Add CommonLinkage; currently tentative definitions
are represented as "weak", but there are subtle differences
in some cases on Darwin, so we need both.  The intent
is that "common" will behave identically to "weak" unless
somebody changes their target to do something else.
No functional change as yet.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51118 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ELFWriter.cpp b/lib/CodeGen/ELFWriter.cpp
index 63fee3a..27f23f4 100644
--- a/lib/CodeGen/ELFWriter.cpp
+++ b/lib/CodeGen/ELFWriter.cpp
@@ -282,7 +282,8 @@
     // If this global is part of the common block, add it now.  Variables are
     // part of the common block if they are zero initialized and allowed to be
     // merged with other symbols.
-    if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage()) {
+    if (GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() ||
+        GV->hasCommonLinkage()) {
       ELFSym CommonSym(GV);
       // Value for common symbols is the alignment required.
       CommonSym.Value = Align;
@@ -313,7 +314,7 @@
     BSSSym.SetType(ELFSym::STT_OBJECT);
 
     switch (GV->getLinkage()) {
-    default:  // weak/linkonce handled above
+    default:  // weak/linkonce/common handled above
       assert(0 && "Unexpected linkage type!");
     case GlobalValue::AppendingLinkage:  // FIXME: This should be improved!
     case GlobalValue::ExternalLinkage: