Fix data race when _Safe_iterator_base::_M_detach() runs concurrently with
the _Safe_container_base destructor.
PR libstdc++/91910
* src/c++11/debug.cc (_Safe_iterator_base::_M_detach()): Load pointer
atomically and lock the mutex before accessing the sequence.
(_Safe_local_iterator_base::_M_detach()): Likewise.
(_Safe_iterator_base::_M_reset()): Clear _M_sequence atomically.
From-SVN: r276184
The __index_type is only ever unsigned char or unsigned short, so not
the same type as size_t.
* include/std/variant (variant::index()): Remove impossible case.
From-SVN: r276100
PR libstdc++/91871
* testsuite/util/testsuite_hooks.h
(conversion::iterator_to_const_iterator()): Do not return an invalid
iterator. Test direct-initialization and direct-list-initialization
as well as implicit conversion.
From-SVN: r276091
If __index_type is a smaller type than size_t, then the result of
size_t(__index_type(-1)) is not equal to size_t(-1), but to an incorrect
value such as size_t(255) or size_t(65535). The old implementation of
variant<T...>::index() uses (size_t(__index_type(_M_index + 1)) - 1)
which is always correct, but generates suboptimal code for many common
cases.
When the __index_type is size_t or valueless variants are not possible
we can just return the value directly.
When the number of alternatives is sufficiently small the result of
converting the _M_index value to the corresponding signed type will be
either non-negative or -1. In those cases converting to the signed type
and then to size_t will either produce the correct positive value or
will sign extend -1 to (size_t)-1 as desired.
For the remaining case we keep the existing arithmetic operations to
ensure the correct result.
PR libstdc++/91788 (partial)
* include/std/variant (variant::index()): Improve codegen for cases
where conversion to size_t already works correctly.
From-SVN: r276056
PR libstdc++/91748
* include/bits/stl_algo.h (for_each_n): Fix random access iterator
case.
* testsuite/25_algorithms/for_each/for_each_n.cc: Test with random
access iterators.
From-SVN: r275683
* testsuite/20_util/result_of/sfinae_friendly_1.cc: Add -Wno-volatile
for C++2a and up. Define HAS_52748_FIXED and fix incorrect tests.
* testsuite/tr1/3_function_objects/result_of.cc: Add -Wno-volatile
for C++2a and up.
From-SVN: r275643
The standard requires overloads of std::to_chars for char and (un)signed
integer types. This means that our constrained function template is
non-conforming, because the difference is observable when using types
that convert to an integer (e.g. wchar_t, which promotes).
As well as defining the deleted bool overload for LWG 3266, replace the
constrained function template with overloads for each type.
* include/std/charconv (to_chars): Rename to __to_chars_i. Define
non-template overloads for each signed and unsigned integer type and
char. Define deleted overload for bool (LWG 3266).
* testsuite/20_util/to_chars/1_neg.cc: Remove.
* testsuite/20_util/to_chars/3.cc: New test.
* testsuite/20_util/to_chars/lwg3266.cc: New test.
From-SVN: r275588
The main difference with existing support is that function addresses
are function descriptor addresses instead. This means that all code
dealing with function pointers now has to cope with function
descriptors instead.
For the same reason, Linux kernel helpers can no longer be called by
dereferencing their address, so we implement wrappers that directly
call the kernel helpers.
When restoring a function address, we also have to restore the FDPIC
register value (r9).
2019-09-10 Christophe Lyon <christophe.lyon@st.com>
Mickaël Guêné <mickael.guene@st.com>
gcc/
* ginclude/unwind-arm-common.h (unwinder_cache): Add reserved5
field.
libgcc/
* config/arm/linux-atomic.c (__kernel_cmpxchg): Add FDPIC support.
(__kernel_dmb): Likewise.
(__fdpic_cmpxchg): New function.
(__fdpic_dmb): New function.
