ARM: Use a Handle to track SDNodes in case they're CSE'd. NFC

The code here is recursively Select-ing a new Node to avoid issues
where N is CSE'd during replaceDAGValue and stops being valid. We can
accomplish the same goal in a more principled way by using a
HandleSDNode.

This is essentially a less dodgy fix for PR25733 than the original
attempt back in r255120.

llvm-svn: 268590

1 files changed, 2 insertions, 4 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index ac1b7d474cb..41cd6eaf74c 100644
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -551,11 +551,9 @@ bool ARMDAGToDAGISel::SelectImmShifterOperand(SDValue N,
     unsigned PowerOfTwo = 0;
     SDValue NewMulConst;
     if (canExtractShiftFromMul(N, 31, PowerOfTwo, NewMulConst)) {
-      BaseReg = SDValue(Select(CurDAG->getNode(ISD::MUL, SDLoc(N), MVT::i32,
-                                               N.getOperand(0), NewMulConst)
-                                   .getNode()),
-                        0);
+      HandleSDNode Handle(N);
       replaceDAGValue(N.getOperand(1), NewMulConst);
+      BaseReg = Handle.getValue();
       Opc = CurDAG->getTargetConstant(ARM_AM::getSORegOpc(ARM_AM::lsl,
                                                           PowerOfTwo),
                                       SDLoc(N), MVT::i32);