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[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 llvm-svn: 302763
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//===---------------- exception_object_alignment.sh.cpp -------------------===// | ||
// | ||
// The LLVM Compiler Infrastructure | ||
// | ||
// This file is dual licensed under the MIT and the University of Illinois Open | ||
// Source Licenses. See LICENSE.TXT for details. | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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// UNSUPPORTED: libcxxabi-no-exceptions | ||
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// RUN: %cxx %flags %compile_flags -O1 %s -o %t.exe | ||
// RUN: %exec %t.exe | ||
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// This test used to segfault on Darwin because field unwindHeader of struct | ||
// __cxa_exception was not 16B aligned. | ||
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namespace { | ||
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struct S { | ||
int a; | ||
int __attribute__((aligned(16))) b; | ||
}; | ||
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class base1 { | ||
protected: | ||
virtual ~base1() throw() {} | ||
}; | ||
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class derived: public base1 { | ||
public: | ||
derived() : member() {} | ||
private: | ||
S member; | ||
}; | ||
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} | ||
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int main() { | ||
try { | ||
throw derived(); | ||
} | ||
catch(...) { | ||
} | ||
return 0; | ||
} |