* config/arm/unwind-arm.h (FDPIC_REGNUM): New define.
(gnu_Unwind_Find_got): New function.
(_Unwind_decode_typeinfo_ptr): Add FDPIC support.
* unwind-arm-common.inc (UCB_PR_GOT): New.
(funcdesc_t): New struct.
(get_eit_entry): Add FDPIC support.
(unwind_phase2): Likewise.
(unwind_phase2_forced): Likewise.
(__gnu_Unwind_RaiseException): Likewise.
(__gnu_Unwind_Resume): Likewise.
(__gnu_Unwind_Backtrace): Likewise.
* unwind-pe.h (read_encoded_value_with_base): Likewise.
libstdc++/
* libsupc++/eh_personality.cc (get_ttype_entry): Add FDPIC
support.
Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
From-SVN: r275568
Define partial specializations for std::remove_cv so that
std::remove_const and std::remove_volatile don't need to be
instantiated.
* include/std/type_traits (__remove_cv_t): New alias template.
(is_void, is_integral, is_floating_point, is_pointer)
(is_member_object_pointer, is_member_function_pointer, is_null_pointer)
(is_member_point), __is_signed_integer, __is_unsigned_integer)
(__make_unsigned_selector, __make_signed_selector, remove_pointer)
(__decay_selector): Use __remove_cv_t.
(remove_cv): Add partial specializations for cv-qualified types.
(__decay_t): New alias template.
(__decay_and_strip, __common_type_impl, __result_of_impl): Use
__decay_t.
(__enable_if_t): Move earlier in the file.
(_Require): Use __enable_if_t.
(swap(T&, T&)): Use _Require.
(swap(T(&)[N])): Use __enable_if_t.
From-SVN: r275562
__to_chars_10_impl is quite fast. According to the IACA the main loop
takes only 6.0 cycles, the whole function with one iteration takes
10.0 cycles. Replacing the __first[pos] and __first[pos - 1] with
__first[0] and __first[1] drops the function time to 7.53 cycles.
2019-09-09 Antony Polukhin <antoshkka@gmail.com>
* include/bits/charconv.h (__detail::__to_chars_10_impl): Replace
final offsets with constants.
From-SVN: r275514
This patch simplifies the constraints on the constructors from arrays by
removing the redundant checks that element_type and value_type are
convertible to element_type. The incorrect uses of __adl_data in those
constructors are removed as well (they should use std::data not
std::ranges::data, and the former doesn't use ADL).
The range/container constructors are now constrained to exclude all
specializations of std::span, not just the current instantiation. The
range constructor now also checks s subset of the contiguous_range
requirements.
All relevant constructor constraints now use the _Require helper in
order to short circuit and avoid unnecessary instantiations after the
first failed constraint.
A new constructor supports initialization from different specializations
of std::span<OtherType, OtherExtent>, as specified in the C++20 draft.
* include/bits/range_access.h (__adl_to_address): Remove.
* include/std/span (__is_base_derived_safe_convertible_v): Replace
with span::__is_compatible.
(__is_std_array_v): Replace with __is_std_array class template and
partial specializations.
(__is_std_array, __is_std_span): New class templates and partial
specializations.
(span::__is_compatible): New alias template for SFINAE constraints.
(span::span(element_type (&)[N])): Remove redundant constraints. Do
not use __adl_data to obtain a pointer.
(span::span(array<value_type, N>&)): Likewise.
(span::span(const array<value_type, N>&)): Likewise.
[_GLIBCXX_P1394] (span::iter_reference_t, span::iterator_t)
(span::iter_value_t, span::derived_from): New alias templates for
SFINAE constraints, until the equivalents are supported in <concepts>
and <iterator>.
[_GLIBCXX_P1394] (span::__is_compatible_iterator): New alias template
for SFINAE constraints.
[_GLIBCXX_P1394] (span::is_compatible_range): New class template for
SFINAE constraints.
[_GLIBCXX_P1394] (span::span(Range&&)): Improve constraints.
[_GLIBCXX_P1394] (span::span(ContiguousIterator, Sentinel)): Likewise.
Use std::to_address instead of __adl_to_address.
[_GLIBCXX_P1394] (span::span(ContiguousIterator, size_type)): Likewise.
[!_GLIBCXX_P1394] (span::__is_compatible_container): New alias
template for SFINAE constraints.
[!_GLIBCXX_P1394] (span::span(Container&))
(span::span(const Container&)): Improve constraints.
[!_GLIBCXX_P1394] (span::span(pointer, size_type))
(span::span(pointer, pointer)): Remove redundant cast of pointer.
(span(const span<OType, OExtent>&)): New constructor.
From-SVN: r275513
The URL for the "What Are Allocators Good For?" article has been a
recurring source of problems. It moved from the C/C++ Users Journal
website to the Dr Dobbs site after CUJ shut down, and the original
domain changed hands, leaving old links pointing to nefarious sites.
Now the URL to the copy on drdobbs.com no longer works either and I
can't find a (legal) copy of the article online. The simplest solution
is to remove the URL.
* doc/xml/manual/allocator.xml: Remove URL for bibliography entry.
* doc/html/*: Regenerate.
From-SVN: r275398
The pthread_cond_clockwait function is available in glibc since the 2.30
release. If this function is available in the C library it can be used
to fix PR libstdc++/41861 by supporting std::chrono::steady_clock
properly with std::condition_variable.
This means that code using std::condition_variable::wait_for or
std::condition_variable::wait_until with std::chrono::steady_clock is no
longer subject to timing out early or potentially waiting for much
longer if the system clock is warped at an inopportune moment.
If pthread_cond_clockwait is available then std::chrono::steady_clock is
deemed to be the "best" clock available which means that it is used for
the relative wait_for calls and absolute wait_until calls using
user-defined clocks. Calls explicitly using std::chrono::system_clock
continue to use CLOCK_REALTIME via __gthread_cond_timedwait.
If pthread_cond_clockwait is not available then
std::chrono::system_clock is deemed to be the "best" clock available
which means that the previous suboptimal behaviour remains.
2019-09-04 Mike Crowe <mac@mcrowe.com>
PR libstdc++/41861
* acinclude.m4 (GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT): Check for new
pthread_cond_clockwait function.
* configure.ac: Use GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT.
* configure: Regenerate.
* config.h.in: Regenerate.
* include/std/condition_variable: (condition_variable): Rename
__steady_clock_t typedef and add system_clock. Change __clock_t to be
a typedef for the preferred clock to convert arbitrary other clocks to.
[_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (wait_until): Add a steady_clock
overload.
(wait_until): Change __clock_t overload to use system_clock.
[_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT] (__wait_until_impl): Add
steady_clock overload that calls pthread_cond_clockwait.
(__wait_until_impl): Change __clock_t overload to use system_clock.
(condition_variable_any) [_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT]: Use
steady_clock for __clock_t if pthread_cond_clockwait is available.
From-SVN: r275390
2019-09-04 Mike Crowe <mac@mcrowe.com>
* testsuite/30_threads/condition_variable/members/2.cc (test01):
Parameterise so that test can be run against an arbitrary clock.
(main): Test using std::chrono::steady_clock and a user-defined
clock in addition to the previous std::chrono::system_clock.
* testsuite/30_threads/condition_variable_any/members/2.cc: Likewise.
From-SVN: r275389
2019-09-03 Chung-Lin Tang <cltang@codesourcery.com>
libatomic/
PR other/79543
* acinclude.m4 (LIBAT_CHECK_LINKER_FEATURES): Fix GNU ld --version
scanning to conform to the GNU Coding Standards.
* configure: Regenerate.
libffi/
PR other/79543
* acinclude.m4 (LIBAT_CHECK_LINKER_FEATURES): Fix GNU ld --version
scanning to conform to the GNU Coding Standards.
