[ADT] Deprecate is_splat and replace all uses with all_equal

[kuhar]

Summary

See the discussion thread for more details:
https://discourse.llvm.org/t/adt-is-splat-and-empty-ranges/64692

[dblaikie]

Great :)

[rriddle]

mlir/lib/Bindings/Python/IRAttributes.cpp

771

This shouldn't be changed.

[kuhar]

mlir/lib/Bindings/Python/IRAttributes.cpp

771

Thanks!

[rriddle]

Assuming tests pass, the MLIR changes LGTM.

llvm/include/llvm/ADT/STLExtras.h

 
 /// Returns true if all Values in the initializer lists are equal or the list
 // is empty.
 template <typename T> bool all_equal(std::initializer_list<T> Values) {
   return all_equal<std::initializer_list<T>>(std::move(Values));
 }
 
 /// Returns true if Range consists of the same value repeated multiple times.
-template <typename R> bool is_splat(R &&Range) {
+template <typename R>
+LLVM_DEPRECATED(
+    "Use 'all_equal(Range)' or '!empty(Range) && all_equal(Range)' instead.",
+    "all_equal")
+bool is_splat(R &&Range) {
   return !llvm::empty(Range) && all_equal(Range);
 }
 
 /// Returns true if Values consists of the same value repeated multiple times.
-template <typename T> bool is_splat(std::initializer_list<T> Values) {
+template <typename T>
+LLVM_DEPRECATED(
+    "Use 'all_equal(Values)' or '!empty(Values) && all_equal(Values)' instead.",
+    "all_equal")
+bool is_splat(std::initializer_list<T> Values) {
   return is_splat<std::initializer_list<T>>(std::move(Values));
 }
 
 /// Provide a container algorithm similar to C++ Library Fundamentals v2's
 /// `erase_if` which is equivalent to:
 ///
 ///   C.erase(remove_if(C, pred), C.end());
 ///

llvm/lib/Analysis/InstructionSimplify.cpp

       return ConstantVector::get(VecC);
     }
   }
 
   // A shuffle of a splat is always the splat itself. Legal if the shuffle's
   // value type is same as the input vectors' type.
   if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
     if (Q.isUndefValue(Op1) && RetTy == InVecTy &&
-        is_splat(OpShuf->getShuffleMask()))
+        all_equal(OpShuf->getShuffleMask()))
       return Op0;
 
   // All remaining transformation depend on the value of the mask, which is
   // not known at compile time for scalable vectors.
   if (Scalable)
     return nullptr;
 
   // Don't fold a shuffle with undef mask elements. This may get folded in a

llvm/lib/Analysis/VectorUtils.cpp

if (isa<VectorType>(V->getType())) {
     //        check that the constant is defined at that index.
     if (auto *C = dyn_cast<Constant>(V))
       return C->getSplatValue() != nullptr;
   }
 
   if (auto *Shuf = dyn_cast<ShuffleVectorInst>(V)) {
     // FIXME: We can safely allow undefs here. If Index was specified, we will
     //        check that the mask elt is defined at the required index.
-    if (!is_splat(Shuf->getShuffleMask()))
+    if (!all_equal(Shuf->getShuffleMask()))
       return false;
 
     // Match any index.
     if (Index == -1)
       return true;
 
     // Match a specific element. The mask should be defined at and match the
     // specified index.
do {
     ArrayRef<int> MaskSlice = Mask.take_front(Scale);
     assert((int)MaskSlice.size() == Scale && "Expected Scale-sized slice.");
 
     // The first element of the slice determines how we evaluate this slice.
     int SliceFront = MaskSlice.front();
     if (SliceFront < 0) {
       // Negative values (undef or other "sentinel" values) must be equal across
       // the entire slice.
-      if (!is_splat(MaskSlice))
+      if (!all_equal(MaskSlice))
         return false;
       ScaledMask.push_back(SliceFront);
     } else {
       // A positive mask element must be cleanly divisible.
       if (SliceFront % Scale != 0)
         return false;
       // Elements of the slice must be consecutive.
       for (int i = 1; i < Scale; ++i)

