[llvm] 25b702f - [DAG] visitXOR - add missing comment for or/and constant setcc demorgan fold. NFC.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2024-10-16T11:15:36+01:00
New Revision: 25b702f2637d5520cacf59e6a92e52956ccc7e8d

URL: https://github.com/llvm/llvm-project/commit/25b702f2637d5520cacf59e6a92e52956ccc7e8d
DIFF: https://github.com/llvm/llvm-project/commit/25b702f2637d5520cacf59e6a92e52956ccc7e8d.diff

LOG: [DAG] visitXOR - add missing comment for or/and constant setcc demorgan fold. NFC.

Noticed while triaging #112347 which is using this fold - we described the or->and fold, but not the equivalent and->or which is also handled.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 608ee8558e9928..0879165aac139d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9594,6 +9594,7 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
   }
 
   // fold (not (or x, y)) -> (and (not x), (not y)) iff x or y are setcc
+  // fold (not (and x, y)) -> (or (not x), (not y)) iff x or y are setcc
   if (isOneConstant(N1) && VT == MVT::i1 && N0.hasOneUse() &&
       (N0Opcode == ISD::OR || N0Opcode == ISD::AND)) {
     SDValue N00 = N0.getOperand(0), N01 = N0.getOperand(1);