#19679: llvm 2.5 port fails to support Link Time Optimization -------------------------------+-------------------------------------------- Reporter: macports@… | Owner: erickt@… Type: defect | Status: new Priority: Normal | Milestone: Component: ports | Version: 1.7.1 Keywords: llvm lto | Port: llvm llvm-gcc42 -------------------------------+-------------------------------------------- Comment(by macports@…): Yes, this is still an issue. The easiest way to test this is to compile something in llvm-gcc42 with "-O4". If libLTO.dylib is not accessible, the linker will complain that the object files (which are really bitcode files in this case) are not of the required architecture. I see several ways to fix this: A) Install a symlink to /opt/local/lib/libLTO.dylib in /usr/lib/ B) Configure compilers with "--with-ld=/Developer/usr/bin/ld" C) Install a symlink to /Developer/usr/bin/ld in /opt/local/libexec/gcc/i686-apple-darwin${os.major}/4.2.1/ D) Provide a custom [http://opensource.apple.com/source/ld64/ ld64] in macports and make it available in /opt/local/libexec/gcc/i686-apple- darwin${os.major}/4.2.1/ No option is really perfect. I'd say that D) would be the cleanest solution, but sadly that is not an option right now because the public ld64 sources seem to be [http://lists.apple.com/archives/Darwin- dev/2009/Sep/msg00025.html incomplete and unusable]. I'm happily living with option A) for several months now under 10.5, but I understand that installing files outside the macports hierarchy is not welcome. Options B) and C) rely on the llvm libraries that come bundled with XCode >=3.1. But it strikes me that you end up using mismatched versions of llvm and libLTO.dylib this way. And option B), which is [http://pdb.finkproject.org/pdb/package.php/llvm-gcc42 what fink does] in their llvm-gcc42 package, doesnt seem to work for clang. I have attached diffs for option A) and option C) and verified that both approaches enable llvm-gcc and clang to compile with "-O4" when installed in the /opt/local hierarchy. -- Ticket URL: <http://trac.macports.org/ticket/19679#comment:3> MacPorts <http://www.macports.org/> Ports system for Mac OS