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

     }
 
     // Try to sink a splat shuffle after a binop with a uniform constant.
     // This is limited to cases where neither the shuffle nor the constant have
     // undefined elements because that could be poison-unsafe or inhibit
     // demanded elements analysis. It is further limited to not change a splat
     // of an inserted scalar because that may be optimized better by
     // load-folding or other target-specific behaviors.
-    if (isConstOrConstSplat(RHS) && Shuf0 && is_splat(Shuf0->getMask()) &&
+    if (isConstOrConstSplat(RHS) && Shuf0 && all_equal(Shuf0->getMask()) &&
         Shuf0->hasOneUse() && Shuf0->getOperand(1).isUndef() &&
         Shuf0->getOperand(0).getOpcode() != ISD::INSERT_VECTOR_ELT) {
       // binop (splat X), (splat C) --> splat (binop X, C)
       SDValue X = Shuf0->getOperand(0);
       SDValue NewBinOp = DAG.getNode(Opcode, DL, VT, X, RHS, Flags);
       return DAG.getVectorShuffle(VT, DL, NewBinOp, DAG.getUNDEF(VT),
                                   Shuf0->getMask());
     }
-    if (isConstOrConstSplat(LHS) && Shuf1 && is_splat(Shuf1->getMask()) &&
+    if (isConstOrConstSplat(LHS) && Shuf1 && all_equal(Shuf1->getMask()) &&
         Shuf1->hasOneUse() && Shuf1->getOperand(1).isUndef() &&
         Shuf1->getOperand(0).getOpcode() != ISD::INSERT_VECTOR_ELT) {
       // binop (splat C), (splat X) --> splat (binop C, X)
       SDValue X = Shuf1->getOperand(0);
       SDValue NewBinOp = DAG.getNode(Opcode, DL, VT, LHS, X, Flags);
       return DAG.getVectorShuffle(VT, DL, NewBinOp, DAG.getUNDEF(VT),
                                   Shuf1->getMask());
     }

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

   bool IsUnaryAbs = false;
   bool Negate = false;
 
   SDNodeFlags Flags;
   if (auto *FPOp = dyn_cast<FPMathOperator>(&I))
     Flags.copyFMF(*FPOp);
 
   // Min/max matching is only viable if all output VTs are the same.
-  if (is_splat(ValueVTs)) {
+  if (all_equal(ValueVTs)) {
     EVT VT = ValueVTs[0];
     LLVMContext &Ctx = *DAG.getContext();
     auto &TLI = DAG.getTargetLoweringInfo();
 
     // We care about the legality of the operation after it has been type
     // legalized.
     while (TLI.getTypeAction(Ctx, VT) != TargetLoweringBase::TypeLegal)
       VT = TLI.getTypeToTransformTo(Ctx, VT);

llvm/lib/IR/Instructions.cpp

   // Make sure the mask elements make sense.
   int V1Size =
       cast<VectorType>(V1->getType())->getElementCount().getKnownMinValue();
   for (int Elem : Mask)
     if (Elem != UndefMaskElem && Elem >= V1Size * 2)
       return false;
 
   if (isa<ScalableVectorType>(V1->getType()))
-    if ((Mask[0] != 0 && Mask[0] != UndefMaskElem) || !is_splat(Mask))
+    if ((Mask[0] != 0 && Mask[0] != UndefMaskElem) || !all_equal(Mask))
       return false;
 
   return true;
 }
 
 bool ShuffleVectorInst::isValidOperands(const Value *V1, const Value *V2,
                                         const Value *Mask) {
   // V1 and V2 must be vectors of the same type.

   ShuffleMask.assign(Mask.begin(), Mask.end());
   ShuffleMaskForBitcode = convertShuffleMaskForBitcode(Mask, getType());
 }
 
 Constant *ShuffleVectorInst::convertShuffleMaskForBitcode(ArrayRef<int> Mask,
                                                           Type *ResultTy) {
   Type *Int32Ty = Type::getInt32Ty(ResultTy->getContext());
   if (isa<ScalableVectorType>(ResultTy)) {
-    assert(is_splat(Mask) && "Unexpected shuffle");
+    assert(all_equal(Mask) && "Unexpected shuffle");
     Type *VecTy = VectorType::get(Int32Ty, Mask.size(), true);
     if (Mask[0] == 0)
       return Constant::getNullValue(VecTy);
     return UndefValue::get(VecTy);
   }
   SmallVector<Constant *, 16> MaskConst;
   for (int Elem : Mask) {
     if (Elem == UndefMaskElem)

