[DAG] Fixed predicate for determining when two frame indices
addresses are comparable. NFCI.
llvm-svn: 307055
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
index 4e899ae..14b804e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -37,13 +37,13 @@
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;