Linking native shared libraries with bytecode libary in the -L path

[llvmbot]

Bugzilla Link	525
Resolution	FIXED
Resolved on	Feb 22, 2010 12:54
Version	trunk
OS	All
Blocks	llvm/llvm-bugzilla-archive#526
Reporter	LLVM Bugzilla Contributor

Extended Description

A directory in our -L path has a libFoo.so native library that we need to
link. It also contains a libBar.so bytecode library.

Another directory in our -L path has a bytecode version of libFoo.so and a
native version of libBar.so.

What do we do?

llvm-g++ -Wl,-native -shared -o libtest.so test.o -L/foobar -lfoo -L/barfoo
-lbar

/foobar
libFoo.so --native
libBar.so --bytecode

/barfoo
libFoo.so --bytecode
libBar.so --native

Now, it is possible to test for this situation, but even if we know that it is
going to happen, how do we tell gcc or the system linker how to do the
correct thing?

[llvmbot]

As decided on an IRC chat, the behavior to implement in LLVM linkers is to
generate an error if the user specifies -L and -l options in such a fashion that
a given directory specified with -L contains both native and bytecode libraries.
Users should be adivsed to keep their bytecode and native libraries in separate
places to avoid this situation ever occurring.

[llvmbot]

Native linker patch
Here is the latest version of the native linker patch.

This differs from the previous patch in one major way... It no longer takes the
crude hack of screening for 'llvm' in the -L path. Instead, gccld now actively
screens for -L paths that contain bytecode shared libraries or true llvm
bytecode archives. Those -L paths that do contain them are omitted from the
call to the system linker.

This should resolve http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=525

We can not just issue an error when the user feeds an -L path to the llvm-g++
compiler, because llvm-g++ itself appends it's lib directories to the call to
gccld.

The result is that llvm-g++'s bytecode archive files (see libstdc++.a and
libc.a) are included in any call to gccld by llvm-g++.

Hopefully this is the correct fix once and for all.

[lattner]

Cool, thanks!

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#526