[libc++] Add a CI configuration where we test the PSTL integration

[philnik]

Summary

This makes sure that the PSTL integration doesn't regress. Eventually,
when we're ready to ship PSTL, this configuration will be enabled by
default in all builds and we can drop this additional CI configuration.

[ldionne]

libcxx/include/functional

3032–3037 ↗

(On Diff #348057)

This change is necessary for the PSTL tests to succeed.

I am fairly certain that we can reduce that failure sufficiently to show that we actually have a bug in std::not_fn. @zoecarver would you be able to take a look since you implemented __perfect_forward_impl?

[ldionne]

Pinging @rarutyun @akukanov for awareness.

[cjdb]

libcxx/include/functional

3032–3037 ↗

(On Diff #348057)

Do we need to add any tests to account for this change?

[ldionne]

libcxx/include/functional

3032–3037 ↗

(On Diff #348057)

Yes, I was asking @zoecarver to look into the failure and add tests for std::not_fn and std::bind_front based on the findings!

[rarutyun]

@ldionne,

I am trying to update this review to continue enabling of PSTL CI with necessary modifications of the pipeline and fixes in PSTL source/tests, but I cannot do that. Seems like I don't have enough permissions to update the review I am not the author of. I am using web interface and when I am pressing "Update diff" I can only create the new revision and don't have an option to update the current one. Probably it's because I don't have direct Phabricator account (I have been using the GitHub one from the very beginning) or probably the reason is different. Together with @MikeDvorskiy we tried to do the same from his account (using web interface as well) and everything works just fine.

Could you please help me with the issue?

@Quuxplusone, @cjdb, @Mordante, if you guys know the answer on the question above, your help is appreciated.

P.S. That problem was observed even earlier so, it seems I've never had such permission

[Mordante]

@rarutyun you first need to commandeer this review, which is in the "Add Action..." drop down.
(AFAIK that requires no special permissions.)

[rarutyun]

In D103198#3349135, @Mordante wrote:

@rarutyun you first need to commandeer this review, which is in the "Add Action..." drop down.
(AFAIK that requires no special permissions.)

Thanks for the suggestion. It works. I am wondering why it works just like that (without commandeering the review) from @MikeDvorskiy account but anyway, thanks for you help.

[philnik]

@rarutyun If you're OK with it I'd like to continue to work on this. I've got a local copy where the CI runs properly. (and 9 tests fail)

[ldionne]

In D103198#3506214, @philnik wrote:

@rarutyun If you're OK with it I'd like to continue to work on this. I've got a local copy where the CI runs properly. (and 9 tests fail)

Yes, please feel free to commandeer.

[philnik]

This should be a working PSTL bot

[h-vetinari]

How realistic is it that this still makes it into LLVM 15? I'd really like to start testing the pstl in our ecosystem a bit, happy to file bug reports too if so, but I'd need a way to be able to build it...

[philnik]

• Fix CMake

[ldionne]

In D103198#3673665, @h-vetinari wrote:

How realistic is it that this still makes it into LLVM 15? I'd really like to start testing the pstl in our ecosystem a bit, happy to file bug reports too if so, but I'd need a way to be able to build it...

Unfortunately, I don't think we'll cherry-pick this to LLVM 15. Proper integration requires additional work, and that would be too much for LLVM 15 since we've already branched. We focused on Ranges and Format for LLVM 15. This should make it for LLVM 16 though.

libcxx/include/algorithm

1673

I think the PSTL should be more tightly integrated with libc++, and we should probably be including libc++'s internal headers directly from it to break these kinds of circular dependencies.

This is going to be non-trivial though because there was an intent to share the PSTL between libc++ and libstdc++ -- I don't know whether that is still desired, and we may need to revisit this if we want to ease the integration between libc++ and PSTL.

@rodgert What is the current state of PSTL within libstdc++? How do you integrate it nowadays? Back in the days, I think you had a script that basically copied the sources to libstdc++ -- if that's still the case, do you have plans to keep it up to date, and can you link to that script so we can take a look at how the integration works?

libcxx/test/configs/llvm-libc++-with-pstl.cfg.in

11

We should be installing the PSTL headers to include/c++/v1 so that we find them alongside other libc++ headers out-of-the-box, and users don't need to add an additional include.

