From e0efedd2c33bf2bef232f255f1449a18d2b61d77 Mon Sep 17 00:00:00 2001
From: Alexey Bataev <a.bataev@outlook.com>
Date: Thu, 30 Dec 2021 13:08:36 -0800
Subject: [PATCH] [SLP][NFC]Fix non-determinism in reordering, NFC.

Need to clear CurrentOrder order mask if it is determined that
extractelements form identity order and need to use a vector-like
construct when iterating over ordered entries in the reorderTopToBottom
function.
---
 llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 37ae13666f7a..1dd31dcae253 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -3040,7 +3040,7 @@ Optional<BoUpSLP::OrdersType> BoUpSLP::getReorderingData(const TreeEntry &TE,
 
 void BoUpSLP::reorderTopToBottom() {
   // Maps VF to the graph nodes.
-  DenseMap<unsigned, SmallPtrSet<TreeEntry *, 4>> VFToOrderedEntries;
+  DenseMap<unsigned, SetVector<TreeEntry *>> VFToOrderedEntries;
   // ExtractElement gather nodes which can be vectorized and need to handle
   // their ordering.
   DenseMap<const TreeEntry *, OrdersType> GathersToOrders;
@@ -3066,7 +3066,7 @@ void BoUpSLP::reorderTopToBottom() {
     // Try to find the most profitable order. We just are looking for the most
     // used order and reorder scalar elements in the nodes according to this
     // mostly used order.
-    const SmallPtrSetImpl<TreeEntry *> &OrderedEntries = It->getSecond();
+    ArrayRef<TreeEntry *> OrderedEntries = It->second.getArrayRef();
     // All operands are reordered and used only in this node - propagate the
     // most used order to the user node.
     MapVector<OrdersType, unsigned,
@@ -4459,6 +4459,8 @@ bool BoUpSLP::canReuseExtract(ArrayRef<Value *> VL, Value *OpValue,
     CurrentOrder.clear();
     return false;
   }
+  if (ShouldKeepOrder)
+    CurrentOrder.clear();
 
   return ShouldKeepOrder;
 }