DAGCombine: clamp hi bit in APInt::getBitsSet to avoid assertion

rdar://12838504


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169951 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 1c28d6d..893cf20 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7433,7 +7433,8 @@
     // start at the previous one.
     if (ShAmt % NewBW)
       ShAmt = (((ShAmt + NewBW - 1) / NewBW) * NewBW) - NewBW;
-    APInt Mask = APInt::getBitsSet(BitWidth, ShAmt, ShAmt + NewBW);
+    APInt Mask = APInt::getBitsSet(BitWidth, ShAmt,
+                                   std::min(BitWidth, ShAmt + NewBW));
     if ((Imm & Mask) == Imm) {
       APInt NewImm = (Imm & Mask).lshr(ShAmt).trunc(NewBW);
       if (Opc == ISD::AND)