From dd0948a1b6ed0264fc0a7793bf690846faf2f97b Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Fri, 18 Dec 2015 03:53:28 +0000
Subject: [PATCH] [RS4GC] Use an value handle to help isolate errors quickly

Inspired by the bug reported in 25846.  Whatever we end up doing about that one, the value handle change is a generally good one since it will help catch this type of mistake more quickly.

Patch by: Manuel Jacob

llvm-svn: 255984
---
 llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index ffa77bb2fd65..d72133287f56 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -641,7 +641,7 @@ public:
 
 private:
   Status status;
-  Value *base; // non null only if status == base
+  AssertingVH<Value> base; // non null only if status == base
 };
 }
 
@@ -1098,10 +1098,10 @@ static Value *findBasePointer(Value *I, DefiningValueMapTy &cache) {
     NewInsts.erase(BaseI);
     ReverseMap.erase(BaseI);
     BaseI->replaceAllUsesWith(Replacement);
-    BaseI->eraseFromParent();
     assert(States.count(BDV));
     assert(States[BDV].isConflict() && States[BDV].getBase() == BaseI);
     States[BDV] = BDVState(BDVState::Conflict, Replacement);
+    BaseI->eraseFromParent();
   };
   const DataLayout &DL = cast<Instruction>(def)->getModule()->getDataLayout();
   while (!Worklist.empty()) {