From fc947bcfba2fc8bc9cc4f8750d1d74c5bf24ee08 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Tue, 18 Apr 2017 17:14:21 +0000
Subject: [APInt] Use lshrInPlace to replace lshr where possible

This patch uses lshrInPlace to replace code where the object that lshr is called on is being overwritten with the result.

This adds an lshrInPlace(const APInt &) version as well.

Differential Revision: https://reviews.llvm.org/D32155

llvm-svn: 300566
---
 llvm/lib/CodeGen/CodeGenPrepare.cpp | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

(limited to 'llvm/lib/CodeGen/CodeGenPrepare.cpp')

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index aa0be910e3b..c862cfd28ad 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -5065,16 +5065,14 @@ bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
       if (!ShlC)
         return false;
       uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
-      auto ShlDemandBits = APInt::getAllOnesValue(BitWidth).lshr(ShiftAmt);
-      DemandBits |= ShlDemandBits;
+      DemandBits.setLowBits(BitWidth - ShiftAmt);
       break;
     }
 
     case llvm::Instruction::Trunc: {
       EVT TruncVT = TLI->getValueType(*DL, I->getType());
       unsigned TruncBitWidth = TruncVT.getSizeInBits();
-      auto TruncBits = APInt::getAllOnesValue(TruncBitWidth).zext(BitWidth);
-      DemandBits |= TruncBits;
+      DemandBits.setLowBits(TruncBitWidth);
       break;
     }
 
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