[llvm] 8888369 - Revert "[SLP]Attempt to vectorize long stores, if short one failed."

Nikita Popov via llvm-commits llvm-commits at lists.llvm.org
Wed Apr 17 18:15:55 PDT 2024


Author: Nikita Popov
Date: 2024-04-18T10:15:45+09:00
New Revision: 888836930b1ed30b2095d45fcffc482560cb0e39

URL: https://github.com/llvm/llvm-project/commit/888836930b1ed30b2095d45fcffc482560cb0e39
DIFF: https://github.com/llvm/llvm-project/commit/888836930b1ed30b2095d45fcffc482560cb0e39.diff

LOG: Revert "[SLP]Attempt to vectorize long stores, if short one failed."

This reverts commit 6f7160eedb2db02f37d4ffd52fff7b0cf88b3fdc.

This still causes large compile-time regressions in some cases.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    llvm/test/Transforms/SLPVectorizer/X86/pr46983.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 806e8085038b35..7694627c3b0430 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -15164,6 +15164,10 @@ bool SLPVectorizerPass::vectorizeStores(ArrayRef<StoreInst *> Stores,
   BoUpSLP::ValueSet VectorizedStores;
   bool Changed = false;
 
+  // Stores the pair of stores (first_store, last_store) in a range, that were
+  // already tried to be vectorized. Allows to skip the store ranges that were
+  // already tried to be vectorized but the attempts were unsuccessful.
+  DenseSet<std::pair<Value *, Value *>> TriedSequences;
   struct StoreDistCompare {
     bool operator()(const std::pair<unsigned, int> &Op1,
                     const std::pair<unsigned, int> &Op2) const {
@@ -15205,10 +15209,8 @@ bool SLPVectorizerPass::vectorizeStores(ArrayRef<StoreInst *> Stores,
       Type *ValueTy = StoreTy;
       if (auto *Trunc = dyn_cast<TruncInst>(Store->getValueOperand()))
         ValueTy = Trunc->getSrcTy();
-      unsigned MinVF = std::max<unsigned>(
-          2, PowerOf2Ceil(TTI->getStoreMinimumVF(
-                 R.getMinVF(DL->getTypeStoreSizeInBits(StoreTy)), StoreTy,
-                 ValueTy)));
+      unsigned MinVF = PowerOf2Ceil(TTI->getStoreMinimumVF(
+          R.getMinVF(DL->getTypeStoreSizeInBits(StoreTy)), StoreTy, ValueTy));
 
