[SLPVectorizer] Move size checks (NFC).

[mgudim]

Add the analyzeRtStrideCandidate function. In the future commits we're going to add the capability to widen strided loads to it. So, in this commit, we move the size / type checks into it, since it can possibly change size / type of load.

[llvmbot]

@llvm/pr-subscribers-vectorizers

@llvm/pr-subscribers-llvm-transforms

Author: Mikhail Gudim (mgudim)

Changes

Add the analyzeRtStrideCandidate function. In the future commits we're going to add the capability to widen strided loads to it. So, in this commit, we move the size / type checks into it, since it can possibly change size / type of load.

---

Full diff: https://github.com/llvm/llvm-project/pull/161867.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp (+29-9)

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index fedca65d241e8..3b1d5d3b5bacc 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -2245,6 +2245,11 @@ class BoUpSLP {
                      Align Alignment, const int64_t Diff, Value *Ptr0,
                      Value *PtrN, StridedPtrInfo &SPtrInfo) const;
 
+  bool analyzeRtStrideCandidate(ArrayRef<Value *> PointerOps, Type *ScalarTy,
+                                Align CommonAlignment,
+                                SmallVectorImpl<unsigned> &SortedIndices,
+                                StridedPtrInfo &SPtrInfo) const;
+
   /// Checks if the given array of loads can be represented as a vectorized,
   /// scatter or just simple gather.
   /// \param VL list of loads.
@@ -6875,6 +6880,27 @@ bool BoUpSLP::isStridedLoad(ArrayRef<Value *> PointerOps, Type *ScalarTy,
   return false;
 }
 
+bool BoUpSLP::analyzeRtStrideCandidate(ArrayRef<Value *> PointerOps,
+                                       Type *ScalarTy, Align CommonAlignment,
+                                       SmallVectorImpl<unsigned> &SortedIndices,
+                                       StridedPtrInfo &SPtrInfo) const {
+  return true;
+  const unsigned Sz = PointerOps.size();
+  // TODO: VecSz may change if we widen the strided load.
+  unsigned VecSz = Sz;
+  FixedVectorType *StridedLoadTy = getWidenedType(ScalarTy, VecSz);
+  if (!(Sz > MinProfitableStridedLoads && TTI->isTypeLegal(StridedLoadTy) &&
+        TTI->isLegalStridedLoadStore(StridedLoadTy, CommonAlignment)))
+    return false;
+  if (const SCEV *Stride =
+          calculateRtStride(PointerOps, ScalarTy, *DL, *SE, SortedIndices)) {
+    SPtrInfo.Ty = getWidenedType(ScalarTy, PointerOps.size());
+    SPtrInfo.StrideSCEV = Stride;
+    return true;
+  }
+  return false;
+}
+
 BoUpSLP::LoadsState BoUpSLP::canVectorizeLoads(
     ArrayRef<Value *> VL, const Value *VL0, SmallVectorImpl<unsigned> &Order,
     SmallVectorImpl<Value *> &PointerOps, StridedPtrInfo &SPtrInfo,
@@ -6915,15 +6941,9 @@ BoUpSLP::LoadsState BoUpSLP::canVectorizeLoads(
   auto *VecTy = getWidenedType(ScalarTy, Sz);
   Align CommonAlignment = computeCommonAlignment<LoadInst>(VL);
   if (!IsSorted) {
-    if (Sz > MinProfitableStridedLoads && TTI->isTypeLegal(VecTy)) {
-      if (const SCEV *Stride =
-              calculateRtStride(PointerOps, ScalarTy, *DL, *SE, Order);
-          Stride && TTI->isLegalStridedLoadStore(VecTy, CommonAlignment)) {
-        SPtrInfo.Ty = getWidenedType(ScalarTy, PointerOps.size());
-        SPtrInfo.StrideSCEV = Stride;
-        return LoadsState::StridedVectorize;
-      }
-    }
+    if (analyzeRtStrideCandidate(PointerOps, ScalarTy, CommonAlignment, Order,
+                                 SPtrInfo))
+      return LoadsState::StridedVectorize;
 
     if (!TTI->isLegalMaskedGather(VecTy, CommonAlignment) ||
         TTI->forceScalarizeMaskedGather(VecTy, CommonAlignment))