bridges/source/cpp_uno/gcc3_ios/except.cxx | 26 ++++++++++++++++++++++++++
bridges/source/cpp_uno/gcc3_ios/unwind-cxx.h | 17 ++++++++++++++++-
2 files changed, 42 insertions(+), 1 deletion(-)
New commits:
commit dba1a27be2438b5dbd1f8d253acb3850c9c044da
Author: Tor Lillqvist <t...@collabora.com>
AuthorDate: Thu Sep 17 14:02:24 2020 +0300
Commit: Tor Lillqvist <t...@collabora.com>
CommitDate: Wed Sep 23 00:11:46 2020 +0300
Add Stephan's "Very bad HACK" to the iOS code, too, for iOS 14
Change-Id: Ie05d2dc77bfdcd323037d2e94b523808df4e1c9c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/102916
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoff...@gmail.com>
Reviewed-by: Tor Lillqvist <t...@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/102980
Tested-by: Tor Lillqvist <t...@collabora.com>
diff --git a/bridges/source/cpp_uno/gcc3_ios/except.cxx
b/bridges/source/cpp_uno/gcc3_ios/except.cxx
index 58f458da34db..d5c49859db27 100644
--- a/bridges/source/cpp_uno/gcc3_ios/except.cxx
+++ b/bridges/source/cpp_uno/gcc3_ios/except.cxx
@@ -351,6 +351,32 @@ void fillUnoException(uno_Any * pUnoExc, uno_Mapping *
pCpp2Uno)
return;
}
+ // Very bad HACK to find out whether we run against a libcxxabi that has a
new
+ // __cxa_exception::reserved member at the start, introduced with LLVM 10
+ //
<https://github.com/llvm/llvm-project/commit/674ec1eb16678b8addc02a4b0534ab383d22fa77>
+ // "[libcxxabi] Insert padding in __cxa_exception struct for
compatibility". The layout of the
+ // start of __cxa_exception is
+ //
+ // [8 byte void *reserve]
+ // 8 byte size_t referenceCount
+ //
+ // where the (bad, hacky) assumption is that reserve (if present) is null
+ // (__cxa_allocate_exception in at least LLVM 11 zero-fills the object,
and nothing actively
+ // sets reserve) while referenceCount is non-null (__cxa_throw sets it to
1, and
+ // __cxa_decrement_exception_refcount destroys the exception as soon as it
drops to 0; for a
+ // __cxa_dependent_exception, the referenceCount member is rather
+ //
+ // 8 byte void* primaryException
+ //
+ // but which also will always be set to a non-null value in
__cxa_rethrow_primary_exception).
+ // As described in the definition of __cxa_exception
+ // (bridges/source/cpp_uno/gcc3_macosx_x86-64/share.hxx), this hack
(together with the "#if 0"
+ // there) can be dropped once we can be sure that we only run against new
libcxxabi that has the
+ // reserve member:
+ if (*reinterpret_cast<void **>(header) == nullptr) {
+ header = reinterpret_cast<__cxa_exception *>(reinterpret_cast<void
**>(header) + 1);
+ }
+
std::type_info *exceptionType = __cxxabiv1::__cxa_current_exception_type();
typelib_TypeDescription * pExcTypeDescr = nullptr;
diff --git a/bridges/source/cpp_uno/gcc3_ios/unwind-cxx.h
b/bridges/source/cpp_uno/gcc3_ios/unwind-cxx.h
index 9a700445c12a..83ed084860fd 100644
--- a/bridges/source/cpp_uno/gcc3_ios/unwind-cxx.h
+++ b/bridges/source/cpp_uno/gcc3_ios/unwind-cxx.h
@@ -59,8 +59,23 @@ namespace __cxxabiv1
// followed by the exception object itself.
struct __cxa_exception
-{
+{
#if __LP64__
+#if 0
+ // This is a new field added with LLVM 10
+ //
<https://github.com/llvm/llvm-project/commit/674ec1eb16678b8addc02a4b0534ab383d22fa77>
+ // "[libcxxabi] Insert padding in __cxa_exception struct for
compatibility". The HACK in
+ // fillUnoException (bridges/source/cpp_uno/gcc3_macosx_x86-64/except.cxx)
tries to find out at
+ // runtime whether a __cxa_exception has this member. Once we can be sure
that we only run
+ // against new libcxxabi that has this member, we can drop the "#if 0"
here and drop the hack
+ // in fillUnoException.
+
+ // Now _Unwind_Exception is marked with __attribute__((aligned)),
+ // which implies __cxa_exception is also aligned. Insert padding
+ // in the beginning of the struct, rather than before unwindHeader.
+ void *reserve;
+#endif
+
// This is a new field to support C++ 0x exception_ptr.
// For binary compatibility it is at the start of this
// struct which is prepended to the object thrown in
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