I suspect that means we'll have to start running the tests against a fake-installation of libc++/libc++abi/PSTL/whatever, which is what we should do anyways because it's closer to what users get. I've been meaning to do that for a while, I'll see if I can do this in the next few weeks.

pstl/include/pstl/internal/utils.h

27

This bit (and a few others) can land separately.

[philnik]

• Address comments

libcxx/include/algorithm

1673

If we want to do that it should probably be in a separate PR.

[philnik]

Rebased

[rodgert]

libcxx/include/algorithm

1673

@rodgert What is the current state of PSTL within libstdc++?

I pulled a new version in 2020 and have not rebased since. I had been waiting on the tag dispatch rewrite before considering the process again. I also not seen any progress on that since January, so maybe I will rethink matters if that continues.

I think any changes to include libc++'s internal headers would be detrimental to the continued to sharing of this codebase. I deliberately have not done that so far with libstdc++ (or I maintain those changes downstream only) because that would almost certainly introduce massive and likely unresolvable breakage for libc++.

[philnik]

Move CMake code to PSTL

[philnik]

Remove debug output

[ldionne]

I just had a discussion with @philnik about this patch. I have come to think that attempting to use the shared version of pstl inside libc++ was not a good idea to begin with.

Standard libraries have subtly different requirements and ways of doing things. For example, we use an ABI tag on our implementation-detail functions so that we have the freedom to change them however we please from release to release. Last I checked, I think libstdc++ handles this differently by not making pre/post condition changes even in implementation-detail functions. Those are both valid ways of doing things and I am not criticizing, however trying to share *header* code between the two standard libraries will surface these kinds of fundamental differences, some of which can't be reconciled with any amount of macros. Another example is circular header dependencies -- without being able to include implementation-detail headers of libc++ from the pstl, we may not be able to get rid of some circular dependencies, and we certainly won't be able to achieve the same level of granularity that we have in libc++. Yet another example is how we deal with removing incidental transitive includes -- we have a process for doing it, but it's not clear to me how we'd establish this in a shared pstl library.

In other words, I think that sharing header-level APIs between standard libraries is not a good idea. Sharing implementation that lives in a dylib or static archive is 100% fine since we can treat it as a third-party dependency. Sharing a well-defined backend implementation is also probably fine, but sharing headers is a different can of worms.

My opinion about this is even stronger after seeing what the decision of using an external code-base in our headers has given us so far -- not much. Because of the complexity of integrating pstl properly into libc++, we've basically been sitting on this and a few other difficult-ish questions ever since it was contributed, leading to us not shipping anything for years. Instead, if we had this code directly in libc++, I am confident we would have shipped *something* at this point and started making improvements to it.

@philnik I would suggest we abandon this revision and instead integrate the pstl directly into libc++, marking it as an experimental feature per our usual conventions. We should strive not to touch the backends too much so as to make it easy (but not necessarily automatic) to keep that in sync with the actual pstl code. That's where 90% of changes happen anyway. Rough suggested path:

• Copy over as-is to libc++
• Add a CI job that enables _LIBCPP_HAS_PARALLEL_ALGORITHMS -- no big CMake changes needed
• Clang-format the public API, but don't touch the back-ends since we're going to try to share that
• Apply libc++ macros as needed (e.g. _LIBCPP_HIDE_FROM_ABI)
• Use the right namespaces
• Get rid of pstl_config.h in favour of <__config>
• Granularize public API headers
• Now we should be able to simplify the glue like <__pstl_algorithm> inclusion to instead include our own granularized headers from <algorithm>
• We should be able to drop the custom _LIBCPP_HAS_PARALLEL_ALGORITHMS and use our existing machinery for experimental features
• We should also import the tests, since right now we're not testing anything

Doing that, we should strive to maintain the clear boundary between the backends and the public API. The public API is ours and we can change it -- the backend is where the real "work" is, and we want to share that with the pstl as much as possible since folks are making updates and improvements to it.

@rodgert This repo is not going to go anywhere, so this will not have an impact on your ability to keep taking updates made to pstl. We (libc++) will just start porting changes from pstl into libc++ manually when they happen (which isn't *that* often so far).

[rarutyun]

Sorry for disappearing. That was because of Intel business suspension in Russia. I was not allowed to work on that kind of stuff.

I am glad that things are moving forward with making Parallel algorithms available as a part of libc++.

Now I am available and ready to help.

[philnik]

In D103198#4139966, @rarutyun wrote:

Sorry for disappearing. That was because of Intel business suspension in Russia. I was not allowed to work on that kind of stuff.

