[PATCH] D93967: [SLP]Need shrink the load vector after reordering.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev created this revision.
ABataev added reviewers: RKSimon, spatel, dtemirbulatov, anton-afanasyev.
Herald added a subscriber: hiraditya.
ABataev requested review of this revision.
Herald added a project: LLVM.

After merging the shuffles, we cannot rely on the previous shuffle
anymore and need to shrink the final shuffle, if it is required.

Reported in D92668 <https://reviews.llvm.org/D92668>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93967

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll


Index: llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
+++ llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
@@ -10,7 +10,8 @@
 ; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x i32>, <2 x i32>* [[TMP0]], align 8
 ; CHECK-NEXT:    [[SHUFFLE:%.*]] = shufflevector <2 x i32> [[TMP1]], <2 x i32> poison, <4 x i32> <i32 1, i32 0, i32 1, i32 0>
 ; CHECK-NEXT:    [[TMP27:%.*]] = getelementptr inbounds i32, i32* [[PTR1:%.*]], i32 3
-; CHECK-NEXT:    [[TMP2:%.*]] = add nsw <2 x i32> [[TMP1]], <i32 -1, i32 -1>
+; CHECK-NEXT:    [[SHRINK_SHUFFLE:%.*]] = shufflevector <4 x i32> [[SHUFFLE]], <4 x i32> poison, <2 x i32> <i32 0, i32 1>
+; CHECK-NEXT:    [[TMP2:%.*]] = add nsw <2 x i32> [[SHRINK_SHUFFLE]], <i32 -1, i32 -1>
 ; CHECK-NEXT:    [[SHUFFLE1:%.*]] = shufflevector <2 x i32> [[TMP2]], <2 x i32> poison, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
 ; CHECK-NEXT:    [[TMP34:%.*]] = getelementptr inbounds i32, i32* [[PTR1]], i32 4
 ; CHECK-NEXT:    [[TMP40:%.*]] = getelementptr inbounds i32, i32* [[PTR1]], i32 5
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4263,17 +4263,13 @@
         Value *V = vectorizeTree(E);
         if (VL.size() == E->Scalars.size() && !E->ReuseShuffleIndices.empty()) {
           // We need to get the vectorized value but without shuffle.
-          if (auto *SV = dyn_cast<ShuffleVectorInst>(V)) {
-            V = SV->getOperand(0);
-          } else {
-            // Reshuffle to get only unique values.
-            SmallVector<int, 4> UniqueIdxs;
-            SmallSet<int, 4> UsedIdxs;
-            for (int Idx : E->ReuseShuffleIndices)
-              if (UsedIdxs.insert(Idx).second)
-                UniqueIdxs.emplace_back(Idx);
-            V = Builder.CreateShuffleVector(V, UniqueIdxs);
-          }
+          // Reshuffle to get only unique values.
+          SmallVector<int, 4> UniqueIdxs;
+          SmallSet<int, 4> UsedIdxs;
+          for (int Idx : E->ReuseShuffleIndices)
+            if (UsedIdxs.insert(Idx).second)
+              UniqueIdxs.emplace_back(Idx);
+          V = Builder.CreateShuffleVector(V, UniqueIdxs, "shrink.shuffle");
         }
         return V;
       }


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