DAG: Add nuw when splitting loads and stores

The object can't straddle the address space
wrap around, so I think it's OK to assume any
offsets added to the base object pointer can't
overflow. Similar logic already appears to be
applied in SelectionDAGBuilder when lowering
aggregate returns.

llvm-svn: 319272

1 files changed, 4 insertions, 11 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 97d4cd3c83b..16a5bbd8b55 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1484,22 +1484,15 @@ void SelectionDAGBuilder::visitRet(const ReturnInst &I) {
     ComputeValueVTs(TLI, DL, I.getOperand(0)->getType(), ValueVTs, &Offsets);
     unsigned NumValues = ValueVTs.size();
 
-    // An aggregate return value cannot wrap around the address space, so
-    // offsets to its parts don't wrap either.
-    SDNodeFlags Flags;
-    Flags.setNoUnsignedWrap(true);
-
     SmallVector<SDValue, 4> Chains(NumValues);
     for (unsigned i = 0; i != NumValues; ++i) {
-      SDValue Add = DAG.getNode(ISD::ADD, getCurSDLoc(),
-                                RetPtr.getValueType(), RetPtr,
-                                DAG.getIntPtrConstant(Offsets[i],
-                                                      getCurSDLoc()),
-                                Flags);
+      // An aggregate return value cannot wrap around the address space, so
+      // offsets to its parts don't wrap either.
+      SDValue Ptr = DAG.getObjectPtrOffset(getCurSDLoc(), RetPtr, Offsets[i]);
       Chains[i] = DAG.getStore(Chain, getCurSDLoc(),
                                SDValue(RetOp.getNode(), RetOp.getResNo() + i),
                                // FIXME: better loc info would be nice.
-                               Add, MachinePointerInfo());
+                               Ptr, MachinePointerInfo());
     }
 
     Chain = DAG.getNode(ISD::TokenFactor, getCurSDLoc(),