I am glad that things are moving forward with making Parallel algorithms available as a part of libc++.

Now I am available and ready to help.

I'm working on integrating the files with libc++ still, so for now there isn't much you can do. I hope I'll get through that in the next week or two.

[rodgert]

Circling back on this -

I don't disagree with any of Louis' points. Regarding circular header
dependencies, I would also like to switch the PSTL to use libstdc++'s
internal implementation headers. I am not really sure how to do that and
still incorporate upstream changes going forward.

I expect to start rebasing libstdc++'s implementation on the current
version of the upstream next month.

libcxx/CMakeLists.txt

 elseif(WIN32) # clang-cl
   if (LIBCXX_ENABLE_SHARED)
     set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-shared-clangcl.cfg.in")
   else()
     set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-static-clangcl.cfg.in")
   endif()
 else()
   if (LIBCXX_ENABLE_SHARED)
+    if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
+      set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-with-pstl.cfg.in")
+    else()
       set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-shared.cfg.in")
+    endif()
   else()
     set(LIBCXX_DEFAULT_TEST_CONFIG "llvm-libc++-static.cfg.in")
   endif()
 endif()
 set(LIBCXX_TEST_CONFIG "${LIBCXX_DEFAULT_TEST_CONFIG}" CACHE STRING
     "The path to the Lit testing configuration to use when running the tests.
      If a relative path is provided, it is assumed to be relative to '<monorepo>/libcxx/test/configs'.")
 if (NOT IS_ABSOLUTE "${LIBCXX_TEST_CONFIG}")

 
 string(TOUPPER "${CMAKE_BUILD_TYPE}" uppercase_CMAKE_BUILD_TYPE)
 if (uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG")
   set(LIBCXX_DEBUG_BUILD ON)
 else()
   set(LIBCXX_DEBUG_BUILD OFF)
 endif()
 
+# PSTL Configuration ===========================================================
+if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
+    get_target_property(LIBCXX_PSTL_SOURCE_DIR pstl::ParallelSTL SOURCE_DIRECTORY)
+    get_target_property(LIBCXX_PSTL_GENERATED_SOURCE_DIR pstl::ParallelSTL GENERATED_DIRECTORY)
+endif()
+
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
 include(HandleLibCXXABI) # Setup the ABI library flags
 
 # Remove flags that may have snuck in.
 # TODO: This shouldn't be necessary anymore since we don't support the Project

libcxx/include/algorithm

template<input_range R1, input_range R2, class Pred = ranges::equal_to,
   template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2,
            weakly_incrementable O, class Comp = ranges::less,
            class Proj1 = identity, class Proj2 = identity>
     requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
     constexpr set_symmetric_difference_result<I1, I2, O>
       set_symmetric_difference(I1 first1, S1 last1, I2 first2, S2 last2, O result,
                                Comp comp = {}, Proj1 proj1 = {},
                                Proj2 proj2 = {});                                                   // since C++20
-  
   template<input_range R1, input_range R2, weakly_incrementable O,
            class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
     requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
     constexpr set_symmetric_difference_result<borrowed_iterator_t<R1>,
                                                       borrowed_iterator_t<R2>, O>
       set_symmetric_difference(R1&& r1, R2&& r2, O result, Comp comp = {},
                                Proj1 proj1 = {}, Proj2 proj2 = {});                                 // since C++20
 
   template<forward_iterator I, sentinel_for<I> S, class T, class Proj = identity,
            indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
     constexpr subrange<I>
       equal_range(I first, S last, const T& value, Comp comp = {}, Proj proj = {});                 // since C++20
-  
   template<forward_range R, class T, class Proj = identity,
            indirect_strict_weak_order<const T*, projected<iterator_t<R>, Proj>> Comp =
              ranges::less>
     constexpr borrowed_subrange_t<R>
       equal_range(R&& r, const T& value, Comp comp = {}, Proj proj = {});                           // since C++20
-  
   template<class I1, class I2, class O>
     using set_union_result = in_in_out_result<I1, I2, O>;                                           // since C++20
 
   template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2,
            weakly_incrementable O, class Comp = ranges::less,
            class Proj1 = identity, class Proj2 = identity>
     requires mergeable<I1, I2, O, Comp, Proj1, Proj2>
     constexpr set_union_result<I1, I2, O>
       set_union(I1 first1, S1 last1, I2 first2, S2 last2, O result, Comp comp = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});                                                // since C++20
 
