Implement acosf function correctly rounded for all rounding modes.
We perform range reduction as follows:
- When `|x| < 2^(-10)`, we use cubic Taylor polynomial:
```
acos(x) = pi/2 - asin(x) ~ pi/2 - x - x^3 / 6.
```
- When `2^(-10) <= |x| <= 0.5`, we use the same approximation that is used for `asinf(x)` when `|x| <= 0.5`:
```
acos(x) = pi/2 - asin(x) ~ pi/2 - x - x^3 * P(x^2).
```
- When `0.5 < x <= 1`, we use the double angle formula: `cos(2y) = 1 - 2 * sin^2 (y)` to reduce to:
```
acos(x) = 2 * asin( sqrt( (1 - x)/2 ) )
```
- When `-1 <= x < -0.5`, we reduce to the positive case above using the formula:
```
acos(x) = pi - acos(-x)
```
Performance benchmark using perf tool from the CORE-MATH project on Ryzen 1700:
```
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh acosf
GNU libc version: 2.35
GNU libc release: stable
CORE-MATH reciprocal throughput : 28.613
System LIBC reciprocal throughput : 29.204
LIBC reciprocal throughput : 24.271
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh asinf --latency
GNU libc version: 2.35
GNU libc release: stable
CORE-MATH latency : 55.554
System LIBC latency : 76.879
LIBC latency : 62.118
```
Reviewed By: orex, zimmermann6
Differential Revision: https://reviews.llvm.org/D133550
This function cannot have any instrumentation because it's
assembly must match exactly what the debugger is expecting.
Previously it was just a list of what sanitizers we expect
libc would be sanitized with but this is untenable.
Update the utility functions for checking exceptional values of math
functions to use cpp::optional return values.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D133134
This adds division and power implementations to UInt. Modulo and
division are handled by the same function. These are necessary for some
higher order mathematics, often involving large floating point numbers.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D132184
builtin_wrappers contains the wrappers for the clz builtins, which do
not depend on anything in fputil. This patch moves the file out of
FPUtil. The location is updated as appropriate.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D133035
The implementation currently supports only non-thumb mode. As a test for
the implementation, mmap and munmap functions have been enabled.
Reviewed By: michaelrj
Differential Revision: https://reviews.llvm.org/D132825
The libc.src.__support.FPUtil.fputil target encompassed many unrelated
files, and provided a lot of hidden dependencies. This patch splits out
all of these files into component parts and cleans up the cmake files
that used them. It does not touch any source files for simplicity, but
there may be changes made to them in future patches.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D132980
Performance by core-math (core-math/glibc 2.31/current llvm-14):
10.845/43.174/13.467
The review is done on top of D132809.
Differential Revision: https://reviews.llvm.org/D132811
1) `double log2_eval(double)` function added with better than float precision is added.
2) Some refactoring done to put all auxiliary functions and corresponding data
to one place to reuse the code.
3) Added tests for new functions.
4) Performance and precision tests of the function shows, that it more precise than exiting log2,
(no exceptional cases), but timing is ~5% higer that on current one.
Differential Revision: https://reviews.llvm.org/D132809
This patch allows for adjusting the size of the array that printf uses
to track the types of arguments in index mode. This is useful for
optimizing the tradeoff between memory usage and performance.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131993
The FormatSection and the writer functions both previously took a char*
and a length to represent a string. Now they use the StringView class to
represent that more succinctly. This change also required fixing
everywhere these were used, so it touches a lot of files.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131994
We held off on this before as `LLVM_LIBDIR_SUFFIX` conflicted with it.
Now we return this.
`LLVM_LIBDIR_SUFFIX` is kept as a deprecated way to set
`CMAKE_INSTALL_LIBDIR`. The other `*_LIBDIR_SUFFIX` are just removed
entirely.
I imagine this is too potentially-breaking to make LLVM 15. That's fine.