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

 
 /// Check if Op1 and Op2 could be used with vmull_high_p64 intrinsic.
 static bool areOperandsOfVmullHighP64(Value *Op1, Value *Op2) {
   return isOperandOfVmullHighP64(Op1) && isOperandOfVmullHighP64(Op2);
 }
 
 static bool isSplatShuffle(Value *V) {
   if (auto *Shuf = dyn_cast<ShuffleVectorInst>(V))
-    return is_splat(Shuf->getShuffleMask());
+    return all_equal(Shuf->getShuffleMask());
   return false;
 }
 
 /// Check if sinking \p I's operands to I's basic block is profitable, because
 /// the operands can be folded into a target instruction, e.g.
 /// shufflevectors extracts and/or sext/zext can be folded into (u,s)subl(2).
 bool AArch64TargetLowering::shouldSinkOperands(
     Instruction *I, SmallVectorImpl<Use *> &Ops) const {

   if (!Ty->isArrayTy()) {
     const TypeSize &TySize = Ty->getPrimitiveSizeInBits();
     return TySize.isScalable() && TySize.getKnownMinSize() > 128;
   }
 
   // All non aggregate members of the type must have the same type
   SmallVector<EVT> ValueVTs;
   ComputeValueVTs(*this, DL, Ty, ValueVTs);
-  return is_splat(ValueVTs);
+  return all_equal(ValueVTs);
 }
 
 bool AArch64TargetLowering::shouldNormalizeToSelectSequence(LLVMContext &,
                                                             EVT) const {
   return false;
 }
 
 static Value *UseTlsOffset(IRBuilderBase &IRB, unsigned Offset) {

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

 
 /// Try to narrow the width of a splat shuffle. This could be generalized to any
 /// shuffle with a constant operand, but we limit the transform to avoid
 /// creating a shuffle type that targets may not be able to lower effectively.
 static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
                                        InstCombiner::BuilderTy &Builder) {
   auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
   if (Shuf && Shuf->hasOneUse() && match(Shuf->getOperand(1), m_Undef()) &&
-      is_splat(Shuf->getShuffleMask()) &&
+      all_equal(Shuf->getShuffleMask()) &&
       Shuf->getType() == Shuf->getOperand(0)->getType()) {
     // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Poison, SplatMask
     // trunc (shuf X, Poison, SplatMask) --> shuf (trunc X), Poison, SplatMask
     Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
     return new ShuffleVectorInst(NarrowOp, Shuf->getShuffleMask());
   }
 
   return nullptr;

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

   //    and SC is a constant vector = <C', C', C', ..., C'>
   // Into:
   //   %E = extractelement <M x iK> %vec, i32 C'
   //   icmp <pred> iK %E, trunc(C)
   Value *Vec;
   ArrayRef<int> Mask;
   if (match(BCSrcOp, m_Shuffle(m_Value(Vec), m_Undef(), m_Mask(Mask)))) {
     // Check whether every element of Mask is the same constant
-    if (is_splat(Mask)) {
+    if (all_equal(Mask)) {
       auto *VecTy = cast<VectorType>(SrcType);
       auto *EltTy = cast<IntegerType>(VecTy->getElementType());
       if (C->isSplat(EltTy->getBitWidth())) {
         // Fold the icmp based on the value of C
         // If C is M copies of an iK sized bit pattern,
         // then:
         //   =>  %E = extractelement <N x iK> %vec, i32 Elem
         //       icmp <pred> iK %SplatVal, <pattern>

llvm/lib/Transforms/Scalar/NewGVN.cpp

   auto *MP = cast<MemoryPhi>(EndDef);
   auto ReachableOperandPred = [&](const Use &U) {
     return ReachableEdges.count({MP->getIncomingBlock(U), MP->getBlock()});
   };
   auto FilteredPhiArgs =
       make_filter_range(MP->operands(), ReachableOperandPred);
   SmallVector<const Value *, 32> OperandList;
   llvm::copy(FilteredPhiArgs, std::back_inserter(OperandList));
-  bool Okay = is_splat(OperandList);
+  bool Okay = all_equal(OperandList);
   if (Okay)
     return singleReachablePHIPath(Visited, cast<MemoryAccess>(OperandList[0]),
                                   Second);
   return false;
 }
 
