Summary: The current implementations of __hash_table::find used by std::unordered_set/unordered_map call key_eq on each key that lands in the same bucket as the key you're looking for. However, since equal objects mush hash to the same value, you can short-circuit the possibly expensive call to key_eq by checking the hashes first.
Reviewers: EricWF
Subscribers: kmensah, cfe-commits
Differential Revision: http://reviews.llvm.org/D21510
llvm-svn: 274857
This patch improves the performance of unordered_set's find by 45% when
the value exists within the set. __hash_tables find method
needs to check if it's reached the end of the bucket by constraining the
hash of the current node and checking it against the bucket index. However
constraining the hash is an expensive operations and it can be avoided if the
two unconstrained hashes are equal. This patch applies that optimization.
This patch also adds a top level directory called benchmarks. 'benchmarks/'
is intended to store any/all benchmarks written for the standard library.
Currently nothing is done with files under 'benchmarks/' but I would like
to move towards introducing a formal format and test runner.
llvm-svn: 274423
This patch is the last in a series that replaces recursive meta-programming
in std::tuple with non-recursive implementations.
Previously std::tuple could only be instantiated with 126 elements before
it blew the max template instantiation depth. Now the size of std::tuple is
essentially unbounded (I've tested with over 5000 elements).
One unfortunate side-effect of this change is that tuple_constructible
and similar no longer short circuit after the first failure. Instead they
evaluate the conditions for all elements. This could be potentially breaking.
I plan to look into this further.
llvm-svn: 274331
This patch attempts to improve the QoI of std::tuples tuple_element and
__make_tuple_types helpers. Previously they required O(N) instantiations,
one for every element in the tuple
The new implementations are O(1) after __tuple_indices<Id...> is created.
llvm-svn: 274330
The previous __make_tuple_indices implementation caused O(N) instantiations
and was pretty inefficient. The C++14 __make_integer_sequence implementation
is much better, since it either uses a builtin to generate the sequence or
a very nice Log8(N) implementation provided by richard smith.
This patch moves the __make_integer_sequence implementation into __tuple
and uses it to implement __make_tuple_indices.
Since libc++ can't expose the name 'integer_sequence' in C++11 this patch
also introduces a dummy type '__integer_sequence' which is used when generating
the sequence. One the sequence is generated '__integer_sequence' can be
converted into the required type; either '__tuple_indices' or 'integer_sequence'.
llvm-svn: 274286
* P0163r0: Implemented in r273839.
* LWG 2309: pthread_mutex_lock only returns this error if certain debug flags
were passed during construction. libc++ does not pass these flags. There is
nothing to do.
* LWG 2310: Wording fix. No impact on libc++'s implementation.
* LWG 2312: libc++'s std::tuple implementation already constrains the overloads
based on the number of arguments.
* LWG 2549: libc++'s std::tuple already applied this fix.
* LWG 2674: libc++ already depends on this relaxed wording.
* LWG 2704, 2706, 2707, 2719, 2720, 2721, 2723, 2725, 2728: All of these filesystem were either
submitted by me and fixed before submission, or have already been applied.
llvm-svn: 274214
Since at least the C++11 standard insert iterators are specified
as having ::reference typedef void. Libc++ was not doing that.
This patch corrects the typedef.
This patch changes the std::iterator base class of insert_iterator,
front_insert_iterator and back_insert_iterator. This should not
be an ABI breaking change.
llvm-svn: 274209
The end pointer should point to one past the end of the newly allocated
buffer.
rdar://problem/24265174
Differential Revision: http://reviews.llvm.org/D20334
llvm-svn: 274132
This patch adds the weak_type typedef in shared_ptr. It is available in
C++17 and newer.
This patch also updates the _LIBCPP_STD_VER and TEST_STD_VER macros to
have the value of 16, since 2016 is the current year.
llvm-svn: 273839
See https://llvm.org/bugs/show_bug.cgi?id=27115
The problem was that the conversion from
'const enable_shared_from_this<T>*' to 'const T*' didn't work if
T inherited enable_shared_from_this as a virtual base class. The fix
is to take the original pointer passed to shared_ptr's constructor in the
__enable_weak_this method and perform an upcast to 'const T*' instead of
performing a downcast from the enable_shared_from_this base.
llvm-svn: 273835
The move constructor for wstring_convert accidentally copied the state member
into the converted count member in the move constructor. This patch fixes
the typo.
