1 files changed, 23 insertions, 8 deletions
diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index a3ed412b738..26470174a48 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1040,7 +1040,8 @@ static unsigned getAddressSpaceOperand(Value *I) {
 
 bool llvm::sortMemAccesses(ArrayRef<Value *> VL, const DataLayout &DL,
                            ScalarEvolution &SE,
-                           SmallVectorImpl<Value *> &Sorted) {
+                           SmallVectorImpl<Value *> &Sorted,
+                           SmallVectorImpl<unsigned> *Mask) {
   SmallVector<std::pair<int64_t, Value *>, 4> OffValPairs;
   OffValPairs.reserve(VL.size());
   Sorted.reserve(VL.size());
@@ -1050,7 +1051,6 @@ bool llvm::sortMemAccesses(ArrayRef<Value *> VL, const DataLayout &DL,
   Value *Ptr0 = getPointerOperand(VL[0]);
   const SCEV *Scev0 = SE.getSCEV(Ptr0);
   Value *Obj0 = GetUnderlyingObject(Ptr0, DL);
-
   for (auto *Val : VL) {
     // The only kind of access we care about here is load.
     if (!isa<LoadInst>(Val))
@@ -1077,14 +1077,29 @@ bool llvm::sortMemAccesses(ArrayRef<Value *> VL, const DataLayout &DL,
     OffValPairs.emplace_back(Diff->getAPInt().getSExtValue(), Val);
   }
 
-  std::sort(OffValPairs.begin(), OffValPairs.end(),
-            [](const std::pair<int64_t, Value *> &Left,
-               const std::pair<int64_t, Value *> &Right) {
-              return Left.first < Right.first;
+  SmallVector<unsigned, 4> UseOrder(VL.size());
+  for (unsigned i = 0; i < VL.size(); i++)
+    UseOrder[i] = i;
+
+  // Sort the memory accesses and keep the order of their uses in UseOrder.
+  std::sort(UseOrder.begin(), UseOrder.end(),
+            [&OffValPairs](unsigned Left, unsigned Right) {
+              return OffValPairs[Left].first < OffValPairs[Right].first;
             });
 
-  for (auto &it : OffValPairs)
-    Sorted.push_back(it.second);
+  for (unsigned i = 0; i < VL.size(); i++)
+    Sorted.emplace_back(OffValPairs[UseOrder[i]].second);
+
+  // Sort UseOrder to compute the Mask.
+  if (Mask) {
+    Mask->reserve(VL.size());
+    for (unsigned i = 0; i < VL.size(); i++)
+      Mask->emplace_back(i);
+    std::sort(Mask->begin(), Mask->end(),
+              [&UseOrder](unsigned Left, unsigned Right) {
+                return UseOrder[Left] < UseOrder[Right];
+              });
+  }
 
   return true;
 }