[llvm] r205018 - SLPVectorizer: Ignore users that are insertelements we can reschedule them
Arnold Schwaighofer
aschwaighofer at apple.com
Mon Mar 31 16:20:00 PDT 2014
Reverted in r205260.
It looks like we fail when we vectorize the function call " %call.i4 = call i8 @llvm.ctlz.i8(i8 %1, i1 false)". Probably, because the second parameter has to stay scalar.
On Mar 31, 2014, at 10:51 AM, Tom Stellard <tom at stellard.net> wrote:
> On Fri, Mar 28, 2014 at 05:21:23PM -0000, Arnold Schwaighofer wrote:
>> Author: arnolds
>> Date: Fri Mar 28 12:21:22 2014
>> New Revision: 205018
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=205018&view=rev
>> Log:
>> SLPVectorizer: Ignore users that are insertelements we can reschedule them
>>
>> Patch by Arch D. Robison!
>>
>
> This commit causes a crash in the libclc build. To reproduce (see
> attached test case):
>
> opt -slp-vectorizer slp-regression.ll -o - -S
>
> -Tom
>
>> Modified:
>> llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>> llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
>>
>> Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=205018&r1=205017&r2=205018&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Fri Mar 28 12:21:22 2014
>> @@ -365,13 +365,13 @@ public:
>> /// A negative number means that this is profitable.
>> int getTreeCost();
>>
>> - /// Construct a vectorizable tree that starts at \p Roots and is possibly
>> - /// used by a reduction of \p RdxOps.
>> - void buildTree(ArrayRef<Value *> Roots, ValueSet *RdxOps = 0);
>> + /// Construct a vectorizable tree that starts at \p Roots, ignoring users for
>> + /// the purpose of scheduling and extraction in the \p UserIgnoreLst.
>> + void buildTree(ArrayRef<Value *> Roots,
>> + ArrayRef<Value *> UserIgnoreLst = None);
>>
>> /// Clear the internal data structures that are created by 'buildTree'.
>> void deleteTree() {
>> - RdxOps = 0;
>> VectorizableTree.clear();
>> ScalarToTreeEntry.clear();
>> MustGather.clear();
>> @@ -527,8 +527,8 @@ private:
>> /// Numbers instructions in different blocks.
>> DenseMap<BasicBlock *, BlockNumbering> BlocksNumbers;
>>
>> - /// Reduction operators.
>> - ValueSet *RdxOps;
>> + /// List of users to ignore during scheduling and that don't need extracting.
>> + ArrayRef<Value *> UserIgnoreList;
>>
>> // Analysis and block reference.
>> Function *F;
>> @@ -542,9 +542,10 @@ private:
>> IRBuilder<> Builder;
>> };
>>
>> -void BoUpSLP::buildTree(ArrayRef<Value *> Roots, ValueSet *Rdx) {
>> +void BoUpSLP::buildTree(ArrayRef<Value *> Roots,
>> + ArrayRef<Value *> UserIgnoreLst) {
>> deleteTree();
>> - RdxOps = Rdx;
>> + UserIgnoreList = UserIgnoreLst;
>> if (!getSameType(Roots))
>> return;
>> buildTree_rec(Roots, 0);
>> @@ -576,8 +577,9 @@ void BoUpSLP::buildTree(ArrayRef<Value *
>> if (!UserInst)
>> continue;
>>
>> - // Ignore uses that are part of the reduction.
>> - if (Rdx && std::find(Rdx->begin(), Rdx->end(), UserInst) != Rdx->end())
>> + // Ignore users in the user ignore list.
>> + if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(), UserInst) !=
>> + UserIgnoreList.end())
>> continue;
>>
>> DEBUG(dbgs() << "SLP: Need to extract:" << *U << " from lane " <<
>> @@ -708,8 +710,9 @@ void BoUpSLP::buildTree_rec(ArrayRef<Val
>> continue;
>> }
>>
>> - // This user is part of the reduction.
>> - if (RdxOps && RdxOps->count(UI))
>> + // Ignore users in the user ignore list.
>> + if (std::find(UserIgnoreList.begin(), UserIgnoreList.end(), UI) !=
>> + UserIgnoreList.end())
>> continue;
>>
>> // Make sure that we can schedule this unknown user.
