[MacPorts] #19679: llvm 2.5 port fails to support Link Time Optimization

[MacPorts]

#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