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https://github.com/llvm-mirror/libcxx.git
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6dbed46df6
Summary:
GCC and Clang handle visibility attributes on the out-of-line definition of externally instantiated templates differently. For example in the reproducer below Clang will emit both 'foo' and 'bar' with default visibility while GCC only emits a non-hidden 'foo'.
```
// RUN: g++ -std=c++11 -shared -O3 test.cpp && sym_extract.py a.out
// RUN: clang++ -std=c++11 -shared -O3 test.cpp && sym_extract.py a.out
#define INLINE_VISIBILITY __attribute__((visibility("hidden"), always_inline))
template <class T>
struct Foo {
void foo();
void bar();
};
template <class T>
void Foo<T>::foo() {}
template <class T>
inline INLINE_VISIBILITY
void Foo<T>::bar() {}
template struct Foo<int>;
```
This difference creates ABI incompatibilities between Clang and GCC built dylibs. Specifically GCC built dylibs lack definitions for various member functions of `basic_string`, `basic_istream`, `basic_ostream`, `basic_iostream`, and `basic_streambuf` (All of these types are externally instantiated).
Surprisingly these missing symbols don't cause many problems because the functions are marked `always_inline` therefore the dylib definition is rarely needed. However when an out-of-line definition is required then GCC built dylibs will fail to link. For example [GCC built dylibs cannot build Clang](http://stackoverflow.com/questions/39454262/clang-build-errors).
This patch works around this issue by adding `_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY` which is used to mark externally instantiated member functions as always inline. When building the library `_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY` sets the symbol's visibility to "default" instead of "hidden", otherwise it acts exactly the same as `_LIBCPP_INLINE_VISIBILITY`.
After applying this patch GCC dylibs now contain:
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE7sungetcEv`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5gbumpEi`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE7sungetcEv`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE9sputbackcEc`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getERNS_15basic_streambufIwS2_EE`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRNS_9basic_iosIwS2_EES6_E`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE4setpEPcS4_`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEEC1EPNS_15basic_streambufIwS2_EE`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE6snextcEv`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE4swapERS3_`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE4swapERS3_`
* `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcm`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRNS_8ios_baseES5_E`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE9pubsetbufEPcl`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE10pubseekoffExNS_8ios_base7seekdirEj`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRNS_9basic_iosIwS2_EES6_E`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5pbumpEi`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5seekpENS_4fposI11__mbstate_tEE`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE7getlineEPcl`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sgetcEv`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getERNS_15basic_streambufIcS2_EE`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRNS_8ios_baseES5_E`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE8in_availEv`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRNS_8ios_baseES5_E`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE6sbumpcEv`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRNS_9basic_iosIcS2_EES6_E`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getERc`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE6snextcEv`
* `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEmw`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE7getlineEPwl`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5tellpEv`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getERw`
* `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEmc`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE7pubsyncEv`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEE3getEPcl`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRNS_9basic_iosIcS2_EES6_E`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE7pubsyncEv`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sputcEc`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5seekpExNS_8ios_base7seekdirE`
* `_ZNKSt3__115basic_streambufIcNS_11char_traitsIcEEE6getlocEv`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5gbumpEi`
* `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEE4swapERS3_`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5seekpENS_4fposI11__mbstate_tEE`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE5tellpEv`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRS3_S4_E`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEE3getEPwl`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEEC2EPNS_15basic_streambufIwS2_EE`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEElsEPFRS3_S4_E`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE4setgEPcS4_S4_`
* `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEPKwmm`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE4setgEPwS4_S4_`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEEC1EPNS_15basic_streambufIwS2_EE`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE8pubimbueERKNS_6localeE`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE4swapERS3_`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEEC2EPNS_15basic_streambufIwS2_EE`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE10pubseekposENS_4fposI11__mbstate_tEEj`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5pbumpEi`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sgetcEv`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEE4swapERS3_`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE10pubseekposENS_4fposI11__mbstate_tEEj`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sputnEPKcl`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEE5seekpExNS_8ios_base7seekdirE`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sgetnEPwl`
* `_ZNSt3__113basic_ostreamIwNS_11char_traitsIwEEElsEPFRNS_8ios_baseES5_E`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE4setpEPwS4_`
* `_ZNSt3__115basic_streambufIcNS_11char_traitsIcEEE5sgetnEPcl`
* `_ZNKSt3__115basic_streambufIwNS_11char_traitsIwEEE6getlocEv`
* `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE8pubimbueERKNS_6localeE`
* `_ZNSt3__114basic_iostreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE8in_availEv`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcmm`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE6sbumpcEv`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE10pubseekoffExNS_8ios_base7seekdirEj`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEEC2EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__113basic_istreamIwNS_11char_traitsIwEEErsEPFRS3_S4_E`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE9sputbackcEw`
* `_ZNSt3__112basic_stringIwNS_11char_traitsIwEENS_9allocatorIwEEE6__initEPKwm`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sputnEPKwl`
* `_ZNSt3__113basic_istreamIcNS_11char_traitsIcEEErsEPFRS3_S4_E`
* `_ZNSt3__113basic_ostreamIcNS_11char_traitsIcEEEC1EPNS_15basic_streambufIcS2_EE`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE9pubsetbufEPwl`
* `_ZNSt3__115basic_streambufIwNS_11char_traitsIwEEE5sputcEw`
This patch has no effect on Clang based builds.
Reviewers: mclow.lists, eugenis, danalbert, jroelofs, EricWF
Subscribers: beanz, cfe-commits, mgorny
Differential Revision: https://reviews.llvm.org/D24600
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@281681 91177308-0d34-0410-b5e6-96231b3b80d8
63 lines
2.1 KiB
Python
Executable File
63 lines
2.1 KiB
Python
Executable File
#!/usr/bin/env python
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#===----------------------------------------------------------------------===##
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#
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# The LLVM Compiler Infrastructure
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#
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# This file is dual licensed under the MIT and the University of Illinois Open
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# Source Licenses. See LICENSE.TXT for details.
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#
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#===----------------------------------------------------------------------===##
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"""
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sym_diff - Compare two symbol lists and output the differences.
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"""
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from argparse import ArgumentParser
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import sys
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from sym_check import diff, util
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def main():
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parser = ArgumentParser(
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description='Extract a list of symbols from a shared library.')
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parser.add_argument(
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'--names-only', dest='names_only',
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help='Only print symbol names',
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action='store_true', default=False)
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parser.add_argument(
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'--removed-only', dest='removed_only',
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help='Only print removed symbols',
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action='store_true', default=False)
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parser.add_argument(
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'-o', '--output', dest='output',
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help='The output file. stdout is used if not given',
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type=str, action='store', default=None)
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parser.add_argument(
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'--demangle', dest='demangle', action='store_true', default=False)
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parser.add_argument(
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'old_syms', metavar='old-syms', type=str,
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help='The file containing the old symbol list or a library')
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parser.add_argument(
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'new_syms', metavar='new-syms', type=str,
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help='The file containing the new symbol list or a library')
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args = parser.parse_args()
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old_syms_list = util.extract_or_load(args.old_syms)
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new_syms_list = util.extract_or_load(args.new_syms)
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added, removed, changed = diff.diff(old_syms_list, new_syms_list)
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if args.removed_only:
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added = {}
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report, is_break = diff.report_diff(added, removed, changed,
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names_only=args.names_only,
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demangle=args.demangle)
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if args.output is None:
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print(report)
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else:
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with open(args.output, 'w') as f:
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f.write(report + '\n')
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sys.exit(is_break)
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if __name__ == '__main__':
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main()
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