We seem to have been gradually growing support for atomic min/max operations
(exposing longstanding IR atomicrmw instructions). But until now there have
been gaps in the expected intrinsics. This adds support for the C11-style
intrinsics (i.e. taking _Atomic, rather than individually blessed by C11
standard), and the variants that return the new value instead of the original
one.
That way, people won't be misled by trying one form and it not working, and the
front-end is more friendly to people using _Atomic types, as we recommend.
Summary:
The optimized (__atomic_foo_<n>) libcalls assume that the atomic object
is properly aligned, so should never be called on an underaligned
object.
This addresses one of several problems identified in PR38846.
Reviewers: jyknight, t.p.northover
Subscribers: jfb, cfe-commits
Differential Revision: https://reviews.llvm.org/D51817
llvm-svn: 341734
Summary:
Using _Atomic to do implicit load / store is just a seq_cst atomic_load / atomic_store. Stores currently assert in Sema::ImpCastExprToType with 'can't implicitly cast lvalue to rvalue with this cast kind', but that's erroneous. The codegen is fine as the test shows.
While investigating I found that Richard had found the problem here: https://reviews.llvm.org/D46112#1113557
<rdar://problem/40347123>
Reviewers: dexonsmith
Subscribers: cfe-commits, efriedma, rsmith, aaron.ballman
Differential Revision: https://reviews.llvm.org/D49458
llvm-svn: 337410
This commit generalizes NRVO to cover C structs (both trivial and
non-trivial structs).
rdar://problem/33599681
Differential Revision: https://reviews.llvm.org/D44968
llvm-svn: 328809
If there are two pointers passed to an atomic Builtin,
Clang doesn't allow the second (non-atomic) one to be qualified
with an address space.
Remove this restriction by recording the address space of passed pointers
in atomics type diagnostics.
llvm-svn: 256243
When a struct's size is not a power of 2, the corresponding _Atomic() type is
promoted to the nearest. We already correctly handled normal C++ expressions of
this form, but direct calls to the __c11_atomic_whatever builtins ended up
performing dodgy operations on the smaller non-atomic types (e.g. memcpy too
much). Later optimisations removed this as undefined behaviour.
This patch converts EmitAtomicExpr to allocate its temporaries at the full
atomic width, sidestepping the issue.
llvm-svn: 252507
This patch adds ObjectFilePCHContainerOperations uses the LLVM backend
to put the contents of a PCH into a __clangast section inside a COFF, ELF,
or Mach-O object file container.
This is done to facilitate module debugging by makeing it possible to
store the debug info for the types defined by a module alongside the AST.
rdar://problem/20091852
llvm-svn: 241620
The parameter types and return type do not need to be volatile just
because the pointer type's pointee type is volatile qualified. This is
an unnecessary pessimization.
llvm-svn: 238892
This is a necessary prerequisite for debugging with modules.
The .pcm files become containers that hold the serialized AST which allows
us to store debug information in the module file that can be shared by all
object files that were built importing the module.
This reapplies r230044 with a fixed configure+make build and updated
dependencies and testcase requirements. Over the last iteration this
version adds
- missing target requirements for testcases that specify an x86 triple,
- a missing clangCodeGen.a dependency to libClang.a in the make build.
rdar://problem/19104245
llvm-svn: 230423
This test includes stdint.h (via stdatomic.h), which might include system
headers (and that might not work, depending on the system configuration).
Attempting to fix llvm-clang-lld-x86_64-debian-fast.
llvm-svn: 218960
Adds a Clang-specific implementation of C11's stdatomic.h header. On systems,
such as FreeBSD, where a stdatomic.h header is already provided, we defer to
that header instead (using our __has_include_next technology). Otherwise, we
provide an implementation in terms of our __c11_atomic_* intrinsics (that were
created for this purpose).
C11 7.1.4p1 requires function declarations for atomic_thread_fence,
atomic_signal_fence, atomic_flag_test_and_set,
atomic_flag_test_and_set_explicit, and atomic_flag_clear, and requires that
they have external linkage. Accordingly, we provide these declarations, but if
a user elides the shadowing macros and uses them, then they must have a libc
(or similar) that actually provides definitions.
atomic_flag is implemented using _Bool as the underlying type. This is
consistent with the implementation provided by FreeBSD and also GCC 4.9 (at
least when __GCC_ATOMIC_TEST_AND_SET_TRUEVAL == 1).
Patch by Richard Smith (rebased and slightly edited by me -- Richard said I
should drive at this point).
llvm-svn: 218957
Summary:
We did a great job getting this wrong:
- We messed up which LLVM IR types to use for arguments and return values.
The optimized libcalls use integer types for values.
Clang attempted to use the IR type which corresponds to the value
passed in instead of using an appropriately sized integer type. This
would result in violations of the ABI for, as an example, floating
point types.
- We didn't bother recording the result of the atomic libcall in the
destination memory.
Instead, call the functions with arguments matching the type of the
libcall prototype's parameters.
This fixes PR20780.
Differential Revision: http://reviews.llvm.org/D5098
llvm-svn: 216714
Most builtins date from before the "cmpxchg weak" was a gleam in the
C++ committee's eye, so fortunately not much needs to change. But a
few of them *do* acknowledge that failure is possible.
For these, we'll emit the usual cartesian product of cmpxchg
operations if we can't statically determine weakness. CodeGen can
sort it out later if the function gets inlined.
The only other non-trivial aspect of this is (I think) that we emit
the scalar expression for "IsWeak" once, at the beginning, and
propagate its value through the successive blocks. There's not much in
it, but it's slightly more consistent with the existing handling of
FailureOrder.
llvm-svn: 210932
This is a minimal fix for clang. I'll soon add support for generating
weak variants when requested, but that's not really necessary for the
LLVM change in isolation.
llvm-svn: 210907
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