Fixes #5599.

Thanks to minux.ma for the suggested fix.

As we now have a harness to test testing internal functions I added some coverage for testing.roundUp, as it is the main consumer of roundDown10.

R=minux.ma, kr, r
CC=golang-dev
https://golang.org/cl/9926043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9693044

The Bell Labs distribution now supports 21-bit runes.

R=golang-dev, akumar
CC=golang-dev
https://golang.org/cl/9249045

Fixes #5609.

R=golang-dev, remyoudompheng, r
CC=golang-dev
https://golang.org/cl/9757045

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9941043

seems to break freebsd-386.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/9915047

Before this change, grow work was done only
during map writes to ensure multithreaded safety.
This can lead to maps remaining in a partially
grown state for a long time, potentially forever.
This change allows grow work to happen during reads,
which will lead to grow work finishing sooner, making
the resulting map smaller and faster.

Grow work is not done in parallel.  Reads can
happen in parallel while grow work is happening.

R=golang-dev, dvyukov, khr, iant
CC=golang-dev
https://golang.org/cl/8852047

instead of regular g stack. We do this so that the g stack
we're currently running on is no longer changing.  Cuts
the root set down a bit (g0 stacks are not scanned, and
we don't need to scan gc's internal state).  Also an
enabler for copyable stacks.

R=golang-dev, cshapiro, khr, 0xe2.0x9a.0x9b, dvyukov, rsc, iant
CC=golang-dev
https://golang.org/cl/9754044

R=golang-dev, r, bradfitz
CC=golang-dev
https://golang.org/cl/8651043

An embedded trampoline is a function that exists to marshal
a receiver of type *S to a receiver of type *T when T is an
embedded field in S.

Embedded trampolines are generated by a special path through
the compiler and are not subject to the general analysis and
annotation done to functions.  Their effects must be provided
explicitly.

R=golang-dev, r, daniel.morsing, minux.ma
CC=golang-dev
https://golang.org/cl/9874043

We require $objtype in make.rc and rc needs $path for finding commands.

Also include $cputype which we may use in the future.

R=golang-dev, minux.ma, r
CC=golang-dev
https://golang.org/cl/9905043

* Add a CXXFiles field to Package, which includes .cc, .cpp and .cxx  files.
* CXXFiles are compiled using g++, which can be overridden using the CXX environment variable.
* Include .hh, .hpp and .hxx files in HFiles.
* Add support for CPPFLAGS (used for both C and C++) and CXXFLAGS (used only for C++) in cgo directive.
* Changed pkg-config cgo directive to modify CPPFLAGS rather than CFLAGS, so both C and C++ files get any flag returned by pkg-config --cflags.

Fixes #1476.

R=iant, r
CC=bradfitz, gobot, golang-dev, iant, minux.ma, remyoudompheng, seb.binet
https://golang.org/cl/8248043

As suggested by ej@evanjones.ca.

Fixes #5604.

R=r
CC=golang-dev
https://golang.org/cl/9899043

Update #5599

R=golang-dev, r, minux.ma
CC=golang-dev
https://golang.org/cl/9738052

mheap.map become a pointer, so nelem(h->map) returns 1 rather than the map size.
As the result coalescing with subsequent spans does not happen.

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/9649046

It is a caching wrapper around SysAlloc() that can allocate small chunks.
Use it for symtab allocations. Reduces number of symtab walks from 4 to 3
(reduces buildfuncs time from 10ms to 7.5ms on a large binary,
reduces initial heap size by 680K on the same binary).
Also can be used for type info allocation, itab allocation.
There are also several places in GC where we do the same thing,
they can be changed to use persistentalloc().
Also can be used in FixAlloc, because each instance of FixAlloc allocates
in 128K regions, which is too eager.
Reincarnation of committed and rolled back https://golang.org/cl/9805043
The latent bugs that it revealed are fixed:
https://golang.org/cl/9837049
https://golang.org/cl/9778048

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/9778049

Then use the limit to make sure MHeap_LookupMaybe & inlined
copies don't return a span if the pointer is beyond the limit.
Use this fact to optimize all call sites.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/9869045

R=golang-dev, khr, rsc
CC=golang-dev
https://golang.org/cl/9728045

As the code now says:

We are forced to return a float64 because the API is silly, but do
the division as integers so we can ask if AllocsPerRun()==1
instead of AllocsPerRun()<2.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/9837049

as was dicussed in cl/9791044

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9853046

Required for preemptive scheduler, see the comment.

