This PR implements a part of WG14 N2653:
- Define C23 char8_t
- Define C11 char16_t
- Define C11 char32_t
Missing goals are:
- The type of UTF-8 character literals is changed from unsigned char to
char8_t. (Since UTF-8 character literals already have type unsigned
char, this is not a semantic change).
- New mbrtoc8() and c8rtomb() functions declared in <uchar.h> enable
conversions between multibyte characters and UTF-8.
- A new ATOMIC_CHAR8_T_LOCK_FREE macro.
- A new atomic_char8_t typedef name.
Closes#88066.
Compared to before, the function names in the stdbit table are sorted by
function name, not order-of-appearance in the standard. Since macros
aren't printed by docgen.py and are still a TODO in the code, they are
also not printed in the new stdbit.h docs.
Adds some checks to docgen.py for conditions that tripped me up.
Add code to docgen.py to add the include of the `|check|` rewriter,
since all other generated files need it.
When supporting "overlay" vs "fullbuild" modes, "what ABI are you
using?" becomes a fundamental question to have concrete answers for.
Overlay mode MUST match the ABI of the system being overlayed onto;
fullbuild more flexible (the only system ABI relevant is the OS kernel).
When implementing llvm-libc we generally prefer the include-what-you use
style of avoiding transitive dependencies (since that makes refactoring
headers more painful, and slows down build times). So what header do you
include for any given type or function declaration? For any given
userspace program, the answer is straightforward. But for llvm-libc
which is trying to support multiple ABIs (at least one per
configuration), the answer is perhaps less clear.
This proposal seeks to add one layer of indirection relative to what's
being done today.
It then converts users of sigset_t and struct epoll_event and the epoll
implemenations over to this convention as an example.
This script+config should help us generate more consistent documentation wrt.
what we currently support or not.
As an example usage:
$ ./libc/utils/docgen/docgen.py fenv.h
Will spit out an RST formatted table that can be copy+pasted into our docs.
The config is not filled out entirely, but doing so and then updating our docs
would be great beginner bugs for new contributors.
Having python+json generate things like docs, or headers (as imagined in
https://github.com/nickdesaulniers/llvm-project/tree/hdr-gen2) is perhaps
easier to work with than tablegen, and doesn't introduce a dependency on a host
tool that needs to be compiled from llvm sources before building the rest of
the libc. This can probably be merged with whatever we end up doing to replace
libc-hdrgen.
Please use
https://llvm.org/docs/CodingStandards.html#python-version-and-source-code-formatting
for keeping this file formatted.
Implements the functions `roundeven()`, `roundevenf()`, `roundevenl()`
from the roundeven family of functions introduced in C23. Also
implements `roundevenf128()`.
Re-organizes the tables that listed libc's support for math functions,
and adds two new columns to the tables indicating where the respective
function definitions and error handling methods are located in the C23
standard draft WG14-N3096.
We compute atan2f(y, x) in 2 stages:
- Fast step: perform computations in double precision , with relative
errors < 2^-50
- Accurate step: if the result from the Fast step fails Ziv's rounding
test, then we perform computations in double-double precision, with
relative errors < 2^-100.
On Ryzen 5900X, worst-case latency is ~ 200 clocks, compared to average
latency ~ 60 clocks, and average reciprocal throughput ~ 20 clocks.
Fixes#86546 and removes the macro `LIBC_HAS_BUILTIN`. This was
necessary to support older compilers that did not support
`__has_builtin`. All of the compilers we support already have this
builtin.
See: https://libc.llvm.org/compiler_support.html
All uses now use `__has_builtin` directly
cc @nickdesaulniers
Summary:
Currently we print `null` for the null pointer in a `%s` expression.
Although it's not defined by the standard, other implementations choose
to use `(null)` to indicate this. We also currently print `(nullptr)` so
I think it's more consistent to use parens in both cases.
Continuing #84689, this one required more changes than the others, so I
am making it a separate PR.
Extends some stuff in `str_to_float.h`, `str_to_integer.h` to work on
types wider than `unsigned long long` and `uint64_t`.
cc @lntue for review.
- Allow `FMod` template to have different computational types and make
it work for 80-bit long double.
- Switch to use `uint64_t` as the intermediate computational types for
`float`, significantly reduce the latency of `fmodf` when the exponent
difference is large.
