From 0c4300fac7e011c5b3072a005a68c4f8ce2e639f Mon Sep 17 00:00:00 2001
From: Evgeny Stupachenko <evstupac@gmail.com>
Date: Wed, 30 Nov 2016 22:23:51 +0000
Subject: [PATCH] Fix LSR best register search algorithm.

Summary:
Fix a case when first register in a search has maximum
RegUses.getUsedByIndices(Reg).count()

Reviewers: qcolombet

Differential Revision: http://reviews.llvm.org/D26877

From: Evgeny Stupachenko <evstupac@gmail.com>
llvm-svn: 288278
---
 llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 2a378a437285..a61f646042ae 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -4178,9 +4178,10 @@ void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {
     for (const SCEV *Reg : RegUses) {
       if (Taken.count(Reg))
         continue;
-      if (!Best)
+      if (!Best) {
         Best = Reg;
-      else {
+        BestNum = RegUses.getUsedByIndices(Reg).count();
+      } else {
         unsigned Count = RegUses.getUsedByIndices(Reg).count();
         if (Count > BestNum) {
           Best = Reg;