From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id AE87B3858401; Thu, 1 Jun 2023 15:09:43 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org AE87B3858401 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1685632183; bh=ivdGfNqr1P6weryhYYEmNa0TTXZ5MGx7RZ8ysBqDqZg=; h=From:To:Subject:Date:From; b=x4RlQgWOy2ms0Hm6JGDFRpDEKEo50n5lc72jh3WbpEM2guadHyqoVKQTy3nDeXyOb y3x2CwQHsVDLtt/mYRuuLfAuI6teHPBlNfx78LEPckKaEt60jVHv6LQlHImMMvotBg FC7jlWz7tW96KX9Yyttv0Zms7CwR/XmphGETmHqQ= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jonathan Wakely To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r14-1470] libstdc++: Fix code size regressions in std::vector [PR110060] X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: 8cbaf679a3c1875c5475bd1cb0fb86fb9d03b2d4 X-Git-Newrev: b7b255e77a271974479c34d1db3daafc04b920bc Message-Id: <20230601150943.AE87B3858401@sourceware.org> Date: Thu, 1 Jun 2023 15:09:43 +0000 (GMT) List-Id: https://gcc.gnu.org/g:b7b255e77a271974479c34d1db3daafc04b920bc commit r14-1470-gb7b255e77a271974479c34d1db3daafc04b920bc Author: Jonathan Wakely Date: Thu Jun 1 10:26:10 2023 +0100 libstdc++: Fix code size regressions in std::vector [PR110060] My r14-1452-gfb409a15d9babc change to add optimization hints to std::vector causes regressions because it makes std::vector::size() and std::vector::capacity() too big to inline. That's the opposite of what I wanted, so revert the changes to those functions. To achieve the original aim of optimizing vec.assign(vec.size(), x) we can add a local optimization hint to _M_fill_assign, so that it doesn't affect all other uses of size() and capacity(). Additionally, add the same hint to the _M_assign_aux overload for forward iterators and add that to the testcase. It would be nice to similarly optimize: if (vec1.size() == vec2.size()) vec1 = vec2; but adding hints to operator=(const vector&) doesn't help. Presumably the relationships between the two sizes and two capacities are too complex to track effectively. libstdc++-v3/ChangeLog: PR libstdc++/110060 * include/bits/stl_vector.h (_Vector_base::_M_invariant): Remove. (vector::size, vector::capacity): Remove calls to _M_invariant. * include/bits/vector.tcc (vector::_M_fill_assign): Add optimization hint to reallocating path. (vector::_M_assign_aux(FwdIter, FwdIter, forward_iterator_tag)): Likewise. * testsuite/23_containers/vector/capacity/invariant.cc: Moved to... * testsuite/23_containers/vector/modifiers/assign/no_realloc.cc: ...here. Check assign(FwdIter, FwdIter) too. * testsuite/23_containers/vector/types/1.cc: Revert addition of -Wno-stringop-overread option. Diff: --- libstdc++-v3/include/bits/stl_vector.h | 23 +--------------------- libstdc++-v3/include/bits/vector.tcc | 17 +++++++++++----- .../assign/no_realloc.cc} | 6 ++++++ .../testsuite/23_containers/vector/types/1.cc | 2 +- 4 files changed, 20 insertions(+), 28 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h index e593be443bc..70ced3d101f 100644 --- a/libstdc++-v3/include/bits/stl_vector.h +++ b/libstdc++-v3/include/bits/stl_vector.h @@ -389,23 +389,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER protected: - __attribute__((__always_inline__)) - _GLIBCXX20_CONSTEXPR void - _M_invariant() const - { -#if __OPTIMIZE__ - if (this->_M_impl._M_finish < this->_M_impl._M_start) - __builtin_unreachable(); - if (this->_M_impl._M_finish > this->_M_impl._M_end_of_storage) - __builtin_unreachable(); - - size_t __sz = this->_M_impl._M_finish - this->_M_impl._M_start; - size_t __cap = this->_M_impl._M_end_of_storage - this->_M_impl._M_start; - if (__sz > __cap) - __builtin_unreachable(); -#endif - } - _GLIBCXX20_CONSTEXPR void _M_create_storage(size_t __n) @@ -1005,10 +988,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR size_type size() const _GLIBCXX_NOEXCEPT - { - _Base::_M_invariant(); - return