[DAGCombine] Add calls to SimplifyDemandedVectorElts from visitINSERT_SUBVECTOR (PR37989)

This uncovered an off-by-one typo in SimplifyDemandedVectorElts's INSERT_SUBVECTOR handling as its bounds check was bailing on safe indices.

llvm-svn: 347313

2 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 770eb3190be..d1bf193cae6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17722,6 +17722,10 @@ SDValue DAGCombiner::visitINSERT_SUBVECTOR(SDNode *N) {
     return DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), VT, Ops);
   }
 
+  // Simplify source operands based on insertion.
+  if (SimplifyDemandedVectorElts(SDValue(N, 0)))
+    return SDValue(N, 0);
+
   return SDValue();
 }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 7fbfc983e6d..47c363f3143 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1569,7 +1569,7 @@ bool TargetLowering::SimplifyDemandedVectorElts(
     EVT SubVT = Sub.getValueType();
     unsigned NumSubElts = SubVT.getVectorNumElements();
     const APInt& Idx = cast<ConstantSDNode>(Op.getOperand(2))->getAPIntValue();
-    if (Idx.uge(NumElts - NumSubElts))
+    if (Idx.ugt(NumElts - NumSubElts))
       break;
     unsigned SubIdx = Idx.getZExtValue();
     APInt SubElts = DemandedElts.extractBits(NumSubElts, SubIdx);