Reapply "[IR] Move optional data in llvm::Function into a hungoff uselist"

Make personality functions, prefix data, and prologue data hungoff
operands of Function.

This is based on the email thread "[RFC] Clean up the way we store
optional Function data" on llvm-dev.

Thanks to sanjoyd, majnemer, rnk, loladiro, and dexonsmith for feedback!

Includes a fix to scrub value subclass data in dropAllReferences.

Differential Revision: http://reviews.llvm.org/D13829

llvm-svn: 256093

1 files changed, 2 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalDCE.cpp b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
index 1cc657458d6..9b276ed28e2 100644
--- a/llvm/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -215,14 +215,8 @@ void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
     // any globals used will be marked as needed.
     Function *F = cast<Function>(G);
 
-    if (F->hasPrefixData())
-      MarkUsedGlobalsAsNeeded(F->getPrefixData());
-
-    if (F->hasPrologueData())
-      MarkUsedGlobalsAsNeeded(F->getPrologueData());
-
-    if (F->hasPersonalityFn())
-      MarkUsedGlobalsAsNeeded(F->getPersonalityFn());
+    for (Use &U : F->operands())
+      MarkUsedGlobalsAsNeeded(cast<Constant>(U.get()));
 
     for (BasicBlock &BB : *F)
       for (Instruction &I : BB)