 // Verify the that the memory equivalence table makes sense relative to the
 // congruence classes.  Note that this checking is not perfect, and is currently

       auto FilteredPhiArgs =
           make_filter_range(FirstMP->operands(), ReachableOperandPred);
       SmallVector<const CongruenceClass *, 16> PhiOpClasses;
       std::transform(FilteredPhiArgs.begin(), FilteredPhiArgs.end(),
                      std::back_inserter(PhiOpClasses), [&](const Use &U) {
                        const MemoryDef *MD = cast<MemoryDef>(U);
                        return ValueToClass.lookup(MD->getMemoryInst());
                      });
-      assert(is_splat(PhiOpClasses) &&
+      assert(all_equal(PhiOpClasses) &&
              "All MemoryPhi arguments should be in the same class");
     }
   }
 #endif
 }
 
 // Verify that the sparse propagation we did actually found the maximal fixpoint
 // We do this by storing the value to class mapping, touching all instructions,

llvm/unittests/ADT/STLExtrasTest.cpp

 TEST(STLExtrasTest, AllEqualInitializerList) {
   EXPECT_TRUE(all_equal({1}));
   EXPECT_TRUE(all_equal({1, 1}));
   EXPECT_FALSE(all_equal({1, 2}));
   EXPECT_FALSE(all_equal({2, 1}));
   EXPECT_TRUE(all_equal({1, 1, 1}));
 }
 
-TEST(STLExtrasTest, IsSplat) {
-  std::vector<int> V;
-  EXPECT_FALSE(is_splat(V));
-
-  V.push_back(1);
-  EXPECT_TRUE(is_splat(V));
-
-  V.push_back(1);
-  V.push_back(1);
-  EXPECT_TRUE(is_splat(V));
-
-  V.push_back(2);
-  EXPECT_FALSE(is_splat(V));
-}
-
-TEST(STLExtrasTest, IsSplatInitializerList) {
-  EXPECT_TRUE(is_splat({1}));
-  EXPECT_TRUE(is_splat({1, 1}));
-  EXPECT_FALSE(is_splat({1, 2}));
-  EXPECT_TRUE(is_splat({1, 1, 1}));
-}
-
 TEST(STLExtrasTest, to_address) {
   int *V1 = new int;
   EXPECT_EQ(V1, to_address(V1));
 
   // Check fancy pointer overload for unique_ptr
   std::unique_ptr<int> V2 = std::make_unique<int>(0);
   EXPECT_EQ(V2.get(), llvm::to_address(V2));
 

mlir/include/mlir/IR/OpBase.td

 // Predicate to verify that all the operands at the given `indices`
 // have the same element type.
 // Type Constraint operands' Element type are all Same At the given `indices`.
 // We query the operands' types into a list and check they are all the same.
 // Precondition:
 // 1) all operands involved are of shaped type and
 // 2) the indices are not out of range.
 class TCopVTEtAreSameAt<list<int> indices> : CPred<
-  "::llvm::is_splat(::llvm::map_range("
+  "::llvm::all_equal(::llvm::map_range("
       "::mlir::ArrayRef<unsigned>({" # !interleave(indices, ", ") # "}), "
       "[this](unsigned i) { return getElementTypeOrSelf(this->getOperand(i)); "
       "}))">;
 
 #endif // OP_BASE

mlir/lib/Bindings/Python/IRAttributes.cpp

c.def("__len__", &PyDenseElementsAttribute::dunderLen)
         .def_static("get", PyDenseElementsAttribute::getFromBuffer,
                     py::arg("array"), py::arg("signless") = true,
                     py::arg("type") = py::none(), py::arg("shape") = py::none(),
                     py::arg("context") = py::none(),
                     kDenseElementsAttrGetDocstring)
         .def_static("get_splat", PyDenseElementsAttribute::getSplat,
                     py::arg("shaped_type"), py::arg("element_attr"),
                     "Gets a DenseElementsAttr where all values are the same")
-        .def_property_readonly("is_splat",
+        .def_property_readonly("all_equal",
                                [](PyDenseElementsAttribute &self) -> bool {
                                  return mlirDenseElementsAttrIsSplat(self);
                                })
         .def_buffer(&PyDenseElementsAttribute::accessBuffer);
   }
 
 private:
   static bool isUnsignedIntegerFormat(const std::string &format) {

mlir/lib/Dialect/Linalg/Transforms/ConstantFold.cpp

if (!llvm::all_of(genericOp.getInputOperands(), [](OpOperand *operand) {
           return operand->get().getType().isa<ShapedType>();
         }))
       return failure();
 
