This patch implements __cxa_init_primary_exception, an extension to the
Itanium C++ ABI. This extension is already present in both libsupc++ and
libcxxrt. This patch also starts making use of this function in
std::make_exception_ptr: instead of going through a full throw/catch
cycle, we are now able to initialize an exception directly, thus making
std::make_exception_ptr around 30x faster.
In the hardening modes that can be used in production (`fast` and
`extensive`), make a failed assertion invoke a trap instruction rather
than calling verbose abort. In the debug mode, still keep calling
verbose abort to provide a better user experience and to allow us to
keep our existing testing infrastructure for verifying assertion
messages. Since the debug mode by definition enables all assertions, we
can be sure that we still check all the assertion messages in the
library when running the test suite in the debug mode.
The main motivation to use trapping in production is to achieve better
code generation and reduce the binary size penalty. This way, the
assertion handler can compile to a single instruction, whereas the
existing mechanism with verbose abort results in generating a function
call that in general cannot be optimized away (made worse by the fact
that it's a variadic function, imposing an additional penalty). See the
[RFC](https://discourse.llvm.org/t/rfc-hardening-in-libc/73925) for more
details. Note that this mechanism can now be completely [overridden at
CMake configuration
time](https://github.com/llvm/llvm-project/pull/77883).
This patch also significantly refactors `check_assertion.h` and expands
its test coverage. The main changes:
- when overriding `verbose_abort`, don't do matching inside the function
-- just print the error message to `stderr`. This removes the need to
set a global matcher and allows to do matching in the parent process
after the child finishes;
- remove unused logic for matching source locations and for using
wildcards;
- make matchers simple functors;
- introduce `DeathTestResult` that keeps data about the test run,
primarily to make it easier to test.
In addition to the refactoring, `check_assertion.h` can now recognize
when a process exits due to a trap.
Previously there were two ways to override the verbose abort function
which gets called when a hardening assertion is triggered:
- compile-time: define the `_LIBCPP_VERBOSE_ABORT` macro;
- link-time: provide a definition of `__libcpp_verbose_abort` function.
This patch adds a new configure-time approach: the vendor can provide
a path to a custom header file which will get copied into the build by
CMake and included by the library. The header must provide a definition
of the
`_LIBCPP_ASSERTION_HANDLER` macro which is what will get called should
a hardening assertion fail. As of this patch, overriding
`_LIBCPP_VERBOSE_ABORT` will still work, but the previous mechanisms
will be effectively removed in a follow-up patch, making the
configure-time mechanism the sole way of overriding the default handler.
Note that `_LIBCPP_ASSERTION_HANDLER` only gets invoked when a hardening
assertion fails. It does not affect other cases where
`_LIBCPP_VERBOSE_ABORT` is currently used (e.g. when an exception is
thrown in the `-fno-exceptions` mode).
The library provides a default version of the custom header file that
will get used if it's not overridden by the vendor. That allows us to
always test the override mechanism and reduces the difference in
configuration between the pristine version of the library and
a platform-specific version.
I recently came across LIBCXXABI_USE_LLVM_UNWINDER and was surprised to
notice it was disabled by default. Since we build libunwind by default
and ship it in the LLVM toolchain, it would seem to make sense that
libc++ and libc++abi rely on libunwind for unwinding instead of using
the system-provided unwinding library (if any).
Most importantly, using the system unwinder implies that libc++abi is
ABI compatible with that system unwinder, which is not necessarily the
case. Hence, it makes a lot more sense to instead default to using the
known-to-be-compatible LLVM unwinder, and let vendors manually select a
different unwinder if desired.
As a follow-up change, we should probably apply the same default to
compiler-rt.
Differential Revision: https://reviews.llvm.org/D150897Fixes#77662
rdar://120801778
There are a few drive-by fixes:
- Since the combination RTTI disabled and exceptions enabled do not
work, this combination is prohibited.
- A small NFC in any fixing clang-tidy.
The code in the Buildkite configuration is prepared for using the std
module. There are more fixes needed for that configuration which will be
done in a separate commit.
