diff --git a/libcxx/docs/DesignDocs/PSTLIntegration.rst b/libcxx/docs/DesignDocs/PSTLIntegration.rst new file mode 100644 --- /dev/null +++ b/libcxx/docs/DesignDocs/PSTLIntegration.rst @@ -0,0 +1,22 @@ +================ +PSTL integration +================ + +The PSTL (or Parallel STL) project is quite complex in its current form and does not provide everything that libc++ +requires, for example ``_LIBCPP_HIDE_FROM_ABI`` or similar annotations and including granularized headers. Furthermore, +the PSTL provides various layers of indirection that make sense in a generic implementation of the parallel algorithms, +but are unnecessarily complex in the context of a single standard library implementation. Because of these drawbacks, we +decided to adopt a modified PSTL in libc++. Specifically, the goals of the modified PSTL are + +- No ``<__pstl_algorithm>`` and similar glue headers -- instead, the implementation files are included directly in + ```` and friends. +- No ```` and ```` headers and friends -- these contain + the implementation and forward declarations for internal functions respectively. The implementation lives inside + ``<__algorithm/pstl_any_of.h>`` and friends, and the forward declarations are not needed inside libc++. +- No ```` and ```` headers and friends -- + these contain the public API. It lives inside ``<__algorithm/pstl_any_of.h>`` and friends instead. +- The headers implementing backends are kept with as few changes as possible to make it easier to keep the backends in + sync with the backends from the original PSTL. +- The configuration headers ``__pstl_config_site.in`` and ``pstl_config.h`` are removed, and any required configuration + is done inside ``__config_site.in`` and ``__config`` respectively. +- libc++-style tests for the public PSTL API diff --git a/libcxx/docs/index.rst b/libcxx/docs/index.rst --- a/libcxx/docs/index.rst +++ b/libcxx/docs/index.rst @@ -179,6 +179,7 @@ DesignDocs/FileTimeType DesignDocs/HeaderRemovalPolicy DesignDocs/NoexceptPolicy + DesignDocs/PSTLIntegration DesignDocs/ThreadingSupportAPI DesignDocs/UniquePtrTrivialAbi DesignDocs/UnspecifiedBehaviorRandomization