Add a `clock_gettime` emulation layer and use it to implement the `time`
entrypoint.
For windows, the monotonic clock is emulated using `QPC`.
The realtime clock is emulated using `GetSystemTimePreciseAsFileTime`.
The previous implementation of the ctype functions assumed ASCII.
This patch changes to a switch/case implementation that looks odd, but
actually is easier for the compiler to understand and optimize.
Downstream builders are having issues with this local include. Use a
fuller
path that's more standard throughout the codebase.
Also some of the comments in the bazel overlay are stale. Remove them.
Reported-by: Brooks Moses <bmoses@google.com>
Downstream ther'es a user that needs the syscall wrappers to be weak. I
intend to set up a proper mechanism for just listing which functions
should be weak eventually, but for now this is necessary.
Follow-up on the `-mllvm --tail-merge-threshold=0` removal promised in
aeccc16497a84d61200f7ccfa3864096349260d3 (see
b2a9ea4420127d10b18ae648b16757665f8bbd7c commit message on why we don't
need this in Bazel, and will only keep in AArch64-specific compile flags
in CMake build).
Implements std::from_chars for float and double.
The implementation uses LLVM-libc to do the real parsing. Since this is
the first time libc++
uses LLVM-libc there is a bit of additional infrastructure code. The
patch is based on the
[RFC] Project Hand In Hand (LLVM-libc/libc++ code sharing)
https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701
Reverts llvm/llvm-project#108939
When `AVX` is available but `-mprefer-vector-width=128` some of the
`mov` instructions turn into the x86 `rep;movsb` instruction leading to
poor performance on "old" architectures (sandybridge, haswell). The
possible solutions are : get rid of the `-mprefer-vector-width` option
or use smaller static copy sizes in
`inline_memcpy_x86_sse2_ge64_sw_prefetching`. Right now a copy size of 3
cache lines (192B) relying exclusively on xmm registers gets turned into
`rep;movsb`.
This detail is not relevant for the upstream Bazel version. llvm-libc unit tests today directly invoke the function under test using the namespace, which reduces the potential problems of linking with some other (system-provided) version of llvm-libc further.
Anywhere a struct is returned from the kernel, we need to explicitly
unpoison it for MSAN. This patch does that for the recv, recvfrom,
recvmsg, and socketpair functions.
There are no more specializations `libc/src/math/x86_64` or
`libc/src/math/aarch64` anymore. All implementations are going through
the generic implementation.
This patch adds the necessary functions to send and receive messages
over a socket. Those functions are: recv, recvfrom, recvmsg, send,
sendto, sendmsg, and socketpair for testing.
This patch adds the %m conversion to printf, which prints the
strerror(errno). Explanation of why is below, this patch also updates
the docs, tests, and build system to accomodate this.
The standard for syslog in posix specifies it uses the same format as
printf, but adds %m which prints the error message string for the
current value of errno. For ease of implementation, it's standard
practice for libc implementers to just add %m to printf instead of
creating a separate parser for syslog.
This is a quick fix to unbreak Bazel build. The right solution would
probably add vdso.cpp in the support library which includes circular
dependency and needs more restructuring.
The wrapper for epoll_pwait2 has been difficult to enable since it
requires a very new version of the linux kernel (5.11). On cmake we
still need to create a mechanism to check if we can build it, but our
current bazel users are all on a new enough kernel version we can just
enable it.
Currently the nan* functions use nullptr dereferencing to crash with
SIGSEGV if the input is nullptr. Both `nan(nullptr)` and `nullptr`
dereferencing are undefined behaviors according to the C standard.
Employing `nullptr` dereference in the `nan` function implementation is
ok if users only linked against the pre-built library, but it might be
completely removed by the compilers' optimizations if it is built from
source together with the users' code.
See for instance: https://godbolt.org/z/fd8KcM9bx
This PR uses volatile load to prevent the undefined behavior if libc is
built without sanitizers, and leave the current undefined behavior if
libc is built with sanitizers, so that the undefined behavior can be
caught for users' codes.