The previous example wasn't a configuration that we actually test, but
was a simplistic configuration with libstdc++ as ABI library.
The previous example configuration has bitrotted and broken in a couple
different ways since it was added:
- In b0fd9497af6d2efd305e9eecfa0c1e265f1b2192, libcxx added uses of weak
symbols that can be overridden by the user. GNU ld fails to export such
weak symbols on MinGW, resulting in errors like:
C:/msys64/mingw64/bin/ld: cannot export _ZNSt3__126__libcpp_assertion_handlerEPKciS1_S1_: symbol wrong type (2 vs 3)
By switching to using LLD, -DLLVM_ENABLE_LLD=ON, alternatively
-DCMAKE_SHARED_LINKER_FLAGS=-fuse-ld=lld, linking still succeeds.
- In a80e65e00ada7a9c16acf17a5fd40b4f12ced3a8, building with
-DLIBCXX_CXX_ABI=libstdc++ in this configuration started failing. Switch
to showing how to build with libcxxabi instead, which is the tested
configuration and also is the typical configuration in how it most
usually would be used on Windows.
These updates allow removing the mentions of the old caveats with the
build configuration.
Since e346fd8a60d4969b29bdd1740a89b1ea43635331 and
cd1b8be8de91bc1c43bac3eea7ebf3b5643b031c, the tests should run fine in
Debug mode, with failed asserts not popping up blocking dialog boxes.
Add a warning to the `Building Libcxx` documentation about the
limitations of the utility of `--fresh` at the top level.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
This is the first step to implement time zone support in libc++. This
adds the complete tzdb_list class and a minimal tzdb class. The tzdb
class only contains the version, which is used by reload_tzdb.
Next to these classes it contains documentation and build system support
needed for time zone support. The code depends on the IANA Time Zone
Database, which should be available on the platform used or provided by
the libc++ vendors.
The code is labeled as experimental since there will be ABI breaks
during development; the tzdb class needs to have the standard headers.
Implements parts of:
- P0355 Extending <chrono> to Calendars and Time Zones
Addresses:
- LWG3319 Properly reference specification of IANA time zone database
Reviewed By: #libc, ldionne
Differential Revision: https://reviews.llvm.org/D154282
`_LIBCPP_ENABLE_ASSERTIONS` was used to enable the "safe" mode in
libc++. Libc++ now provides the hardened mode and the debug mode that
replace the safe mode.
For backward compatibility, enabling `_LIBCPP_ENABLE_ASSERTIONS` now
enables the hardened mode. Note that the hardened mode provides
a narrower set of checks than the previous "safe" mode (only
security-critical checks that are performant enough to be used in
production).
Differential Revision: https://reviews.llvm.org/D154997
This reverts commit bec8a372fc0db95852748691c0f4933044026b25.
This causes many of these errors to appear when rebuilding runtimes part
of fuchsia's toolchain:
ld.lld: error:
/usr/local/google/home/paulkirth/llvm-upstream/build/lib/x86_64-unknown-linux-gnu/libunwind.a(libunwind.cpp.o)
is incompatible with elf64-x86-64
This can be reproduced by making a complete toolchain, saving any source
file with no changes, then rerunning ninja distribution.
This variable is derived from LLVM_DEFAULT_TARGET_TRIPLE by default,
but using a separate variable allows additional normalization to be
performed if needed.
Differential Revision: https://reviews.llvm.org/D137451
This patch enables libc++ build as shared library in all combinations of ASCII/EBCDIC and 32-bit/64-bit variants. In particular it introduces:
# ASCII version of libc++ named as libc++_a.so
# Script to rename DLL name inside the generated side deck
# Various names for dataset members where DLL libraries and their side decks will reside
# Add the following options:
- LIBCXX_SHARED_OUTPUT_NAME
- LIBCXX_ADDITIONAL_COMPILE_FLAGS
- LIBCXX_ADDITIONAL_LIBRARIES
- LIBCXXABI_ADDITIONAL_COMPILE_FLAGS
- LIBCXXABI_ADDITIONAL_LIBRARIES
**Background and rational of this patch**
The linker on z/OS creates a list of exported symbols in a file called side deck. The list contains the symbol name as well as the name of the DLL which implements the symbol. The name of the DLL depends on what is specified in the -o command line option. If it points to a USS file, than the DLL name in the side deck will be the USS file name. If it points to a member of a dataset then the DLL name in the side deck is the member name.
