We don't know what we need yet, so add them all.
Add them even on x86 architectures (as no-ops) so that
the GC can refer to them unconditionally.

Eventually we'll know what we want and probably
have just one 'prefetch' with an appropriate meaning
on each architecture.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/179160043

LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, rsc
https://golang.org/cl/180040043

[dev.garbage] runtime: Turn concurrent GC on by default. Avoid write barriers for GC internal structures such as free lists.

LGTM=rsc
R=rsc
CC=golang-codereviews, rsc
https://golang.org/cl/179000043

Brings in Linux time signature fixes. Should fix build.

TBR=austin
CC=golang-codereviews
https://golang.org/cl/176870043

The garbage collector is now written in Go.
There is plenty to clean up (just like on dev.cc).

all.bash passes on darwin/amd64, darwin/386, linux/amd64, linux/386.

TBR=rlh
R=austin, rlh, bradfitz
CC=golang-codereviews
https://golang.org/cl/173250043

* _sfloat dispatches to runtime._sfloat2 with the Go calling convention, so the seecond argument is a [15]uint32, not a *[15]uint32.
* adjust _sfloat2 to return the new pc in 68(R13) as expected.

LGTM=rsc
R=minux, austin, rsc
CC=golang-codereviews
https://golang.org/cl/174160043

It's rather unsporting of the kernel to give us a pointer to unaligned memory.

This fixes one crash, the next crash occurs in the soft float emulation.

LGTM=minux, rsc, austin
R=minux, rsc, austin
CC=golang-codereviews
https://golang.org/cl/177730043

warning: src/liblink/asm9.c:501 set and not used: bflag
warning: src/liblink/list9.c:259 format mismatch .5lux INT, arg 4
warning: src/liblink/list9.c:261 format mismatch .5lux INT, arg 3
warning: src/liblink/list9.c:319 more arguments than format VLONG
warning: src/liblink/obj9.c:222 set and not used: autoffset

LGTM=bradfitz, austin
R=rsc, bradfitz
CC=austin, golang-codereviews
https://golang.org/cl/175070043

Fixes build.
Tested that all these systems can make.bash.

TBR=austin
CC=golang-codereviews
https://golang.org/cl/177770043

While we are here, add the linux/power64 version.

LGTM=austin
R=austin
CC=aram, dvyukov, golang-codereviews
https://golang.org/cl/177750043

TBR=austin
CC=golang-codereviews
https://golang.org/cl/176760044

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/176750043

This is to reduce the delta between dev.cc and dev.garbage to just garbage collector changes.

These are the files that had merge conflicts and have been edited by hand:
        malloc.go
        mem_linux.go
        mgc.go
        os1_linux.go
        proc1.go
        panic1.go
        runtime1.go

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/174180043

Now the only difference between dev.cc and dev.garbage
is the runtime conversion on the one side and the
garbage collection on the other. They both have the
same set of changes from default and dev.power64.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/172570043

LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/173200044

This is the revision that dev.cc is branched from.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/169590043

This change fixes the Solaris port.

LGTM=dave, rsc
R=rsc, dave
CC=brad, golang-codereviews
https://golang.org/cl/168600045

LGTM=rsc
R=rsc
CC=dvyukov, golang-codereviews
https://golang.org/cl/172530043

LGTM=rsc
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/171660043

This adds registerization support to 9g equivalent to what the
other compilers have.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/174980043

None of the other compilers have a tag for this enum.
Cleaning all of this up to use proper types will happen after
the conversion.

LGTM=minux, rsc
R=rsc, minux
CC=golang-codereviews
https://golang.org/cl/166690043

Previously, the 6g and 8g registerizers scanned for used
registers beyond the end of a region being considered for
registerization.  This ancient artifact was copied from the C
compilers, where it was probably necessary to track implicitly
used registers.  In the Go compilers it's harmless (because it
can only over-restrict the set of available registers), but no
longer necessary because the Go compilers correctly track
register use/set information.  The consequences of this extra
scan were (at least) that 1) we would not consider allocating
the AX register if there was a deferproc call in the future
because deferproc uses AX as a return register, so we see the
use of AX, but don't track that AX is set by the CALL, and 2)
we could not consider allocating the DX register if there was
a MUL in the future because MUL implicitly sets DX and (thanks
to an abuse of copyu in this code) we would also consider DX
used.

This commit fixes these problems by nuking this code.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/174110043

This was originally done to the C port in rev 17d3b45534b5 and
seemingly got lost during the conversion.

