[llvm] r288278 - Fix LSR best register search algorithm.

[Evgeny Stupachenko via llvm-commits]

Author: evstupac
Date: Wed Nov 30 16:23:51 2016
New Revision: 288278

URL: http://llvm.org/viewvc/llvm-project?rev=288278&view=rev
Log:
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 at gmail.com>

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=288278&r1=288277&r2=288278&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Wed Nov 30 16:23:51 2016
@@ -4178,9 +4178,10 @@ void LSRInstance::NarrowSearchSpaceByPic
     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;