     // Make sure all element types are the same.
     auto getOperandElementType = [](OpOperand *operand) {
       return operand->get().getType().cast<ShapedType>().getElementType();
     };
-    if (!llvm::is_splat(llvm::map_range(genericOp.getInputAndOutputOperands(),
+    if (!llvm::all_equal(llvm::map_range(genericOp.getInputAndOutputOperands(),
                                          getOperandElementType)))
       return failure();
 
     // We can only handle the case where we have int/float elements.
     auto elementType = outputType.getElementType();
     if (!elementType.isIntOrFloat())
       return failure();
 
     // Require all indexing maps to be permutations for now. This is common and

mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp

 // spv.IAddCarryOp
 //===----------------------------------------------------------------------===//
 
 LogicalResult spirv::IAddCarryOp::verify() {
   auto resultType = getType().cast<spirv::StructType>();
   if (resultType.getNumElements() != 2)
     return emitOpError("expected result struct type containing two members");
 
-  if (!llvm::is_splat({operand1().getType(), operand2().getType(),
+  if (!llvm::all_equal({operand1().getType(), operand2().getType(),
                         resultType.getElementType(0),
                         resultType.getElementType(1)}))
     return emitOpError(
         "expected all operand types and struct member types are the same");
 
   return success();
 }
 
 ParseResult spirv::IAddCarryOp::parse(OpAsmParser &parser,
                                       OperationState &result) {

 // spv.ISubBorrowOp
 //===----------------------------------------------------------------------===//
 
 LogicalResult spirv::ISubBorrowOp::verify() {
   auto resultType = getType().cast<spirv::StructType>();
   if (resultType.getNumElements() != 2)
     return emitOpError("expected result struct type containing two members");
 
-  if (!llvm::is_splat({operand1().getType(), operand2().getType(),
+  if (!llvm::all_equal({operand1().getType(), operand2().getType(),
                         resultType.getElementType(0),
                         resultType.getElementType(1)}))
     return emitOpError(
         "expected all operand types and struct member types are the same");
 
   return success();
 }
 
 ParseResult spirv::ISubBorrowOp::parse(OpAsmParser &parser,
                                        OperationState &result) {

mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp

         return failure();
       }
     }
     if (transposeMaps.empty())
       return failure();
     // This is an elementwise op, so all transposed operands should have the
     // same type. We need to additionally check that all transposes uses the
     // same map.
-    if (!llvm::is_splat(transposeMaps))
+    if (!llvm::all_equal(transposeMaps))
       return rewriter.notifyMatchFailure(op, "different transpose map");
 
     SmallVector<Value, 4> srcValues;
     srcValues.reserve(op->getNumOperands());
 
     // If there are constant operands, we need to insert inverse transposes for
     // them. Calculate the inverse order first.
     auto order = extractVector<unsigned>(transposeMaps.front());

mlir/test/mlir-tblgen/predicate.td

let arguments = (ins
     AnyTensor:$b,
     AnyTensor:$c,
     AnyTensor:$d,
     AnyTensor:$e
   );
 }
 
 // CHECK-LABEL: OpJAdaptor::verify
-// CHECK:      ::llvm::is_splat(::llvm::map_range(
+// CHECK:      ::llvm::all_equal(::llvm::map_range(
 // CHECK-SAME:   ::mlir::ArrayRef<unsigned>({0, 2, 3}),
 // CHECK-SAME:   [this](unsigned i) { return getElementTypeOrSelf(this->getOperand(i)); }))
 // CHECK: "failed to verify that operands indexed at 0, 2, 3 should all have the same type"
 
 def OpK : NS_Op<"op_for_AnyTensorOf", []> {
   let arguments = (ins TensorOf<[F32, I32]>:$x);
 }
 

mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp

static void collectAllDefs(StringRef selectedDialect,
   if (records.empty())
     return;
 
   auto defs = llvm::map_range(
       records, [&](const llvm::Record *rec) { return AttrOrTypeDef(rec); });
   if (selectedDialect.empty()) {
     // If a dialect was not specified, ensure that all found defs belong to the
     // same dialect.
-    if (!llvm::is_splat(llvm::map_range(
+    if (!llvm::all_equal(llvm::map_range(
             defs, [](const auto &def) { return def.getDialect(); }))) {
       llvm::PrintFatalError("defs belonging to more than one dialect. Must "
                             "select one via '--(attr|type)defs-dialect'");
     }
     resultDefs.assign(defs.begin(), defs.end());
   } else {
     // Otherwise, generate the defs that belong to the selected dialect.
     auto dialectDefs = llvm::make_filter_range(defs, [&](const auto &def) {