[PATCH] D33840: [DAGCombine] Do not try to deduplicate commutative operations if both operand are the same.
Amaury SECHET via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 2 09:39:28 PDT 2017
deadalnix created this revision.
It is creating useless work as the commuted nodes is the same as the node we are working on in that case.
https://reviews.llvm.org/D33840
Files:
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1569,7 +1569,7 @@
SDValue N1 = N->getOperand(1);
// Constant operands are canonicalized to RHS.
- if (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1)) {
+ if (N0 != N1 && (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1))) {
SDValue Ops[] = {N1, N0};
SDNode *CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops,
N->getFlags());
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