[Atomics][LoopIdiom] Recognize unordered atomic memcpy

Summary:
Expanding the loop idiom test for memcpy to also recognize
unordered atomic memcpy. The only difference for recognizing
an unordered atomic memcpy and instead of a normal memcpy is
that the loads and/or stores involved are unordered atomic operations.

Background:  http://lists.llvm.org/pipermail/llvm-dev/2017-May/112779.html

Patch by Daniel Neilson!

Reviewers: reames, anna, skatkov

Reviewed By: reames, anna

Subscribers: llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D33243

llvm-svn: 304806
diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index e051dff..488cb33 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -468,6 +468,10 @@
   return TTIImpl->getTgtMemIntrinsic(Inst, Info);
 }
 
+unsigned TargetTransformInfo::getAtomicMemIntrinsicMaxElementSize() const {
+  return TTIImpl->getAtomicMemIntrinsicMaxElementSize();
+}
+
 Value *TargetTransformInfo::getOrCreateResultFromMemIntrinsic(
     IntrinsicInst *Inst, Type *ExpectedType) const {
   return TTIImpl->getOrCreateResultFromMemIntrinsic(Inst, ExpectedType);