[llvm] 4284afd - [SLP]Need shrink the load vector after reordering.

[Alexey Bataev via llvm-commits]

Author: Alexey Bataev
Date: 2021-01-07T04:50:48-08:00
New Revision: 4284afdf9432f7d756f56b0ab21d69191adefa8d

URL: https://github.com/llvm/llvm-project/commit/4284afdf9432f7d756f56b0ab21d69191adefa8d
DIFF: https://github.com/llvm/llvm-project/commit/4284afdf9432f7d756f56b0ab21d69191adefa8d.diff

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

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

Differential Revision: https://reviews.llvm.org/D93967

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index abd0470270d5..8d6453f277ea 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4260,18 +4260,13 @@ Value *BoUpSLP::vectorizeTree(ArrayRef<Value *> VL) {
       if (E->isSame(VL)) {
         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;
       }

diff  --git a/llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll b/llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
index 110e1177774b..533b48eec295 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
@@ -10,7 +10,8 @@ define void @wombat(i32* %ptr, i32* %ptr1) {
 ; 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