This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Add flag to optionally ignore ELF interposition


On Tue, 20 May 2014, Jan Hubicka wrote:

> Hi,
> as disucssed some time ago, our assumption that every symbol of shared library can
> be interposed at runtime is expensive and prevents a lot of useful optimizations,
> including inlining or IPA propagation.
> 
> While this is useful feature, it is rather incommon to use it for bigger C++
> projects, like firefox and at least clang seems to ignore the ELF interposition
> rules and always inline/propagate. This patch adds flag to control the behaviour.
> Symbols explicitly delcared WEAK are still considered as interposable.

I could see a use for an option listing the symbols that can be 
interposed.  (For example, glibc supports interposition of a limited 
number of malloc-related symbols, but if it were made to support building 
with LTO in future that it would make sense to be able to optimize calls 
to most other functions.)

-- 
Joseph S. Myers
joseph@codesourcery.com


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]