[SystemZ] Do not crash when selecting an OR of two constants

In rare cases, common code will attempt to select an OR of two
constants.  This confuses the logic in splitLargeImmediate,
causing an internal error during isel.  Fixed by simply leaving
this case to common code to handle.

This fixes PR34859.

llvm-svn: 318187

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index 802af1ae861..3073d2fcde1 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -1263,8 +1263,10 @@ void SystemZDAGToDAGISel::Select(SDNode *Node) {
     // Fall through.
   or_xor:
     // If this is a 64-bit operation in which both 32-bit halves are nonzero,
-    // split the operation into two.
-    if (Node->getValueType(0) == MVT::i64)
+    // split the operation into two.  If both operands here happen to be
+    // constant, leave this to common code to optimize.
+    if (Node->getValueType(0) == MVT::i64 &&
+        Node->getOperand(0).getOpcode() != ISD::Constant)
       if (auto *Op1 = dyn_cast<ConstantSDNode>(Node->getOperand(1))) {
         uint64_t Val = Op1->getZExtValue();
         if (!SystemZ::isImmLF(Val) && !SystemZ::isImmHF(Val)) {