1 files changed, 17 insertions, 11 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
index 4e899ae6668e..0d69441ebb7f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -37,13 +37,13 @@ bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
 
     const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
 
-    // Match non-equal FrameIndexes - a FrameIndex stemming from an
-    // alloca will not have it's ObjectOffset set until post-DAG and
-    // as such we must assume the two framesIndices are incomparable.
+    // Match non-equal FrameIndexes - If both frame indices are fixed
+    // we know their relative offsets and can compare them. Otherwise
+    // we must be conservative.
     if (auto *A = dyn_cast<FrameIndexSDNode>(Base))
       if (auto *B = dyn_cast<FrameIndexSDNode>(Other.Base))
-        if (!MFI.getObjectAllocation(A->getIndex()) &&
-            !MFI.getObjectAllocation(B->getIndex())) {
+        if (MFI.isFixedObjectIndex(A->getIndex()) &&
+            MFI.isFixedObjectIndex(B->getIndex())) {
           Off += MFI.getObjectOffset(B->getIndex()) -
                  MFI.getObjectOffset(A->getIndex());
           return true;
@@ -60,12 +60,18 @@ BaseIndexOffset BaseIndexOffset::match(SDValue Ptr, const SelectionDAG &DAG) {
   int64_t Offset = 0;
   bool IsIndexSignExt = false;
 
-  // Consume constant adds
-  while (Base->getOpcode() == ISD::ADD &&
-         isa<ConstantSDNode>(Base->getOperand(1))) {
-    int64_t POffset = cast<ConstantSDNode>(Base->getOperand(1))->getSExtValue();
-    Offset += POffset;
-    Base = Base->getOperand(0);
+  // Consume constant adds & ors with appropriate masking.
+  while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
+    if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
+      // Only consider ORs which act as adds.
+      if (Base->getOpcode() == ISD::OR &&
+          !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
+        break;
+      Offset += C->getSExtValue();
+      Base = Base->getOperand(0);
+      continue;
+    }
+    break;
   }
 
   if (Base->getOpcode() == ISD::ADD) {