   template<input_range R1, input_range R2, weakly_incrementable O,
            class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
     requires mergeable<iterator_t<R1>, iterator_t<R2>, O, Comp, Proj1, Proj2>
     constexpr set_union_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>, O>
       set_union(R1&& r1, R2&& r2, O result, Comp comp = {},
                 Proj1 proj1 = {}, Proj2 proj2 = {});                                                // since C++20
 
   template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2,
            class Proj1 = identity, class Proj2 = identity,
            indirect_strict_weak_order<projected<I1, Proj1>, projected<I2, Proj2>> Comp =
              ranges::less>
     constexpr bool includes(I1 first1, S1 last1, I2 first2, S2 last2, Comp comp = {},
                             Proj1 proj1 = {}, Proj2 proj2 = {});                                   // Since C++20
-  
   template<input_range R1, input_range R2, class Proj1 = identity,
            class Proj2 = identity,
            indirect_strict_weak_order<projected<iterator_t<R1>, Proj1>,
                                       projected<iterator_t<R2>, Proj2>> Comp = ranges::less>
     constexpr bool includes(R1&& r1, R2&& r2, Comp comp = {},
                             Proj1 proj1 = {}, Proj2 proj2 = {});                                   // Since C++20
 }
 

 // standard-mandated includes
 #include <initializer_list>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 #if defined(_LIBCPP_HAS_PARALLEL_ALGORITHMS) && _LIBCPP_STD_VER >= 17
-#   include <__pstl_algorithm>
+// TODO: Remove this include once we fix transitive includes of <algorithm>
+#  include <__functional/not_fn.h>
+#  include <__pstl_algorithm>
 #endif
 
 #endif // _LIBCPP_ALGORITHM

libcxx/include/unordered_map

 #include <__memory/addressof.h>
 #include <__node_handle>
 #include <__utility/forward.h>
 #include <stdexcept>
 #include <tuple>
 #include <version>
 
 #ifndef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
-#  include <algorithm>
 #  include <bit>
 #  include <iterator>
 #endif
 
 // standard-mandated includes
 
 // [iterator.range]
 #include <__iterator/access.h>

libcxx/src/CMakeLists.txt

if (APPLE AND LLVM_USE_SANITIZER)
   endif()
 endif()
 
 if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS AND NOT TARGET pstl::ParallelSTL)
   message(FATAL_ERROR "Could not find ParallelSTL")
 endif()
 
 function(cxx_set_common_defines name)
+# PSTL configuration ===========================================================
   if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
     target_link_libraries(${name} PUBLIC pstl::ParallelSTL)
   endif()
 endfunction()
 
 split_list(LIBCXX_COMPILE_FLAGS)
 split_list(LIBCXX_LINK_FLAGS)
 

libcxx/test/configs/cmake-bridge.cfg.in

 config.recursiveExpansionLimit = 10
 config.test_exec_root = os.path.join('@CMAKE_BINARY_DIR@', 'test')
 
 # Add substitutions for bootstrapping the test suite configuration
 import shlex
 config.substitutions.append(('%{cxx}', shlex.quote('@CMAKE_CXX_COMPILER@')))
 config.substitutions.append(('%{libcxx}', '@LIBCXX_SOURCE_DIR@'))
 config.substitutions.append(('%{include}', '@LIBCXX_GENERATED_INCLUDE_DIR@'))
+config.substitutions.append(('%{pstl-include}', '@LIBCXX_PSTL_SOURCE_DIR@'))
+config.substitutions.append(('%{pstl-generated-include}', '@LIBCXX_PSTL_GENERATED_SOURCE_DIR@'))
 config.substitutions.append(('%{target-include}', '@LIBCXX_GENERATED_INCLUDE_TARGET_DIR@'))
 config.substitutions.append(('%{lib}', '@LIBCXX_LIBRARY_DIR@'))
 config.substitutions.append(('%{executor}', '@LIBCXX_EXECUTOR@'))

libcxx/test/configs/llvm-libc++-with-pstl.cfg.in

+# This testing configuration handles running the test suite against LLVM's libc++
+# using a shared library.
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}',
+    '-isysroot {}'.format('@CMAKE_OSX_SYSROOT@') if '@CMAKE_OSX_SYSROOT@' else ''
+))
+config.substitutions.append(('%{compile_flags}',
+    '-nostdinc++ -I %{include} -I %{target-include} -I %{pstl-include} -I %{pstl-generated-include} -I %{libcxx}/test/support'
+))
+config.substitutions.append(('%{link_flags}',
+    '-nostdlib++ -L %{lib} -Wl,-rpath,%{lib} -lc++ -pthread'
+))
+config.substitutions.append(('%{exec}',
+    '%{executor} --execdir %T -- '
+))
+
+import os, site
+site.addsitedir(os.path.join('@LIBCXX_SOURCE_DIR@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)

libcxx/test/libcxx/clang_tidy.sh.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: has-clang-tidy
 