I have a more minimal version of this in the disto (NixOS) patches for
LLVM 15 (like previous versions). This more expansive version I will
test harder after the release is cut.
Reviewed By: sebastian-ne, ldionne, #libc, #libc_abi
Differential Revision: https://reviews.llvm.org/D130586
* In the full build mode, `ninja install-libc` will install the headers as
well the static archive named libc.a.
* In the default mode, `ninja install-llvmlibc` will only install the
static archive libllvmlibc.a.
Reviewed By: jeffbailey
Differential Revision: https://reviews.llvm.org/D132015
In the printf_core CMake, the file pieces are defined as object
libraries that depend on the File data structure. If these are added
unconditionally they'll try to evaluate that dependancy even when there
is no File available. This patch adds a guard to prevent that error.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131921
To use the FILE data structure, LLVM-libc must be in fullbuild mode
since it expects its own implementation. This means that (f)printf can't
be used without fullbuild, but s(n)printf only uses strings. This patch
adjusts the CMake to allow for this.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D131913
To accurately measure the size of sprintf in a finished binary, the
easiest method is to simply build a binary with and without sprintf.
This patch adds an integration test that can be built with and without
sprintf, as well as targets to build it.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131735
Implement tanf function correctly rounded for all rounding modes.
We use the range reduction that is shared with `sinf`, `cosf`, and `sincosf`:
```
k = round(x * 32/pi) and y = x * (32/pi) - k.
```
Then we use the tangent of sum formula:
```
tan(x) = tan((k + y)* pi/32) = tan((k mod 32) * pi / 32 + y * pi/32)
= (tan((k mod 32) * pi/32) + tan(y * pi/32)) / (1 - tan((k mod 32) * pi/32) * tan(y * pi/32))
```
We need to make a further reduction when `k mod 32 >= 16` due to the pole at `pi/2` of `tan(x)` function:
```
if (k mod 32 >= 16): k = k - 31, y = y - 1.0
```
And to compute the final result, we store `tan(k * pi/32)` for `k = -15..15` in a table of 32 double values,
and evaluate `tan(y * pi/32)` with a degree-11 minimax odd polynomial generated by Sollya with:
```
> P = fpminimax(tan(y * pi/32)/y, [|0, 2, 4, 6, 8, 10|], [|D...|], [0, 1.5]);
```
Performance benchmark using `perf` tool from the CORE-MATH project on Ryzen 1700:
```
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh tanf
CORE-MATH reciprocal throughput : 18.586
System LIBC reciprocal throughput : 50.068
LIBC reciprocal throughput : 33.823
LIBC reciprocal throughput : 25.161 (with `-msse4.2` flag)
LIBC reciprocal throughput : 19.157 (with `-mfma` flag)
$ CORE_MATH_PERF_MODE="rdtsc" ./perf.sh tanf --latency
GNU libc version: 2.31
GNU libc release: stable
CORE-MATH latency : 55.630
System LIBC latency : 106.264
LIBC latency : 96.060
LIBC latency : 90.727 (with `-msse4.2` flag)
LIBC latency : 82.361 (with `-mfma` flag)
```
Reviewed By: orex
Differential Revision: https://reviews.llvm.org/D131715
Specifically, POSIX functions pthread_key_create, pthread_key_delete,
pthread_setspecific and pthread_getspecific have been added. The C
standard equivalents tss_create, tss_delete, tss_set and tss_get have
also been added.
Reviewed By: lntue, michaelrj
Differential Revision: https://reviews.llvm.org/D131647
The convert_alpha_numeric function is intentionally non-templated so
that its code can be reused for different bases in code-size sensitive
cases. Previously it was inside the IntegerToString class which created
a different version for each base.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D131725
Change sinf/cosf range reduction to mod pi/32 to be shared with tanf,
since polynomial approximations for tanf on subintervals of length pi/16 do not
provide enough accuracy.
