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however the documentation was largely outdated.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
The warning was introduced with the recently merged SPARCv9
support in 2b9554b885.
The cast matches the existing surrounding cases.
Differential Revision: https://reviews.llvm.org/D119353
Standalone build have been deprecated for some time now, so this
commit removes support for those builds entirely from libc++, libc++abi
and libunwind.
This, along with the removal of other legacy ways to build, will allow
for major build system simplifications.
Differential Revision: https://reviews.llvm.org/D119255
Add SPARC to the list of platforms for which we provide a full
unwind implementation which leads to _Unwind_Backtrace being defined within
libunwind.so.
Likewise for PPC (see D118320 for background).
Reviewed By: #libunwind, MaskRay, Arfrever
Differential Revision: https://reviews.llvm.org/D119068
Adds libunwind support for SPARCv9 (aka sparc64). This is a rebase of @kettenis' patch D32450, which I created (with his permission) because the original review has become inactive.
The changes are of a cosmetic nature to make it fit better with the new code style, and to reuse the existing SPARCv8 code, whenever possible.
Please let me know if I posted this on the wrong place. Also, the summary of the original review is reproduced below:
> This adds unwinder support for 64-bit SPARC (aka SPARCv9). The implementation was done on OpenBSD/sparc64, so it takes StackGhost into account:
>
> https://www.usenix.org/legacy/publications/library/proceedings/sec01/full_papers/frantzen/frantzen_html/index.html
>
> Since StackGhost xor's return addresses with a random cookie before storing them on the stack, the unwinder has to do some extra work to recover those. This is done by introducing a new kRegisterInCFADecrypt "location" type that is used to implement the DW_CFA_GNU_window_save opcode. That implementation is SPARC-specific, but should work for 32-bit SPARC as well. DW_CFA_GNU_window_save is only ever generated on SPARC as far as I know.
Co-authored-by: Mark Kettenis
Reviewed By: #libunwind, thesamesam, MaskRay, Arfrever
Differential Revision: https://reviews.llvm.org/D116857
We previously had a few varied definitions of this floating around.
I had tried to make the one installed with LLVM handle all the cases, and then made the others use it, but this ran into issues with `HandleOutOfTreeLLVM` not working for compiler-rt, and also `CMAKE_EXE_LINKER_FLAGS` not working right without `CMP0056` set to the new behavior.
My compromise solution is this:
- No not completely deduplicate: the runtime libs will instead use a version that still exists as part of the internal and not installed common shared CMake utilities. This avoids `HandleOutOfTreeLLVM` or a workaround for compiler-rt.
- Continue to use `CMAKE_REQUIRED_FLAGS`, which effects compilation and linking. Maybe this is unnecessary, but it's safer to leave that as a future change. Also means we can avoid `CMP0056` for now, to try out later, which is good incrementality too.
- Call it `llvm_check_compiler_linker_flag` since it, in fact is about both per its implementation (before and after this patch), so there is no name collision.
In the future, we might still enable CMP0056 and make compiler-rt work with HandleOutOfTreeLLVM, which case we delete `llvm_check_compiler_flag` and go back to the old way (as these are, in fact, linking related flags), but that I leave for someone else as future work.
The original issue was reported to me in https://reviews.llvm.org/D116521#3248117 as
D116521 made clang and LLVM use the common cmake utils.
Reviewed By: sebastian-ne, phosek, #libunwind, #libc, #libc_abi, ldionne
Differential Revision: https://reviews.llvm.org/D117537
Originally reported downstream in Gentoo: https://bugs.gentoo.org/832140
```
/var/tmp/portage/sys-libs/llvm-libunwind-13.0.0/work/libunwind/src/libunwind.cpp:77:3: error: #error Architecture not supported
77 | # error Architecture not supported
| ^~~~~
[...]
/var/tmp/portage/sys-libs/llvm-libunwind-13.0.0/work/libunwind/src/libunwind.cpp: In function ‘int __unw_init_local(unw_cursor_t*, unw_context_t*)’:
/var/tmp/portage/sys-libs/llvm-libunwind-13.0.0/work/libunwind/src/libunwind.cpp:80:57: error: ‘REGISTER_KIND’ was not declared in this scope
80 | new (reinterpret_cast<UnwindCursor<LocalAddressSpace, REGISTER_KIND> *>(cursor))
| ^~~~~~~~~~~~~
[...]