>> @@ -1737,8 +1740,9 @@ Value *BoUpSLP::vectorizeTree() {
>> DEBUG(dbgs() << "SLP: \tvalidating user:" << *U << ".\n");
>>
>> assert((ScalarToTreeEntry.count(U) ||
>> - // It is legal to replace the reduction users by undef.
>> - (RdxOps && RdxOps->count(U))) &&
>> + // It is legal to replace users in the ignorelist by undef.
>> + (std::find(UserIgnoreList.begin(), UserIgnoreList.end(), U) !=
>> + UserIgnoreList.end())) &&
>> "Replacing out-of-tree value with undef");
>> }
>> #endif
>> @@ -1942,8 +1946,11 @@ private:
>> bool tryToVectorizePair(Value *A, Value *B, BoUpSLP &R);
>>
>> /// \brief Try to vectorize a list of operands.
>> + /// \@param BuildVector A list of users to ignore for the purpose of
>> + /// scheduling and that don't need extracting.
>> /// \returns true if a value was vectorized.
>> - bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R);
>> + bool tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
>> + ArrayRef<Value *> BuildVector = None);
>>
>> /// \brief Try to vectorize a chain that may start at the operands of \V;
>> bool tryToVectorize(BinaryOperator *V, BoUpSLP &R);
>> @@ -2116,7 +2123,8 @@ bool SLPVectorizer::tryToVectorizePair(V
>> return tryToVectorizeList(VL, R);
>> }
>>
>> -bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R) {
>> +bool SLPVectorizer::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
>> + ArrayRef<Value *> BuildVector) {
>> if (VL.size() < 2)
>> return false;
>>
>> @@ -2166,13 +2174,33 @@ bool SLPVectorizer::tryToVectorizeList(A
>> << "\n");
>> ArrayRef<Value *> Ops = VL.slice(i, OpsWidth);
>>
>> - R.buildTree(Ops);
>> + ArrayRef<Value *> BuildVectorSlice;
>> + if (!BuildVector.empty())
>> + BuildVectorSlice = BuildVector.slice(i, OpsWidth);
>> +
>> + R.buildTree(Ops, BuildVectorSlice);
>> int Cost = R.getTreeCost();
>>
>> if (Cost < -SLPCostThreshold) {
>> DEBUG(dbgs() << "SLP: Vectorizing pair at cost:" << Cost << ".\n");
>> - R.vectorizeTree();
>> + Value *VectorizedRoot = R.vectorizeTree();
>>
>> + // Reconstruct the build vector by extracting the vectorized root. This
>> + // way we handle the case where some elements of the vector are undefined.
>> + // (return (inserelt <4 xi32> (insertelt undef (opd0) 0) (opd1) 2))
>> + if (!BuildVectorSlice.empty()) {
>> + Instruction *InsertAfter = cast<Instruction>(VectorizedRoot);
>> + for (auto &V : BuildVectorSlice) {
>> + InsertElementInst *IE = cast<InsertElementInst>(V);
>> + IRBuilder<> Builder(++BasicBlock::iterator(InsertAfter));
>> + Instruction *Extract = cast<Instruction>(
>> + Builder.CreateExtractElement(VectorizedRoot, IE->getOperand(2)));
>> + IE->setOperand(1, Extract);
>> + IE->removeFromParent();
>> + IE->insertAfter(Extract);
>> + InsertAfter = IE;
>> + }
>> + }
>> // Move to the next bundle.
>> i += VF - 1;
>> Changed = true;
>> @@ -2281,7 +2309,7 @@ static Value *createRdxShuffleMask(unsig
>> /// *p =
>> ///
>> class HorizontalReduction {
>> - SmallPtrSet<Value *, 16> ReductionOps;
>> + SmallVector<Value *, 16> ReductionOps;
>> SmallVector<Value *, 32> ReducedVals;
>>
>> BinaryOperator *ReductionRoot;
>> @@ -2375,7 +2403,7 @@ public:
>> // We need to be able to reassociate the adds.
>> if (!TreeN->isAssociative())
>> return false;
>> - ReductionOps.insert(TreeN);
>> + ReductionOps.push_back(TreeN);
>> }
>> // Retract.
