The floating-point overloads of from_char are only declared if
_GLIBCXX_HAVE_USELOCALE is #defined as nonzero. That's exposed from
charconv as __cpp_lib_to_chars >= 201611L, so guard the test body with
that.
for libstdc++-v3/ChangeLog
PR c++/105324
* testsuite/20_util/from_chars/pr105324.cc: Guard test body
with conditional for floating-point overloads of from_char.
As with std::isdigit in r12-6281-gc83ecfbe74a5cf, we shouldn't be using
std::tolower in <charconv> either.
PR libstdc++/103911
libstdc++-v3/ChangeLog:
* src/c++17/floating_from_chars.cc (find_end_of_float): Accept
two delimeters for the exponent part in the form of a possibly
NULL string of length two. Don't use std::tolower.
(pattern): Adjust calls to find_end_of_float accordingly.
The hexfloat parser for binary32/64 added in r12-6645-gcc3bf3404e4b1c
overlooked that the exponent part can also begin with an uppercase 'P'.
PR libstdc++/105441
libstdc++-v3/ChangeLog:
* src/c++17/floating_from_chars.cc (__floating_from_chars_hex):
Also accept 'P' as the start of the exponent.
* testsuite/20_util/from_chars/7.cc: Add corresponding testcase.
The --with-long-double-abi=ibm build is missing some exports that are
present in the --with-long-double-abi=ieee build. Those symbols never
should have been exported at all, but now that they have been, they
should be exported consistently by both ibm and ieee.
This simply defines them as aliases for equivalent symbols that are
already present. The abi-tag on num_get::_M_extract_int isn't really
needed, because it only uses a std::string as a local variable, not in
the return type or function parameters, so it's safe to define the
_M_extract_int[abi:cxx11] symbols as aliases for the corresponding
function without the abi-tag.
This causes some new symbols to be added to the GLIBCXX_3.4.29 version
for the ibm long double build mode, but there is no advantage to adding
them to 3.4.30 for that build. That would just create more
inconsistencies.
libstdc++-v3/ChangeLog:
PR libstdc++/105417
* config/abi/post/powerpc64-linux-gnu/baseline_symbols.txt:
Regenerate.
* src/c++11/compatibility-ldbl-alt128.cc [_GLIBCXX_USE_DUAL_ABI]:
Define __gnu_ieee128::num_get<C>::_M_extract_int[abi:cxx11]<I>
symbols as aliases for corresponding symbols without abi-tag.
The following patch updates the Solaris baselines for GCC 12.1.
Tested on i386-pc-solaris2.11 and sparc-sun-solaris2.11 (Solaris 11.3
and 11.4 in each case).
The only (expected) difference between the 11.3 and 11.4 versions is
--- baseline_symbols.txt.s113s 2022-04-28 10:37:11.464068450 +0000
+++ baseline_symbols.txt.s114s 2022-04-27 16:54:31.995636805 +0000
@@ -4070,3 +4070,3 @@
-FUNC:_ZSt10from_charsPKcS0_RdSt12chars_format@@GLIBCXX_3.4.30
-FUNC:_ZSt10from_charsPKcS0_ReSt12chars_format@@GLIBCXX_3.4.30
-FUNC:_ZSt10from_charsPKcS0_RfSt12chars_format@@GLIBCXX_3.4.30
+FUNC:_ZSt10from_charsPKcS0_RdSt12chars_format@@GLIBCXX_3.4.29
+FUNC:_ZSt10from_charsPKcS0_ReSt12chars_format@@GLIBCXX_3.4.29
+FUNC:_ZSt10from_charsPKcS0_RfSt12chars_format@@GLIBCXX_3.4.29
which is handled by the fix for PR libstdc++/103407. I'm using the 11.4
version here.
2022-04-27 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
libstdc++-v3:
* config/abi/post/i386-solaris/baseline_symbols.txt: Regenerate.
* config/abi/post/i386-solaris/amd64/baseline_symbols.txt:
Likewise.
* config/abi/post/sparc-solaris/baseline_symbols.txt: Likewise.