```
PPC is actually a supported architecture, but GCC (tested with 11.2.0)
on powerpc32 seems to only define: `__PPC__, _ARCH_PPC, __PPC,
__powerpc` and //not// `__ppc__`.
This instead uses `__powerpc__` which should be around on PPC32
and PPC64 (but we check it after PPC64, so it's fine).
Signed-off-by: Sam James <sam@gentoo.org>
Differential Revision: https://reviews.llvm.org/D118320
We previously had a few varied definitions of this floating around. I made the one installed with LLVM handle all the cases, and then made the others use it.
This issue was reported to me in https://reviews.llvm.org/D116521#3248117 as
D116521 made clang and llvm use the common cmake utils.
Reviewed By: sebastian-ne, phosek, #libunwind, #libc, #libc_abi, ldionne
Differential Revision: https://reviews.llvm.org/D117537
Its defaulting logic must go after `project(..)` to work correctly, but `project(..)` is often in a standalone condition making this
awkward, since the rest of the condition code may also need GNUInstallDirs.
The good thing is there are the various standalone booleans, which I had missed before. This makes splitting the conditional blocks less awkward.
Reviewed By: arichardson, phosek, beanz, ldionne, #libunwind, #libc, #libc_abi
Differential Revision: https://reviews.llvm.org/D117639
This is better than libunwind and libcxxabi fishing it out of libcxx's
module directory.
It is done in prepartion for a better version of D117537 which deduplicates
CMake logic instead of just renaming to avoid a name clash.
Reviewed By: phosek, #libunwind, #libc_abi, Ericson2314
Differential Revision: https://reviews.llvm.org/D117617
These two are not conceptually the same; the former is a pointer shoved
in an integer, the latter is an offset or length. On the architectures
supported by libunwind, these two have the same underlying type, namely
unsigned int on ILP32, unsigned long on LP64 and unsigned long long on
LLP64. However, on CHERI, and thus Arm's Morello, they are not the same,
as pointers are hardware capabilities that carry additional metadata
including bounds and permissions, which is preserved in uintptr_t but
not in size_t. Thus, fix all length variables to be of type size_t not
uintptr_t, as we have done downstream for a while in CHERI LLVM but did
not get round to upstreaming.
Note that dyld_unwind_sections is currently defined in Apple's headers
as genuinely using uintptr_t to represent lengths. This is a bad API and
should be fixed, which would be totally API and ABI compatible due to
size_t and uintptr_t being the same type on all supported Apple systems,
but our definition is left matching theirs until such a time as they fix
their bogus types.
This is intended to be an NFC change on all architectures supported by
LLVM upstream, only being a functional change for CHERI downstream in
CHERI LLVM.
This is the original patch in my GNUInstallDirs series, now last to merge as the final piece!
It arose as a new draft of D28234. I initially did the unorthodox thing of pushing to that when I wasn't the original author, but since I ended up
- Using `GNUInstallDirs`, rather than mimicking it, as the original author was hesitant to do but others requested.
- Converting all the packages, not just LLVM, effecting many more projects than LLVM itself.
I figured it was time to make a new revision.
I have used this patch series (and many back-ports) as the basis of https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS), which was merged last spring (2021). It looked like people were generally on board in D28234, but I make note of this here in case extra motivation is useful.
---
As pointed out in the original issue, a central tension is that LLVM already has some partial support for these sorts of things. Variables like `COMPILER_RT_INSTALL_PATH` have already been dealt with. Variables like `LLVM_LIBDIR_SUFFIX` however, will require further work, so that we may use `CMAKE_INSTALL_LIBDIR`.
These remaining items will be addressed in further patches. What is here is now rote and so we should get it out of the way before dealing more intricately with the remainder.
Reviewed By: #libunwind, #libc, #libc_abi, compnerd
Differential Revision: https://reviews.llvm.org/D99484
This is the original patch in my GNUInstallDirs series, now last to merge as the final piece!
