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().
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.
* 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.
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.
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.
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
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
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
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