* config/abi/post/sparc-solaris/sparcv9/baseline_symbols.txt:
Likewise.
The recursive calls to filesystem::copy should stop if any of them
reports an error.
libstdc++-v3/ChangeLog:
PR libstdc++/99290
* src/c++17/fs_ops.cc (fs::copy): Pass error_code to
directory_iterator constructor, and check on each iteration.
* src/filesystem/ops.cc (fs::copy): Likewise.
* testsuite/27_io/filesystem/operations/copy.cc: Check for
errors during recursion.
* testsuite/experimental/filesystem/operations/copy.cc:
Likewise.
The following patch updates baseline_symbols.txt on arches where I have
latest libstdc++ builds (my ws + Fedora package builds).
I've manually excluded:
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11IjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11IlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11ImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11ItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11IxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intB5cxx11IyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11IjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11IlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11ImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11ItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11IxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
+FUNC:_ZNKSt17__gnu_cxx_ieee1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intB5cxx11IyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_@@GLIBCXX_IEEE128_3.4.29
additions on ppc64le as those look unexpected.
Those symbols didn't show up in Fedora 11.3.1 build with recent glibc,
while other GLIBCXX_IEEE128_3.4.29 symbols are in 11.x already.
What this patch includes are only @@GLIBCXX_3.4.30 symbol additions, same
symbols on all files, except that powerpc64 adds also
_ZNSt17__gnu_cxx_ieee12816__convert_from_vERKP15__locale_structPciPKcz@@GLIBCXX_IEEE128_3.4.30
so everything included in the patch looks right to me.
2022-04-27 Jakub Jelinek <jakub@redhat.com>
* config/abi/post/x86_64-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/x86_64-linux-gnu/32/baseline_symbols.txt: Update.
* config/abi/post/i486-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/aarch64-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/s390x-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/powerpc-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/powerpc64-linux-gnu/baseline_symbols.txt: Update.
* config/abi/post/powerpc64-linux-gnu/32/baseline_symbols.txt: Update.
For the atomic specializations for shared_ptr and weak_ptr we can reuse
the existing SharedPointerPrinter, with a small tweak.
libstdc++-v3/ChangeLog:
* python/libstdcxx/v6/printers.py (SharedPointerPrinter): Add
support for atomic<shared_ptr<T>> and atomic<weak_ptr<T>>.
(StdAtomicPrinter): New printer.
(build_libstdcxx_dictionary): Register new printer.
* testsuite/libstdc++-prettyprinters/cxx11.cc: Test std::atomic.
* testsuite/libstdc++-prettyprinters/cxx20.cc: Test atomic smart
pointers.
This DR was approved at the February 2022 plenary.
libstdc++-v3/ChangeLog:
* include/bits/shared_ptr_atomic.h (atomic<shared_ptr>): Add
constructor for constant initialization from nullptr_t.
* testsuite/20_util/shared_ptr/atomic/atomic_shared_ptr.cc:
Check for new constructor.
This DR was approved at the February 2022 plenary.
libstdc++-v3/ChangeLog:
* include/bits/fs_path.h (hash<filesystem::path>): Define.
* testsuite/27_io/filesystem/path/nonmember/hash_value.cc:
Check std::hash specialization.
libstdc++-v3/ChangeLog:
* include/bits/ptr_traits.h (__cpp_lib_constexpr_memory): Define
conditionally.
* include/bits/unique_ptr.h (__cpp_lib_constexpr_memory):
Define for C++23.
(default_delete, default_delete<T[]>, __uniq_ptr_impl)
(unique_ptr, unique_ptr<T[], D>): Add constexpr to all member
functions.
* include/std/version (__cpp_lib_constexpr_memory): Define new
value for C++23.
* testsuite/20_util/unique_ptr/assign/constexpr.cc: New test.
* testsuite/20_util/unique_ptr/comparison/constexpr.cc: New test.
* testsuite/20_util/unique_ptr/cons/constexpr_c++20.cc: New test.
* testsuite/20_util/unique_ptr/creation/constexpr.cc: New test.
