From 98c6583bb34dd565934a48da328b3d8d3e75b497 Mon Sep 17 00:00:00 2001 From: Simon Pilgrim Date: Fri, 4 Jul 2025 16:28:39 +0100 Subject: [PATCH] [DAG] visitXOR - convert ISD::ABS matching to SDPatternMatch Lets us remove all the horrible commutative handling --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 55f994f357b75..3daa65d3cb324 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -10001,15 +10001,11 @@ SDValue DAGCombiner::visitXOR(SDNode *N) { // fold Y = sra (X, size(X)-1); xor (add (X, Y), Y) -> (abs X) if (!LegalOperations || hasOperation(ISD::ABS, VT)) { - SDValue A = N0Opcode == ISD::ADD ? N0 : N1; - SDValue S = N0Opcode == ISD::SRA ? N0 : N1; - if (A.getOpcode() == ISD::ADD && S.getOpcode() == ISD::SRA) { - SDValue A0 = A.getOperand(0), A1 = A.getOperand(1); - SDValue S0 = S.getOperand(0); - if ((A0 == S && A1 == S0) || (A1 == S && A0 == S0)) - if (ConstantSDNode *C = isConstOrConstSplat(S.getOperand(1))) - if (C->getAPIntValue() == (VT.getScalarSizeInBits() - 1)) - return DAG.getNode(ISD::ABS, DL, VT, S0); + SDValue X, Y; + if (sd_match(N, m_Xor(m_Add(m_Value(X), m_Value(Y)), m_Deferred(Y))) && + sd_match(Y, m_Sra(m_Specific(X), + m_SpecificInt(VT.getScalarSizeInBits() - 1)))) { + return DAG.getNode(ISD::ABS, DL, VT, X); } }