1 files changed, 5 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d6d1591ef03..2a1738c774f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9414,10 +9414,13 @@ SDValue DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
 
   // fold (sext_in_reg (sext x)) -> (sext x)
   // fold (sext_in_reg (aext x)) -> (sext x)
-  // if x is small enough.
+  // if x is small enough or if we know that x has more than 1 sign bit and the
+  // sign_extend_inreg is extending from one of them.
   if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND) {
     SDValue N00 = N0.getOperand(0);
-    if (N00.getScalarValueSizeInBits() <= EVTBits &&
+    unsigned N00Bits = N00.getScalarValueSizeInBits();
+    if ((N00Bits <= EVTBits ||
+         (N00Bits - DAG.ComputeNumSignBits(N00)) < EVTBits) &&
         (!LegalOperations || TLI.isOperationLegal(ISD::SIGN_EXTEND, VT)))
       return DAG.getNode(ISD::SIGN_EXTEND, SDLoc(N), VT, N00);
   }