[llvm] 01b98e6 - [SelectionDAG] Don't repeatedly add a node to the worklist in ComputeLiveOutVRegInfo. NFC

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2019-12-23T22:04:14-08:00
New Revision: 01b98e6fd54f498018be4e298d98e711ab42b796

URL: https://github.com/llvm/llvm-project/commit/01b98e6fd54f498018be4e298d98e711ab42b796
DIFF: https://github.com/llvm/llvm-project/commit/01b98e6fd54f498018be4e298d98e711ab42b796.diff

LOG: [SelectionDAG] Don't repeatedly add a node to the worklist in ComputeLiveOutVRegInfo. NFC

For sqlite3 amalgram, this decreases the number of Worklist.push_back calls (603084) by 10%.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index b25a9ab854a5..58e2dcfa18de 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -738,23 +738,20 @@ void SelectionDAGISel::SelectBasicBlock(BasicBlock::const_iterator Begin,
 }
 
 void SelectionDAGISel::ComputeLiveOutVRegInfo() {
-  SmallPtrSet<SDNode*, 16> VisitedNodes;
+  SmallPtrSet<SDNode *, 16> Added;
   SmallVector<SDNode*, 128> Worklist;
 
   Worklist.push_back(CurDAG->getRoot().getNode());
+  Added.insert(CurDAG->getRoot().getNode());
 
   KnownBits Known;
 
   do {
     SDNode *N = Worklist.pop_back_val();
 
-    // If we've already seen this node, ignore it.
-    if (!VisitedNodes.insert(N).second)
-      continue;
-
     // Otherwise, add all chain operands to the worklist.
     for (const SDValue &Op : N->op_values())
-      if (Op.getValueType() == MVT::Other)
+      if (Op.getValueType() == MVT::Other && Added.insert(Op.getNode()).second)
         Worklist.push_back(Op.getNode());
 
     // If this is a CopyToReg with a vreg dest, process it.