From 3109dd325be23b8218af5314873e070af4cb025b Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Wed, 24 Jul 2019 15:43:50 +0000
Subject: [PATCH] [SDAG] convert (sub x, 1) to (add x, -1) in ctpop expansion;
NFC
We canonicalize to the add form, so create that directly for efficiency.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366914 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/CodeGen/SelectionDAG/TargetLowering.cpp | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index dc2348f6cb8..d6ac17e8e5e 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2876,9 +2876,9 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
// (ctpop x) u< 2 -> (x & x-1) == 0
// (ctpop x) u> 1 -> (x & x-1) != 0
if ((Cond == ISD::SETULT && C1 == 2) || (Cond == ISD::SETUGT && C1 == 1)){
- SDValue Sub = DAG.getNode(ISD::SUB, dl, CTVT, CTOp,
- DAG.getConstant(1, dl, CTVT));
- SDValue And = DAG.getNode(ISD::AND, dl, CTVT, CTOp, Sub);
+ SDValue NegOne = DAG.getAllOnesConstant(dl, CTVT);
+ SDValue Add = DAG.getNode(ISD::ADD, dl, CTVT, CTOp, NegOne);
+ SDValue And = DAG.getNode(ISD::AND, dl, CTVT, CTOp, Add);
ISD::CondCode CC = Cond == ISD::SETULT ? ISD::SETEQ : ISD::SETNE;
return DAG.getSetCC(dl, VT, And, DAG.getConstant(0, dl, CTVT), CC);
}
--
2.40.0