If CMake could deal with z/OS datasets we could use -o that points to a dataset member name, but this does not seem to work so we have to produce a USS file as the DLL and then copy the content of the produced side deck to a dataset as well as rename the USS file name in the side deck to a dataset member name that corresponds to that DLL.
Reviewed By: muiez, SeanP, ldionne, #libc, #libc_abi
Differential Revision: https://reviews.llvm.org/D118503
Now that all jobs have moved over to the new style of Lit configuration,
we can remove all traces of the legacy testing configuration system.
This includes:
- Cache settings that are not honored or useful anymore
- Several CMake options that were only useful in the context of the
legacy Lit configuration system
- A bunch of Python support code that is not used anymore
- The legacy lit.cfg.in files themselves
Differential Revision: https://reviews.llvm.org/D134650
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 particular remove the ability to expel incomplete features from the
library at configure-time, since this can now be done through the
_LIBCPP_ENABLE_EXPERIMENTAL macro.
Also, never provide symbols related to incomplete features inside the
dylib, instead provide them in c++experimental.a (this changes the
symbols list, but not for any configuration that should have shipped).
Differential Revision: https://reviews.llvm.org/D128928
This re-applies bb939931a1ad, which had been reverted by 09cebfb978de
because it broke Chromium. The issues seen by Chromium should be
addressed by 1d0f79558ca4.
Differential Revision: https://reviews.llvm.org/D128927
This caused build failures when building Clang and libc++ together on Mac:
fatal error: 'experimental/memory_resource' file not found
See the code review for details. Reverting until the problem and how to
solve it is better understood.
(Updates to some test files were not reverted, since they seemed
unrelated and were later updated by 340b48b267b96.)
> This is the first part of a plan to ship experimental features
> by default while guarding them behind a compiler flag to avoid
> users accidentally depending on them. Subsequent patches will
> also encompass incomplete features (such as <format> and <ranges>)
> in that categorization. Basically, the idea is that we always
> build and ship the c++experimental library, however users can't
> use what's in it unless they pass the `-funstable` flag to Clang.
>
> Note that this patch intentionally does not start guarding
> existing <experimental/FOO> content behind the flag, because
> that would merely break users that might be relying on such
> content being in the headers unconditionally. Instead, we
> should start guarding new TSes behind the flag, and get rid
> of the existing TSes we have by shipping their Standard
> counterpart.
>
> Also, this patch must jump through a few hoops like defining
> _LIBCPP_ENABLE_EXPERIMENTAL because we still support compilers
> that do not implement -funstable yet.
>
> Differential Revision: https://reviews.llvm.org/D128927
This reverts commit bb939931a1adb9a47a2de13c359d6a72aeb277c8.
This is the first part of a plan to ship experimental features
by default while guarding them behind a compiler flag to avoid
users accidentally depending on them. Subsequent patches will
also encompass incomplete features (such as <format> and <ranges>)
in that categorization. Basically, the idea is that we always
build and ship the c++experimental library, however users can't
use what's in it unless they pass the `-funstable` flag to Clang.
Note that this patch intentionally does not start guarding
existing <experimental/FOO> content behind the flag, because
that would merely break users that might be relying on such
content being in the headers unconditionally. Instead, we
should start guarding new TSes behind the flag, and get rid
of the existing TSes we have by shipping their Standard
counterpart.
Also, this patch must jump through a few hoops like defining
_LIBCPP_ENABLE_EXPERIMENTAL because we still support compilers
that do not implement -funstable yet.
Differential Revision: https://reviews.llvm.org/D128927
This commit re-applies 9ee97ce3b830, which was reverted by 61d417ce
because it broke the LLDB data formatter tests. It also re-applies
6148c79a (the manual GN change associated to it).