R=golang-dev, daniel.morsing
CC=golang-dev
https://golang.org/cl/9841047

Escape analysis already gives that the underlying array
does not escape but the result was ignored.

Fixes #5484.

R=golang-dev, dave, daniel.morsing
CC=golang-dev
https://golang.org/cl/9662046

Fixes #5591.

R=golang-dev, dave, minux.ma, cshapiro
CC=carl shapiro <cshapiro, golang-dev
https://golang.org/cl/9839046

Fixes #5405.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/9856043

A nosplits was assumed to have no argument information and no
pointer map.  However, nosplits created by the linker often
have both.  This change uses the pointer map size as an
alternate source of argument size when processing a nosplit.

In addition, the symbol table construction pointer map size
and argument size consistency check is strengthened.  If a
nptrs is greater than 0 it must be equal to the number of
argument words.

R=golang-dev, khr, khr
CC=golang-dev
https://golang.org/cl/9666047

to avoid unintentionally clobber R9/R10.
Thanks Lucio for the suggestion.

PS: yes, this could be considered a big change (but not an API change), but
as it turns out even temporarily changes R9/R10 in user code is unsafe and
leads to very hard to diagnose problems later, better to disable using R9/R10
when the user first uses it.
See CL 6300043 and CL 6305100 for two problems caused by misusing R9/R10.

R=golang-dev, khr, rsc
CC=golang-dev
https://golang.org/cl/9840043

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/9826043

R=golang-dev, dave, iant
CC=golang-dev
https://golang.org/cl/9738045

R=iant
CC=golang-dev
https://golang.org/cl/9738046

The old code put the index before the period in the precision;
it should be after so it's always before the star, as documented.
A little trickier to do in one pass but compensated for by more
tests and catching a couple of other error cases.

R=rsc
CC=golang-dev
https://golang.org/cl/9751044

Currently we only check the leaf node's issuer against the list of
distinguished names in the server's CertificateRequest message. This
will fail if the client certiciate has more than one certificate in
the path and the leaf node issuer isn't in the list of distinguished
names, but the issuer's issuer was in the distinguished names.

R=agl, agl
CC=gobot, golang-dev
https://golang.org/cl/9795043

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/9798049

This is needed for preemptive scheduler, because during
stoptheworld we want to wait with timeout and re-preempt
M's on timeout.

R=golang-dev, remyoudompheng, iant
CC=golang-dev
https://golang.org/cl/9375043

See https://en.wikipedia.org/wiki/Newton%27s_method#Square_root_of_a_number

R=golang-dev, minux.ma, adg
CC=golang-dev
https://golang.org/cl/9145044

R=golang-dev
CC=golang-dev
https://golang.org/cl/9853043

With this change the compiler emits a bitmap for each function
covering its stack frame arguments area.  If an argument word
is known to contain a pointer, a bit is set.  The garbage
collector reads this information when scanning the stack by
frames and uses it to ignores locations known to not contain a
pointer.

R=golang-dev, bradfitz, daniel.morsing, dvyukov, khr, khr, iant, cshapiro
CC=golang-dev
https://golang.org/cl/9223046

This depends on: 9791044: runtime: allocate page table lazily
Once page table is moved out of heap, the heap becomes small.
This removes unnecessary dereferences during heap access.
No logical changes.

R=golang-dev, khr
CC=golang-dev
https://golang.org/cl/9802043

This removes the 256MB memory allocation at startup,
which conflicts with ulimit.
Also will allow to eliminate an unnecessary memory dereference in GC,
because the page table is usually mapped at known address.
Update #5049.
Update #5236.

R=golang-dev, khr, r, khr, rsc
CC=golang-dev
https://golang.org/cl/9791044

we need it for GC anyway.

R=golang-dev, khr, dave, khr
CC=golang-dev
https://golang.org/cl/9728044

Currently the test closes random files descriptors,
which leads to hang (in particular if netpoll fd is closed).
Try to open only fd 3, since the parent process expects it to be fd 3 anyway.
Fixes #5571.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/9778048