When lowering memcpys to loads and stores, make sure we don't promote alignments
past the natural stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174085 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index b672926..5724122 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3561,6 +3561,15 @@
if (DstAlignCanChange) {
Type *Ty = MemOps[0].getTypeForEVT(*DAG.getContext());
unsigned NewAlign = (unsigned) TLI.getDataLayout()->getABITypeAlignment(Ty);
+
+ // Don't promote to an alignment that would require dynamic stack
+ // realignment.
+ const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo();
+ if (!TRI->needsStackRealignment(MF))
+ while (NewAlign > Align &&
+ TLI.getDataLayout()->exceedsNaturalStackAlignment(NewAlign))
+ NewAlign /= 2;
+
if (NewAlign > Align) {
// Give the stack frame object a larger alignment if needed.
if (MFI->getObjectAlignment(FI->getIndex()) < NewAlign)