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Algorithm:
```
1) atan(x) = sign(x) * atan(|x|)
2) If |x| > 1 + 1/32, atan(|x|) = pi/2 - atan(1/|x|)
3) For 1/16 < |x| < 1 + 1/32, we find k such that: | |x| - k/16 | <= 1/32.
Let y = |x| - k/16, then using the angle summation formula, we have:
atan(|x|) = atan(k/16) + atan( (|x| - k/16) / (1 + |x| * k/16) )
= atan(k/16) + atan( y / (1 + (y + k/16) * k/16 )
= atan(k/16) + atan( y / ((1 + k^2/256) + y * k/16) )
4) Let u = y / (1 + k^2/256), then we can rewritten the above as:
atan(|x|) = atan(k/16) + atan( u / (1 + u * k/16) )
~ atan(k/16) + (u - k/16 * u^2 + (k^2/256 - 1/3) * u^3 +
+ (k/16 - (k/16)^3) * u^4) + O(u^5)
```
With all the computations are done in single precision (float), the
total of approximation errors and rounding errors is bounded by 4 ULPs.
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This patch provides definitions for `pkey_*` functions for linux x86_64.
`pkey_alloc`, `pkey_free`, and `pkey_mprotect` are simple syscall
wrappers. `pkey_set` and `pkey_get` modify architecture-specific
registers. The logic for these live in architecture specific
directories:
* `libc/src/sys/mman/linux/x86_64/pkey_common.h` has a real
implementation
* `libc/src/sys/mman/linux/generic/pkey_common.h` contains stubs that
just return `ENOSYS`.
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This patch adds the posix function `inet_addr`. Since most of the
parsing logic is delegated to `inet_aton`, I have only included some
basic smoke tests for testing purposes.
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These functions should be declared in `stdlib.h`, not `wchar.h`, as
confusing as it is. Move them to the proper header file and matching
directories in src/ and test/ trees.
This was discovered while testing libc++ build against llvm-libc, which
re-declares functions like mbtowc in std-namespace in `<cstdlib>`
header, and then uses those functions in its locale implementation.
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These are simply implemented as specializations of strtofloatingpoint
for double / long double and for wchar_t. The unit tests are copied from
the strtod / strtold ones.
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By only defining it if LIBC_ASSERT macro is not defined.
Fixes https://github.com/llvm/llvm-project/issues/162392
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Addresses `TODO`s in file.cpp by replacing data copies via for loops
with calls to inline_memcpy.
Signed-off-by: Shreeyash Pandey <shreeyash335@gmail.com>
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This change follows the pattern of
315dfe5865962d8a3d60e21d1fffce5214fe54ef by making strtofloat also
accept wchar_t* strings
(in addition to regular char*). It uses overloads from wctype_utils or
specialized functions to ensure comparison with literal characters (or
literal strings) pick char or wchar_t variants based on the argument
type.
The wcstof implementation is added, with unit test cases copied from
strtof test suite.
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(#167417)
ctype_utils/wctype_utils were chaged in
120689e46679c6db37cd9e839ec0721e80a22d4f and
e7f7973899f76773ae6e9a6b1e8c7e9f9cc5cb56, respectively to operate on
char/wchar_t. Now we can switch to the overloaded names (e.g. have noth
`isspace(char` and `isspace(wchar_t)`) to simplify the templatized
strtointeger implementation from
315dfe5865962d8a3d60e21d1fffce5214fe54ef and make it easier to
potentially add templatized strtofloat implementation.
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Closes #161461
- This is my first time contributing to libc's POSIX, so for reference I
used `clock_gettime` implementation for Linux. For convenience, here is
the description of `clock_settime` function
[behavior](https://www.man7.org/linux/man-pages/man3/clock_settime.3.html)
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Implements fchown
fixes: #166856
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Now that https://github.com/llvm/llvm-project/pull/166517 has landed and
[Writer](https://github.com/llvm/llvm-project/blob/main/libc/src/stdio/printf_core/writer.h#L130)
has been refactored to track bytes written as size_t, strftime can be
refactored as well to handle size_t return values.
Can't think of a proper way to test this without creating a 2GB+ string,
but existing tests cover most cases.