LGTM=bradfitz
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/167700043

Memory management was consolitated with the BSD ports, since
it was almost identical.

Assembly thunks are gone, being replaced by the new //go:linkname
feature.

This change supersedes CL 138390043 (runtime: convert solaris
netpoll to Go), which was previously reviewed and tested.

This change is only the first step, the port now builds,
but doesn't run. Binaries fail to exec:

    ld.so.1: 6.out: fatal: 6.out: TLS requirement failure : TLS support is unavailable
    Killed

This seems to happen because binaries don't link with libc.so
anymore. We will have to solve that in a different CL.

Also this change is just a rough translation of the original
C code, cleanup will come in a different CL.

[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]

LGTM=rsc
R=rsc, dave
CC=golang-codereviews, iant, khr, minux, r, rlh
https://golang.org/cl/174960043

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/175000043

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/169490043

LGTM=dave, rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/169460043

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/174050043

For D_OREG addresses, store the used registers in regindex
instead of reguse because they're really part of addressing.

Add implicit register use/set for DUFFZERO/DUFFCOPY.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/174050044

Scalararg and ptrarg are not "signal safe".
Go code filling them out can be interrupted by a signal,
and then the signal handler runs, and if it also ends up
in Go code that uses scalararg or ptrarg, now the old
values have been smashed.
For the pieces of code that do need to run in a signal handler,
we introduced onM_signalok, which is really just onM
except that the _signalok is meant to convey that the caller
asserts that scalarg and ptrarg will be restored to their old
values after the call (instead of the usual behavior, zeroing them).

Scalararg and ptrarg are also untyped and therefore error-prone.

Go code can always pass a closure instead of using scalararg
and ptrarg; they were only really necessary for C code.
And there's no more C code.

For all these reasons, delete scalararg and ptrarg, converting
the few remaining references to use closures.

Once those are gone, there is no need for a distinction between
onM and onM_signalok, so replace both with a single function
equivalent to the current onM_signalok (that is, it can be called
on any of the curg, g0, and gsignal stacks).

The name onM and the phrase 'm stack' are misnomers,
because on most system an M has two system stacks:
the main thread stack and the signal handling stack.

Correct the misnomer by naming the replacement function systemstack.

Fix a few references to "M stack" in code.

The main motivation for this change is to eliminate scalararg/ptrarg.
Rick and I have already seen them cause problems because
the calling sequence m.ptrarg[0] = p is a heap pointer assignment,
so it gets a write barrier. The write barrier also uses onM, so it has
all the same problems as if it were being invoked by a signal handler.
We worked around this by saving and restoring the old values
and by calling onM_signalok, but there's no point in keeping this nice
home for bugs around any longer.

This CL also changes funcline to return the file name as a result
instead of filling in a passed-in *string. (The *string signature is
left over from when the code was written in and called from C.)
That's arguably an unrelated change, except that once I had done
the ptrarg/scalararg/onM cleanup I started getting false positives
about the *string argument escaping (not allowed in package runtime).
The compiler is wrong, but the easiest fix is to write the code like
Go code instead of like C code. I am a bit worried that the compiler
is wrong because of some use of uninitialized memory in the escape
analysis. If that's the reason, it will go away when we convert the
compiler to Go. (And if not, we'll debug it the next time.)

LGTM=khr
R=r, khr
CC=austin, golang-codereviews, iant, rlh
https://golang.org/cl/174950043

LGTM=bradfitz, r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/167650043

Also improve missing GC mark diagnostics.

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

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/174970043

Last try and then someone with a FreeBSD has to do it.

TBR=r
CC=golang-codereviews
https://golang.org/cl/171590043

TBR=r
CC=golang-codereviews
https://golang.org/cl/168600043

Will prod freebsd build along.
Not claiming it will fix it.

TBR=r
CC=golang-codereviews
https://golang.org/cl/171580044

It builds.
Don't know if it works, but it's a lot closer than having everything in C.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/168590043

Also include onM_signalok fix from issue 8995.

Fixes linux/arm build.
Fixes #8995.

LGTM=r
R=r, dave
CC=golang-codereviews
https://golang.org/cl/168580043

This was recorded as an hg mv instead of an hg cp.
For now a C version is needed for the Go compiler.

TBR=r
CC=golang-codereviews
https://golang.org/cl/174020043

The conversion was done with an automated tool and then
modified only as necessary to make it compile and run.

vlrt.c was only called from C. Pure delete.

[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]

LGTM=r
R=r, austin
CC=dvyukov, golang-codereviews, iant, khr
https://golang.org/cl/174860043