Undo reversion on commit: Revert "Revert "Repress sanitization on User dtor.
Modify msan macros for applying attribute""

This reverts commit 020e70a79878c96457e6882bcdfaf6628baf32b7.

llvm-svn: 246470
diff --git a/llvm/lib/IR/Metadata.cpp b/llvm/lib/IR/Metadata.cpp
index 7d8c352..51548a8 100644
--- a/llvm/lib/IR/Metadata.cpp
+++ b/llvm/lib/IR/Metadata.cpp
@@ -401,7 +401,9 @@
   return Ptr;
 }
 
-void MDNode::operator delete(void *Mem) {
+// Repress memory sanitization, due to use-after-destroy by operator
+// delete. Bug report 24578 identifies this issue.
+LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE void MDNode::operator delete(void *Mem) {
   MDNode *N = static_cast<MDNode *>(Mem);
   size_t OpSize = N->NumOperands * sizeof(MDOperand);
   OpSize = RoundUpToAlignment(OpSize, llvm::alignOf<uint64_t>());