last
reason anyone would reach for the 123(PC) form instead.

Note that this is on the dev.power64 branch, but it changes all
the assemblers. The change will ship in Go 1.5 (perhaps after
being ported into the new assembler).

Came up as part of CL 167730043.

LGTM=r
R=r
CC=austin, dave, golang-codereviews, minux
https://golang.org/cl/159670043

In CL 160670043 the write function was changed
so a zero-length write is now allowed. This leads
the ExampleWriter_Init test to fail.

The reason is that Plan 9 preserves message
boundaries, while the os library expects systems
that don't preserve them. We have to ignore
zero-length writes so they will never turn into EOF.

This issue was previously discussed in CL 7406046.

LGTM=bradfitz
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/163510043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/166850043

Power64 servers do not currently support sub-word size atomic
memory access, so atomicor8 uses word size atomic access.
However, previously atomicor8 made no attempt to align this
access, resulting in errors.  Fix this by aligning the pointer
to a word boundary and shifting the value appropriately.
Since atomicor8 is used in GC, add a test to runtime·check to
make sure this doesn't break in the future.

This also fixes an incorrect branch label, an incorrectly
sized argument move, and adds argument names to help go vet.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/165820043

Also a few other minor changes.

Fixes #8712.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/164150043

TBR=crawshaw
CC=golang-codereviews
https://golang.org/cl/162390043

LGTM=rsc, aram, minux
R=golang-codereviews, aram, minux, rsc
CC=golang-codereviews
https://golang.org/cl/162370045

The "to" field was the penultimate argument to outgcode,
instead of the last argument, which swapped the third and
fourth operands.  The argument order was correct in a.y, so
just swap the meaning of the arguments in outgcode.  This
hadn't come up because we hadn't used these more obscure
operations in any hand-written assembly until now.

LGTM=rsc, dave
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/160690043

Fixes #9007.

LGTM=iant, r
R=r, iant
CC=golang-codereviews
https://golang.org/cl/160670043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/165800043

Fixes #8787.

LGTM=rsc
R=rsc, dvyukov
CC=golang-codereviews
https://golang.org/cl/153670043

No easy way to test (would have to actually trigger some routing
events from kernel) but the code is clearly wrong as written.
If the header says there is a submessage, we need to at least
skip over its bytes, not just continue to the next iteration.

Fixes #8203.

LGTM=r
R=r
CC=golang-codereviews, mikioh.mikioh, p
https://golang.org/cl/164140044

get -u now checks that remote repo paths match the
ones predicted by the import paths: if you are get -u'ing
rsc.io/pdf, it has to be checked out from the right location.
This is important in case the rsc.io/pdf redirect changes.

In some cases, people have good reasons to use
non-standard remote repos. Add -f flag to allow that.
The f can stand for force or fork, as you see fit.

Fixes #8850.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/164120043

The wrapper code was being emitted before the stack
reservation, rather than after.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/161540043