Differential Revision: https://reviews.llvm.org/D127444
Instead of marking private symbols with internal_linkage (which leads to
one copy per translation unit -- rather wasteful), use an ABI tag that
gets rev'd with each libc++ version. That way, we know that we can't have
name collisions between implementation-detail functions across libc++
versions, so we'll never violate the ODR. However, within a single program,
each symbol still has a proper name with external linkage, which means
that the linker is free to deduplicate symbols even across TUs.
This actually means that we can guarantee that versions of libc++ can
be mixed within the same program without ever having to take a code size
hit, and without having to manually opt-in -- it should just work out of
the box.
Differential Revision: https://reviews.llvm.org/D127444
This patch overhauls how we pick up the ABI library. Instead of setting
ad-hoc flags, it creates interface targets that can be linked against by
the rest of the build, which is easier to follow and extend to support
new ABI libraries.
This is intended to be a NFC change, however there are some additional
simplifications and improvements we can make in the future that would
require a slight behavior change.
Differential Revision: https://reviews.llvm.org/D120727
Since a8d15a926689c126c4d316788786e0160cfc1d5d / D110975, this is
the default, even if winpthread headers are available, so we don't
need to cargo cult setting this option in all builds.
Differential Revision: https://reviews.llvm.org/D122717
This patch adds a lightweight assertion handler mechanism that can be
overriden at link-time in a fashion similar to `operator new`.
This is a third take on https://llvm.org/D121123 (which allowed customizing
the assertion handler at compile-time), and https://llvm.org/D119969
(which allowed customizing the assertion handler at runtime only).
This approach is, I think, the best of all three explored approaches.
Indeed, replacing the assertion handler in user code is ergonomic,
yet we retain the ability to provide a custom assertion handler when
deploying to older platforms that don't have a default handler in
the dylib.
As-is, this patch provides a pretty good amount of backwards compatibility
with the previous debug mode:
- Code that used to set _LIBCPP_DEBUG=0 in order to get basic assertions
in their code will still get basic assertions out of the box, but
those assertions will be using the new assertion handler support.
- Code that was previously compiled with references to __libcpp_debug_function
and friends will work out-of-the-box, no changes required. This is
because we provide the same symbols in the dylib as we used to.
- Code that used to set a custom __libcpp_debug_function will stop
compiling, because we don't provide that declaration anymore. Users
will have to migrate to the new way of setting a custom assertion
handler, which is extremely easy. I suspect that pool of users is
very limited, so breaking them at compile-time is probably acceptable.
The main downside of this approach is that code being compiled with
assertions enabled but deploying to an older platform where the assertion
handler didn't exist yet will fail to compile. However users can easily
fix the problem by providing a custom assertion handler and defining
the _LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED macro to
let the library know about the custom handler. In a way, this is
actually a feature because it avoids a load-time error that one would
otherwise get when trying to run the code on the older target.
Differential Revision: https://reviews.llvm.org/D121478
Add an explicit LIBCXX_CXX_ABI=system-libcxxabi option for linking to
system-installed libc++abi. This fixes the ability to link against one
when building libcxx via the runtimes build, as otherwise the build
system insists on linking into in-tree targets.
Differential Revision: https://reviews.llvm.org/D119539
Instead, folks can use the equivalent variables provided by CMake
to set those. This removal aims to reduce complexity and potential
for confusion when setting the target triple for building the runtimes,
and make it correct when `CMAKE_OSX_ARCHITECTURES` is used (right now
both `-arch` and `--target=` will end up being passed, which is downright
incorrect).
Differential Revision: https://reviews.llvm.org/D112155
We are moving away from building the runtimes with LLVM_ENABLE_PROJECTS,
however the documentation was largely outdated. This commit updates all
the documentation I could find to use LLVM_ENABLE_RUNTIMES instead of
LLVM_ENABLE_PROJECTS for building runtimes.
Note that in the near future, libcxx, libcxxabi and libunwind will stop
supporting being built with LLVM_ENABLE_PROJECTS altogether. I don't know
what the plans are for other runtimes like libc, openmp and compiler-rt,
so I didn't make any changes to the documentation that would imply
something for those projects.