It arose as a new draft of D28234. I initially did the unorthodox thing of pushing to that when I wasn't the original author, but since I ended up
- Using `GNUInstallDirs`, rather than mimicking it, as the original author was hesitant to do but others requested.
- Converting all the packages, not just LLVM, effecting many more projects than LLVM itself.
I figured it was time to make a new revision.
I have used this patch series (and many back-ports) as the basis of https://github.com/NixOS/nixpkgs/pull/111487 for my distro (NixOS), which was merged last spring (2021). It looked like people were generally on board in D28234, but I make note of this here in case extra motivation is useful.
---
As pointed out in the original issue, a central tension is that LLVM already has some partial support for these sorts of things. Variables like `COMPILER_RT_INSTALL_PATH` have already been dealt with. Variables like `LLVM_LIBDIR_SUFFIX` however, will require further work, so that we may use `CMAKE_INSTALL_LIBDIR`.
These remaining items will be addressed in further patches. What is here is now rote and so we should get it out of the way before dealing more intricately with the remainder.
Reviewed By: #libunwind, #libc, #libc_abi, compnerd
Differential Revision: https://reviews.llvm.org/D99484
In D116873 I did this for libunwind prior to defining a new install path
variable. But I think the change is good on its own, and libc++{,abi}
could also use it.
libc++ needed the base header var defined above the conditional part to
use it for the prefi+ed headers in the non-target-specific case. For
consistency, I therefore put the unconditional ones above for all 3
libs, which is why I touched the libunwind code (seeing that it had the
core change already)
Reviewed By: phosek, #libunwind, #libc, #libc_abi, ldionne
Differential Revision: https://reviews.llvm.org/D116988
This is created on analogy with the other CACHE PATHs in this package,
and other `*_INSTALL_INCLUDE_DIR` in other packages.
The branching is adjusted to deduplicate some existing code, and
likewise avoid having to define this new variable more than once.
This will be used for D99484.
Reviewed By: #libunwind, compnerd
Differential Revision: https://reviews.llvm.org/D116873
When building libcxx, libcxxabi, and libunwind the build environment may
specify any number of sanitizers. For some build feature tests these
sanitizers must be disabled to prevent spurious linking errors. With
-fsanitize= this is straight forward with -fno-sanitize=all. With
-fsanitize-coverage= there is no -fno-sanitize-coverage=all, but there
is the equivalent undocumented but tested -fsanitize-coverage=0.
The current build rules fail to disable 'trace-pc-guard'. By disabling
all sanitize-coverage flags, including 'trace-pc-guard', possible
spurious linker errors are prevented. In particular, this allows libcxx,
libcxxabi, and libunwind to be built with HonggFuzz.
CMAKE_REQUIRED_FLAGS is extra compile flags when running CMake build
configuration steps (like check_cxx_compiler_flag). It does not affect
the compile flags for the actual build of the project (unless of course
these flags change whether or not a given source compiles and links or
not). So libcxx, libcxxabi, and libunwind will still be built with any
specified sanitize-coverage as before. The build configuration steps
(which are mostly checking to see if certain compiler flags are
available) will not try to compile and link "int main() { return 0;}"
(or other specified source) with sanitize-coverage (which can fail to
link at this stage in building, since the final compile flags required
are yet to be determined).
The change to LIBFUZZER_CFLAGS was done to keep it consistent with the
obvious intention of disabling all sanitize-coverage. This appears to
be intentional, preventing the fuzzer driver itself from showing up in
any coverage calculations.
Reviewed By: #libunwind, #libc, #libc_abi, ldionne, phosek
Differential Revision: https://reviews.llvm.org/D116050
Although we moved to Github Issues. The bug report message refers to
Bugzilla still. This patch tries to update these URLs.
Reviewed By: MaskRay, Quuxplusone, jhenderson, libunwind, libc++
Differential Revision: https://reviews.llvm.org/D116351
In D116472 we created conditionally defined variables for the tools to
unbreak the legacy build where they are in `llvm/tools`.
The runtimes are not tools, so that flexibility doesn't matter. Still,
it might be nice to define (unconditionally) and use the variable for
the runtimes simply to make the code a bit clearer and document what is
going on.
