[libcxx-commits] [PATCH] D114109: [libc++] Enable <atomic> when threads are disabled

[Louis Dionne via Phabricator via libcxx-commits]

ldionne created this revision.
Herald added subscribers: arichardson, mgorny.
ldionne requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

std::atomic is, for the most part, just a thin veneer on top of compiler
builtins. Hence, it should be available even when threads are not available
on the system, and in fact there has been requests for such support.

This patch:

- Moves __libcpp_thread_poll_with_backoff to its own header so it can be used in <atomic> when threads are disabled.
- Adds a dummy backoff policy for atomic polling that doesn't know about threads.
- Adjusts the <atomic> feature-test macros so they are provided even when threads are disabled.
- Runs the <atomic> tests when threads are disabled.

rdar://77873569


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D114109

Files:
  libcxx/include/CMakeLists.txt
  libcxx/include/__config
  libcxx/include/__thread/poll_with_backoff.h
  libcxx/include/__threading_support
  libcxx/include/atomic
  libcxx/include/thread
  libcxx/include/version
  libcxx/src/memory.cpp
  libcxx/test/libcxx/atomics/atomics.align/align.pass.cpp
  libcxx/test/libcxx/atomics/atomics.flag/init_bool.pass.cpp
  libcxx/test/libcxx/atomics/atomics.order/memory_order.underlying_type.pass.cpp
  libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add.verify.cpp
  libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add_explicit.verify.cpp
  libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub.verify.cpp
  libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub_explicit.verify.cpp
  libcxx/test/libcxx/atomics/diagnose_invalid_memory_order.verify.cpp
  libcxx/test/libcxx/atomics/ext-int.verify.cpp
  libcxx/test/libcxx/atomics/libcpp-has-no-threads.compile.fail.cpp
  libcxx/test/libcxx/atomics/libcpp-has-no-threads.pass.cpp
  libcxx/test/libcxx/atomics/version.pass.cpp
  libcxx/test/libcxx/diagnostics/detail.headers/thread/poll_with_backoff.module.verify.cpp
  libcxx/test/std/atomics/atomics.fences/atomic_signal_fence.pass.cpp
  libcxx/test/std/atomics/atomics.fences/atomic_thread_fence.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_clear.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_clear_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_test.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_test_and_set.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_test_and_set_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.flag/atomic_flag_test_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.flag/clear.pass.cpp
  libcxx/test/std/atomics/atomics.flag/default.pass.cpp
  libcxx/test/std/atomics/atomics.flag/init.pass.cpp
  libcxx/test/std/atomics/atomics.flag/test_and_set.pass.cpp
  libcxx/test/std/atomics/atomics.general/replace_failure_order.pass.cpp
  libcxx/test/std/atomics/atomics.general/replace_failure_order_codegen.sh.cpp
  libcxx/test/std/atomics/atomics.lockfree/isalwayslockfree.pass.cpp
  libcxx/test/std/atomics/atomics.lockfree/lockfree.pass.cpp
  libcxx/test/std/atomics/atomics.order/kill_dependency.pass.cpp
  libcxx/test/std/atomics/atomics.order/memory_order.pass.cpp
  libcxx/test/std/atomics/atomics.order/memory_order_new.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/address.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/bool.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/constexpr_noexcept.compile.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/copy_semantics_traits.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/cstdint_typedefs.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/integral.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/integral_typedefs.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/standard_layout.compile.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/throw.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.pass.cpp
  libcxx/test/std/atomics/atomics.types.generic/trivially_copyable.verify.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_compare_exchange_strong.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_compare_exchange_strong_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_compare_exchange_weak.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_compare_exchange_weak_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_exchange.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_exchange_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_and.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_and_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_or.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_or_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_xor.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_xor_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_init.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_is_lock_free.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_load.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_load_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_store.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_store_explicit.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/atomic_var_init.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/copy.assign.ptr.volatile.verify.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/copy.assign.volatile.verify.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/ctor.pass.cpp
  libcxx/test/std/atomics/atomics.types.operations/atomics.types.operations.req/dtor.pass.cpp
  libcxx/test/std/atomics/types.pass.cpp
  libcxx/test/std/depr/depr.atomics/depr.atomics.nonmembers/atomic_init.depr_in_cxx20.verify.cpp
  libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.pass.cpp
  libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.pass.cpp
  libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_strong_explicit.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_compare_exchange_weak_explicit.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_exchange_explicit.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_is_lock_free.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_load_explicit.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store.pass.cpp
  libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared.atomic/atomic_store_explicit.pass.cpp
  libcxx/utils/generate_feature_test_macro_components.py

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