This makes Clang take advantage of the recent IR addition of a
"failure" memory ordering requirement. As with the "success" ordering,
we try to emit just a single version if the expression is constant,
but fall back to runtime detection (to allow optimisation across
function-call boundaries).
rdar://problem/15996804
llvm-svn: 203837
This is a conservative check, because it's valid for the expression to be
non-constant, and in cases like that we just don't know whether it's valid.
rdar://problem/16242991
llvm-svn: 203561
Summary:
'Expected' should only be modified if the operation fails.
This fixes PR18899.
Reviewers: chandlerc, rsmith, rjmccall
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D2922
llvm-svn: 203493
__atomic_test_and_set, __atomic_clear, plus a pile of undocumented __GCC_*
predefined macros.
Implement library fallback for __atomic_is_lock_free and
__c11_atomic_is_lock_free, and implement __atomic_always_lock_free.
Contrary to their documentation, GCC's __atomic_fetch_add family don't
multiply the operand by sizeof(T) when operating on a pointer type.
libstdc++ relies on this quirk. Remove this handling for all but the
__c11_atomic_fetch_add and __c11_atomic_fetch_sub builtins.
Contrary to their documentation, __atomic_test_and_set and __atomic_clear
take a first argument of type 'volatile void *', not 'void *' or 'bool *',
and __atomic_is_lock_free and __atomic_always_lock_free have an argument
of type 'const volatile void *', not 'void *'.
With this change, libstdc++4.7's <atomic> passes libc++'s atomic test suite,
except for a couple of libstdc++ bugs and some cases where libc++'s test
suite tests for properties which implementations have latitude to vary.
llvm-svn: 154640
This is not quite sufficient for libstdc++'s <atomic>: we still need
__atomic_test_and_set and __atomic_clear, and may need a more complete
__atomic_is_lock_free implementation.
We are also missing an implementation of __atomic_always_lock_free,
__atomic_nand_fetch, and __atomic_fetch_nand, but those aren't needed
for libstdc++.
llvm-svn: 154579
<stdatomic.h> header.
In passing, fix LanguageExtensions to note that C11 and C++11 are no longer
"upcoming standards" but are now actually standardized.
llvm-svn: 154513
LLVM intrinsics for.
I have an implementation of these functions, which wants to go in a libgcc_s
equivalent in compiler-rt. It's currently here:
http://people.freebsd.org/~theraven/atomic.c
It will be committed to compiler-rt as soon as I work out where would be a
sensible place to put it...
llvm-svn: 153666
Tim Northover