Also, consistently put project dirs at the beginning, not end of `CMAKE_MODULE_PATH`. This ensures they will properly shadow similarly named stuff that happens to be later on the path.
Reviewed By: mstorsjo, #libunwind, #libc, #libc_abi, ldionne
Differential Revision: https://reviews.llvm.org/D116477
This adds a CMake option (defaults to OFF to not be intrusive) to activate
2 new targets `install-unwind-headers` and `install-unwind-headers-stripped`.
So, for example:
cmake -S runtimes -B build -G Ninja \
-DLLVM_ENABLE_RUNTIMES='libunwind' \
-DLIBUNWIND_INSTALL_HEADERS=ON
And then, `ninja -C build install-unwind` would install headers in addition
to good ol' dylibs and archives, i.e., targets `install-unwind*` `DEPENDS`
on `install-unwind-headers*`. On the other hand,
`ninja -C build install-unwind-headers` gives you headers only.
Differential Revision: https://reviews.llvm.org/D115535
There's a lot of history behind this, so here's a summary:
1. I stopped forcing -fPIC when building the runtimes in 30f305efe2,
before the LLVM 9 release back in 2019.
2. Someone complained that libc++.a couldn't be used in shared libraries
built without -fPIC (http://llvm.org/PR43604) since the LLVM 9 release.
This had been caused by my removal of -fPIC when building libc++.a in (1).
3. I suggested two ways of fixing the issue, the first being to force
-fPIC back unconditionally (http://llvm.org/D104328), and the second
being to specify that option explicitly when building the LLVM release
(http://llvm.org/D104327). We converged on the first solution.
4. I landed D104328, which forced building the runtimes with -fPIC.
This was included in the LLVM 13.0 release.
5. People complained about that and requested that we be able to
customize this setting (basically we should have done the second
solution).
This patch makes it such that the LLVM release script will specifically
ask for building with -fPIC using CMAKE_POSITION_INDEPENDENT_CODE,
however by default the runtimes will not force that option onto users.
This patch has the unintended effect that Clang and the LLVM libraries
(not only the runtime ones like libc++) will also be built with -fPIC
in the release. It would be better if we could specify that -fPIC is to
be used only when building the runtimes, however this is left as a
future improvement. The release should probably be using a bootstrapping
build and passing those options to the stage that builds the runtimes
only, see https://reviews.llvm.org/D112748 for that change.
Differential Revision: https://reviews.llvm.org/D110261
This patch implements the following:
- Emit PACBTI-M build attributes in libunwind asm files
- Authenticate LR in DWARF32 using PACBTI
Use Armv8.1-M.Main PACBTI extension to authenticate the return address
(stored in the LR register) before moving it to the PC (IP) register.
The AUTG instruction is used with the candidate return address, the CFA,
and the authentication code that is retrieved from the saved
pseudo-register RA_AUTH_CODE.
- Authenticate LR in EHABI using PACBTI
Authenticate the contents of the LR register using Armv8.1-M.Main PACBTI
extension.
A new frame unwinding instruction is introduced (0xb4). This
instruction pops out of the stack the return address authentication
code, which is then used in conjunction with the SP and the next-to-be
instruction pointer to perform authentication.
This authentication code is popped into a new register,
UNW_ARM_PSEUDO_PAC, which is a pseudo-register.
This patch is part of a series that adds support for the PACBTI-M extension of
the Armv8.1-M architecture, as detailed here:
https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension
The PACBTI-M specification can be found in the Armv8-M Architecture Reference
Manual:
https://developer.arm.com/documentation/ddi0553/latest
The following people contributed to this patch:
- Momchil Velikov
- Victor Campos
- Ties Stuij
Reviewed By: #libunwind, danielkiss, mstorsjo
Differential Revision: https://reviews.llvm.org/D112430
It's possible for this test not to pass if the libc used does not provide
unwind info for raise. We can replace it with __builtin_cast, which can lead
to a SIGTRAP on x86_64 and a SIGILL on aarch64.
Using this alternative, a nop is needed before the __builtin_cast. This is
because libunwind incorrectly decrements pc, which can cause pc to jump into
the previous function and use the incorrect FDE.