Once this lands, I will also cherry-pick this on the release/14.x branch
to make sure that LLVM's documentation is up-to-date and reflects what
we intend to support in the future.
Differential Revision: https://reviews.llvm.org/D119351
Previously, _LIBCPP_ABI_UNSTABLE would be used interchangeably with
_LIBCPP_ABI_VERSION >= 2. This was confusing and creating unnecessary
complexity.
This patch removes _LIBCPP_ABI_UNSTABLE -- instead, the LIBCXX_ABI_UNSTABLE
CMake option will result in the LIBCXX_ABI_VERSION being set to '2', the
current unstable ABI. As a result, in the code, we only have _LIBCPP_ABI_VERSION
to check in order to query the current ABI version.
As a fly-by, this also defines the ABI namespace during CMake configuration
to reduce complexity in __config. I believe it was previously done this
way because we used to try to use __config_site as seldom as possible.
Now that we always ship a __config_site, it doesn't really matter and
I think being explicit about how the library is configured in the __config_site
is actually a feature.
Differential Revision: https://reviews.llvm.org/D119173
This patch removes the ability to build the runtimes in the 32 bit
multilib configuration, i.e. using -m32. Instead of doing this, one
should cross-compile the runtimes for the appropriate target triple,
like we do for all other triples.
As it stands, -m32 has several issues, which all seem to be related to
the fact that it's not well supported by the operating systems that
libc++ support. The simplest path towards fixing this is to remove
support for the configuration, which is also the best course of action
if there is little interest for keeping that configuration. If there
is a desire to keep this configuration around, we'll need to do some
work to figure out the underlying issues and fix them.
Differential Revision: https://reviews.llvm.org/D114473
This commit makes the new "runtimes" build (with <monorepo>/runtimes as
the root of the CMake invocation) the default way of building libc++.
The other supported way of building libc++ is the "bootstrapping" build,
where `<monorepo>/llvm` is used as the root of the CMake invocation.
All other ways of building libc++ are deprecated effective immediately.
There should be no use-case for building libc++ that isn't supported by
one of these two builds, and the two new builds work on all environments
and are lightweight. They will also make it possible to greatly simplify
the build infrastructure of the runtimes, which is currently way too
convoluted.
Differential Revision: https://reviews.llvm.org/D111356
Some embedded platforms do not wish to support the C library functionality
for handling wchar_t because they have no use for it. It makes sense for
libc++ to work properly on those platforms, so this commit adds a carve-out
of functionality for wchar_t.
Unfortunately, unlike some other carve-outs (e.g. random device), this
patch touches several parts of the library. However, despite the wide
impact of this patch, I still think it is important to support this
configuration since it makes it much simpler to port libc++ to some
embedded platforms.
Differential Revision: https://reviews.llvm.org/D111265
Adds a new CMake option to disable the usage of incomplete headers.
These incomplete headers are not guaranteed to be ABI stable. This
option is intended to be used by vendors so they can avoid their users
from code that's not ready for production usage.
The option is enabled by default.
Differential Revision: https://reviews.llvm.org/D106763
This is a second attempt at D101497, which landed as
9a9bc76c0eb72f0f2732c729a460abbd5239c2e3 but had to be reverted in
8cf7ddbdd4e5af966a369e170c73250f2e3920e7.
This issue was that in the case that `COMPILER_RT_INSTALL_PATH` is
empty, expressions like "${COMPILER_RT_INSTALL_PATH}/bin" evaluated to
"/bin" not "bin" as intended and as was originally.
One solution is to make `COMPILER_RT_INSTALL_PATH` always non-empty,
defaulting it to `CMAKE_INSTALL_PREFIX`. D99636 adopted that approach.
But, I think it is more ergonomic to allow those project-specific paths
to be relative the global ones. Also, making install paths absolute by
default inhibits the proper behavior of functions like
`GNUInstallDirs_get_absolute_install_dir` which make relative install
paths absolute in a more complicated way.
Given all this, I will define a function like the one asked for in
https://gitlab.kitware.com/cmake/cmake/-/issues/19568 (and needed for a
similar use-case).
