Add a new WeakVH value handle; NFC

Summary:
WeakVH nulls itself out if the value it was tracking gets deleted, but
it does not track RAUW.

Reviewers: dblaikie, davide

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D32267

llvm-svn: 301425

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 23a0f7a2601..18e44dcd352 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -825,8 +825,10 @@ void ValueHandleBase::ValueIsDeleted(Value *V) {
       // pointer.
       Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
       break;
+    case Weak:
     case WeakTracking:
-      // WeakTracking just goes to null, which will unlink it from the list.
+      // WeakTracking and Weak just go to null, which unlinks them
+      // from the list.
       Entry->operator=(nullptr);
       break;
     case Callback:
@@ -874,7 +876,8 @@ void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
 
     switch (Entry->getKind()) {
     case Assert:
-      // Asserting handle does not follow RAUW implicitly.
+    case Weak:
+      // Asserting and Weak handles do not follow RAUW implicitly.
       break;
     case Tracking:
       // Tracking goes to new value like a WeakTrackingVH. Note that this may