support preferred targets for llvm-config --libs (and similar commands)

[llvmbot]

Bugzilla Link	3883
Version	2.5
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

With llvm-config from llvm 2.4 it was possible to specify:

llvm-config --libs engine nativecodegen

If you where building for eg. the ARM platform that gave you all the libraries and object files to get a working JIT compiler for ARM.

In llvm 2.5 this is not the case anymore. You only get the platform independent stuff. Instead you need to specify:

llvm-config --libs engine nativecodegen asmcodegen

in order to get the ARM stuff in. Since I already had to chose which backends I want in when calling 'cmake' it would be nice to have a component that will return all libraries for the specified backends without the need to explicitly name the architecture (or architectures).

So 'armcodegen' should not go away but there should be a 'all backends that I already chose'codegen.

The reason for the need to have such a component that it otherwise causes unneccessary burden on configure scripts of projects that use LLVM.

[llvmbot]

I see that in llvm 3.x there is no longer an "asmcodegen" component.

Is tthis still an issue?