[all-commits] [llvm/llvm-project] 92832e: [libc++] Enable <atomic> when threads are disabled

[Louis Dionne via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 92832e4889ae6038cc8b3e6e449af2a9b9374ab4
      https://github.com/llvm/llvm-project/commit/92832e4889ae6038cc8b3e6e449af2a9b9374ab4
  Author: Louis Dionne <ldionne.2 at gmail.com>
  Date:   2021-11-17 (Wed, 17 Nov 2021)

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

  Log Message:
  -----------
  [libc++] Enable <atomic> when threads are disabled

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

Differential Revision: https://reviews.llvm.org/D114109