Reviewed By: orex
Differential Revision: https://reviews.llvm.org/D131652
The functions converting integers into decimal, hexadecimal, and octal,
are all very similar. This patch moves to a combined converter to save
code size.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131302
The default IntegerToString class only supports base 10, this patch adds
a version which supports any base between 2 and 36 inclusive. This will
be used in an upcoming patch.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131301
Previously, the integer_to_string tests used EXPECT_TRUE(.equals)
which doesn't have useful error messages. Now they properly check
equality with the EXPECT_EQ macro, which allows for comparing the
strings more naturally.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131300
This data structure uses a backing cpp::array object and supports a
vector like push_back API. In comparison with a traditional vector
data structure, it is of a fixed capacity and cannot be resized.
Differential Revision: https://reviews.llvm.org/D131377
Add "using" and "status" sections to the sidebar to make getting these
easier.
Fixed mobile formatting not overflow left and right.
Tested:
Chrome on Desktop, using mobile restrictions in devtools.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131369
This design is borrowed from the lldb folks (thank you!) to declutter
the page.
* The version number at the top is removed.
* Links are pushed over to a sidebar
* The sidebar has headings
There are other minor changes:
* The warning about this project not being ready is now an RST "warning"
* Links to the Bug Reports and the Source Code are Added
* Refer to this project as either "The LLVM C LIbrary" or "The libc"
Tested:
Built locally
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D131242
This class has only the minimum functionality in it to provide what the
TZ variable parsing needs. In particular, the standard makes guarantees
about how trivial the destructors are, throws an expception if it's used
incorrectly, etc. There are also missing features.
Tested:
Trivial testsuite added, and use in development.
Reviewed By: gchatelet
Differential Revision: https://reviews.llvm.org/D129920
Since this now allows, the init/fini array iteration has been added in
a similar fashion to x86_64 and the corresponding test enabled.
Reviewed By: jeffbailey
Differential Revision: https://reviews.llvm.org/D131133
Migrating all private STL code to the standard STL case but keeping it under the CPP namespace to avoid confusion.
Differential Revision: https://reviews.llvm.org/D130771
Migrating all private STL code to the standard STL case but keeping it under the CPP namespace to avoid confusion.
Differential Revision: https://reviews.llvm.org/D130762
Migrating all private STL code to the standard STL case but keeping it under the CPP namespace to avoid confusion.
Differential Revision: https://reviews.llvm.org/D130760
Migrating all private STL code to the standard STL case but keeping it under the CPP namespace to avoid confusion.
Differential Revision: https://reviews.llvm.org/D130773
Migrating all private STL code to the standard STL case but keeping it under the CPP namespace to avoid confusion. Starting with the type_traits header.
Differential Revision: https://reviews.llvm.org/D130727
New exp2 function algorithm:
1) Improved performance: 8.176 vs 15.270 by core-math perf tool.
2) Improved accuracy. Only two special values left.
3) Lookup table size reduced twice.
Differential Revision: https://reviews.llvm.org/D129005
Change `sinf` range reduction to mod pi/16 to be shared with `cosf`.
Previously, `sinf` used range reduction `mod pi`, but this cannot be used to implement `cosf` since the minimax algorithm for `cosf` does not converge due to critical points at `pi/2`. In order to be able to share the same range reduction functions for both `sinf` and `cosf`, we change the range reduction to `mod pi/16` for the following reasons:
- The table size is sufficiently small: 32 entries for `sin(k * pi/16)` with `k = 0..31`. It could be reduced to 16 entries if we treat the final sign separately, with an extra multiplication at the end.
- The polynomials' degrees are reduced to 7/8 from 15, with extra computations to combine `sin` and `cos` with trig sum equality.
- The number of exceptional cases reduced to 2 (with FMA) and 3 (without FMA).
- The latency is reduced while maintaining similar throughput as before.
Reviewed By: zimmermann6
Differential Revision: https://reviews.llvm.org/D130629
The floating point functions all use the same inf and nan formatting. By
separating this functionality out of the %a conversion I make it
available for reuse by %f/e/g.
