Fix a nasty bug in LegalizeTypes (spotted in

CodeGen/PowerPC/illegal-element-type.ll): suppose
a node X is processed, and processing maps it to
a node Y.  Then X continues to exist in the DAG,
but with no users.  While processing some other
node, a new node may be created that happens to
be equal to X, and thus X will be reused rather
than a truly new node.  This can cause X to
"magically reappear", and since it is in the
Processed state in will not be reprocessed, so
at the end of type legalization the illegal node
X can still be present.  The solution is to replace
X with Y whenever X gets resurrected like this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47601 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 10 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypesPromote.cpp b/lib/CodeGen/SelectionDAG/LegalizeTypesPromote.cpp
index 3d4ba7b500..2ff1693e89 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypesPromote.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypesPromote.cpp
@@ -368,11 +368,10 @@ bool DAGTypeLegalizer::PromoteOperand(SDNode *N, unsigned OpNo) {
     // Mark N as new and remark N and its operands.  This allows us to correctly
     // revisit N if it needs another step of promotion and allows us to visit
     // any new operands to N.
-    N->setNodeId(NewNode);
-    MarkNewNodes(N);
+    ReanalyzeNode(N);
     return true;
   }
-  
+
   assert(Res.getValueType() == N->getValueType(0) && N->getNumValues() == 1 &&
          "Invalid operand expansion");
   
@@ -448,10 +447,8 @@ SDOperand DAGTypeLegalizer::PromoteOperand_SELECT(SDNode *N, unsigned OpNo) {
   // that the value is properly zero extended.
   unsigned BitWidth = Cond.getValueSizeInBits();
   if (!DAG.MaskedValueIsZero(Cond, 
-                             APInt::getHighBitsSet(BitWidth, BitWidth-1))) {
+                             APInt::getHighBitsSet(BitWidth, BitWidth-1)))
     Cond = DAG.getZeroExtendInReg(Cond, MVT::i1);
-    MarkNewNodes(Cond.Val); 
-  }
 
   // The chain (Op#0) and basic block destination (Op#2) are always legal types.
   return DAG.UpdateNodeOperands(SDOperand(N, 0), Cond, N->getOperand(1),
@@ -466,11 +463,9 @@ SDOperand DAGTypeLegalizer::PromoteOperand_BRCOND(SDNode *N, unsigned OpNo) {
   // that the value is properly zero extended.
   unsigned BitWidth = Cond.getValueSizeInBits();
   if (!DAG.MaskedValueIsZero(Cond, 
-                             APInt::getHighBitsSet(BitWidth, BitWidth-1))) {
+                             APInt::getHighBitsSet(BitWidth, BitWidth-1)))
     Cond = DAG.getZeroExtendInReg(Cond, MVT::i1);
-    MarkNewNodes(Cond.Val); 
-  }
-  
+
   // The chain (Op#0) and basic block destination (Op#2) are always legal types.
   return DAG.UpdateNodeOperands(SDOperand(N, 0), N->getOperand(0), Cond,
                                 N->getOperand(2));