+// XFAIL: with-pstl
+
 // TODO: run clang-tidy with modules enabled once they are supported
 // RUN: clang-tidy %s --warnings-as-errors=* -header-filter=.* --config-file=%S/../../.clang-tidy -- -Wweak-vtables -Wno-unknown-warning-option %{compile_flags} -fno-modules
 // -Wno-unknown-warning-option tells clang-tidy to ignore '-W' command-line arguments that it doesn't know.
 // There are some GCC-specific ones where clang-tidy would warn otherwise.
 
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED

libcxx/test/libcxx/min_max_macros.compile.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // Test that headers are not tripped up by the surrounding code defining the
 // min() and max() macros.
 
 // The system-provided <uchar.h> seems to be broken on AIX
 // XFAIL: LIBCXX-AIX-FIXME
 
+// XFAIL: with-pstl
+
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
 #endif
 
 #define TEST_MACROS() static_assert(min() == true && max() == true, "")
 #define min() true
 #define max() true

libcxx/test/libcxx/nasty_macros.compile.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // Test that headers are not tripped up by the surrounding code defining various
 // alphabetic macros.
 
 // The system-provided <uchar.h> seems to be broken on AIX
 // XFAIL: LIBCXX-AIX-FIXME
 
+// XFAIL: with-pstl
+
 // Prevent <ext/hash_map> from generating deprecated warnings for this test.
 #if defined(__DEPRECATED)
 #    undef __DEPRECATED
 #endif
 
 #define NASTY_MACRO This should not be expanded!!!
 
 // libc++ does not use single-letter names as a matter of principle.

libcxx/test/libcxx/transitive_includes/expected.unordered_map

-algorithm
 atomic
 bit
 chrono
 climits
 cmath
 compare
 concepts
 cstddef

libcxx/utils/ci/buildkite-pipeline.yml

agents:
       queue: "libcxx-builders"
       os: "linux"
     retry:
       automatic:
         - exit_status: -1  # Agent was lost
           limit: 2
     timeout_in_minutes: 120
 
+  - label: "With PSTL support"
+    command: "libcxx/utils/ci/run-buildbot with-pstl"
+    artifact_paths:
+      - "**/test-results.xml"
+    agents:
+      queue: "libcxx-builders"
+      os: "linux"
+    retry:
+      automatic:
+        - exit_status: -1  # Agent was lost
+          limit: 2
+    timeout_in_minutes: 120
+
   - label: "No transitive includes"
     command: "libcxx/utils/ci/run-buildbot generic-no-transitive-includes"
     artifact_paths:
       - "**/test-results.xml"
       - "**/*.abilist"
     agents:
       queue: "libcxx-builders"
       os: "linux"

libcxx/utils/ci/run-buildbot

${CMAKE} \
           -DLIBCXXABI_ENABLE_WERROR=YES \
           -DLIBUNWIND_ENABLE_WERROR=YES \
           -DLLVM_LIT_ARGS="-sv --show-unsupported --xunit-xml-output test-results.xml --timeout=1500 --time-tests" \
           "${@}"
 }
 
 function generate-cmake() {
     generate-cmake-base \
-          -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" \
+          -DLLVM_ENABLE_RUNTIMES="pstl;libcxx;libcxxabi;libunwind" \
           -DLIBCXX_CXX_ABI=libcxxabi \
           "${@}"
 }
 
 function generate-cmake-libcxx-win() {
     # TODO: Clang-cl in MSVC configurations don't have access to compiler_rt
     # builtins helpers for int128 division. See
     # https://reviews.llvm.org/D91139#2429595 for a comment about longterm
generic-no-experimental)
     check-runtimes
     check-abi-list
 ;;
 generic-abi-unstable)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-abi-unstable.cmake"
     check-runtimes
 ;;
+with-pstl)
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-cxx20.cmake" \
+                   -DLIBCXX_TEST_CONFIG="llvm-libc++-with-pstl.cfg.in" \
+                   -DLIBUNWIND_TEST_CONFIG="llvm-libunwind-shared.cfg.in" \
+                   -DCMAKE_BUILD_WITH_INSTALL_RPATH=TRUE \
+                   -DLIBCXX_ENABLE_PARALLEL_ALGORITHMS=ON
+    check-runtimes
+;;
 apple-system)
     clean
 
