[SelectionDAG] Add constant buildvector support to isKnownNeverZero

This allows us to use SelectionDAG::isKnownNeverZero in DAGCombiner::visitREM (visitSDIVLike/visitUDIVLike handle the checking for constants).

llvm-svn: 336779

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 4b02b0cf9c5..9870f21666f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3626,12 +3626,18 @@ bool SelectionDAG::isKnownNeverZero(SDValue Op) const {
   assert(!Op.getValueType().isFloatingPoint() &&
          "Floating point types unsupported - use isKnownNeverZeroFloat");
 
+  // If the value is a constant, we can obviously see if it is a zero or not.
+  if (ISD::matchUnaryPredicate(
+          Op, [](ConstantSDNode *C) { return !C->isNullValue(); }))
+    return true;
+
   // TODO: Recognize more cases here.
   switch (Op.getOpcode()) {
   default: break;
   case ISD::OR:
-    if (const ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op.getOperand(1)))
-      return !C->isNullValue();
+    if (isKnownNeverZero(Op.getOperand(1)) ||
+        isKnownNeverZero(Op.getOperand(0)))
+      return true;
     break;
   }