While working on this I discovered that wstring_convert doesn't actually
provide a move constructor according to the standard and therefore this
constructor is a libc++ extension. I'll look further into whether libc++ should
provide this constructor at all. Neither libstdc++ or MSVC's STL provide it.
llvm-svn: 273831
This patch makes the bind placeholders in std::placeholders both (1) const and
(2) constexpr (See below).
This is technically a breaking change for any code using the placeholders
outside of std::bind and depending on them being non-const. However I don't
think this will break any real world code.
(1) Previously the placeholders were non-const extern globals in all
dialects. This patch changes these extern globals to be const in all dialects.
Since the cv-qualifiers don't participate in name mangling for globals this
is an ABI compatible change.
(2) Make the placeholders constexpr in C++11 and beyond. Although LWG 2488 only
applies to C++17 I don't see any reason not to backport this change.
llvm-svn: 273824
Summary: this fixes build error when built with c++14 and no exceptions
Reviewers: rmaprath
Subscribers: weimingz, grandinj, rmaprath, cfe-commits
Differential Revision: http://reviews.llvm.org/D21673
llvm-svn: 273697
So the macros TEST_HAS_NO_EXCEPTIONS and TEST_HAS_NO_RTTI were always
getting defined because I spelt __cpp_exceptions and __cpp_rtti as
__cxx_exceptions and __cxx_rtti.
Tests incoming after this patch.
llvm-svn: 273381
Libc++ has to deduce the 'allocator_arg_t' parameter as 'AllocArgT' for the
following constructor:
template <class Alloc> tuple(allocator_arg_t, Alloc const&)
Previously libc++ has tried to support tags derived from 'allocator_arg_t' by
using 'is_base_of<AllocArgT, allocator_arg_t>'. However this breaks whenever a
2-tuple contains a reference to an incomplete type as its first parameter.
See https://llvm.org/bugs/show_bug.cgi?id=27684
llvm-svn: 273334
This changes how filesystem::permissions(p, perms) handles symlinks. Previously
symlinks were not resolved by default instead only getting resolved when
"perms::resolve_symlinks" was used. After this change symlinks are resolved
by default and perms::symlink_nofollow must be given to change this.
This issue has not yet been moved to Ready status, and I will revert if it
doesn't get moved at the current meeting. However I feel confident that it
will and it's nice to have implementations when moving issues.
llvm-svn: 273328
The filesystem tests were expecting the paths to the build/source directories
did not contain any symlinks. This patch resolves those symlinks before running
the test suite.
llvm-svn: 273323
Summary:
An implementation of std::experimental::propagate_const from Library Fundamentals Technical Specification v2.
No tests are provided for disallowed types like fancy pointers or function pointers as no code was written to handle these.
Reviewers: EricWF, mclow.lists
Differential Revision: http://reviews.llvm.org/D12486
llvm-svn: 273122
* Fix non-null violation in strstream.cpp
Overflow was calling memcpy with a null parameter and a size of 0.
* Fix std/atomics/atomics.flag/ tests:
a.test_and_set() was reading from an uninitialized atomic, but wasn't
using the value. The tests now clear the flag before performing the
first test_and_set. This allows UBSAN to test that clear doesn't read
an invalid value.
* Fix std/experimental/algorithms/alg.random.sample/sample.pass.cpp
The tests were dereferencing a past-the-end pointer to an array so that
they could do pointer arithmetic with it. Instead of dereference the iterator
I changed the tests to use the special 'base()' test iterator method.
* Add -fno-sanitize=float-divide-by-zero to suppress division by zero UBSAN diagnostics.
The tests that cause float division by zero are explicitly aware that they
are doing that. Since this is well defined for IEEE floats suppress the warnings
for now.
llvm-svn: 273107
Use strtof and strtod for floats and doubles respectively instead of
always using strtold. The other parts of the change are already implemented
in libc++.
This patch also has a drive by fix to wbuffer_convert::underflow() which
prevents it from calling memmove(buff, null, 0).
llvm-svn: 273106
Marshall Clow