Differential Revision: https://reviews.llvm.org/D114818
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
When unwind step reaches the end of the stack that means the force unwind should notify the stop function.
This is not an error, it could mean just the thread is cleaned up completely.
Reviewed By: #libunwind, mstorsjo
Differential Revision: https://reviews.llvm.org/D109856
When testing with sanitizers enabled, we need to link against a plethora
of system libraries. Using `-nodefaultlibs` like we used to breaks this,
and we would have to add all these system libraries manually, which is
not portable and error prone. Instead, stop using `-nodefaultlibs` so
that we get the libraries added by default by the compiler.
The only caveat with this approach is that we are now relying on the
fact that `-L <path-to-local-libunwind>` will cause the just built
libunwind to be selected before the system implementation (either of
libunwind or libgcc_s.so), which is somewhat fragile.
This patch also turns the 32 bit multilib build into a soft failure
since we are in the process of removing it anyway, see D114473 for
details. This patch is incompatible with the 32 bit multilib build
because Ubuntu does not provide a proper libstdc++ for 32 bits, and
that is required when running with sanitizers enabled.
Differential Revision: https://reviews.llvm.org/D114385
The libgcc runtime library provides __register_frame and
__deregister_frame functions, which can be used by dynamic code
generators to register an .eh_frame section, which contains one or
more Call Frame Information records, each consisting of a Common
Information Entry record followed by one or more Frame Description
Entry records. This libunwind library also provides __register_frame
and __deregister_frame functions, but they are aliases for
__unw_add_dynamic_fde and __unw_remove_dynamic_fde and thus can only
take a single FDE.
This patch adds __unw_add_dynamic_eh_frame_section and
__unw_remove_dynamic_eh_frame_section functions which explicitly use
the .eh_frame format. Clients such as the ORCv2 platform and runtime
can check for these functions and use them if unwinding is being
provided by libunwind, or fall back to __register_frame and
__deregister_frame if unwinding is provided by libgcc.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D111863
Summary:
This patch marks libunwind test case signal_frame.pass.cpp as UNSUPPORTED on AIX because the AIX assembler does not support CFI directives.
Reviewed by: danielkiss, MaskRay, ldionne, libunwind
Differential Revision: https://reviews.llvm.org/D113607
We've stopped doing it in libc++ for a while now because these names
would end up rotting as we move things around and copy/paste stuff.
This cleans up all the existing files so as to stop the spreading
as people copy-paste headers around.
If Clang is set up to link directly against libunwind (via the
--unwindlib option, or the corresponding builtin default option),
configuring libunwind will fail while bootstrapping (before the
initial libunwind is built), because every cmake test will
fail due to -lunwind not being found, and linking the shared library
will fail similarly.
Check if --unwindlib=none is supported, and add it in that case.
Using check_c_compiler_flag on its own doesn't work, because that only
adds the tested flag to the compilation command, and if -lunwind is
missing, the linking step would still fail - instead try adding it
to CMAKE_REQUIRED_FLAGS and restore the variable if it doesn't work.
This avoids having to pass --unwindlib=none while building libunwind.
Differential Revision: https://reviews.llvm.org/D112126
After recent changes to the Docker image, all hell broke loose and the
CI started failing. This patch marks a few tests as unsupported until
we can figure out what the issues are and fix them.
In the future, it would be ideal if the nodes could pick up the Dockerfile
present in the revision being tested, which would allow us to test changes
to the Dockerfile in the CI, like we do for all other code changes.
Differential Revision: https://reviews.llvm.org/D112737
There's a lot of duplicated calls to find various compiler-rt libraries
from build of runtime libraries like libunwind, libc++, libc++abi and
compiler-rt. The compiler-rt helper module already implemented caching
for results avoid repeated Clang invocations.
This change moves the compiler-rt implementation into a shared location
and reuses it from other runtimes to reduce duplication and speed up
the build.
Differential Revision: https://reviews.llvm.org/D88458
Instead of going through libc++'s run.py, we can simply run the executable
directly since we don't need to setup a working directory or control the
environment.
Differential Revision: https://reviews.llvm.org/D112649
Summary:
This commit switches libunwind from using the complicated logic in
libc++'s testing configuration to a from-scratch configuration.