     arch="$(uname -m)"
     xcrun --sdk macosx                                              \
         ${MONOREPO_ROOT}/libcxx/utils/ci/apple-install-libcxx.sh    \
             --llvm-root ${MONOREPO_ROOT}                            \
             --build-dir ${BUILD_DIR}                                \

libcxx/utils/libcxx/test/features.py

macros = {
   '_LIBCPP_NO_VCRUNTIME': 'libcpp-no-vcruntime',
   '_LIBCPP_ABI_VERSION': 'libcpp-abi-version',
   '_LIBCPP_HAS_NO_FILESYSTEM_LIBRARY': 'no-filesystem',
   '_LIBCPP_HAS_NO_RANDOM_DEVICE': 'no-random-device',
   '_LIBCPP_HAS_NO_LOCALIZATION': 'no-localization',
   '_LIBCPP_HAS_NO_WIDE_CHARACTERS': 'no-wide-characters',
   '_LIBCPP_HAS_NO_UNICODE': 'libcpp-has-no-unicode',
   '_LIBCPP_ENABLE_DEBUG_MODE': 'libcpp-has-debug-mode',
+  '_LIBCPP_HAS_PARALLEL_ALGORITHMS': 'with-pstl',
 }
 for macro, feature in macros.items():
   DEFAULT_FEATURES.append(
     Feature(name=lambda cfg, m=macro, f=feature: f + ('={}'.format(compilerMacros(cfg)[m]) if compilerMacros(cfg)[m] else ''),
             when=lambda cfg, m=macro: m in compilerMacros(cfg))
   )
 
 

libcxxabi/CMakeLists.txt

 elseif(WIN32) # clang-cl
   if (LIBCXXABI_ENABLE_SHARED)
     set(LIBCXXABI_DEFAULT_TEST_CONFIG "llvm-libc++abi-shared-clangcl.cfg.in")
   else()
     set(LIBCXXABI_DEFAULT_TEST_CONFIG "llvm-libc++abi-static-clangcl.cfg.in")
   endif()
 else()
   if (LIBCXXABI_ENABLE_SHARED)
+    if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
+      set(LIBCXXABI_DEFAULT_TEST_CONFIG "llvm-libc++abi-with-pstl.cfg.in")
+    else()
       set(LIBCXXABI_DEFAULT_TEST_CONFIG "llvm-libc++abi-shared.cfg.in")
+    endif()
   else()
     set(LIBCXXABI_DEFAULT_TEST_CONFIG "llvm-libc++abi-static.cfg.in")
   endif()
 endif()
 set(LIBCXXABI_TEST_CONFIG "${LIBCXXABI_DEFAULT_TEST_CONFIG}" CACHE STRING
   "The path to the Lit testing configuration to use when running the tests.
    If a relative path is provided, it is assumed to be relative to '<monorepo>/libcxxabi/test/configs'.")
 if (NOT IS_ABSOLUTE "${LIBCXXABI_TEST_CONFIG}")

 set(LIBCXXABI_CXX_FLAGS "")
 set(LIBCXXABI_COMPILE_FLAGS "")
 set(LIBCXXABI_LINK_FLAGS "")
 set(LIBCXXABI_LIBRARIES "")
 
 # Include macros for adding and removing libc++abi flags.
 include(HandleLibcxxabiFlags)
 
+# PSTL Configuration ===========================================================
+if (LIBCXX_ENABLE_PARALLEL_ALGORITHMS)
+    get_target_property(LIBCXXABI_PSTL_SOURCE_DIR pstl::ParallelSTL SOURCE_DIRECTORY)
+    get_target_property(LIBCXXABI_PSTL_GENERATED_SOURCE_DIR pstl::ParallelSTL GENERATED_DIRECTORY)
+endif()
+
 #===============================================================================
 # Setup Compiler Flags
 #===============================================================================
 
