[PATCH] D101460: [SLP]Try to vectorize tiny trees with shuffled gathers of extractelements.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev updated this revision to Diff 346236.
ABataev added a comment.

Rebase + address the comment


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D101460/new/

https://reviews.llvm.org/D101460

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/AArch64/ext-trunc.ll


Index: llvm/test/Transforms/SLPVectorizer/AArch64/ext-trunc.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/AArch64/ext-trunc.ll
+++ llvm/test/Transforms/SLPVectorizer/AArch64/ext-trunc.ll
@@ -17,12 +17,18 @@
 ; CHECK-NEXT:    [[GEP0:%.*]] = getelementptr inbounds i64, i64* [[P:%.*]], i64 [[S0]]
 ; CHECK-NEXT:    [[LOAD0:%.*]] = load i64, i64* [[GEP0]], align 4
 ; CHECK-NEXT:    [[E1:%.*]] = extractelement <4 x i32> [[SUB0]], i32 1
-; CHECK-NEXT:    [[S1:%.*]] = sext i32 [[E1]] to i64
-; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr inbounds i64, i64* [[P]], i64 [[S1]]
-; CHECK-NEXT:    [[LOAD1:%.*]] = load i64, i64* [[GEP1]], align 4
 ; CHECK-NEXT:    [[E2:%.*]] = extractelement <4 x i32> [[SUB0]], i32 2
-; CHECK-NEXT:    [[S2:%.*]] = sext i32 [[E2]] to i64
-; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr inbounds i64, i64* [[P]], i64 [[S2]]
+; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <2 x i32> poison, i32 [[E1]], i32 0
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <2 x i32> [[TMP0]], i32 [[E2]], i32 1
+; CHECK-NEXT:    [[TMP2:%.*]] = sext <2 x i32> [[TMP1]] to <2 x i64>
+; CHECK-NEXT:    [[TMP3:%.*]] = trunc <2 x i64> [[TMP2]] to <2 x i32>
+; CHECK-NEXT:    [[TMP4:%.*]] = extractelement <2 x i32> [[TMP3]], i32 0
+; CHECK-NEXT:    [[TMP5:%.*]] = sext i32 [[TMP4]] to i64
+; CHECK-NEXT:    [[GEP1:%.*]] = getelementptr inbounds i64, i64* [[P]], i64 [[TMP5]]
+; CHECK-NEXT:    [[LOAD1:%.*]] = load i64, i64* [[GEP1]], align 4
+; CHECK-NEXT:    [[TMP6:%.*]] = extractelement <2 x i32> [[TMP3]], i32 1
+; CHECK-NEXT:    [[TMP7:%.*]] = sext i32 [[TMP6]] to i64
+; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr inbounds i64, i64* [[P]], i64 [[TMP7]]
 ; CHECK-NEXT:    [[LOAD2:%.*]] = load i64, i64* [[GEP2]], align 4
 ; CHECK-NEXT:    [[E3:%.*]] = extractelement <4 x i32> [[SUB0]], i32 3
 ; CHECK-NEXT:    [[S3:%.*]] = sext i32 [[E3]] to i64
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4140,13 +4140,18 @@
 
   // Handle splat and all-constants stores. Also try to vectorize tiny trees
   // with the second gather nodes if they have less scalar operands rather than
-  // the initial tree element (may be profitable to shuffle the second gather).
+  // the initial tree element (may be profitable to shuffle the second gather)
+  // or they are extractelements, which form shuffle.
+  SmallVector<int> Mask;
   if (VectorizableTree[0]->State == TreeEntry::Vectorize &&
       (allConstant(VectorizableTree[1]->Scalars) ||
        isSplat(VectorizableTree[1]->Scalars) ||
        (VectorizableTree[1]->State == TreeEntry::NeedToGather &&
         VectorizableTree[1]->Scalars.size() <
-            VectorizableTree[0]->Scalars.size())))
+            VectorizableTree[0]->Scalars.size()) ||
+       (VectorizableTree[1]->State == TreeEntry::NeedToGather &&
+        VectorizableTree[1]->getOpcode() == Instruction::ExtractElement &&
+        isShuffle(VectorizableTree[1]->Scalars, Mask))))
     return true;
 
   // Gathering cost would be too much for tiny trees.


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