- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Unconditionally compile the __sync_* atomics support functions into compiler-rt
for ARM.
This is quite ugly, because it has to work around a clang bug that does not
allow built-in functions to be defined, even when they're ones that are
expected to be built as part of a library.

Reviewed by: ed

Build __clear_cache on ARM with clang now it supports it.

Let ARM use the custom tailored atomic intrinsics.

Use improved __sync_*() intrinsics for MIPS in userspace as well.

r251524 introduced custom tailored versions for MIPS of these functions
for kernel-space code. We can just reuse them in userspace as well.

Add __sync_synchronize().

This function can easily be implemented on top of the mb() macro
provided by <machine/atomic.h>.

Use #ifdef instead of #if defined.

This makes these tests a bit more consistent with the tests done at the
bottom of the file.

Unbreak <stdatomic.h> on ARM + Clang.

Clang only supports atomic operations for ARMv6. For non-ARMv6, we still
need to emit these functions.

Clang's prototype for these functions slightly differs, as it is truly
based on GCC's documentation. It requires the use of signed types, but
also requires varargs. Still, we are not allowed to simply implement
this function directly. Cleverly work around this by implementing it
under a different name and using __strong_reference().

Enable libcompiler-rt on MIPS.

Originally we disabled libcompiler-rt on MIPS and SPARC64, because of an
issue where __clzdi2 and __ctzdi2 would cause endless recursion. This
bug has been fixed in r230021 already, but for some reason we only
switched to libcompiler-rt on SPARC64 -- not MIPS.

This means we can finally use <stdatomic.h> on all our architectures.

Add the __aeabi_mem* functions to compiler-rt as clang uses them.

Use the compiler-rt version __{u,}divsi3 and __{u,}modsi3 on ARM EABI

There should have been a tab after SRCS+=

Add the __aeabi_*divmod functions to the compiler-rt build

Get libcompiler-rt and libgcc building on ARM with clang.

* Don't provide clear_cache or the __sync_* functions on ARM with clang as
they are provided by clang as builtin functions.
* Tell clang it is aloud to compile some libgcc code using heinous GCC
extensions.

Switch sparc64 to using libcompiler_rt; since r230021 we have a workaround
in place allowing it to be used there and since r235388 (see also r235486)
we also have usable div/mod optimizations like libgcc has.

Upgrade libcompiler_rt to upstream revision 147390.

This version of libcompiler_rt adds support for __mulo[sdt]i4(), which
computes a multiply and its overflow flag. There are also a lot of
cleanup fixes to headers that don't really affect us.

Updating to this revision should make it a bit easier to contribute
changes back to the LLVM developers.

Add locally implemented atomic intrinsics to libcompiler_rt.

The built-in atomic operations are not implemented in our version of GCC
4.2 for the ARM and MIPS architectures. Instead of emitting locked
instructions, they generate calls to functions that can be implemented
in the C runtime.

Only implement the atomic operations that are used by <stdatomic.h> for
datatype sizes that are supported by atomic(9). This means that on these
architectures, we can only use atomic operations on 32-bits and 64-bits
variables, which is typically sufficient.

This makes <stdatomic.h> work on all architectures except MIPS, since
MIPS and SPARC64 still use libgcc. Converting these architectures to
libcompiler_rt is on my todo list.

Upgrade libcompiler_rt from revision 117047 to 132478.

It seems there have only been a small amount to the compiler-rt source
code in the mean time. I'd rather have the code in sync as much as
possible by the time we release 9.0. Changes:

- The libcompiler_rt library is now dual licensed under both the
University of Illinois "BSD-Like" license and the MIT license.

- Our local modifications for using .hidden instead of .private_extern
have been upstreamed, meaning our changes to lib/assembly.h can now be
reverted.

- A possible endless recursion in __modsi3() has been fixed.

- Support for ARM EABI has been added, but it has no effect on FreeBSD
(yet).

- The functions __udivmodsi4 and __divmodsi4 have been added.

Requested by: many, including bf@ and Pedro Giffuni

Mark libcompiler_rt as not needed executable stack on powerpc.

Reviewed and tested by: nwhitehorn

Fix braino in r217101. -Wa is used to supply assembler flag to cc driver.

Noted by: Anonymous <swell.k gmail com>

On amd64 and i386, force assembler to mark objects compiled from the
assembler source for libcompiler_rt as not needed executable stack. This
is done with a hammer instead of properly marking each assembly file
with section .note.GNU-stack to avoid modifying contributed source.

Discussed with: ed

Switch mips architectures back to libgcc.

MIPS64 n64 binaries are broken with libcompiler_rt at this time.
Switch mips back to libgcc until the cause of breakage is analyzed
and fixed.

Revert to libgcc for sparc64.

I've had a report of a sparc64 system where cc1 generates illegal
instructions. We still have to diagnose this properly, but instead of
hosing all sparc64 boxes out there, fall back to libgcc to prevent more
damage.

Reported by: Florian Smeets

Set symbol visibility to hidden.

Not doing so may cause all sorts of random libraries to expose
libcompiler_rt's functions, which should of course not be done.

Discussed with: kan, kib

Import libcompiler_rt into HEAD and add Makefiles.

Obtained from: user/ed/compiler-rt