Merging Apple's Objective-C 2.0 compiler changes

[Marcus Daniels]

  On 9/13/10 2:04 PM, Ian Lance Taylor wrote:
> Therefore, I see a clear benefit to clang->gcc, but I
> do not see a clear benefit to gcc->llvm.
Suppose you have large Fortran applications, and want to accelerate 
parts of them on graphics processors.
Several of the OpenCL implementations use LLVM for runtime code 
generation, so one could compile the application to LTO, and let it go 
through some expensive stages of the GCC optimizer, and have LLVM 
bitcode staged for final translation to the GPU ISA.

In general, make the distinction between heavy ahead-of-time compilation 
and light just-in-time compilation along the lines of GCC and LLVM.