UsedDirective for some symbols in llvm.used into
Darwin-specific code.  I've decided LessPrivateGlobal
is potentially a useful abstraction and left it in
the target-independent area, with improved comment.

llvm-svn: 56024

objects in llvm.used (thanks Anton).  Makes visible
the magic 'l' prefix for symbols on Darwin which are
to be passed through the assembler, then removed at
linktime (previously all references to this had been
hidden in the ObjC FE code, oh well).

llvm-svn: 55973

llvm-svn: 55962

llvm-svn: 55919

llvm-svn: 55779

list that have internal linkage; the linker doesn't need
or want this.  (These objects must still be preserved
at compile time, so just removing them from the llvm.used
list doesn't work.)  Should affect only Darwin.

llvm-svn: 55722

llvm-svn: 55134

llvm-svn: 55092

llvm-svn: 54978

llvm-svn: 54901

In particular, Collector was confusing to implementors. Several
thought that this compile-time class was the place to implement
their runtime GC heap. Of course, it doesn't even exist at runtime.
Specifically, the renames are:

  Collector               -> GCStrategy
  CollectorMetadata       -> GCFunctionInfo
  CollectorModuleMetadata -> GCModuleInfo
  CollectorRegistry       -> GCRegistry
  Function::getCollector  -> getGC (setGC, hasGC, clearGC)

Several accessors and nested types have also been renamed to be
consistent. These changes should be obvious.

llvm-svn: 54899

llvm-svn: 54891

llvm-svn: 54885