Reviewed By: lntue, sivachandra
Differential Revision: https://reviews.llvm.org/D129665
The standard says two equal pointers must compare equal
so there is no need to call the user comparator function
in this case.
Differential Revision: https://reviews.llvm.org/D130310
With correctly rounded implementations, these functions will be tested for all
rounding modes. Since fegetround and fesetround are not implemented for arm32,
these tests will fail in all non-default rounding modes. We will re-enable
these entrypoints and tests once fegetround and fesetround are implemented for
arm32.
Add float type and flag for nearest integer to automatically test with
and without SSE4.2 flag.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D129916
Printf's integer converter has been modified to use the new converter. In
future, it will be used to implement other parts of the libc.
Reviewed By: michaelrj
Differential Revision: https://reviews.llvm.org/D130227
Currently, there are two string parsers that can be used in a call to
strtofloatingpoint. There is the main parser used by Clinger's fast path
and Eisel-Lemire, and the backup parser used by Simple Decimal
Conversion. There was a bug in the backup parser where if the number had
more than 800 digits (the size of the SDC buffer) before the decimal
point, it would just ignore the digits after the 800th and not count
them into the exponent. This patch fixes that issue and adds regression
tests.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D130032
The API in StringView.h for remove_prefix was incorrect and was returning a
new StringView rather than just altering the view.
As part of this, also removed some of the safety features. The comment
correctly noted that the behaviour is undefined in some cases,
but the code and test cases checked for that.
One caller was relying on the old behaviour, so fixed it and added some
comments.
Tested:
check-libc
llvmlibc
libc-loader-tests
Reviewed By: gchatelet
Differential Revision: https://reviews.llvm.org/D129950
This adds functionality for rounding towards negative inf, positive inf,
and zero to the float hex conversion (%a).
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D129702
This patch adds all the string and stdlib entrypoints, as well as a few
math entrypoints to the arm32 build.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D129821
Add support for three more string_view functions
1) starts_with(char)
2) ends_with(char)
3) find_first_of(char, size_t)
Reimplemented trim in terms of the new starts_with and ends_with.
Tested:
New unit tests.
Reviewed By: gchatelet
Differential Revision: https://reviews.llvm.org/D129618
The integration tests use the loader which sets up the main thread's
self object. So, all integration tests have to depend on the threads
implementation.
The specified rounding mode will be used and restored
to what it was before the test ran.
Additionally, it moves ForceRoundingMode and RoundingMode
out of MPFRUtils to be used in more places.
Differential Revision: https://reviews.llvm.org/D129685
Move the constants for printf's return values into core_structs, and
update the converters to match.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D128767
This is simple switch from a unittest to an integration test. It is
being done as a preparatory step to adding TLS support to thread
creation. TLS setup and initialization is tightly coupled with the
loader and hence all thread related tests should be integration tests.
A detached thread cleans itself up at completion. So, the CLEAR_TID memory is
also gone by the time the kernel tries to signal potential waiters. By nulling
the CLEAR_TID address, we prevent the kernel from signalling at a non-existent
futex location.
Previosly, a pointer to the thread data structure was stored in the
start args. However, the thread data structure need not have the
lifetime of the thread. On the the other hand, thread attributes are
stored on the thread stack so they live as long as the thread lives.
This patch adds the %a/A conversions to printf, as well as the compiler
flag to disable floating point handling entirely. This will allow our
printf implementation to display every type of argument allowed by
printf, although some formats are still incomplete.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D129240
This adds dependencies on the corresponding sqrt function to each
generic sqrt test. This is so that on platforms that don't support the
math functions, the tests are not run.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D129388
The get_explicit_mantissa function returns the mantissa of an FPBits
floating point value with the implicit leading 1, if appropriate. This
function existed previously, but did not handle non-normal numbers
properly.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D129241
In Fuchsia, all tests in a directory, ie stdlib, are linked
into one executable, this causes problems for multiple
definitions of the vtables of the div tests because their
class has the same name. This patch just trivially changes
their name to be unique between all div tests.
