diff options
| author | Jonathan Wakely <jwakely@redhat.com> | 2021-12-08 19:36:24 +0000 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2021-12-08 23:41:03 +0000 |
| commit | c15aa46cca0649b68613d3292cf71c7cc57ef78f (patch) | |
| tree | fa11127d7fef8066bda5f640cbd3ffda7c2c52cc | |
| parent | b77968a70537429b4f548f90c369d26e6b6943cc (diff) | |
| download | gcc-c15aa46cca0649b68613d3292cf71c7cc57ef78f.zip gcc-c15aa46cca0649b68613d3292cf71c7cc57ef78f.tar.gz gcc-c15aa46cca0649b68613d3292cf71c7cc57ef78f.tar.bz2 | |
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.
| -rw-r--r-- | libstdc++-v3/include/bits/shared_ptr_base.h | 5 |
1 files 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 90ad309..f315d8f 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<long long*>(&_M_use_count); _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count); |