size_type(this->_M_impl._M_finish - this->_M_impl._M_start); - } + { return size_type(this->_M_impl._M_finish - this->_M_impl._M_start); } /** Returns the size() of the largest possible %vector. */ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR @@ -1095,7 +1075,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER size_type capacity() const _GLIBCXX_NOEXCEPT { - _Base::_M_invariant(); return size_type(this->_M_impl._M_end_of_storage - this->_M_impl._M_start); } diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc index d6fdea2dd01..acd11e2dc68 100644 --- a/libstdc++-v3/include/bits/vector.tcc +++ b/libstdc++-v3/include/bits/vector.tcc @@ -270,15 +270,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER vector<_Tp, _Alloc>:: _M_fill_assign(size_t __n, const value_type& __val) { + const size_type __sz = size(); if (__n > capacity()) { + if (__n <= __sz) + __builtin_unreachable(); vector __tmp(__n, __val, _M_get_Tp_allocator()); __tmp._M_impl._M_swap_data(this->_M_impl); } - else if (__n > size()) + else if (__n > __sz) { std::fill(begin(), end(), __val); - const size_type __add = __n - size(); + const size_type __add = __n - __sz; _GLIBCXX_ASAN_ANNOTATE_GROW(__add); this->_M_impl._M_finish = std::__uninitialized_fill_n_a(this->_M_impl._M_finish, @@ -316,10 +319,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _M_assign_aux(_ForwardIterator __first, _ForwardIterator __last, std::forward_iterator_tag) { + const size_type __sz = size(); const size_type __len = std::distance(__first, __last); if (__len > capacity()) { + if (__len <= __sz) + __builtin_unreachable(); + _S_check_init_len(__len, _M_get_Tp_allocator()); pointer __tmp(_M_allocate_and_copy(__len, __first, __last)); std::_Destroy(this->_M_impl._M_start, this->_M_impl._M_finish, @@ -332,14 +339,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER this->_M_impl._M_finish = this->_M_impl._M_start + __len; this->_M_impl._M_end_of_storage = this->_M_impl._M_finish; } - else if (size() >= __len) + else if (__sz >= __len) _M_erase_at_end(std::copy(__first, __last, this->_M_impl._M_start)); else { _ForwardIterator __mid = __first; - std::advance(__mid, size()); + std::advance(__mid, __sz); std::copy(__first, __mid, this->_M_impl._M_start); - const size_type __attribute__((__unused__)) __n = __len - size(); + const size_type __attribute__((__unused__)) __n = __len - __sz; _GLIBCXX_ASAN_ANNOTATE_GROW(__n); this->_M_impl._M_finish = std::__uninitialized_copy_a(__mid, __last, diff --git a/libstdc++-v3/testsuite/23_containers/vector/capacity/invariant.cc b/libstdc++-v3/testsuite/23_containers/vector/modifiers/assign/no_realloc.cc similarity index 70% rename from libstdc++-v3/testsuite/23_containers/vector/capacity/invariant.cc rename to libstdc++-v3/testsuite/23_containers/vector/modifiers/assign/no_realloc.cc index d68db694add..659f18dba56 100644 --- a/libstdc++-v3/testsuite/23_containers/vector/capacity/invariant.cc +++ b/libstdc++-v3/testsuite/23_containers/vector/modifiers/assign/no_realloc.cc @@ -1,5 +1,6 @@ // { dg-do compile } // { dg-options "-O3 -g0" } +// { dg-require-normal-mode "" } // { dg-final { scan-assembler-not "_Znw" } } // GCC should be able to optimize away the paths involving reallocation. @@ -14,3 +15,8 @@ void fill_val(std::vector& vec, int i) { vec.assign(vec.size(), i); } + +void fill_range(std::vector& vec, const int* first) +{ + vec.assign(first, first + vec.size()); +} diff --git a/libstdc++-v3/testsuite/23_containers/vector/types/1.cc b/libstdc++-v3/testsuite/23_containers/vector/types/1.cc index 9be07d9fd5c..079e5af9556 100644 --- a/libstdc++-v3/testsuite/23_containers/vector/types/1.cc +++ b/libstdc++-v3/testsuite/23_containers/vector/types/1.cc @@ -18,7 +18,7 @@ // . // { dg-do compile } -// { dg-options "-Wno-unused-result -Wno-stringop-overread" } +// { dg-options "-Wno-unused-result" } #include #include