* testsuite/20_util/unique_ptr/modifiers/constexpr.cc: New test.
* testsuite/20_util/unique_ptr/specialized_algorithms/constexpr.cc:
New test.
This change was LWG 3117.
The test is copied from 20_util/function/cons/deduction.cc
libstdc++-v3/ChangeLog:
PR libstdc++/105375
* include/std/future (packaged_task): Add deduction guides.
* testsuite/30_threads/packaged_task/cons/deduction.cc: New test.
Re-using the std::span printer, this now shows the contents of the
initializer list instead of the pointer and length members.
Signed-off-by: Philipp Fent <fent@in.tum.de>
libstdc++-v3/ChangeLog:
* python/libstdcxx/v6/printers.py (StdSpanPrinter._iterator):
Rename as iterator.
(StdInitializerListPrinter): Define new printer.
(build_libstdcxx_dictionary): Register new printer.
* testsuite/libstdc++-prettyprinters/cxx11.cc: Check printer for
initializer_list.
<recording this here for future reference>
PR102994 "atomics: std::atomic<ptr>::wait is not marked const" raises the
issue that the current libstdc++ implementation marks the notify members
const, the implementation strategy used by libstdc++, as well as libc++
and the Microsoft STL, do not require the atomic to be mutable (it is hard
to conceive of a desirable implementation approach that would require it).
The original paper proposing the wait/notify functionality for atomics
(p1185) also had these members marked const for the first three revisions,
but that was changed without explanation in r3 and subsequent revisions of
the paper.
After raising the issue to the authors of p1185 and the author of the
libc++ implementation, the consensus seems to be "meh, it's harmless" so
there seems little appetite for an LWG issue to revisit the subject.
This patch changes the libstdc++ implementation to be in agreement with
the standard by removing const from those notify_one/notify_all members.
libstdc++-v3/ChangeLog:
PR libstdc++/102994
* include/bits/atomic_base.h (atomic_flag::notify_one,
notify_all): Remove const qualification.
(__atomic_base::notify_one, notify_all): Likewise.
* include/std/atomic (atomic<bool>::notify_one, notify_all):
Likewise.
(atomic::notify_one, notify_all): Likewise.
(atomic<T*>::notify_one, notify_all): Likewise.
(atomic_notify_one, atomic_notify_all): Likewise.
* testsuite/29_atomics/atomic/wait_notify/102994.cc: Adjust test
to account for change in notify_one/notify_all signature.
In starts_with_ci and in __floating_from_chars_hex's inf/nan handling,
we were assuming that the letters are contiguous and that 'A' + 32 == 'a'
which is true for ASCII but not for other character encodings.
This patch fixes starts_with_ci by using a constexpr lookup table that
maps uppercase letters to lowercase, and fixes __floating_from_chars_hex
by using __from_chars_alnum_to_val.
libstdc++-v3/ChangeLog:
* include/std/charconv (__from_chars_alnum_to_val_table):
Simplify initialization of __lower/__upper_letters.
(__from_chars_alnum_to_val): Default the template parameter to
false.
* src/c++17/floating_from_chars.cc (starts_with_ci): Don't
assume the uppercase and lowercase letters are contiguous.
(__floating_from_chars_hex): Likewise.
This makes the initializer for __table in __from_chars_alnum_to_val
dependent in an artificial way, which works around the reported modules
testsuite ICE by preventing the compiler from evaluating the initializer
parse time.
Compared to the alternative workaround of using a non-local class type
for __table, this workaround has the advantage of slightly speeding up
compilation of <charconv>, since now the table won't get built (via
constexpr evaluation) until the integer std::from_chars overload is
instantiated.
PR c++/105297
PR c++/105322
libstdc++-v3/ChangeLog:
* include/std/charconv (__from_chars_alnum_to_val): Make
initializer for __table dependent in an artificial way.
I'm not sure what I was thinking when I added this assertion, maybe it
was supposed to be alignment == 1 (which is what the pmr::string actually
uses). The simplest fix is to just remove the assertion.
