Summary:
The GPU runs these tests using the files built from the `libc` project.
These will be placed in `include/<triple>` and `lib/<triple>`. We use
the `amdhsa-loader` and `nvptx-loader` tools, which are also provided by
`libc`. These launch a kernel called `_start` which calls `main` so we
can pretend like GPU programs are normal terminal applications.

We force serial exeuction here, because `llvm-lit` runs way too many
processes in parallel, which has a bad habit of making the GPU drivers
hang or run out of resources. This allows the compilation to be run in
parallel while the jobs themselves are serialized via a file lock.

In the future this can likely be refined to accept user specified
architectures, or better handle including the root directory by exposing
that instead of just `include/<triple>/c++/v1/`.

This currently fails ~1% of the tests on AMDGPU and ~3% of the tests on
NVPTX. This will hopefully be reduced further, and later patches can
XFAIL a lot of them once it's down to a reasonable number.

Future support will likely want to allow passing in a custom
architecture instead of simply relying on `-mcpu=native`.

This commit introduces basic annotations for `std::basic_string`,
mirroring the approach used in `std::vector` and `std::deque`.
Initially, only long strings with the default allocator will be
annotated. Short strings (_SSO - short string optimization_) and strings
with non-default allocators will be annotated in the near future, with
separate commits dedicated to enabling them. The process will be similar
to the workflow employed for enabling annotations in `std::deque`.

**Please note**: these annotations function effectively only when libc++
and libc++abi dylibs are instrumented (with ASan). This aligns with the
prevailing behavior of Memory Sanitizer.

To avoid breaking everything, this commit also appends
`_LIBCPP_INSTRUMENTED_WITH_ASAN` to `__config_site` whenever libc++ is
compiled with ASan. If this macro is not defined, string annotations are
not enabled. However, linking a binary that does **not** annotate
strings with a dynamic library that annotates strings, is not permitted.

Originally proposed here: https://reviews.llvm.org/D132769

Related patches on Phabricator:
- Turning on annotations for short strings:
https://reviews.llvm.org/D147680
- Turning on annotations for all allocators:
https://reviews.llvm.org/D146214

This PR is a part of a series of patches extending AddressSanitizer C++
container overflow detection capabilities by adding annotations, similar
to those existing in `std::vector` and `std::deque` collections. These
enhancements empower ASan to effectively detect instances where the
instrumented program attempts to access memory within a collection's
internal allocation that remains unused. This includes cases where
access occurs before or after the stored elements in `std::deque`, or
between the `std::basic_string`'s size (including the null terminator)
and capacity bounds.

The introduction of these annotations was spurred by a real-world
software bug discovered by Trail of Bits, involving an out-of-bounds
memory access during the comparison of two strings using the
`std::equals` function. This function was taking iterators
(`iter1_begin`, `iter1_end`, `iter2_begin`) to perform the comparison,
using a custom comparison function. When the `iter1` object exceeded the
length of `iter2`, an out-of-bounds read could occur on the `iter2`
object. Container sanitization, upon enabling these annotations, would
effectively identify and flag this potential vulnerability.

This Pull Request introduces basic annotations for `std::basic_string`.
Long strings exhibit structural similarities to `std::vector` and will
be annotated accordingly. Short strings are already implemented, but
will be turned on separately in a forthcoming commit. Look at [a
comment](https://github.com/llvm/llvm-project/pull/72677#issuecomment-1850554465)
below to read about SSO issues at current moment.

Due to the functionality introduced in
[D132522](https://github.com/llvm/llvm-project/commit/dd1b7b797a116eed588fd752fbe61d34deeb24e4),
the `__sanitizer_annotate_contiguous_container` function now offers
compatibility with all allocators. However, enabling this support will
be done in a subsequent commit. For the time being, only strings with
the default allocator will be annotated.

If you have any questions, please email:
- advenam.tacet@trailofbits.com
- disconnect3d@trailofbits.com

While doing this, I also found a few tests that were either clearly
incorrect (e.g. testing the wrong function) or that lacked basic test
coverage like testing std::string itself (e.g. the test was only checking
std::basic_string with a custom allocator). In these cases, I did a few
conservative drive-by changes.

Differential Revision: https://reviews.llvm.org/D140550
Co-authored-by: Brendan Emery <brendan.emery@esrlabs.com>

This applies clang-format to the std::string unit tests in preparation
for landing https://reviews.llvm.org/D140550.

Differential Revision: https://reviews.llvm.org/D140612

- add the `from_range_t` constructors and the related deduction guides;
- add the `insert_range`/`assign_range`/etc. member functions.

(Note: this patch is split from https://reviews.llvm.org/D142335)

Differential Revision: https://reviews.llvm.org/D149832

Some tests in our test suite are unbelievably slow on GCC due to the
use of the always_inline attribute. See [1] for more details.

This patch introduces the GCC-ALWAYS_INLINE-FIXME lit feature to
disable tests that are plagued by that issue. At the same time, it
moves several existing tests from ad-hoc `UNSUPPORTED: gcc-12` markup
to the new GCC-ALWAYS_INLINE-FIXME feature, and marks the slowest tests
reported by the CI as `UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME`.

[1]: https://discourse.llvm.org/t/rfc-stop-supporting-extern-instantiations-with-gcc/71277/1

Differential Revision: https://reviews.llvm.org/D152736

This has been done using the following command
  find libcxx/test -type f -exec perl -pi -e 's|^([^/]+?)((?<!::)(?<!::u)u?int(_[a-z]+)?[0-9]{1,2}_t)|\1std::\2|' \{} \;

And manually removed some false positives in std/depr/depr.c.headers.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D145880

Reviewed By: ldionne, #libc, huixie90

Spies: huixie90, libcxx-commits, arphaman

Differential Revision: https://reviews.llvm.org/D131856

This patch switches the build compiler for AIX from ibm-clang to clang. ibm-clang++_r has `-pthread` by default, but clang for AIX doesn't, so `-pthread` had to be added to the test config. A bunch of tests now pass, so the `XFAIL` was removed. This patch also switch the build to use the visibility support available in clang-15 to control symbols exported by the shared library (AIX traditionally uses explicit export lists for this purpose).

Reviewed By: #libc, #libc_abi, daltenty, #libunwind, ldionne

Differential Revision: https://reviews.llvm.org/D127470

In D122982 I accidentally disabled the memmove optimization. This re-enables it and adds more cases where copy forwards to memmove.
Fixes https://github.com/llvm/llvm-project/issues/33687

Reviewed By: var-const, #libc, ldionne

Spies: pkasting, ayzhao, dcheng, xbolva00, libcxx-commits

Differential Revision: https://reviews.llvm.org/D124328