diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp index b73de2ed6ff9a..1484c4d3aca42 100644 --- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp +++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp @@ -2283,14 +2283,6 @@ class BoUpSLP { ~BoUpSLP(); private: - /// Determine if a vectorized value \p V in can be demoted to - /// a smaller type with a truncation. We collect the values that will be - /// demoted in ToDemote and additional roots that require investigating in - /// Roots. - bool collectValuesToDemote(Value *V, SmallVectorImpl &ToDemote, - SmallVectorImpl &Roots, - DenseSet &Visited) const; - /// Check if the operands on the edges \p Edges of the \p UserTE allows /// reordering (i.e. the operands can be reordered because they have only one /// user and reordarable). @@ -9052,7 +9044,8 @@ InstructionCost BoUpSLP::getTreeCost(ArrayRef VectorizedVals) { // for the extract and the added cost of the sign extend if needed. auto *VecTy = FixedVectorType::get(EU.Scalar->getType(), BundleWidth); TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput; - auto It = MinBWs.find(EU.Scalar); + auto *ScalarRoot = VectorizableTree[0]->Scalars[0]; + auto It = MinBWs.find(ScalarRoot); if (It != MinBWs.end()) { auto *MinTy = IntegerType::get(F->getContext(), It->second.first); unsigned Extend = @@ -13081,20 +13074,19 @@ unsigned BoUpSLP::getVectorElementSize(Value *V) { // Determine if a value V in a vectorizable expression Expr can be demoted to a // smaller type with a truncation. We collect the values that will be demoted // in ToDemote and additional roots that require investigating in Roots. -bool BoUpSLP::collectValuesToDemote(Value *V, - SmallVectorImpl &ToDemote, - SmallVectorImpl &Roots, - DenseSet &Visited) const { +static bool collectValuesToDemote(Value *V, SmallPtrSetImpl &Expr, + SmallVectorImpl &ToDemote, + SmallVectorImpl &Roots) { // We can always demote constants. if (isa(V)) { ToDemote.push_back(V); return true; } - // If the value is not a vectorized instruction in the expression with only - // one use, it cannot be demoted. + // If the value is not an instruction in the expression with only one use, it + // cannot be demoted. auto *I = dyn_cast(V); - if (!I || !I->hasOneUse() || !getTreeEntry(I) || !Visited.insert(I).second) + if (!I || !I->hasOneUse() || !Expr.count(I)) return false; switch (I->getOpcode()) { @@ -13118,16 +13110,16 @@ bool BoUpSLP::collectValuesToDemote(Value *V, case Instruction::And: case Instruction::Or: case Instruction::Xor: - if (!collectValuesToDemote(I->getOperand(0), ToDemote, Roots, Visited) || - !collectValuesToDemote(I->getOperand(1), ToDemote, Roots, Visited)) + if (!collectValuesToDemote(I->getOperand(0), Expr, ToDemote, Roots) || + !collectValuesToDemote(I->getOperand(1), Expr, ToDemote, Roots)) return false; break; // We can demote selects if we can demote their true and false values. case Instruction::Select: { SelectInst *SI = cast(I); - if (!collectValuesToDemote(SI->getTrueValue(), ToDemote, Roots, Visited) || - !collectValuesToDemote(SI->getFalseValue(), ToDemote, Roots, Visited)) + if (!collectValuesToDemote(SI->getTrueValue(), Expr, ToDemote, Roots) || + !collectValuesToDemote(SI->getFalseValue(), Expr, ToDemote, Roots)) return false; break; } @@ -13137,7 +13129,7 @@ bool BoUpSLP::collectValuesToDemote(Value *V, case Instruction::PHI: { PHINode *PN = cast(I); for (Value *IncValue : PN->incoming_values()) - if (!collectValuesToDemote(IncValue, ToDemote, Roots, Visited)) + if (!collectValuesToDemote(IncValue, Expr, ToDemote, Roots)) return false; break; } @@ -13164,16 +13156,36 @@ void BoUpSLP::computeMinimumValueSizes() { if (!TreeRootIT) return; + // If the expression is not rooted by a store, these roots should have + // external uses. + // TOSO: investigate if this can be relaxed. + SmallPtrSet Expr(TreeRoot.begin(), TreeRoot.end()); + for (auto &EU : ExternalUses) + if (!Expr.erase(EU.Scalar)) + return; + if (!Expr.empty()) + return; + + // Collect the scalar values of the vectorizable expression. We will use this + // context to determine which values can be demoted. If we see a truncation, + // we mark it as seeding another demotion. + for (auto &EntryPtr : VectorizableTree) + Expr.insert(EntryPtr->Scalars.begin(), EntryPtr->Scalars.end()); + + // Ensure the roots of the vectorizable tree don't form a cycle. They must + // have a single external user that is not in the vectorizable tree. + for (auto *Root : TreeRoot) + if (!Root->hasOneUse() || Expr.count(*Root->user_begin())) + return; + // Conservatively determine if we can actually truncate the roots of the // expression. Collect the values that can be demoted in ToDemote and // additional roots that require investigating in Roots. SmallVector ToDemote; SmallVector Roots; - for (auto *Root : TreeRoot) { - DenseSet Visited; - if (!collectValuesToDemote(Root, ToDemote, Roots, Visited)) + for (auto *Root : TreeRoot) + if (!collectValuesToDemote(Root, Expr, ToDemote, Roots)) return; - } // The maximum bit width required to represent all the values that can be // demoted without loss of precision. It would be safe to truncate the roots @@ -13203,9 +13215,9 @@ void BoUpSLP::computeMinimumValueSizes() { // maximum bit width required to store the scalar by using ValueTracking to // compute the number of high-order bits we can truncate. if (MaxBitWidth == DL->getTypeSizeInBits(TreeRoot[0]->getType()) && - all_of(TreeRoot, [](Value *V) { - return all_of(V->users(), - [](User *U) { return isa(U); }); + llvm::all_of(TreeRoot, [](Value *R) { + assert(R->hasOneUse() && "Root should have only one use!"); + return isa(R->user_back()); })) { MaxBitWidth = 8u; @@ -13254,10 +13266,8 @@ void BoUpSLP::computeMinimumValueSizes() { // If we can truncate the root, we must collect additional values that might // be demoted as a result. That is, those seeded by truncations we will // modify. - while (!Roots.empty()) { - DenseSet Visited; - collectValuesToDemote(Roots.pop_back_val(), ToDemote, Roots, Visited); - } + while (!Roots.empty()) + collectValuesToDemote(Roots.pop_back_val(), Expr, ToDemote, Roots); // Finally, map the values we can demote to the maximum bit with we computed. DenseMap Signendness;