 # Configure target flags
 if(ZOS)
   add_target_flags_if_supported("-fzos-le-char-mode=ebcdic")
 endif()

libcxxabi/src/CMakeLists.txt

 endif()
 
 if (NOT TARGET pstl::ParallelSTL)
   message(STATUS "Could not find ParallelSTL, libc++abi will not attempt to use it but the build may fail if the libc++ in use needs it to be available.")
 endif()
 
 # Build the shared library.
 add_library(cxxabi_shared_objects OBJECT EXCLUDE_FROM_ALL ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
+if (TARGET pstl::ParallelSTL)
+  target_link_libraries(cxxabi_shared_objects PUBLIC pstl::ParallelSTL)
+endif()
 if (LIBCXXABI_USE_LLVM_UNWINDER)
   if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
     target_link_libraries(cxxabi_shared_objects PUBLIC unwind_shared_objects) # propagate usage requirements
     target_sources(cxxabi_shared_objects PUBLIC $<TARGET_OBJECTS:unwind_shared_objects>)
   else()
     target_link_libraries(cxxabi_shared_objects PUBLIC unwind_shared)
   endif()
 endif()
if (LIBCXXABI_ENABLE_EXCEPTIONS)
         reexport_symbols("${CMAKE_CURRENT_SOURCE_DIR}/../lib/personality-v0.exp")
       endif()
     endif()
   endif()
 endif()
 
 # Build the static library.
 add_library(cxxabi_static_objects OBJECT EXCLUDE_FROM_ALL ${LIBCXXABI_SOURCES} ${LIBCXXABI_HEADERS})
+if (TARGET pstl::ParallelSTL)
+  target_link_libraries(cxxabi_static_objects PUBLIC pstl::ParallelSTL)
+endif()
 if (LIBCXXABI_USE_LLVM_UNWINDER AND LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY)
   target_link_libraries(cxxabi_static_objects PUBLIC unwind_static_objects) # propagate usage requirements
   target_sources(cxxabi_static_objects PUBLIC $<TARGET_OBJECTS:unwind_static_objects>)
 endif()
 target_link_libraries(cxxabi_static_objects PRIVATE cxx-headers ${LIBCXXABI_STATIC_LIBRARIES} ${LIBCXXABI_LIBRARIES})
 target_link_libraries(cxxabi_static_objects PUBLIC cxxabi-headers)
 set_target_properties(cxxabi_static_objects
   PROPERTIES

libcxxabi/test/configs/cmake-bridge.cfg.in

 # TODO: This is a non-standard Lit attribute and we should have another way of accessing this.
 config.host_triple = '@LLVM_HOST_TRIPLE@'
 
 config.substitutions.append(('%{cxx}', '@CMAKE_CXX_COMPILER@'))
 config.substitutions.append(('%{libcxx}', '@LIBCXXABI_LIBCXX_PATH@'))
 config.substitutions.append(('%{include}', '@LIBCXXABI_SOURCE_DIR@/include'))
 config.substitutions.append(('%{cxx-include}', '@LIBCXXABI_HEADER_DIR@/include/c++/v1'))
 config.substitutions.append(('%{cxx-target-include}', '@LIBCXXABI_HEADER_DIR@/include/%{triple}/c++/v1'))
+config.substitutions.append(('%{pstl-include}', '@LIBCXXABI_PSTL_SOURCE_DIR@'))
+config.substitutions.append(('%{pstl-generated-include}', '@LIBCXXABI_PSTL_GENERATED_SOURCE_DIR@'))
 config.substitutions.append(('%{lib}', '@LIBCXXABI_LIBRARY_DIR@'))
 config.substitutions.append(('%{executor}', '@LIBCXXABI_EXECUTOR@'))
 
 if @LIBCXXABI_USE_LLVM_UNWINDER@:
     config.substitutions.append(('%{maybe-include-libunwind}', '-I "@LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL@"'))
 else:
     config.substitutions.append(('%{maybe-include-libunwind}', ''))

libcxxabi/test/configs/llvm-libc++abi-with-pstl.cfg.in

+# This testing configuration handles running the test suite against LLVM's libc++abi
+# using a shared library.
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}',
+    '-isysroot {}'.format('@CMAKE_OSX_SYSROOT@') if '@CMAKE_OSX_SYSROOT@' else ''
+))
+config.substitutions.append(('%{compile_flags}',
+    '-nostdinc++ -I %{include} -I %{pstl-include} -I %{pstl-generated-include} -I %{cxx-include} -I %{cxx-target-include} %{maybe-include-libunwind} -I %{libcxx}/test/support -I %{libcxx}/src -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS'
+))
+config.substitutions.append(('%{link_flags}',
+    '-nostdlib++ -L %{lib} -Wl,-rpath,%{lib} -lc++ -lc++abi -pthread'
+))
+config.substitutions.append(('%{exec}',
+    '%{executor} --execdir %T -- '
+))
+
+import os, site
+site.addsitedir(os.path.join('@LIBCXXABI_LIBCXX_PATH@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)