---
Original message:
Instead of using `COMPILER_RT_INSTALL_PATH` through the CMake for
complier-rt, just use it to define variables for the subdirs which
themselves are used.
This preserves compatibility, but later on we might consider getting rid
of `COMPILER_RT_INSTALL_PATH` and just changing the defaults for the
subdir variables directly.
---
There was a seaming bug where the (non-Apple) per-target libdir was
`${target}` not `lib/${target}`. I suspect that has to do with the docs
on `COMPILER_RT_INSTALL_PATH` saying was the library dir when that's no
longer true, so I just went ahead and fixed it, allowing me to define
fewer and more sensible variables.
That last part should be the only behavior changes; everything else
should be a pure refactoring.
---
I added some documentation of these variables too. In particular, I
wanted to highlight the gotcha where `-DSomeCachePath=...` without the
`:PATH` will lead CMake to make the path absolute. See [1] for
discussion of the problem, and [2] for the brief official documentation
they added as a result.
[1]: https://cmake.org/pipermail/cmake/2015-March/060204.html
[2]: https://cmake.org/cmake/help/latest/manual/cmake.1.html#options
In 38b2dec37ee735d5409148e71ecba278caf0f969 the problem was somewhat
misidentified and so `:STRING` was used, but `:PATH` is better as it
sets the correct type from the get-go.
---
D99484 is the main thrust of the `GnuInstallDirs` work. Once this lands,
it should be feasible to follow both of these up with a simple patch for
compiler-rt analogous to the one for libcxx.
Reviewed By: phosek, #libc_abi, #libunwind
Differential Revision: https://reviews.llvm.org/D105765
This patch overhauls the documentation around building libc++
for vendors, and using libc++ for end-users. It also:
- Removes mention of the standalone build, which we've been trying to
get rid of for a long time.
- Removes mention of using a local ABI installation, which we don't do
and is documented as "not recommended".
- Removes mention of the separate libc++filesystem.a library, which isn't
relevant anymore since filesystem support is in the main library.
- Adds mention of the GDB pretty printers and how to use them.
These variables were introduced during early work on the runtimes build
but were obsoleted by {LIBCXX,LIBCXXABI,LIBUNWIND}_INSTALL_LIBRARY_DIR.
Differential Revision: https://reviews.llvm.org/D99697
Refresh the existing paragraphs on building in MSVC configurations,
add a sample of one working configuration for MinGW, and add more
details on what's necessary to run the tests these days.
Differential Revision: https://reviews.llvm.org/D97166
This commit makes it clear that the typeinfo comparison implementation
is automatically selected by default, and that the CMake option only
overrides the value. This has been a source of confusion and bugs ever
since we've introduced complexity in that area, so I'm trying to simplify
it while still allowing for some control on the implementation.
Differential Revision: https://reviews.llvm.org/D91574
Since we require that libc++ is built as part of the monorepo layout, we
can assume the path of the rest of LLVM and avoid requiring that LLVM_PATH
be set explicitly.
When the __config_site header is generated, but LIBCXX_HAS_MERGED_TYPEINFO_NAMES_DEFAULT
wasn't specified, _LIBCPP_HAS_MERGED_TYPEINFO_NAMES_DEFAULT would be defined
to 0, which was the NonUnique RTTI comparison implementation. The intent
was to use the Unique RTTI comparison implementation in that case, which
caused https://llvm.org/PR45549.
Instead, use a proper "switch" to select the RTTI comparison implementation.
Note that 0 can't be used as a value, because that is treated the same
by CMake as a variable that is just not defined.
Differential Revision: https://reviews.llvm.org/D80037
We've been meaning to remove those targets for a while, and the fix is
simple enough cause they're all just aliases to other targets.
This is a re-application of f383fb40b17, wich was reverted in 04d48111b
because the build bots had not been updated yet. The build bot configurations
have now been updated not to use the deprecated targets, and I verified
that they were using the non-deprecated targets, so we should be good
unless I missed a bot.
Differential Revision: https://reviews.llvm.org/D76104
This reverts commit f383fb40b. It looks like several of our build bots
are still using the legacy target names, so we'll change those before
we commit this change again.
