From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 026E23858C27; Wed, 8 Dec 2021 23:47:12 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 026E23858C27 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 r12-5848] libstdc++: Fix undefined shift when _Atomic_word is 64-bit X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: b77968a70537429b4f548f90c369d26e6b6943cc X-Git-Newrev: c15aa46cca0649b68613d3292cf71c7cc57ef78f Message-Id: <20211208234712.026E23858C27@sourceware.org> Date: Wed, 8 Dec 2021 23:47:12 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Dec 2021 23:47:12 -0000 https://gcc.gnu.org/g:c15aa46cca0649b68613d3292cf71c7cc57ef78f commit r12-5848-gc15aa46cca0649b68613d3292cf71c7cc57ef78f Author: Jonathan Wakely Date: Wed Dec 8 19:36:24 2021 +0000 libstdc++: Fix undefined shift when _Atomic_word is 64-bit The check for _Atomic_word being 32-bit is just a normal runtime condition for C++11 and C++14, because it doesn't use if-constexpr. That means the 1LL << (CHAR_BIT * sizeof(_Atomic_word)) expression expands to 1LL << 64 on Solaris, which is ill-formed. This adds another indirection so that the shift width is zero if the code is unreachable. libstdc++-v3/ChangeLog: * include/bits/shared_ptr_base.h (_Sp_counted_base::_M_release()): Make shift width conditional on __double_word condition. Diff: --- libstdc++-v3/include/bits/shared_ptr_base.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h index 90ad30947b0..f315d8f354f 100644 --- a/libstdc++-v3/include/bits/shared_ptr_base.h +++ b/libstdc++-v3/include/bits/shared_ptr_base.h @@ -325,8 +325,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr bool __aligned = __alignof(long long) <= alignof(void*); if _GLIBCXX17_CONSTEXPR (__lock_free && __double_word && __aligned) { - constexpr long long __unique_ref - = 1LL + (1LL << (__CHAR_BIT__ * sizeof(_Atomic_word))); + constexpr int __wordbits = __CHAR_BIT__ * sizeof(_Atomic_word); + constexpr int __shiftbits = __double_word ? __wordbits : 0; + constexpr long long __unique_ref = 1LL + (1LL << __shiftbits); auto __both_counts = reinterpret_cast(&_M_use_count); _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);