       if (MaxVF < MinVF) {
         LLVM_DEBUG(dbgs() << "SLP: Vectorization infeasible as MaxVF (" << MaxVF
@@ -15234,74 +15236,40 @@ bool SLPVectorizerPass::vectorizeStores(ArrayRef<StoreInst *> Stores,
         VF = Size > MaxVF ? NonPowerOf2VF : Size;
         Size *= 2;
       });
-      unsigned End = Operands.size();
-      unsigned Repeat = 0;
-      constexpr unsigned MaxAttempts = 2;
-      SmallBitVector Range(Operands.size());
-      while (true) {
-        ++Repeat;
-        for (unsigned Size : CandidateVFs) {
-          int StartIdx = Range.find_first_unset();
-          while (StartIdx != -1) {
-            int EndIdx = Range.find_next(StartIdx);
-            unsigned Sz = EndIdx == -1 ? End : EndIdx;
-            for (unsigned Cnt = StartIdx; Cnt + Size <= Sz;) {
-              ArrayRef<Value *> Slice = ArrayRef(Operands).slice(Cnt, Size);
-              assert(all_of(Slice,
-                            [&](Value *V) {
-                              return cast<StoreInst>(V)
-                                         ->getValueOperand()
-                                         ->getType() ==
-                                     cast<StoreInst>(Slice.front())
-                                         ->getValueOperand()
-                                         ->getType();
-                            }) &&
-                     "Expected all operands of same type.");
-              if (vectorizeStoreChain(Slice, R, Cnt, MinVF)) {
-                // Mark the vectorized stores so that we don't vectorize them
-                // again.
-                VectorizedStores.insert(Slice.begin(), Slice.end());
-                // Mark the vectorized stores so that we don't vectorize them
-                // again.
-                Changed = true;
-                // If we vectorized initial block, no need to try to vectorize
-                // it again.
-                Range.set(Cnt, Cnt + Size);
-                if (Cnt < StartIdx + MinVF)
-                  Range.set(StartIdx, Cnt);
-                if (Cnt > EndIdx - Size - MinVF) {
-                  Range.set(Cnt + Size, EndIdx);
-                  End = Cnt;
-                }
-                Cnt += Size;
-                continue;
-              }
-              ++Cnt;
-            }
-            if (Sz >= End)
-              break;
-            StartIdx = Range.find_next_unset(EndIdx);
+      unsigned StartIdx = 0;
+      for (unsigned Size : CandidateVFs) {
+        for (unsigned Cnt = StartIdx, E = Operands.size(); Cnt + Size <= E;) {
+          ArrayRef<Value *> Slice = ArrayRef(Operands).slice(Cnt, Size);
+          assert(
+              all_of(
+                  Slice,
+                  [&](Value *V) {
+                    return cast<StoreInst>(V)->getValueOperand()->getType() ==
+                           cast<StoreInst>(Slice.front())
+                               ->getValueOperand()
+                               ->getType();
+                  }) &&
+              "Expected all operands of same type.");
+          if (!VectorizedStores.count(Slice.front()) &&
+              !VectorizedStores.count(Slice.back()) &&
+              TriedSequences.insert(std::make_pair(Slice.front(), Slice.back()))
+                  .second &&
+              vectorizeStoreChain(Slice, R, Cnt, MinVF)) {
+            // Mark the vectorized stores so that we don't vectorize them again.
+            VectorizedStores.insert(Slice.begin(), Slice.end());
+            Changed = true;
+            // If we vectorized initial block, no need to try to vectorize it
+            // again.
+            if (Cnt == StartIdx)
+              StartIdx += Size;
+            Cnt += Size;
+            continue;
           }
+          ++Cnt;
         }
-        // All values vectorize - exit.
-        if (Range.all())
-          break;
-        // Check if tried all attempts or no need for the last attempts at all.
-        if (Repeat >= MaxAttempts)
-          break;
-        constexpr unsigned MaxVFScale = 4;
-        constexpr unsigned StoresLimit = 16;
-        const unsigned MaxTotalNum = std::min(
-            std::max<unsigned>(StoresLimit, MaxVFScale * MaxVF),
-            bit_floor(static_cast<unsigned>(Range.find_last_unset() -
-                                            Range.find_first_unset() + 1)));
-        if (MaxVF >= MaxTotalNum)
+        // Check if the whole array was vectorized already - exit.
+        if (StartIdx >= Operands.size())
           break;
-        // Last attempt to vectorize max number of elements, if all previous
-        // attempts were unsuccessful because of the cost issues.
-        CandidateVFs.clear();
-        for (unsigned Size = MaxTotalNum; Size > MaxVF; Size /= 2)
-          CandidateVFs.push_back(Size);
       }
     }
   };

