[DSE] Teach the pass that atomic memory intrinsics are stores.

Summary:
This change teaches DSE that the atomic memory intrinsics are stores
that can be eliminated, and can allow other stores to be eliminated.
This change specifically does not teach DSE that these intrinsics
can be partially eliminated (i.e. length reduced, and dest/src changed);
that will be handled in another change.

Reviewers: mkazantsev, skatkov, apilipenko, efriedma, rsmith

Reviewed By: efriedma

Subscribers: dmgreen, llvm-commits

Differential Revision: https://reviews.llvm.org/D45535

llvm-svn: 330629

1 files changed, 20 insertions, 4 deletions

diff --git a/llvm/lib/Analysis/MemoryLocation.cpp b/llvm/lib/Analysis/MemoryLocation.cpp
index 9db6c499129..55924db284e 100644
--- a/llvm/lib/Analysis/MemoryLocation.cpp
+++ b/llvm/lib/Analysis/MemoryLocation.cpp
@@ -65,6 +65,14 @@ MemoryLocation MemoryLocation::get(const AtomicRMWInst *RMWI) {
 }
 
 MemoryLocation MemoryLocation::getForSource(const MemTransferInst *MTI) {
+  return getForSource(cast<AnyMemTransferInst>(MTI));
+}
+
+MemoryLocation MemoryLocation::getForSource(const AtomicMemTransferInst *MTI) {
+  return getForSource(cast<AnyMemTransferInst>(MTI));
+}
+
+MemoryLocation MemoryLocation::getForSource(const AnyMemTransferInst *MTI) {
   uint64_t Size = UnknownSize;
   if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
     Size = C->getValue().getZExtValue();
@@ -77,17 +85,25 @@ MemoryLocation MemoryLocation::getForSource(const MemTransferInst *MTI) {
   return MemoryLocation(MTI->getRawSource(), Size, AATags);
 }
 
-MemoryLocation MemoryLocation::getForDest(const MemIntrinsic *MTI) {
+MemoryLocation MemoryLocation::getForDest(const MemIntrinsic *MI) {
+  return getForDest(cast<AnyMemIntrinsic>(MI));
+}
+
+MemoryLocation MemoryLocation::getForDest(const AtomicMemIntrinsic *MI) {
+  return getForDest(cast<AnyMemIntrinsic>(MI));
+}
+
+MemoryLocation MemoryLocation::getForDest(const AnyMemIntrinsic *MI) {
   uint64_t Size = UnknownSize;
-  if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
+  if (ConstantInt *C = dyn_cast<ConstantInt>(MI->getLength()))
     Size = C->getValue().getZExtValue();
 
   // memcpy/memmove can have AA tags. For memcpy, they apply
   // to both the source and the destination.
   AAMDNodes AATags;
-  MTI->getAAMetadata(AATags);
+  MI->getAAMetadata(AATags);
 
-  return MemoryLocation(MTI->getRawDest(), Size, AATags);
+  return MemoryLocation(MI->getRawDest(), Size, AATags);
 }
 
 MemoryLocation MemoryLocation::getForArgument(ImmutableCallSite CS,