pstl/CMakeLists.txt

configure_file("include/__pstl_config_site.in"
                @ONLY)
 
 target_include_directories(ParallelSTL
     INTERFACE
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
     $<BUILD_INTERFACE:${PSTL_GENERATED_HEADERS_DIR}>
     $<INSTALL_INTERFACE:include>)
 
+set_target_properties(ParallelSTL PROPERTIES
+                      SOURCE_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/include
+                      GENERATED_DIRECTORY ${PSTL_GENERATED_HEADERS_DIR}
+                     )
+
 ###############################################################################
 # Setup tests
 ###############################################################################
 enable_testing()
 add_subdirectory(test)
 
 ###############################################################################
 # Install the target and the associated CMake files

pstl/include/pstl/internal/algorithm_impl.h

__brick_find_if(_RandomAccessIterator __first, _RandomAccessIterator __last, _Predicate __pred,
     typedef typename std::iterator_traits<_RandomAccessIterator>::difference_type _SizeType;
     return __unseq_backend::__simd_first(
         __first, _SizeType(0), __last - __first,
         [&__pred](_RandomAccessIterator __it, _SizeType __i) { return __pred(__it[__i]); });
 }
 
 template <class _Tag, class _ExecutionPolicy, class _ForwardIterator, class _Predicate>
 _ForwardIterator
-__pattern_find_if(_Tag __tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last,
+__pattern_find_if(_Tag, _ExecutionPolicy&&, _ForwardIterator __first, _ForwardIterator __last,
                   _Predicate __pred) noexcept
 {
     return __internal::__brick_find_if(__first, __last, __pred, typename _Tag::__is_vector{});
 }
 
 template <class _IsVector, class _ExecutionPolicy, class _RandomAccessIterator, class _Predicate>
 _RandomAccessIterator
 __pattern_find_if(__parallel_tag<_IsVector> __tag, _ExecutionPolicy&& __exec, _RandomAccessIterator __first,

pstl/include/pstl/internal/undef_macros.h

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifdef min
+#  undef min
+#endif
+
+#ifdef max
+#  undef max
+#endif

pstl/include/pstl/internal/utils.h

 {
 namespace __internal
 {
 
 template <typename _Fp>
 auto
 __except_handler(_Fp __f) -> decltype(__f())
 {
+#if defined(__cpp_exceptions) && __cpp_exceptions >= 199711L
     try
     {
         return __f();
     }
     catch (const std::bad_alloc&)
     {
         throw; // re-throw bad_alloc according to the standard [algorithms.parallel.exceptions]
     }
     catch (...)
     {
         std::terminate(); // Good bye according to the standard [algorithms.parallel.exceptions]
     }
+#else
+    return __f();
+#endif // defined(__cpp_exceptions) && __cpp_exceptions >= 199711L
 }
 
 template <typename _Fp>
 void
 __invoke_if(std::true_type, _Fp __f)
 {
     __f();
 }

runtimes/CMakeLists.txt

list(INSERT CMAKE_MODULE_PATH 0
   "${LLVM_COMMON_CMAKE_UTILS}"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"
   "${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/../llvm/cmake/modules"
 )
 
 # We order libraries to mirror roughly how they are layered, except that compiler-rt can depend
 # on libc++, so we put it after.
-set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp")
+set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;pstl;libcxxabi;libcxx;compiler-rt;openmp")
 set(LLVM_ALL_RUNTIMES "${LLVM_DEFAULT_RUNTIMES};llvm-libgcc")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build (${LLVM_ALL_RUNTIMES}), or \"all\".")
 if(LLVM_ENABLE_RUNTIMES STREQUAL "all" )
   set(LLVM_ENABLE_RUNTIMES ${LLVM_DEFAULT_RUNTIMES})
 endif()
 include(SortSubset)
 sort_subset("${LLVM_ALL_RUNTIMES}" "${LLVM_ENABLE_RUNTIMES}" LLVM_ENABLE_RUNTIMES)