Implement the isSafeToDiscardIfUnused predicate and use it in globalopt and

globaldce. Globaldce was already removing linkonce globals, but globalopt was
not.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158476 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index 81a11a4c92..8b969f3354 100644
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -164,6 +164,12 @@ public:
     return Linkage == CommonLinkage;
   }
 
+  /// isDiscardableIfUnused - Whether the definition of this global may be
+  /// discarded if it is not used in its compilation unit.
+  static bool isDiscardableIfUnused(LinkageTypes Linkage) {
+    return isLinkOnceLinkage(Linkage) || isLocalLinkage(Linkage);
+  }
+
   /// mayBeOverridden - Whether the definition of this global may be replaced
   /// by something non-equivalent at link time.  For example, if a function has
   /// weak linkage then the code defining it may be replaced by different code.
@@ -221,6 +227,10 @@ public:
   void setLinkage(LinkageTypes LT) { Linkage = LT; }
   LinkageTypes getLinkage() const { return Linkage; }
 
+  bool isDiscardableIfUnused() const {
+    return isDiscardableIfUnused(Linkage);
+  }
+
   bool mayBeOverridden() const { return mayBeOverridden(Linkage); }
 
   bool isWeakForLinker() const { return isWeakForLinker(Linkage); }