The assertion is no longer enabled by default on trunk, but it's still
there for the --enablke-libstdcxx-debug build, and is still wrong. The
fix is needed on the gcc-11 branch.
libstdc++-v3/ChangeLog:
PR libstdc++/105324
* src/c++17/floating_from_chars.cc (buffer_resource::do_allocate):
Remove assertion.
* testsuite/20_util/from_chars/pr105324.cc: New test.
The macro being tested here is wrong, but just happens to have the same
value as the one supposed to be tests.
libstdc++-v3/ChangeLog:
* testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc:
Check correct feature test macro.
This fixes missing libiconv symbols when libstdc++ is built on a system
that has libiconv installed. If the libiconv headers are found then
libstdc++ depends on libiconv_open etc instead of libc's iconv_open. But
without this fix libstdc++ is not linked to the libiconv library that
provides the definitions of those symbols.
As discussed in PR 93602 this changed means that libstdc++.so.6 might
have an rpath pointing to the location of the libiconv.so library. If
that is not desired, then GCC must be configured to link to a static
libiconv.a instead, using either --with-libiconv-type=static or an
in-tree build of libiconv.
libstdc++-v3/ChangeLog:
PR libstdc++/93602
* doc/xml/manual/prerequisites.xml: Document libiconv
workarounds.
* doc/html/manual/setup.html: Regenerate.
* src/Makefile.am (CXXLINK): Add $(LTLIBICONV).
* src/Makefile.in: Regenerate.
Assertions were originally enabled in the compiled-in floating-point
std::to_chars implementation to help shake out any bugs, but they
apparently impose a significant performance penalty, most notably for
the hex formatting which is around 25% slower with assertions enabled.
This seems too high a cost for unconditionally enabling them.
The newly added calls to __builtin_unreachable work around the compiler
no longer knowing that the set of valid values of 'fmt' is limited (which
was previously upheld by an assert).
libstdc++-v3/ChangeLog:
* src/c++17/floating_to_chars.cc (_GLIBCXX_ASSERTIONS): Don't
define.
(__floating_to_chars_shortest): Add __builtin_unreachable calls to
squelch false-positive -Wmaybe-uninitialized and -Wreturn-type
warnings.
(__floating_to_chars_precision): Likewise.
This improves the debug output for C++20 spans.
Before:
{static extent = 18446744073709551615, _M_ptr = 0x7fffffffb9a8, _M_extent = {_M_extent_value = 2}}
Now with StdSpanPrinter:
std::span of length 2 = {1, 2}
Signed-off-by: Philipp Fent <fent@in.tum.de>
libstdc++-v3/ChangeLog:
* python/libstdcxx/v6/printers.py (StdSpanPrinter): Define.
* testsuite/libstdc++-prettyprinters/cxx20.cc: Test it.
Using == instead of = causes a configuration error with dash as the
shell:
checking whether to build libbacktrace support... /home/devel/building/work/src/gcc-12-20220417/libstdc++-v3/configure: 77471: test: auto: unexpected operator
/home/devel/building/work/src/gcc-12-20220417/libstdc++-v3/configure: 77474: test: auto: unexpected operator
auto
This means we fail to change the value from "auto" to "no" and so this
test passes:
GLIBCXX_CONDITIONAL(ENABLE_BACKTRACE, [test "$enable_libstdcxx_backtrace" != no])
This leads to the libbacktrace directory being included in the build
without being configured properly, and bootstrap fails.
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): Fix shell operators.
* configure: Regenerate.
In the first iteration of __from_chars_pow2_base's main loop, we need
to remember the value of the leading significant digit for sake of the
overflow check at the end (for base > 2).
This patch manually unrolls this first iteration so as to not encumber
the entire loop with logic that only the first iteration needs. This
seems to significantly improve performance:
Base Before After (seconds, lower is better)
2 9.36 9.37
8 3.66 2.93
16 2.93 1.91
32 2.39 2.24
libstdc++-v3/ChangeLog:
* include/std/charconv (__from_chars_pow2_base): Manually
unroll the first iteration of the main loop and simplify
accordingly.