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This PR creates an SVE-based implementation for strlen by translating
from the AOR code in tree. Microbenchmark shows improvements against
NEON when N>=64. Although both implementations fall behind glibc by a
large margin,
this may be a good start point to explore SVE implementations.
Together with the PR:
1. Added two more tests of strlen with special nul symbols.
2. Added strlen's fuzzer and fix a typo in previous heap fuzzer.
```
=== strlen(16 bytes) ===
libc: 1.56115 ns/call, 9.54499 GiB/s
neon: 1.59393 ns/call, 9.34867 GiB/s
sve: 1.66097 ns/call, 8.97134 GiB/s
=== strlen(64 bytes) ===
libc: 2.06967 ns/call, 28.7991 GiB/s
neon: 2.59914 ns/call, 22.9325 GiB/s
sve: 2.58628 ns/call, 23.0465 GiB/s
=== strlen(256 bytes) ===
libc: 3.74165 ns/call, 63.7202 GiB/s
neon: 8.98243 ns/call, 26.5428 GiB/s
sve: 7.36426 ns/call, 32.3751 GiB/s
=== strlen(1024 bytes) ===
libc: 10.5327 ns/call, 90.5438 GiB/s
neon: 34.363 ns/call, 27.7529 GiB/s
sve: 26.9329 ns/call, 35.4092 GiB/s
=== strlen(4096 bytes) ===
libc: 37.7304 ns/call, 101.104 GiB/s
neon: 145.911 ns/call, 26.144 GiB/s
sve: 103.208 ns/call, 36.9612 GiB/s
=== strlen(1048576 bytes) ===
libc: 9623.4 ns/call, 101.478 GiB/s
neon: 36138.2 ns/call, 27.023 GiB/s
sve: 26605.6 ns/call, 36.7051 GiB/s
```
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fwrite and friends don't modify errno if no error occurred. Therefore
frite_unlocked's return value shouldn't be constructed from errno
without checking if an error actually occurred.
This fixes an error introduced by
https://github.com/llvm/llvm-project/commit/9e2f73fe9052a4fbf382a06e30b2441c6d99fb7e
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(#166846)
The previous implementation in #166252 (rolled back in #166658) caused
buildbot failures due to a bug in an added test. The modified
`UseAfterClose` did not pass a `struct flock` value to `fcntl`:
https://github.com/llvm/llvm-project/blob/2d5170594147b42a37698760d6e0194eec4f1390/libc/test/src/fcntl/fcntl_test.cpp#L175
Which ASAN caught and errored in the `fcntl` implementation when the
unspecified argument was accessed:
https://github.com/llvm/llvm-project/blob/c12cb2892c808af459eaa270b8738a2b375ecc9b/libc/src/__support/OSUtil/linux/fcntl.cpp#L59
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Add in SVE/SVE2/MOPS features for aarch64 cpus. These features may be
interesting for future memory/math routines.
SVE/SVE2 are now being accepted in more implementations:
```
❯ echo | clang-21 -dM -E - -march=native | grep -i ARM_FEAT
#define __ARM_FEATURE_ATOMICS 1
#define __ARM_FEATURE_BF16 1
#define __ARM_FEATURE_BF16_SCALAR_ARITHMETIC 1
#define __ARM_FEATURE_BF16_VECTOR_ARITHMETIC 1
#define __ARM_FEATURE_BTI 1
#define __ARM_FEATURE_CLZ 1
#define __ARM_FEATURE_COMPLEX 1
#define __ARM_FEATURE_CRC32 1
#define __ARM_FEATURE_DIRECTED_ROUNDING 1
#define __ARM_FEATURE_DIV 1
#define __ARM_FEATURE_DOTPROD 1
#define __ARM_FEATURE_FMA 1
#define __ARM_FEATURE_FP16_SCALAR_ARITHMETIC 1
#define __ARM_FEATURE_FP16_VECTOR_ARITHMETIC 1
#define __ARM_FEATURE_FRINT 1
#define __ARM_FEATURE_IDIV 1
#define __ARM_FEATURE_JCVT 1
#define __ARM_FEATURE_LDREX 0xF
#define __ARM_FEATURE_MATMUL_INT8 1
#define __ARM_FEATURE_NUMERIC_MAXMIN 1
#define __ARM_FEATURE_PAUTH 1
#define __ARM_FEATURE_QRDMX 1
#define __ARM_FEATURE_RCPC 1
#define __ARM_FEATURE_SVE 1
#define __ARM_FEATURE_SVE2 1
#define __ARM_FEATURE_SVE_BF16 1
#define __ARM_FEATURE_SVE_MATMUL_INT8 1
#define __ARM_FEATURE_SVE_VECTOR_OPERATORS 2
#define __ARM_FEATURE_UNALIGNED 1
```
MOPS is another set of extension for string operations, but may not be
generally available for now:
```
❯ echo | clang-21 -dM -E - -march=armv9.2a+mops | grep -i MOPS
#define __ARM_FEATURE_MOPS 1
```
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On exit from the loop, char_ptr had not been updated to match block_ptr,
resulting in erroneous results. Moving all updates out of the loop fixes
that.
