Previously this test was entirely disabled under asan, but not
hwasan. Instead of disabling the test, make the test compatible
with both asan and hwasan by disabling sanitizers only on the
subroutine that does the stack-smashing.
The existing options for bin→dec float conversion are all based on the
Ryū algorithm, which generates 9 output digits at a time using a table
lookup. For users who can't afford the space cost of the table, the
table-lookup subroutine is replaced with one that computes the needed
table entry on demand, but the algorithm is otherwise unmodified.
The performance problem with computing table entries on demand is that
now you need to calculate a power of 10 for each 9 digits you output.
But if you're calculating a custom power of 10 anyway, it's easier to
just compute one, and multiply the _whole_ mantissa by it.
This patch adds a header file alongside `float_dec_converter.h`, which
replaces the whole Ryū system instead of just the table-lookup routine,
implementing this alternative simpler algorithm. The result is accurate
enough to satisfy (minimally) the accuracy demands of IEEE 754-2019 even
in 128-bit long double. The new float128 test cases demonstrate this by
testing the cases closest to the 39-digit rounding boundary.
In my tests of generating 39 output digits (the maximum number supported
by this algorithm) this code is also both faster and smaller than the
USE_DYADIC_FLOAT version of the existing Ryū code.
When IntegerToString converts a BigInt into decimal, it determines each
digit by computing `n % 10` and then resets n to `n / 10`, until the
number becomes zero. The div and mod operations are done using
`BigInt::divide_unsigned`, which uses the simplest possible bit-by-bit
iteration, which is a slow algorithm in general, but especially so if
the divisor 10 must first be promoted to a BigInt the same size as the
dividend. The effect is to make each division take quadratic time, so
that the overall decimal conversion is cubic – and the division is
quadratic in the number of _bits_, so the constant of proportionality is
also large.
In this patch I've provided custom code to extract decimal digits much
faster, based on knowing that the divisor is always 10, and processing a
word at a time. So each digit extraction is linear-time with a much
smaller constant of proportionality.
Full comments are in the code. The general strategy is to do the
reduction mod 10 first to determine the output digit; then subtract it
off, so that what's left is guaranteed to be an exact multiple of 10;
and finally divide by 10 using modular-arithmetic techniques rather than
reciprocal-approximation-based ordinary integer division.
I didn't find any existing tests of IntegerToString on a BigInt, so I've
added one.
While GCC's -Wdeprecated is on by default and doesn't do much,
Clang's -Wdeprecated enables many more things. More apply in
C++20, so switch a test file that tickled one to using that. In
future, C++20 should probably be made the baseline for compiling
all the libc code.
This PR aims to add the groundwork to test the precision of libc complex
functions against MPC. I took `cargf` as a test to verify that the infra
works fine.
Summary:
This is a blocker on another patch in the OpenMP runtime. The problem is
that NVIDIA truly doesn't handle RPC-based allocations very well. It
cannot reliably update the MMU while a kernel is running and it will
usually deadlock if called from a separate thread due to internal use of
TLS.
This patch just removes the definition of `malloc` and `free` for NVPTX.
The result here is that they will be undefined, which is the cue for the
`nvlink` linker to define them for us. So, as far as `libc` is concerned
it still implements malloc.
Update string_utils' string_length to work with char* or wchar_t*, so that it
may be reusable when implementing wmemchr, wcspbrk, wcsrchr, wcsstr.
Link: #121183
Link: #124027
Co-authored-by: Nick Desaulniers <ndesaulniers@google.com>
---------
Co-authored-by: Tristan Ross <tristan.ross@midstall.com>
Also, update the unit tests that were checking for SIGSEGV to not check for a
specific signal.
To further improve this check, it may be worth:
- renaming the configuration option/macro/docs to be clearer about intent.
- swap __builtin_trap for __builtin_unreachable, removing the preprocessor
variants of LIBC_CRASH_ON_NULLPTR, then unconditionally using
`-fsanitize=unreachable -fsanitize-trap=unreachable` in cmake flags when
LIBC_ADD_NULL_CHECKS is enabled.
- building with `-fno-delete-null-pointer-checks` when LIBC_ADD_NULL_CHECKS (or
when some larger yet to be added hardening config) is enabled.
Link: #111546
Found while trying to consolidate our command line flags between tests and
underlying object files.
error: extra ';' after member function definition [-Werror,-Wextra-semi]
Link: #119281
Aligning blocks to max_align_t is neither necessary nor sufficient to
ensure that the usable_space() is so aligned. Instead, we make this an
invariant of Block and maintain it in init() and split().
This allows targets like riscv32 with small pointers and large
max_align_t to maintain the property that all available blocks are
aligned for malloc(). This change adjusts the tests to match and also
updates them closer to llvm-libc style.
This adds a test that consists of compiling `#include <...>`,
pretty much alone, for each public header file in each different
language mode (`-std=...` compiler switch) with -Werror and many
warnings enabled.
There are several headers that have bugs when used alone, and
many more headers that have bugs in certain language modes. So
for now, compiling the new tests is gated on the cmake switch
-DLLVM_LIBC_BUILD_HEADER_TESTS=ON. When all the bugs are fixed,
the switch will be removed so future regressions don't land.
implement sys/uio/writev according to POSIX standard. This vectorized IO
API is needed by many logging libraries to achieve atomic logging
multiple strings.
These make cross compiling the test suite more difficult, as you need
the
sysroot to contain these headers and libraries cross compiled for your
target.
It's straightforward to stick with the corresponding C headers.
While working on strftime I noticed some constants were being defined in
unexpected places. One thing led to another, and I ended up doing a
major cleanup of the time functions.
What's included:
All uses of <time.h> in /src and /test removed (except for LibcTest.cpp)
The various time constants have been moved to time_constants.h, and the
`time_constants` namespace.
struct tm gets its own type indirection header now.
Summary:
This test uses too much stack and crashes, make the buffer `static` to
push it to `.bss`. This shouldn't change behavior because the tests are
all run single threaded.
Make sure to clear out all FE_ALL_EXCEPT bits both before and after
invoking function under test -- otherwise the very first check for the
exception bits in the unit test may fail due to bits set prior to test
invocation.
FreeListHeap uses the _end symbol which conflicts with the _end symbol
defined by GPU start.cpp files so for now we exclude the test and the
fuzzer on GPU.