diff  --git a/llvm/test/Transforms/SLPVectorizer/X86/pr46983.ll b/llvm/test/Transforms/SLPVectorizer/X86/pr46983.ll
index 3deab0975ce764..75505f632a43f3 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/pr46983.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/pr46983.ll
@@ -100,17 +100,41 @@ define void @store_i8(ptr nocapture %0, i32 %1, i32 %2) {
 define void @store_i64(ptr nocapture %0, i32 %1, i32 %2) {
 ; SSE-LABEL: @store_i64(
 ; SSE-NEXT:    [[TMP4:%.*]] = zext i32 [[TMP1:%.*]] to i64
-; SSE-NEXT:    [[TMP5:%.*]] = load <4 x i64>, ptr [[TMP0:%.*]], align 8, !tbaa [[TBAA5:![0-9]+]]
-; SSE-NEXT:    [[TMP6:%.*]] = insertelement <4 x i64> poison, i64 [[TMP4]], i64 0
-; SSE-NEXT:    [[TMP7:%.*]] = shufflevector <4 x i64> [[TMP6]], <4 x i64> poison, <4 x i32> zeroinitializer
-; SSE-NEXT:    [[TMP8:%.*]] = mul <4 x i64> [[TMP5]], [[TMP7]]
-; SSE-NEXT:    [[TMP9:%.*]] = lshr <4 x i64> [[TMP8]], <i64 15, i64 15, i64 15, i64 15>
-; SSE-NEXT:    [[TMP10:%.*]] = trunc <4 x i64> [[TMP9]] to <4 x i32>
-; SSE-NEXT:    [[TMP11:%.*]] = icmp ult <4 x i32> [[TMP10]], <i32 255, i32 255, i32 255, i32 255>
-; SSE-NEXT:    [[TMP12:%.*]] = trunc <4 x i64> [[TMP9]] to <4 x i32>
-; SSE-NEXT:    [[TMP13:%.*]] = select <4 x i1> [[TMP11]], <4 x i32> [[TMP12]], <4 x i32> <i32 255, i32 255, i32 255, i32 255>
-; SSE-NEXT:    [[TMP14:%.*]] = zext <4 x i32> [[TMP13]] to <4 x i64>
-; SSE-NEXT:    store <4 x i64> [[TMP14]], ptr [[TMP0]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP5:%.*]] = load i64, ptr [[TMP0:%.*]], align 8, !tbaa [[TBAA5:![0-9]+]]
+; SSE-NEXT:    [[TMP6:%.*]] = mul i64 [[TMP5]], [[TMP4]]
+; SSE-NEXT:    [[TMP7:%.*]] = lshr i64 [[TMP6]], 15
+; SSE-NEXT:    [[TMP8:%.*]] = trunc i64 [[TMP7]] to i32
+; SSE-NEXT:    [[TMP9:%.*]] = icmp ult i32 [[TMP8]], 255
+; SSE-NEXT:    [[TMP10:%.*]] = and i64 [[TMP7]], 4294967295
+; SSE-NEXT:    [[TMP11:%.*]] = select i1 [[TMP9]], i64 [[TMP10]], i64 255
+; SSE-NEXT:    store i64 [[TMP11]], ptr [[TMP0]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP12:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 8
+; SSE-NEXT:    [[TMP13:%.*]] = load i64, ptr [[TMP12]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP14:%.*]] = mul i64 [[TMP13]], [[TMP4]]
+; SSE-NEXT:    [[TMP15:%.*]] = lshr i64 [[TMP14]], 15
+; SSE-NEXT:    [[TMP16:%.*]] = trunc i64 [[TMP15]] to i32
+; SSE-NEXT:    [[TMP17:%.*]] = icmp ult i32 [[TMP16]], 255
+; SSE-NEXT:    [[TMP18:%.*]] = and i64 [[TMP15]], 4294967295
+; SSE-NEXT:    [[TMP19:%.*]] = select i1 [[TMP17]], i64 [[TMP18]], i64 255
+; SSE-NEXT:    store i64 [[TMP19]], ptr [[TMP12]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP20:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 16
+; SSE-NEXT:    [[TMP21:%.*]] = load i64, ptr [[TMP20]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP22:%.*]] = mul i64 [[TMP21]], [[TMP4]]
+; SSE-NEXT:    [[TMP23:%.*]] = lshr i64 [[TMP22]], 15
+; SSE-NEXT:    [[TMP24:%.*]] = trunc i64 [[TMP23]] to i32
+; SSE-NEXT:    [[TMP25:%.*]] = icmp ult i32 [[TMP24]], 255
+; SSE-NEXT:    [[TMP26:%.*]] = and i64 [[TMP23]], 4294967295
+; SSE-NEXT:    [[TMP27:%.*]] = select i1 [[TMP25]], i64 [[TMP26]], i64 255
+; SSE-NEXT:    store i64 [[TMP27]], ptr [[TMP20]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP28:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 24
+; SSE-NEXT:    [[TMP29:%.*]] = load i64, ptr [[TMP28]], align 8, !tbaa [[TBAA5]]
+; SSE-NEXT:    [[TMP30:%.*]] = mul i64 [[TMP29]], [[TMP4]]
+; SSE-NEXT:    [[TMP31:%.*]] = lshr i64 [[TMP30]], 15
+; SSE-NEXT:    [[TMP32:%.*]] = trunc i64 [[TMP31]] to i32
+; SSE-NEXT:    [[TMP33:%.*]] = icmp ult i32 [[TMP32]], 255
+; SSE-NEXT:    [[TMP34:%.*]] = and i64 [[TMP31]], 4294967295
+; SSE-NEXT:    [[TMP35:%.*]] = select i1 [[TMP33]], i64 [[TMP34]], i64 255
+; SSE-NEXT:    store i64 [[TMP35]], ptr [[TMP28]], align 8, !tbaa [[TBAA5]]
 ; SSE-NEXT:    ret void
 ;
 ; AVX-LABEL: @store_i64(


        


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