Adjust derefences to always be inside bounds checks.
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Reverts llvm/llvm-project#166252
Causing buildbot failures on `libc-x86_64-debian-dbg-asan`.
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This patch also configures fcntl lock tests to run with F_OFD_* command
variants, as all existing lock tests do not exercise process-associated-
or OFD-specific functionality.
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Previously, if the `open` or `openat` syscalls returned 0 as a (valid)
file descriptor, the `creat` and `openat` wrappers would erroneously
return -1.
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https://github.com/llvm/llvm-project/issues/159474
Another try of trying to land
https://github.com/llvm/llvm-project/pull/166382
- Fix some leftover tests checking for specific errnos
- Guard errno checking tests to not run on the GPU
@michaelrj-google
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This is a counterpart of
https://github.com/llvm/llvm-project/pull/166225 but for wctype_utils
(which are not yet widely used). For now, I'm just changing the types
from wint_t to wchar_t to match the regular ctype_utils change. The next
change may rename most of the functions to match the name of ctype_utils
variants, so that we could be calling them from the templated code
operating on "const char*" and "const wchar_t*" strings, and the right
function signature would be picked up.
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(#166225)
Functions like isalpha / tolower can operate on chars internally. This
allows us to get rid of unnecessary casts and open a way to creating
wchar_t overloads with the same names (e.g. for isalpha), that would
simplify templated code for conversion functions (see
315dfe5865962d8a3d60e21d1fffce5214fe54ef).
Add the int->char converstion to public entrypoints implementation
instead. We also need to introduce bounds check on the input argument
values - these functions' behavior is unspecified if the argument is
neither EOF nor fits in "unsigned char" range, but the tests we've had
verified that they always return false for small negative values. To
preserve this behavior, cover it explicitly.
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src/__support/math folder. (#162019)
Part of #147386
in preparation for: https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450
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Found in testing against abseil. Two bugs were found:
1) SHIFT_AMOUNT in float_converter<long double> would sometimes be
negative causing an underflow when passed as the amount to left shift
by for BigInt.
2) is_lowest_block had an off-by-one because it was adding 1 to the
block index.
Both are fixed and there are new tests to catch regressions.
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https://github.com/llvm/llvm-project/issues/159474
Resubmitting https://github.com/llvm/llvm-project/pull/162876 with fixes
as it broke some buildbots:
- Fix comparisons of integer expressions of different signedness
- Not check for specific errnos in tests, as they might not be available
on all platforms
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Implements chown and getgid per the POSIX specification and adds
corresponding unit tests. getgid is added as it is required by the chown
unit tests. This PR will address #165785
Co-authored-by: shubh@DOE <shubhp@mbm3a24.local>
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[#159474](https://github.com/llvm/llvm-project/issues/159474)
- All printf variants set errno and consistently return -1 on error,
instead of returning various predefined error codes
- Return value overflow handling is added
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* Removes the copy-pasta implementation of wcstointeger,
and migrate the wcsto* family of functions to use a template
version of strtointeger.
* Fixes the out-of-bound read in the original implementation(s)
when the entire input string consists of whitespaces
(then the sign check can access OOB memory)
The code is currently slightly peppered with "if constexpr" statements
to distinguish between char and wchar_t. We can probably
simplify it in subsequent changes by:
* using overrides, so that internal::isalnum() is overriden for
both char and wchar_t (since C++ luckily allows us to reuse names).