Differential revision: https://reviews.llvm.org/D129248
Using the LLVM rules for install ensures that DESTDIR and other expected
variables for an LLVM install work correctly.
Tested:
Manually with DESTDIR=/tmp/testinstall/ ninja install-llvmlibc
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D129041
Previous implementation splits value ranges around threads. Because of
very different performance of testing functions over different ranges,
CPU utilization were poor. Current implementation split test range
over small pieces and threads take the pieces when they finish with
previous. Therefore the CPU load is constant during testing.
Differential Revision: https://reviews.llvm.org/D128995
Bots have been failing in full build mode because ´#include <sstream>´ would pull pthread which is not possible when code is compiled with ´-freestanding´.
Differential Revision: https://reviews.llvm.org/D128809
This patch adds %n to printf, as well as a compiler flag to disable it.
This is due to it having serious security issues when misused.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D127517
The unit tests introduced in patch D128335 are causing build failures,
and the fix is non-trivial. This patch disables these tests temporarily
until a proper fix can be implemented.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D128746
This patch fixes the problem the bots were having with the algorithm
test not including pthreads correctly. They will likely need a manual
forced clean build for this to take effect.
Differential Revision: https://reviews.llvm.org/D128742
This patch is a subpart of D125768 intented to make the review easier.
This patch introduces the same algorithms as in `libc/src/string/memory_utils/elements.h` but using the new API.
Differential Revision: https://reviews.llvm.org/D128335
It was previously a header library. Making it an object library will
allow us to declare thread local variables which can used to setup a
thread's self object.
This is a implementation of find remainder fmod function from standard libm.
The underline algorithm is developed by myself, but probably it was first
invented before.
Some features of the implementation:
1. The code is written on more-or-less modern C++.
2. One general implementation for both float and double precision numbers.
3. Spitted platform/architecture dependent and independent code and tests.
4. Tests covers 100% of the code for both float and double numbers. Tests cases with NaN/Inf etc is copied from glibc.
5. The new implementation in general 2-4 times faster for “regular” x,y values. It can be 20 times faster for x/y huge value, but can also be 2 times slower for double denormalized range (according to perf tests provided).
6. Two different implementation of division loop are provided. In some platforms division can be very time consuming operation. Depend on platform it can be 3-10 times slower than multiplication.
Performance tests:
The test is based on core-math project (https://gitlab.inria.fr/core-math/core-math). By Tue Ly suggestion I took hypot function and use it as template for fmod. Preserving all test cases.
`./check.sh <--special|--worst> fmodf` passed.
`CORE_MATH_PERF_MODE=rdtsc ./perf.sh fmodf` results are
```
GNU libc version: 2.35
GNU libc release: stable
21.166 <-- FPU
51.031 <-- current glibc
37.659 <-- this fmod version.
```
This is mostly a mechanical change. In a future pass, all tests from
pthread which create threads will also be converted to integration tests.
Some of thread related features are tightly coupled with the loader. So,
they can only be tested with the in-house loader. Hence, going forward, all
tests which create threads will have to be integration tests.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D128381
This is a reland of D126773 / b2a9ea4420.
The removal of `-mllvm -combiner-global-alias-analysis` has landed separately
in D128051 / 7b73f53790.
And the removal of `-mllvm --tail-merge-threshold=0` is scheduled for
removal in a subsequent patch.
This patch is a subpart of D125768 intented to make the review easier.
The `SizedOp` struct represents operations to be performed on a certain number of bytes.
It is responsible for breaking them down into platform types and forwarded to the `Backend`.
The `Backend` struct represents a lower level abstraction that works only on types (`uint8_t`, `__m128i`, ...).
It is similar to instruction selection.