>> Stack.pop_back();
>> @@ -2412,7 +2440,7 @@ public:
>>
>> for (; i < NumReducedVals - ReduxWidth + 1; i += ReduxWidth) {
>> ArrayRef<Value *> ValsToReduce(&ReducedVals[i], ReduxWidth);
>> - V.buildTree(ValsToReduce, &ReductionOps);
>> + V.buildTree(ValsToReduce, ReductionOps);
>>
>> // Estimate cost.
>> int Cost = V.getTreeCost() + getReductionCost(TTI, ReducedVals[i]);
>> @@ -2531,13 +2559,16 @@ private:
>> ///
>> /// Returns true if it matches
>> ///
>> -static bool findBuildVector(InsertElementInst *IE,
>> - SmallVectorImpl<Value *> &Ops) {
>> - if (!isa<UndefValue>(IE->getOperand(0)))
>> +static bool findBuildVector(InsertElementInst *FirstInsertElem,
>> + SmallVectorImpl<Value *> &BuildVector,
>> + SmallVectorImpl<Value *> &BuildVectorOpds) {
>> + if (!isa<UndefValue>(FirstInsertElem->getOperand(0)))
>> return false;
>>
>> + InsertElementInst *IE = FirstInsertElem;
>> while (true) {
>> - Ops.push_back(IE->getOperand(1));
>> + BuildVector.push_back(IE);
>> + BuildVectorOpds.push_back(IE->getOperand(1));
>>
>> if (IE->use_empty())
>> return false;
>> @@ -2707,12 +2738,16 @@ bool SLPVectorizer::vectorizeChainsInBlo
>> }
>>
>> // Try to vectorize trees that start at insertelement instructions.
>> - if (InsertElementInst *IE = dyn_cast<InsertElementInst>(it)) {
>> - SmallVector<Value *, 8> Ops;
>> - if (!findBuildVector(IE, Ops))
>> + if (InsertElementInst *FirstInsertElem = dyn_cast<InsertElementInst>(it)) {
>> + SmallVector<Value *, 16> BuildVector;
>> + SmallVector<Value *, 16> BuildVectorOpds;
>> + if (!findBuildVector(FirstInsertElem, BuildVector, BuildVectorOpds))
>> continue;
>>
>> - if (tryToVectorizeList(Ops, R)) {
>> + // Vectorize starting with the build vector operands ignoring the
>> + // BuildVector instructions for the purpose of scheduling and user
>> + // extraction.
>> + if (tryToVectorizeList(BuildVectorOpds, R, BuildVector)) {
>> Changed = true;
>> it = BB->begin();
>> e = BB->end();
>>
>> Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll?rev=205018&r1=205017&r2=205018&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll (original)
>> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/insert-element-build-vector.ll Fri Mar 28 12:21:22 2014
>> @@ -194,4 +194,28 @@ define <4 x float> @simple_select_partia
>> ret <4 x float> %rb
>> }
>>
>> +; Make sure that vectorization happens even if insertelements operations
>> +; must be rescheduled. The case here is from compiling Julia.
>> +define <4 x float> @reschedule_extract(<4 x float> %a, <4 x float> %b) {
>> +; CHECK-LABEL: @reschedule_extract(
>> +; CHECK: %1 = fadd <4 x float> %a, %b
>> + %a0 = extractelement <4 x float> %a, i32 0
>> + %b0 = extractelement <4 x float> %b, i32 0
>> + %c0 = fadd float %a0, %b0
>> + %v0 = insertelement <4 x float> undef, float %c0, i32 0
>> + %a1 = extractelement <4 x float> %a, i32 1
>> + %b1 = extractelement <4 x float> %b, i32 1
>> + %c1 = fadd float %a1, %b1
>> + %v1 = insertelement <4 x float> %v0, float %c1, i32 1
>> + %a2 = extractelement <4 x float> %a, i32 2
>> + %b2 = extractelement <4 x float> %b, i32 2
>> + %c2 = fadd float %a2, %b2
>> + %v2 = insertelement <4 x float> %v1, float %c2, i32 2
>> + %a3 = extractelement <4 x float> %a, i32 3
>> + %b3 = extractelement <4 x float> %b, i32 3
>> + %c3 = fadd float %a3, %b3
>> + %v3 = insertelement <4 x float> %v2, float %c3, i32 3
>> + ret <4 x float> %v3
>> +}
>> +
>> attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
>>
>>
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