Commit Graph

6 Commits

Author SHA1 Message Date
Rafael Espindola
1f21e0dd0d Remove the linker_private and linker_private_weak linkages.
These linkages were introduced some time ago, but it was never very
clear what exactly their semantics were or what they should be used
for. Some investigation found these uses:

* utf-16 strings in clang.
* non-unnamed_addr strings produced by the sanitizers.

It turns out they were just working around a more fundamental problem.
For some sections a MachO linker needs a symbol in order to split the
section into atoms, and llvm had no idea that was the case. I fixed
that in r201700 and it is now safe to use the private linkage. When
the object ends up in a section that requires symbols, llvm will use a
'l' prefix instead of a 'L' prefix and things just work.

With that, these linkages were already dead, but there was a potential
future user in the objc metadata information. I am still looking at
CGObjcMac.cpp, but at this point I am convinced that linker_private
and linker_private_weak are not what they need.

The objc uses are currently split in

* Regular symbols (no '\01' prefix). LLVM already directly provides
whatever semantics they need.
* Uses of a private name (start with "\01L" or "\01l") and private
linkage. We can drop the "\01L" and "\01l" prefixes as soon as llvm
agrees with clang on L being ok or not for a given section. I have two
patches in code review for this.
* Uses of private name and weak linkage.

The last case is the one that one could think would fit one of these
linkages. That is not the case. The semantics are

* the linker will merge these symbol by *name*.
* the linker will hide them in the final DSO.

Given that the merging is done by name, any of the private (or
internal) linkages would be a bad match. They allow llvm to rename the
symbols, and that is really not what we want. From the llvm point of
view, these objects should really be (linkonce|weak)(_odr)?.

For now, just keeping the "\01l" prefix is probably the best for these
symbols. If we one day want to have a more direct support in llvm,
IMHO what we should add is not a linkage, it is just a hidden_symbol
attribute. It would be applicable to multiple linkages. For example,
on weak it would produce the current behavior we have for objc
metadata. On internal, it would be equivalent to private (and we
should then remove private).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203866 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-13 23:18:37 +00:00
Ahmed Charles
f4ccd11075 Replace OwningPtr<T> with std::unique_ptr<T>.
This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203083 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-06 05:51:42 +00:00
Ahmed Charles
1a6eca243f [C++11] Replace OwningPtr::take() with OwningPtr::release().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202957 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-05 10:19:29 +00:00
Rafael Espindola
0ff25b31d8 Now that it is possible, use the mangler in IRObjectFile.
A really simple patch marks the end of a lot of yak shaving :-)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202463 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-28 02:17:23 +00:00
Rafael Espindola
1e0843084a Add missing include.
Should fix the bots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201882 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-21 20:21:55 +00:00
Rafael Espindola
91f86b7e1c Add a SymbolicFile interface between Binary and ObjectFile.
This interface allows IRObjectFile to be implemented without having dummy
methods for all section and segment related methods.

Both llvm-ar and llvm-nm are changed to use it. Unfortunately the mangler is
still not plugged in since it requires some refactoring to make a Module hold
a DataLayout.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201881 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-21 20:10:59 +00:00