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957c61cbbf
This change upgrades to GCC 12.3 and GNU binutils 2.42. The GNU linker appears to have changed things so that only a single de-duplicated str table is present in the binary, and it gets placed wherever the linker wants, regardless of what the linker script says. To cope with that we need to stop using .ident to embed licenses. As such, this change does significant work to revamp how third party licenses are defined in the codebase, using `.section .notice,"aR",@progbits`. This new GCC 12.3 toolchain has support for GNU indirect functions. It lets us support __target_clones__ for the first time. This is used for optimizing the performance of libc string functions such as strlen and friends so far on x86, by ensuring AVX systems favor a second codepath that uses VEX encoding. It shaves some latency off certain operations. It's a useful feature to have for scientific computing for the reasons explained by the test/libcxx/openmp_test.cc example which compiles for fifteen different microarchitectures. Thanks to the upgrades, it's now also possible to use newer instruction sets, such as AVX512FP16, VNNI. Cosmo now uses the %gs register on x86 by default for TLS. Doing it is helpful for any program that links `cosmo_dlopen()`. Such programs had to recompile their binaries at startup to change the TLS instructions. That's not great, since it means every page in the executable needs to be faulted. The work of rewriting TLS-related x86 opcodes, is moved to fixupobj.com instead. This is great news for MacOS x86 users, since we previously needed to morph the binary every time for that platform but now that's no longer necessary. The only platforms where we need fixup of TLS x86 opcodes at runtime are now Windows, OpenBSD, and NetBSD. On Windows we morph TLS to point deeper into the TIB, based on a TlsAlloc assignment, and on OpenBSD/NetBSD we morph %gs back into %fs since the kernels do not allow us to specify a value for the %gs register. OpenBSD users are now required to use APE Loader to run Cosmo binaries and assimilation is no longer possible. OpenBSD kernel needs to change to allow programs to specify a value for the %gs register, or it needs to stop marking executable pages loaded by the kernel as mimmutable(). This release fixes __constructor__, .ctor, .init_array, and lastly the .preinit_array so they behave the exact same way as glibc. We no longer use hex constants to define math.h symbols like M_PI. |
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|---|---|---|
| .. | ||
| mem | ||
| testing | ||
| array.internal.h | ||
| atomic.h | ||
| atomic.internal.h | ||
| BUILD.mk | ||
| common.c | ||
| common.internal.h | ||
| compat.S | ||
| counter.h | ||
| cv.h | ||
| debug.h | ||
| futex.c | ||
| futex.internal.h | ||
| heap.internal.h | ||
| LICENSE.txt | ||
| mu.c | ||
| mu.h | ||
| mu_semaphore.c | ||
| mu_semaphore.h | ||
| mu_semaphore.internal.h | ||
| mu_semaphore_futex.c | ||
| mu_semaphore_gcd.c | ||
| mu_semaphore_sem.c | ||
| mu_wait.h | ||
| note.h | ||
| notice.c | ||
| once.h | ||
| panic.c | ||
| races.internal.h | ||
| README.cosmo | ||
| time.h | ||
| wait_s.internal.h | ||
| waiter.h | ||
| yield.c | ||
DESCRIPTION
*NSYNC is a synchronization primitives library.
LICENSE
Apache 2.0
ORIGIN
git@github.com:google/nsync
commit ac5489682760393fe21bd2a8e038b528442412a7
Author: Mike Burrows <m3b@google.com>
Date: Wed Jun 1 16:47:52 2022 -0700
LOCAL CHANGES
- Fix nsync_mu_unlock() on Apple Silicon
- Time APIs were so good that they're now in libc
- Double linked list API was so good that it's now in libc
- Support Apple's ulock futexes which are internal but nicer than GCD
- Ensure resources such as POSIX semaphores are are released on fork.
- Modified *NSYNC to allocate waiter objects on the stack. We need it
because we use *NSYNC mutexes to implement POSIX mutexes, which are
too low-level to safely depend on malloc, or even mmap in our case.
- Rewrote most of the semaphore and futex system call support code so
it works well with Cosmopolitan's fat runtime portability. *NSYNC's
unit test suite passes on all supported platforms. However the BSDs
currently appear to be overutilizing CPU time compared with others.
This appears to be the fault of the OSes rather than *NSYNC / Cosmo
- Support POSIX thread cancellation. APIs that wait on condition vars
are now cancellation points. In PTHREAD_CANCEL_MASKED mode they may
return ECANCELED. In PTHREAD_CANCEL_DEFERRED mode the POSIX threads
library will unwind the stack to re-acquire locks and free waiters.
On the other hand the *NSYNC APIs for mutexes will now safely block
thread cancellation, but you can still use *NSYNC notes to do that.