This applies the following optimizations to the integer std::from_chars
implementation:
1. Use a lookup table for converting an alphanumeric digit to its
base-36 value instead of using a range test (for 0-9) and switch
(for a-z and A-Z). The table is constructed using a C++14
constexpr function which doesn't assume a particular character
encoding or __CHAR_BIT__ value. This new conversion function
__from_chars_alnum_to_val is templated on whether we care
only about the decimal digits, in which case we can perform the
conversion with a single subtraction since the digit characters
are guaranteed to be contiguous (unlike the letters).
2. Generalize __from_chars_binary to handle all power-of-two bases.
This function (now named __from_chars_pow2_base) is also templated
on whether we care only about the decimal digits for the benefit of
faster digit conversion for base 2, 4 and 8.
3. In __from_chars_digit, use
static_cast<unsigned char>(__c - '0') < __base
instead of
'0' <= __c && __c <= ('0' + (__base - 1)).
as the digit recognition test (exhaustively verified that the two
tests are equivalent).
4. In __from_chars_alnum, use a nested loop to consume the rest of the
digits in the overflow case (mirroring __from_chars_digit) so that
the main loop doesn't have to maintain the overflow flag __valid.
At this point, __from_chars_digit is nearly identical to
__from_chars_alnum, so this patch merges the two functions by removing
the former and templatizing the latter according to whether we care only
about the decimal digits. Finally,
5. In __from_chars_alnum, maintain a lower bound on the number of
unused bits in the result and use it to omit the overflow check
when it's safe to do so.
In passing, this patch replaces the non-portable function ascii_to_hexit
used by __floating_from_chars_hex with the new conversion function.
Some runtime measurements for a simple 15-line benchmark that roundtrips
printing/parsing 200 million integers via std::to/from_chars (average of
5 runs):
Base Before After (seconds, lower is better)
2 9.37 9.37
3 15.79 12.13
8 4.15 3.67
10 4.90 3.86
11 6.84 5.03
16 4.14 2.93
32 3.85 2.39
36 5.22 3.26
libstdc++-v3/ChangeLog:
* include/std/charconv (__from_chars_alnum_to_val_table): Define.
(__from_chars_alnum_to_val): Define.
(__from_chars_binary): Rename to ...
(__from_chars_pow2_base): ... this. Generalize to handle any
power-of-two base using __from_chars_alnum_to_val.
(__from_chars_digit): Optimize digit recognition to a single
test instead of two tests. Use [[__unlikely___]] attribute.
(__from_chars_alpha_to_num): Remove.
(__from_chars_alnum): Use __from_chars_alnum_to_val. Use a
nested loop for the overflow case. Maintain a lower bound
on the number of available bits in the result and use it to
omit the overflow check.
(from_chars): Adjust appropriately.
* src/c++17/floating_from_chars.cc (ascii_to_hexit): Remove.
(__floating_from_chars_hex): Use __from_chars_alnum_to_val
to recognize a hex digit instead.
The RISC-V port requires libatomic to be linked in order to resolve
various atomic functions, which results in builds that have
"--with-libstdcxx-lock-policy=auto" defaulting to mutex-based locks.
Changing this to direct atomics breaks the ABI, this forces the auto
detection mutex-based atomics on RISC-V in order to avoid a silent ABI
break for users.
See Bug 84568 for more discussion. In the long run there may be a way
to get the higher-performance atomics without an ABI flag day, but
that's going to be a much more complicated operation. We don't even
have support for the inline atomics yet, but given that some folks have
been discussing hacks to make these libatomic routines appear implicitly
it seems prudent to just turn off the automatic detection for RISC-V.
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_LOCK_POLICY): Force auto to mutex
for RISC-V.
* configure: Regenerate.
As reported in PR libbacktrace/105240, libbacktrace leaks memory when
using malloc for allocations. I originally thought it would be simpler
to just use malloc unconditionally (because it's supported on all
targets) but the leaks make that problematic.
This adds libbacktrace's detection for mmap to the libstdc++
configury, so that we use mmap.c and mmapio.c when possible. This avoids
the leaks seen previously, at least on linux.