Differential Revision: https://reviews.llvm.org/D126768
The TLS loader test has been enabled for aarch64.
Handling of PT_TLS' filesz and memsz for x86_64 has also been fixed.
Reviewed By: jeffbailey
Differential Revision: https://reviews.llvm.org/D128032
The pointer converter handles the %p conversion. It uses the hex
converter for most of the conversion.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D127995
In the sign writer, a size_t was being compared to an int. This patch
casts the size_t to an int so that the comparison doesn't cause a sign
comparison warning.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D127984
This patch removes usage of `-mllvm -combiner-global-alias-analysis`
and relies on compiler builtin to implement `memcpy`.
Note that `-mllvm -combiner-global-alias-analysis` is actually only useful for
functions where buffers can alias (namely `memcpy` and `memmove`). The other
memory functions where not benefiting from the flag anyways.
The upside is that the memory functions can now be compiled from source with
thinlto (thinlto would not be able to carry on the flag when doing inlining).
The downside is that for compilers other than clang (i.e. not providing
`__builtin_memcpy_inline`) the codegen may be worse.
Differential Revision: https://reviews.llvm.org/D128051
Previously, any line buffered write of size 0 would cause an error.
The variable used to track the index of the last newline started at
the size of the write - 1, which underflowed. Now it's handled properly,
and a test has been added to prevent regressions.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D127914
This patch adds the entrypoint for printf. With this, building a
"hello world" program with just LLVM-libc is possible.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D126831
Add return values to converter functions to allow for better error
handling when writing files. Also move the file writing code around to
be easier to read.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D127773
Tests for pthread_detach and thrd_detach have not been added. Instead, a
test for the underlying implementation has been added as it makes use of
an internal wait method to synchronize with detached threads.
Reviewed By: lntue, michaelrj
Differential Revision: https://reviews.llvm.org/D127479
Implement double precision FMA (Fused Multiply-Add) for targets without
FMA instructions using __uint128_t to store the intermediate results.
Reviewed By: michaelrj, sivachandra
Differential Revision: https://reviews.llvm.org/D124495
A previous patch added the constant EXP_MANT_MASK to the FloatProperties
for other types of long double. This patch adds it to the special 80-bit
x87 long double.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D127550
Previously all FILE objects were fully buffered, this patch adds line
buffering and unbuffered output, as well as applying them to stdout and
stderr.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D126829
A small refactoring of builtin functions in preparation to adding fmod/fmodf function.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D127088
Previously printf_main was a header library, but header library
dependencies don't work properly so it's been moved to an object
library. Additionally, the writers have been marked inline.
Reviewed By: sivachandra, lntue
Differential Revision: https://reviews.llvm.org/D126830
This patch adds support for d, i, and u conversions in printf, as well
as comprehensive unit tests.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D125929
The compile options now match that of thrd_create. Two compile options
are of importance:
1. -O3 - This is required so that stack is not used between the clone
syscall and the start function in the child thread.
2. -fno-omit-frame-pointer - This is required so that we can sniff out
the thread start args from the child thread's stack memory.
Without these two options, pthread_create will exhibit flaky behavior.
Reviewed By: lntue, michaelrj
Differential Revision: https://reviews.llvm.org/D127381
previously the printf converter tests reused the same string_writer,
which meant that each test depended on the tests before it to succeed.
This makes a new string_writer for each test to simplify and clarify the
tests.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D127341
Rewrite the introduction of the page to state clearly the goals of
LLVM's libc project.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D127174
list(POP_FRONT) is only added to cmake in 3.15, while our base line
version is 3.13
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D127129
Detect if the architecture supports FMA instructions and if
the targets depend on fma.
Reviewed By: gchatelet
Differential Revision: https://reviews.llvm.org/D123615
They do not yet support all the feature/attributes in pthread_attr_t.
Future changes will add such support.
Reviewed By: lntue
Differential Revision: https://reviews.llvm.org/D126718
Tue Ly