* configure: Regenerate.
libgomp/
PR other/79543
* acinclude.m4 (LIBGOMP_CHECK_LINKER_FEATURES): Fix GNU ld --version
scanning to conform to the GNU Coding Standards.
* configure: Regenerate.
libitm/
PR other/79543
* acinclude.m4 (LIBITM_CHECK_LINKER_FEATURES): Fix GNU ld --version
scanning to conform to the GNU Coding Standards.
* configure: Regenerate.
libstdc++-v3/
PR other/79543
* acinclude.m4 (GLIBCXX_CHECK_LINKER_FEATURES): Fix GNU ld --version
scanning to conform to the GNU Coding Standards.
* configure: Regenerate.
From-SVN: r275341
Bunch of micro optimizations for std::to_chars:
* For base == 8 replacing the lookup in __digits table with arithmetic
computations leads to a same CPU cycles for a loop (exchanges two movzx
with 3 bit ops). However this saves 129 bytes of data and totally avoids
a chance of cache misses on __digits.
* For base == 16 replacing the lookup in __digits table with
arithmetic computations leads to a few additional instructions, but
totally avoids a chance of cache misses on __digits (- ~9 cache misses
for worst case) and saves 513 bytes of const data.
* Replacing __first[pos] and __first[pos - 1] with __first[1] and
__first[0] on final iterations saves ~2% of code size.
* Removing trailing '\0' from arrays of digits allows the linker to
merge the symbols (so that "0123456789abcdefghijklmnopqrstuvwxyz" and
"0123456789abcdef" could share the same address). This improves data
locality and reduces binary sizes.
* Using __detail::__to_chars_len_2 instead of a generic
__detail::__to_chars_len makes the operation O(1) instead of O(N). It
also makes the code two times shorter.
In sum: this significantly reduces the size of a binary (for about 4KBs
only for base-8 conversion), deals with latency (CPU cache misses)
without changing the iterations count and without adding costly
instructions into the loops.
2019-08-30 Antony Polukhin <antoshkka@gmail.com>
* include/std/charconv (__detail::__to_chars_8)
__detail::__to_chars_16): Replace array of precomputed digits with
arithmetic operations to avoid CPU cache misses. Remove zero
termination from array of digits to allow symbol merge with generic
implementation of __detail::__to_chars. Replace final offsets with
constants. Use __detail::__to_chars_len_2 instead of a generic
__detail::__to_chars_len.
(__detail::__to_chars): Remove zero termination from array of digits.
(__detail::__to_chars_2): Leading digit is always '1'.
From-SVN: r275205
The memmove optimizations for std::uninitialized_copy/fill/_n will
compile even if the type is not copy constructible, because std::copy
doesn't require copy construction to work. But the uninitialized
algorithms do require it.
This adds explicit static assertions to ensure we don't allow ill-formed
initializations.
PR libstdc++/89164
* include/bits/stl_algobase.h (__copy_move): Give descriptive names
to template parameters.
* include/bits/stl_uninitialized.h (uninitialized_copy)
(uninitialized_fill, uninitialized_fill_n): Add static assertions to
diagnose invalid uses.
* testsuite/20_util/specialized_algorithms/uninitialized_copy/1.cc:
Adjust expected error.
* testsuite/20_util/specialized_algorithms/uninitialized_copy/89164.cc:
New test.
* testsuite/20_util/specialized_algorithms/uninitialized_copy_n/
89164.cc: New test.
* testsuite/20_util/specialized_algorithms/uninitialized_fill/89164.cc:
New test.
* testsuite/20_util/specialized_algorithms/uninitialized_fill_n/
89164.cc: New test.
* testsuite/23_containers/vector/cons/89164.cc: New test.
* testsuite/23_containers/vector/cons/89164_c++17.cc: New test.
From-SVN: r275177
