This is an archive of the discontinued LLVM Phabricator instance.

Differential D96063

[🍒]Disable CFI in __get_elem to allow casting a pointer to uninitialized memory
ClosedPublic

Authored by ldionne on Feb 4 2021, 10:38 AM.

Details

Reviewers
tstellar
Group Reviewers
Restricted Project
Summary

Fixes usage of shared_ptr with CFI enabled, which is llvm.org/pr48993.

(cherry pick of commit bab74864168bb5e28ecbc0294fe1095d8da7f569)

Diff Detail

Event Timeline

ldionne created this revision.Feb 4 2021, 10:38 AM
Herald added a subscriber: jkorous. · View Herald TranscriptFeb 4 2021, 10:38 AM
ldionne requested review of this revision.Feb 4 2021, 10:38 AM
Herald added a project: Restricted Project. · View Herald TranscriptFeb 4 2021, 10:38 AM
Herald added a reviewer: Restricted Project. · View Herald Transcript
Herald added a subscriber: libcxx-commits. · View Herald Transcript
tstellar accepted this revision.Feb 4 2021, 10:39 AM

LGTM.

Harbormaster completed remote builds in B87956: Diff 321510.Feb 5 2021, 3:39 PM
ldionne accepted this revision as: Restricted Project.Feb 8 2021, 10:49 AM
This revision is now accepted and ready to land.Feb 8 2021, 10:49 AM
ldionne closed this revision.Feb 8 2021, 10:51 AM

bc39d53d9a4f1ed7c903648f3fd408296fd55c95

Revision Contents

PathSize
libcxx/
include/
2 lines

Diff 321510

libcxx/include/memory

Show First 20 Lines • Show All 2,641 Lines • ▼ Show 20 Lines struct _ALIGNAS_TYPE(_CompressedPair) _Storage {
__get_alloc()->~_Alloc(); __get_alloc()->~_Alloc();
} }
_Alloc* __get_alloc() _NOEXCEPT { _Alloc* __get_alloc() _NOEXCEPT {
_CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_); _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
typename _CompressedPair::_Base1* __first = _CompressedPair::__get_first_base(__as_pair); typename _CompressedPair::_Base1* __first = _CompressedPair::__get_first_base(__as_pair);
_Alloc *__alloc = reinterpret_cast<_Alloc*>(__first); _Alloc *__alloc = reinterpret_cast<_Alloc*>(__first);
return __alloc; return __alloc;
} }
_Tp* __get_elem() _NOEXCEPT { _LIBCPP_NO_CFI _Tp* __get_elem() _NOEXCEPT {
_CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_); _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair); typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair);
_Tp *__elem = reinterpret_cast<_Tp*>(__second); _Tp *__elem = reinterpret_cast<_Tp*>(__second);
return __elem; return __elem;
} }
}; };
static_assert(_LIBCPP_ALIGNOF(_Storage) == _LIBCPP_ALIGNOF(_CompressedPair), ""); static_assert(_LIBCPP_ALIGNOF(_Storage) == _LIBCPP_ALIGNOF(_CompressedPair), "");
▲ Show 20 Lines • Show All 1,636 Lines • Show Last 20 Lines