Shift-left (ISD::SHL) operation crashes on "DAG Legalization" phase.

https://llvm.org/bugs/show_bug.cgi?id=29058.

While node legalization we tried to legalize its operands.
If an operand node is replaced during legalization the user node may be destroyed.

Differential Revision: https://reviews.llvm.org/D24244

llvm-svn: 280862

1 files changed, 27 insertions, 21 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 71e9197b41c..9c560541d13 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1067,35 +1067,41 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
     case ISD::SRL:
     case ISD::SRA:
     case ISD::ROTL:
-    case ISD::ROTR:
+    case ISD::ROTR: {
       // Legalizing shifts/rotates requires adjusting the shift amount
       // to the appropriate width.
-      if (!Node->getOperand(1).getValueType().isVector()) {
-        SDValue SAO =
-          DAG.getShiftAmountOperand(Node->getOperand(0).getValueType(),
-                                    Node->getOperand(1));
-        HandleSDNode Handle(SAO);
-        LegalizeOp(SAO.getNode());
-        NewNode = DAG.UpdateNodeOperands(Node, Node->getOperand(0),
-                                         Handle.getValue());
+      SDValue Op0 = Node->getOperand(0);
+      SDValue Op1 = Node->getOperand(1);
+      if (!Op1.getValueType().isVector()) {
+        SDValue SAO = DAG.getShiftAmountOperand(Op0.getValueType(), Op1);
+        // The getShiftAmountOperand() may create a new operand node or
+        // return the existing one. If new operand is created we need
+        // to update the parent node.
+        // Do not try to legalize SAO here! It will be automatically legalized
+        // in the next round.
+        if (SAO != Op1)
+          NewNode = DAG.UpdateNodeOperands(Node, Op0, SAO);
       }
-      break;
+    }
+    break;
     case ISD::SRL_PARTS:
     case ISD::SRA_PARTS:
-    case ISD::SHL_PARTS:
+    case ISD::SHL_PARTS: {
       // Legalizing shifts/rotates requires adjusting the shift amount
       // to the appropriate width.
-      if (!Node->getOperand(2).getValueType().isVector()) {
-        SDValue SAO =
-          DAG.getShiftAmountOperand(Node->getOperand(0).getValueType(),
-                                    Node->getOperand(2));
-        HandleSDNode Handle(SAO);
-        LegalizeOp(SAO.getNode());
-        NewNode = DAG.UpdateNodeOperands(Node, Node->getOperand(0),
-                                         Node->getOperand(1),
-                                         Handle.getValue());
+      SDValue Op0 = Node->getOperand(0);
+      SDValue Op1 = Node->getOperand(1);
+      SDValue Op2 = Node->getOperand(2);
+      if (!Op2.getValueType().isVector()) {
+        SDValue SAO = DAG.getShiftAmountOperand(Op0.getValueType(), Op2);
+        // The getShiftAmountOperand() may create a new operand node or
+        // return the existing one. If new operand is created we need
+        // to update the parent node.
+        if (SAO != Op2)
+          NewNode = DAG.UpdateNodeOperands(Node, Op0, Op1, SAO);
       }
-      break;
+    }
+    break;
     }
 
     if (NewNode != Node) {