From: Craig Topper <craig.topper@gmail.com>
Date: Thu, 20 Apr 2017 04:23:43 +0000 (+0000)
Subject: [SelectionDAG] Use getActiveBits() and countTrailingZeros() to avoid creating tempora... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=bb107535ba4b642f0bb587389e8d44d0f997dfdc;p=llvm

[SelectionDAG] Use getActiveBits() and countTrailingZeros() to avoid creating temporary APInts with lshr and trunc. NFCI

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300819 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 24fd206a2d4..8006b804597 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -839,7 +839,7 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
         SDValue InnerOp = InOp.getNode()->getOperand(0);
         EVT InnerVT = InnerOp.getValueType();
         unsigned InnerBits = InnerVT.getSizeInBits();
-        if (ShAmt < InnerBits && NewMask.lshr(InnerBits) == 0 &&
+        if (ShAmt < InnerBits && NewMask.getActiveBits() <= InnerBits &&
             isTypeDesirableForOp(ISD::SHL, InnerVT)) {
           EVT ShTy = getShiftAmountTy(InnerVT, DL);
           if (!APInt(BitWidth, ShAmt).isIntN(ShTy.getSizeInBits()))
@@ -865,9 +865,8 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
             ->getZExtValue();
           if (InnerShAmt < ShAmt &&
               InnerShAmt < InnerBits &&
-              NewMask.lshr(std::min(InnerBits - InnerShAmt + ShAmt,
-                                    BitWidth)) == 0 &&
-              NewMask.trunc(ShAmt) == 0) {
+              NewMask.getActiveBits() <= (InnerBits - InnerShAmt + ShAmt) &&
+              NewMask.countTrailingZeros() >= ShAmt) {
             SDValue NewSA =
               TLO.DAG.getConstant(ShAmt - InnerShAmt, dl,
                                   Op.getOperand(1).getValueType());