From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Fri, 3 Mar 2017 16:35:57 +0000 (+0000)
Subject: Use APInt::getOneBitSet instead of APInt::getBitsSet for sign bit mask creation
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b5264466287644712c68cf476d8b38b410b9220a;p=llvm

Use APInt::getOneBitSet instead of APInt::getBitsSet for sign bit mask creation

Avoids all the unnecessary extra bitrange creation/shift stages.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296879 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 3785f402c3e..b1bfd47eb02 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1099,7 +1099,7 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
     APInt InMask    = APInt::getLowBitsSet(BitWidth, InBits);
-    APInt InSignBit = APInt::getBitsSet(BitWidth, InBits - 1, InBits);
+    APInt InSignBit = APInt::getOneBitSet(BitWidth, InBits - 1);
     APInt NewBits   = ~InMask & NewMask;
 
     // If none of the top bits are demanded, convert this into an any_extend.