These calls are allowed to fail spuriously.
29.6.5.25:
Remark: A weak compare-and-exchange operation may fail spuriously.
That is, even when the contents of memory referred to by expected
and object are equal, it may return false and store back to expected
the same memory contents that were originally there. [ Note: This
spurious failure enables implementation of compare and-exchange on a
broader class of machines, e.g., load-locked store-conditional
machines. A consequence of spurious failure is that nearly all uses
of weak compare-and-exchange will be in a loop.
To fix this, we replace any assert() that expects
std::atomic::compare_exchange_weak() to return true with a loop. If the
call does not return true within N runs (with N currently equal to 10),
then the test fails.
http://llvm.org/bugs/show_bug.cgi?id=20546
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@217319 91177308-0d34-0410-b5e6-96231b3b80d8
The way the standard currently specifies the default constructor for atomic<T>
requires T to be nothrow default constructible. This patch makes our test types
meet this requirement.
Note: The nothrow default constructible requirment is subject to the outcome of
LWG issue 1265.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@216561 91177308-0d34-0410-b5e6-96231b3b80d8
The tests use placement new to check that atomic values get properly zero-initialized. I had to modify the atomic_is_lock_free test, because default initialization of an object of const type 'const A' (aka 'const atomic<int>') requires a user-provided default constructor.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@180945 91177308-0d34-0410-b5e6-96231b3b80d8
at the moment, but they allow these tests to be used to test clang against
libstdc++. Add myself to the credits file, as suggested by Howard.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@155085 91177308-0d34-0410-b5e6-96231b3b80d8
compare-and-exchange failed (it should update the expected value to the current
value, and the tests were checking that it didn't...).
Results of the atomics part of the test suite on FreeBSD with clang trunk and
the atomic.c from compiler-rt (currently kludged into the test, not installed
properly):
****************************************************
Results for /root/libc++/test/atomics:
using clang version 3.1 (trunk 153415)
Target: x86_64-unknown-freebsd10.0
Thread model: posix
with -std=c++0x -stdlib=libc++ -pthread /tmp/atomic.o
----------------------------------------------------
sections without tests : 0
sections with failures : 0
sections without failures: 14
+ ----
total number of sections : 14
----------------------------------------------------
number of tests failed : 0
number of tests passed : 52
+ ----
total number of tests : 52
****************************************************
Yay!
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@154095 91177308-0d34-0410-b5e6-96231b3b80d8
