[SLPVectorizer] Change arguments of 'isStridedLoad' (NFC)

This is needed to reduce the diff for the future work on widening
strided loads. Also, with this change we'll be able to re-use this for
the case when each pointer represents a start of a group of contiguous
loads.

Author: Mikhail Gudim

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -2234,10 +2234,9 @@ class BoUpSLP {
   /// TODO: If load combining is allowed in the IR optimizer, this analysis
   ///       may not be necessary.
   bool isLoadCombineCandidate(ArrayRef<Value *> Stores) const;
-  bool isStridedLoad(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
-                     ArrayRef<unsigned> Order, const TargetTransformInfo &TTI,
-                     const DataLayout &DL, ScalarEvolution &SE,
-                     const int64_t Diff, StridedPtrInfo &SPtrInfo) const;
+  bool isStridedLoad(ArrayRef<Value *> PointerOps, Type *ScalarTy,
+                     Align Alignment, int64_t Diff, Value *Ptr0, Value *PtrN,
+                     StridedPtrInfo &SPtrInfo) const;
 
   /// Checks if the given array of loads can be represented as a vectorized,
   /// scatter or just simple gather.
@@ -6817,13 +6816,10 @@ isMaskedLoadCompress(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
 /// 4. Any pointer operand is an instruction with the users outside of the
 /// current graph (for masked gathers extra extractelement instructions
 /// might be required).
-bool BoUpSLP::isStridedLoad(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
-                            ArrayRef<unsigned> Order,
-                            const TargetTransformInfo &TTI,
-                            const DataLayout &DL, ScalarEvolution &SE,
-                            const int64_t Diff,
-                            StridedPtrInfo &SPtrInfo) const {
-  const size_t Sz = VL.size();
+bool BoUpSLP::isStridedLoad(ArrayRef<Value *> PointerOps, Type *ScalarTy,
+                            Align Alignment, int64_t Diff, Value *Ptr0,
+                            Value *PtrN, StridedPtrInfo &SPtrInfo) const {
+  const size_t Sz = PointerOps.size();
   if (Diff % (Sz - 1) != 0)
     return false;
 
@@ -6835,7 +6831,6 @@ bool BoUpSLP::isStridedLoad(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
   });
 
   const uint64_t AbsoluteDiff = std::abs(Diff);
-  Type *ScalarTy = VL.front()->getType();
   auto *VecTy = getWidenedType(ScalarTy, Sz);
   if (IsAnyPointerUsedOutGraph ||
       (AbsoluteDiff > Sz &&
@@ -6846,20 +6841,9 @@ bool BoUpSLP::isStridedLoad(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
     int64_t Stride = Diff / static_cast<int64_t>(Sz - 1);
     if (Diff != Stride * static_cast<int64_t>(Sz - 1))
       return false;
-    Align Alignment =
-        cast<LoadInst>(Order.empty() ? VL.front() : VL[Order.front()])
-            ->getAlign();
-    if (!TTI.isLegalStridedLoadStore(VecTy, Alignment))
+    if (!TTI->isLegalStridedLoadStore(VecTy, Alignment))
       return false;
-    Value *Ptr0;
-    Value *PtrN;
-    if (Order.empty()) {
-      Ptr0 = PointerOps.front();
-      PtrN = PointerOps.back();
-    } else {
-      Ptr0 = PointerOps[Order.front()];
-      PtrN = PointerOps[Order.back()];
-    }
+
     // Iterate through all pointers and check if all distances are
     // unique multiple of Dist.
     SmallSet<int64_t, 4> Dists;
@@ -6868,14 +6852,14 @@ bool BoUpSLP::isStridedLoad(ArrayRef<Value *> VL, ArrayRef<Value *> PointerOps,
       if (Ptr == PtrN)
         Dist = Diff;
       else if (Ptr != Ptr0)
-        Dist = *getPointersDiff(ScalarTy, Ptr0, ScalarTy, Ptr, DL, SE);
+        Dist = *getPointersDiff(ScalarTy, Ptr0, ScalarTy, Ptr, *DL, *SE);
       // If the strides are not the same or repeated, we can't
       // vectorize.
       if (((Dist / Stride) * Stride) != Dist || !Dists.insert(Dist).second)
         break;
     }
     if (Dists.size() == Sz) {
-      Type *StrideTy = DL.getIndexType(Ptr0->getType());
+      Type *StrideTy = DL->getIndexType(Ptr0->getType());
       SPtrInfo.StrideVal = ConstantInt::get(StrideTy, Stride);
       SPtrInfo.Ty = getWidenedType(ScalarTy, Sz);
       return true;
@@ -6964,7 +6948,8 @@ BoUpSLP::LoadsState BoUpSLP::canVectorizeLoads(
                                    cast<Instruction>(V), UserIgnoreList);
                              }))
       return LoadsState::CompressVectorize;
-    if (isStridedLoad(VL, PointerOps, Order, *TTI, *DL, *SE, *Diff, SPtrInfo))
+    if (isStridedLoad(PointerOps, ScalarTy, CommonAlignment, *Diff, Ptr0, PtrN,
+                      SPtrInfo))
       return LoadsState::StridedVectorize;
   }
   if (!TTI->isLegalMaskedGather(VecTy, CommonAlignment) ||