Introducing the "linker_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. 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".

llvm-svn: 107205

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 71ad3fb6f99..56420539b71 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -755,11 +755,12 @@ shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
   /// the directive emitted (this occurs in ObjC metadata).
   if (!GV) return false;
 
-  // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
+  // Check whether the mangled name has the "Private", "LinkerPrivate", or
+  // "LinkerWeak" prefix.
   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
     // FIXME: ObjC metadata is currently emitted as internal symbols that have
-    // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
-    // this horrible hack can go away.
+    // \1L and \1l prefixes on them.  Fix them to be Private / LinkerPrivate /
+    // LinkerWeak and this horrible hack can go away.
     MCSymbol *Sym = Mang->getSymbol(GV);
     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
       return false;