Implement the "linker_private_weak" linkage type. This will be used for
Objective-C metadata types which should be marked as "weak", but which the
linker will remove upon final linkage. However, this linkage isn't specific to
Objective-C.

For example, the "objc_msgSend_fixup_alloc" symbol is defined like this:

      .globl l_objc_msgSend_fixup_alloc
      .weak_definition l_objc_msgSend_fixup_alloc
      .section __DATA, __objc_msgrefs, coalesced
      .align 3
l_objc_msgSend_fixup_alloc:
       .quad   _objc_msgSend_fixup
       .quad   L_OBJC_METH_VAR_NAME_1

This is different from the "linker_private" linkage type, because it can't have
the metadata defined with ".weak_definition".

Currently only supported on Darwin platforms.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107433 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/ARM/2009-08-23-linkerprivate.ll b/test/CodeGen/ARM/2009-08-23-linkerprivate.ll
index 0fad533..392c70a 100644
--- a/test/CodeGen/ARM/2009-08-23-linkerprivate.ll
+++ b/test/CodeGen/ARM/2009-08-23-linkerprivate.ll
@@ -2,7 +2,7 @@
 
 ; ModuleID = '/Volumes/MacOS9/tests/WebKit/JavaScriptCore/profiler/ProfilerServer.mm'
 
-@"\01l_objc_msgSend_fixup_alloc" = linker_private hidden global i32 0, section "__DATA, __objc_msgrefs, coalesced", align 16		; <i32*> [#uses=0]
+@"\01l_objc_msgSend_fixup_alloc" = linker_private_weak hidden global i32 0, section "__DATA, __objc_msgrefs, coalesced", align 16
 
 ; CHECK: .globl l_objc_msgSend_fixup_alloc
 ; CHECK: .weak_definition l_objc_msgSend_fixup_alloc