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[libc++] Make sure we can build libc++ with -fvisibility=hidden

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Summary:
When building with -fvisibility=hidden, some symbols do not get exported from
libc++.dylib. This means that some entities are not explicitly given default
visibility in the source code, and that we rely on the fact -fvisibility=default
is the default. This commit explicitly gives default visibility to those
symbols to avoid being dependent on the command line flags used.

The commit also remove symbols from the dylib -- those symbols do not
actually need to be exported from the dylib and this should not be an
ABI break.

Finally, in the future, we may want to mark the whole std:: namespace as
having hidden visibility (to switch from opt-out to opt-in), in which
case the changes done in this commit will be required.

Reviewers: EricWF

Subscribers: mgorny, christof, dexonsmith, libcxx-commits

Differential Revision: https://reviews.llvm.org/D52662

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@345260 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Louis Dionne
2018-10-25 12:13:43 +00:00
parent 92d87364ff
commit 07f95bd10d
15 changed files with 75 additions and 32 deletions
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28
lib/abi/CHANGELOG.TXT
View File

@@ -16,6 +16,34 @@ New entries should be added directly below the "Version" header.
Version 7.0
-----------
* rXXXXX - Making libc++ build under -fvisibility=hidden
The change marks __thread_specific_ptr<__thread_struct>::__at_thread_exit(void*)
with hidden visibility. This removes a symbol from the shared libraries,
however this is not an ABI break because it's impossible for programs linking
against libc++.dylib to actually depend on that symbol. The reason is that
the symbol is exported from the shared library through an implicit
instantiation present in the dylib itself only. Furthermore, if a user's
dylib was implicitly instantiating __thread_specific_ptr<T>::__at_thread_exit
(because it's defined in the headers), marking that symbol as hidden would
not be an ABI break for them because none of their users could actually be
using the symbol in their dylib (because it's an implicit instantiation).
This change also marks __start_std_streams as hidden -- this variable is
only required to initialize the streams, and nobody should depend on it
from outside the dylib.
x86_64-linux-gnu
----------------
Symbol removed: _ZNSt3__121__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv
Symbol removed: _ZNSt3__119__start_std_streamsE
x86_64-apple-darwin16.0
-----------------------
Symbol removed: __ZNSt3__221__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv
Symbol removed: __ZNSt3__119__start_std_streamsE
* r338479 - Elementary string conversions for integral types
The change emits __u64toa and __u32toa under std::__1::__itoa.

2
lib/abi/x86_64-apple-darwin.v1.abilist
View File

@@ -1197,13 +1197,11 @@
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__119__shared_weak_countD0Ev'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__119__shared_weak_countD1Ev'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__119__shared_weak_countD2Ev'}
{'type': 'OBJECT', 'is_defined': True, 'name': '__ZNSt3__119__start_std_streamsE', 'size': 0}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__119__thread_local_dataEv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__119declare_no_pointersEPcm'}
{'type': 'OBJECT', 'is_defined': True, 'name': '__ZNSt3__119piecewise_constructE', 'size': 0}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__120__get_collation_nameEPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__120__throw_system_errorEiPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__121__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__121__throw_runtime_errorEPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__121__undeclare_reachableEPv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__121recursive_timed_mutex4lockEv'}

2
lib/abi/x86_64-apple-darwin.v2.abilist
View File

@@ -1119,13 +1119,11 @@
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__219__shared_weak_countD0Ev'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__219__shared_weak_countD1Ev'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__219__shared_weak_countD2Ev'}
{'type': 'OBJECT', 'is_defined': True, 'name': '__ZNSt3__219__start_std_streamsE', 'size': 0}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__219__thread_local_dataEv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__219declare_no_pointersEPcm'}
{'type': 'OBJECT', 'is_defined': True, 'name': '__ZNSt3__219piecewise_constructE', 'size': 0}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__220__get_collation_nameEPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__220__throw_system_errorEiPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__221__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__221__throw_runtime_errorEPKc'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__221__undeclare_reachableEPv'}
{'type': 'FUNC', 'is_defined': True, 'name': '__ZNSt3__221recursive_timed_mutex4lockEv'}

2
lib/abi/x86_64-unknown-linux-gnu.v1.abilist
View File

@@ -1098,13 +1098,11 @@
{'name': '_ZNSt3__119__shared_weak_countD0Ev', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__119__shared_weak_countD1Ev', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__119__shared_weak_countD2Ev', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__119__start_std_streamsE', 'is_defined': True, 'type': 'OBJECT', 'size': 1}
{'name': '_ZNSt3__119__thread_local_dataEv', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__119declare_no_pointersEPcm', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__119piecewise_constructE', 'is_defined': True, 'type': 'OBJECT', 'size': 1}
{'name': '_ZNSt3__120__get_collation_nameEPKc', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__120__throw_system_errorEiPKc', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__121__thread_specific_ptrINS_15__thread_structEE16__at_thread_exitEPv', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__121__throw_runtime_errorEPKc', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__121__undeclare_reachableEPv', 'is_defined': True, 'type': 'FUNC'}
{'name': '_ZNSt3__121recursive_timed_mutex4lockEv', 'is_defined': True, 'type': 'FUNC'}