* this wouldn't help for direct comparison with literals -
for this as a somewhat ugly workaround like is_char_literal(c, '0',
L'0')
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Optimization flags are now handled through a common flag. These are no
longer necessary.
Fixes #112409
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This patch fixes a bug in strftime's return value when the formatted
output exactly fills the buffer, not including the null terminator. The
previous check failed to account for the null terminator in this case,
incorrectly returning the written count instead of 0.
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This options sets a compile option when building sources inside the
string directory, and this option affects string_utils.h. But
string_utils.h is #included from more places than just the string
directory (such as from __support/CPP/string.h), leading to both
narrow-reads in those cases, but more seriously, ODR violations when the
two different string_length implementations are included int he same
program.
Having this option at the top level avoids this problem.
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Fixes: https://github.com/llvm/llvm-project/issues/164653
Signed-off-by: Shreeyash Pandey <shreeyash335@gmail.com>
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Fixes https://github.com/llvm/llvm-project/issues/129361
@michaelrj-google @PiJoules
---------
Signed-off-by: Shreeyash Pandey <shreeyash335@gmail.com>
Co-authored-by: Michael Jones <michaelrj@google.com>
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* Add FILE type declaration, as it should be presented in `<wchar.h>`,
as well as in `<stdio.h>`
* Fix argument type in `wcsrtombs` / `wcsnrtombs` function - it should
be restrict pointer to `mbstate_t`. Add restrict qualifier to internal
implementation as well.
This brings us closer to being able to build libcxx with wide-character
support against llvm-libc headers.
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accurate path is skipped. (#164522)
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Create a POSIX `<nl_types.h>` header with `catopen`, `catclose`, and
`catgets` function declarations.
Provide the stub/placeholder implementations which always return error.
This is consistent with the way
locales are currently (un-)implemented in llvm-libc.
Notably, providing `<nl_types.h>` fixes the last remaining issue with
building libc++ against llvm-libc
(on certain configuration of x86_64 Linux) after disabling threads and
wide-characters in libc++.
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Based on the double precision's sin/cos fast path algorithm:
Step 1: Perform range reduction `y = x mod pi/8` with target errors <
2^-54.
This is because the worst case mod pi/8 for single precision is ~2^-31,
so to have up to 1 ULP errors from
the range reduction, the targeted errors should `be 2^(-31 - 23) =
2^-54`.
Step 2: Polynomial approximation
We use degree-5 and degree-4 polynomials to approximate sin and cos of
the reduced angle respectively.
Step 3: Combine the results using trig identities
```math
\begin{align*}
\sin(x) &= \sin(y) \cdot \cos(k \cdot \frac{\pi}{8}) + \cos(y) \cdot \sin(k \cdot \frac{\pi}{8}) \\
\cos(x) &= \cos(y) \cdot \cos(k \cdot \frac{\pi}{8}) - \sin(y) \cdot \sin(k \cdot \frac{\pi}{8})
\end{align*}
```
Overall errors: <= 3 ULPs for default rounding modes (tested
exhaustively).
Current limitation: large range reduction requires FMA instructions for
binary32. This restriction will be removed in the followup PR.
---------
Co-authored-by: Petr Hosek <phosek@google.com>
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This patch adds the implementation for `inet_aton` function. Since this
function is not explicitly included in POSIX, I have marked it with
`llvm_libc_ext`. It is widely available and commonly used, and can also
be used to implement `inet_addr`, which is included in POSIX.
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Closes #164403
GCC fails to compile libc currently. This PR fixes this by capturing
'POLY_COEFFS' by reference.
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(#164012)
Reverts llvm/llvm-project#145933 due to broken aarch64 buildbots.
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fix #145932
---------
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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src/__support/math folder. (#162017)
Part of #147386
in preparation for: https://discourse.llvm.org/t/rfc-make-clang-builtin-math-functions-constexpr-with-llvm-libc-to-support-c-23-constexpr-math-functions/86450
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Fix #163711.
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Reverts llvm/llvm-project#107540
This PR demonstrated improvements on micro-benchmarks but the gains did
not seem to materialize in production. We are reverting this change for
now to get more data. This PR might be reintegrated later once we're
more confident in its effects.
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