diff options
| author | Akira Hatanaka <ahatanaka@apple.com> | 2017-05-11 05:58:52 +0000 |
|---|---|---|
| committer | Akira Hatanaka <ahatanaka@apple.com> | 2017-05-11 05:58:52 +0000 |
| commit | e8b16fa9d547942f8d68af852fb1b25aae85f2a5 (patch) | |
| tree | 5ec9c3a14068040626ded062db68ccae97906a87 /src/cxa_exception.hpp | |
| parent | 97146e2a61d690531be6441da3a482e6603832ad (diff) | |
[libcxxabi] Align unwindHeader on a double-word boundary.
r276215 made a change to annotate _Unwind_Exception with attribute
"aligned" so that an exception object following field __cxa_exception
is sufficiently aligned. This fix hasn't been incorporated to unwind.h
on Darwin since it is an ABI breaking change.
Instead of annotating struct _Unwind_Exception with the attribute, this
commit annotates field unwindHeader of __cxa_exception. This ensures the
exception object is sufficiently aligned without breaking the ABI.
rdar://problem/25364625
Differential Revision: https://reviews.llvm.org/D33030
git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@302763 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'src/cxa_exception.hpp')
| -rw-r--r-- | src/cxa_exception.hpp | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/cxa_exception.hpp b/src/cxa_exception.hpp index c009db4..2d34698 100644 --- a/src/cxa_exception.hpp +++ b/src/cxa_exception.hpp @@ -61,7 +61,13 @@ struct _LIBCXXABI_HIDDEN __cxa_exception { size_t referenceCount; #endif - _Unwind_Exception unwindHeader; + // This field is annotated with attribute aligned so that the exception + // object following the field is sufficiently aligned and there is no + // gap between the field and the exception object. r276215 made a change to + // annotate _Unwind_Exception with __attribute__((aligned)), but we cannot + // incorporate the fix on Darwin since it is an ABI-breaking change, which + // is why we need the attribute on this field. + _Unwind_Exception unwindHeader __attribute__((aligned)); }; // http://sourcery.mentor.com/archives/cxx-abi-dev/msg01924.html @@ -96,7 +102,9 @@ struct _LIBCXXABI_HIDDEN __cxa_dependent_exception { void* primaryException; #endif - _Unwind_Exception unwindHeader; + // See the comment in __cxa_exception as to why this field has attribute + // aligned. + _Unwind_Exception unwindHeader __attribute__((aligned)); }; struct _LIBCXXABI_HIDDEN __cxa_eh_globals { |