fix PR9841 by having GVN not process dead loads. This was

causing it to get into infinite loops when it would widen a 
load (which can necessarily leave around dead loads).

llvm-svn: 131847

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 1da5238bbb6..2515fd112c1 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1607,6 +1607,11 @@ bool GVN::processLoad(LoadInst *L) {
   if (L->isVolatile())
     return false;
 
+  if (L->use_empty()) {
+    markInstructionForDeletion(L);
+    return true;
+  }
+  
   // ... to a pointer that has been loaded from before...
   MemDepResult Dep = MD->getDependency(L);