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): Check for mmap.
* config.h.in: Regenerate.
* configure: Regenerate.
If a large stacktrace is reduced to a max depth that is less than half
the capacity it will now be reallocated to remove the unused capacity.
libstdc++-v3/ChangeLog:
* include/std/stacktrace (basic_stacktrace::current): Reallocate
a smaller container if the unused capacity is larger than the
used size.
Because std::basic_stacktrace<A> is an allocator-aware container its
elements should be initialized using allocator_traits<A>::construct and
destroyed using allocator_traits<A>::destroy.
This adds new _M_clone and _M_assign helper functions to construct
elements correctly and uses those functions instead of calling
std::uninitialized_copy_n.
The _Impl::_M_destroy function needs to be passed an allocator to
destroy the elements correctly, so is replaced by _M_resize which can
also be used to trim the container to a smaller size.
Because destroying and creating std::stacktrace_entry objects is cheap,
the copy/move assignment operators can just destroy all existing
elements and use _Impl._M_clone or _Impl._M_assign to create new ones.
libstdc++-v3/ChangeLog:
* include/std/stacktrace (basic_stacktrace): Use _Impl::_M_clone
or _Impl::_M_assign to initialize elements in allocated storage.
(basic_stacktrace::_M_clear()): Use _Impl::_M_resize instead of
_Impl::_M_destroy.
(basic_stacktrace::_Impl::_M_destroy()): Replace with ...
(basic_stacktrace::_Impl::_M_resize(size_type, allocator&)): New
function.
(basic_stacktrace::_Impl::_M_push_back): Use _M_xclone. Construct
new element using allocator.
(basic_stacktrace::_Impl::_M_clone): New function.
(basic_stacktrace::_Impl::_M_xclone): New function.
(basic_stacktrace::_Impl::_M_assign): New function.
We can avoid the overhead of handling a bad_alloc exception from
std::allocator<std::stacktrace_entry>::allocate by just calling the
nothrow operator new instead.
libstdc++-v3/ChangeLog:
* include/std/stacktrace (basic_stacktrace::_Impl::_M_allocate):
Use nothrow new instead of try block for std::allocator.
(basic_stacktrace::_Impl::_M_deallocate): Use delete for
std::allocator.
This adds an alternative callback for use in the overload of
basic_stacktrace::current that takes a max_depth parameter. The new
callback will not allow the container to grow past the initial capacity,
which is set to the specified maximum depth. This avoids allocating
memory for hundreds of frames only to discard them again because of a
small maximum depth limit.
For larger maximum depths the normal callback is used, with a smaller
initial capacity that can grow as needed. The container will be resized
to the given max depth after the entire backtrace has been produced
(relying on the fact that std::stacktrace_entry objects are trivially
destructible to elide their destruction).
Currently the value for "larger" limits is 128, so a max depth <= 128
will allocate capacity for exactly that many frames. A larger max depth
(or an unspecified max depth) will use an initial capacity of 64 frames
and grow as needed. Since each frame is only a uintptr_t value it might
be reasonable to increase the first value so that memory usage can be
capped for larger maximum depths.
This change also delays the creation of the libbacktrace state until we
actually need it, so that the state is not created if allocation fails.
libstdc++-v3/ChangeLog:
* include/std/stacktrace (basic_stacktrace::current): Replace
calls to _M_reserve and _S_curr_cb with call to _M_prepare.
Check return value of backtrace_simple when max depth given.
(basic_stacktrace::_M_reserve): Remove.
(basic_stacktrace::_S_curr_cb): Remove.
(basic_stacktrace::_M_prepare(size_type)): New function to
reserve initial capacity and return callback.
(basic_stacktrace::_Impl::_M_allocate): Remove check for 0 < n
and remove redundant zeroing of _M_frames and _M_capacity.
(basic_stacktrace::_Impl::_M_push_back): Add [[unlikely]]
attribute. Assign _Impl instead of swapping.
* testsuite/19_diagnostics/stacktrace/current.cc: New test.