I tried to make sure that all cases that were handled in the old
config were handled by this one too, so hopefully this shouldn't
break anyone. However, if you encounter issues with this change,
please let me know and feel free to revert if I don't reply quickly.
This change was engineered to be easily revertable.
This commit is a re-application of 5a8ad80b6f, which was reverted in
070a2ddcb6 because it broke the Bootstrapping build. This has now been
addressed by tweaking the from-scratch config.
Differential Revision: https://reviews.llvm.org/D112082
We recently introduced a from-scratch config to run the libunwind tests.
However, that config was always looking for libunwind in <install>/lib,
and never in <install>/<target>/lib, which is necessary for tests to
work when the per-target-runtime-dir configuration is enabled.
This commit fixes that. I believe this is what caused the CI failures we
saw after 5a8ad80b6f and caused it to be reverted.
Differential Revision: https://reviews.llvm.org/D112322
In 395271a, I simplified how we handled the target triple for the
runtimes. However, in doing so, we stopped considering the default
in CMAKE_CXX_COMPILER_TARGET, so we'd use the LLVM_DEFAULT_TARGET_TRIPLE
(which is the host triple) even if CMAKE_CXX_COMPILER_TARGET was specified.
This commit fixes that problem and also refactors the code so that it's
easy to see what the default value is.
The fact that nobody seems to have been broken by this makes me think
that perhaps nobody is using CMAKE_CXX_COMPILER_TARGET to specify the
triple -- but it should still work.
Differential Revision: https://reviews.llvm.org/D111672
This commit switches libunwind from using the complicated logic in
libc++'s testing configuration to a from-scratch configuration.
I tried to make sure that all cases that were handled in the old
config were handled by this one too, so hopefully this shouldn't
break anyone. However, if you encounter issues with this change,
please let me know and feel free to revert if I don't reply quickly.
This change was engineered to be easily revertable.
Differential Revision: https://reviews.llvm.org/D112082
Running tests for libunwind is a lot simpler than running tests for
libc++, so a simple Lit config file is sufficient. The benefit is that
we disentangle the libunwind test configuration from the libc++ and
libc++abi test configuration. The setup was too complicated, which led
to some bugs (notably we were running against the system libunwind on
Apple platforms).
Differential Revision: https://reviews.llvm.org/D111664
There's a lot of duplicated calls to find various compiler-rt libraries
from build of runtime libraries like libunwind, libc++, libc++abi and
compiler-rt. The compiler-rt helper module already implemented caching
for results avoid repeated Clang invocations.
This change moves the compiler-rt implementation into a shared location
and reuses it from other runtimes to reduce duplication and speed up
the build.
Differential Revision: https://reviews.llvm.org/D88458
Instead of always defining LIBCXXABI_NO_TIMER to run the tests, only
define LIBCXXABI_USE_TIMER when we want to enable the timer. This makes
the libc++abi testing configuration simpler.
As a fly-by fix, remove the unused LIBUNWIND_NO_TIMER macro from libunwind.
Differential Revision: https://reviews.llvm.org/D111667
Vendors take libc++ and ship it in various ways. Some vendors might
ship it differently from what upstream LLVM does, i.e. the install
location might be different, some ABI properties might differ, etc.
In the past few years, I've come across several instances where
having a place to test some of these properties would have been
incredibly useful. I also just got bitten by the lack of tests
of that kind, so I'm adding some now.
The tests added by this commit for Apple platforms have numerous
TODOs that capture discrepancies between the upstream LLVM CMake
and the slightly-modified build we perform internally to produce
Apple's system libc++. In the future, the goal would be to upstream
all those differences so that it's possible to build a faithful
Apple system libc++ with the upstream LLVM sources only.
But this isn't only useful for Apple - this lays out the path for
any vendor being able to add their own checks (either upstream or
downstream) to libc++.
This is a re-application of 9892d1644f, which was reverted in 138dc27186
because it broke the build. The issue was that we didn't apply the required
changes to libunwind and our CI didn't notice it because we were not
running the libunwind tests. This has been fixed now, and we're running
the libunwind tests in CI now too.
Differential Revision: https://reviews.llvm.org/D110736
Louis Dionne