Specialize.cpp

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//===- Specialize.cpp - linalg generic ops to named ops  ------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements a method to specialize generic operations to named
// operations. Conceptually it is the opposite of generalize.cpp.
//
//===----------------------------------------------------------------------===//
 
#include "mlir/Analysis/SliceAnalysis.h"
#include "mlir/Dialect/Complex/IR/Complex.h"
#include "mlir/Dialect/Linalg/IR/Linalg.h"
#include "mlir/Dialect/Linalg/IR/LinalgInterfaces.h"
#include "mlir/Dialect/Linalg/Passes.h"
#include "mlir/Dialect/Linalg/Transforms/Transforms.h"
#include "mlir/Dialect/Math/IR/Math.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
 
namespace mlir {
#define GEN_PASS_DEF_LINALGSPECIALIZEGENERICOPSPASS
#include "mlir/Dialect/Linalg/Passes.h.inc"
} // namespace mlir
 
#define DEBUG_TYPE "linalg-specialization"
 
using namespace mlir;
using namespace mlir::linalg;
 
//===----------------------------------------------------------------------===//
// Specialize linalg generic to elementwise ops.
//===----------------------------------------------------------------------===//
 
// Given an elementwise single binary linalg generic op, checks whether the
// binary op accesses operands as swapped. e.g.
// this differentiates between a linalg-generic body that contains:
//    ^bb0(%a: f32, %b: f32, %c : f32):
//         %0 = arith.subf %a, %b : f32
//         linalg.yield %0: f32
// against:
//    ^bb0(%a: f32, %b: f32, %c : f32):
//         %0 = arith.subf %b, %a : f32
//         linalg.yield %0: f32
// Former is linalg.sub(a,b), latter is linalg.sub(b,a).
static bool areBinOpsSwapped(GenericOp genericOp) {
  Block *body = genericOp.getBody();
  Operation *op = &body->front();
  bool swapped = false;
  if (op->getOpOperand(0).get() != body->getArgument(0)) {
    swapped = true;
    assert(op->getOpOperand(0).get() == body->getArgument(1) &&
           op->getOpOperand(1).get() == body->getArgument(0) &&
           "binary op uses just one block arg");
  }
  return swapped;
}
 
// Given an elementwise single unary linalg generic op whose body operation is a
// binary operation, check if one of its operands is a scalar value defined
// outside the generic op, set its index, and return true. Otherwise return
// false. The index is unique because the block argument is used at
// least by one operand, as checked in `isaElemwiseSingleUnaryOpInterface`.
//
// Example:
//   %cst = arith.constant 3.14 : f32
//   %0 = linalg.generic { indexing_maps = [#mapA, #mapRes], ... }
//          ins(%A : tensor<?xf32>) outs(...) {
//   ^bb0(%a: f32, %out : f32):
//     %0 = arith.mulf %a, %cst : f32
//     linalg.yield %0: f32
//   } -> tensor<?xf32>
// Here, the returned index is 1, and the generic op can be represented as
//   %0 = linalg.elementwise <mul>
//          indexing_maps = [#mapA, affine_map<(d0) -> ()>, #mapRes]
//          ins(%A, %cst : tensor<?xf32>, f32) outs(...) -> tensor<?xf32>
static bool findIndexOfScalarOperand(GenericOp genericOp, int &index) {
  Block *body = genericOp.getBody();
  Operation *op = &body->front();
  for (auto [i, v] : llvm::enumerate(op->getOperands())) {
    if (auto blockArg = dyn_cast<BlockArgument>(v);
        blockArg && blockArg.getOwner() == body)
      continue; // not an outside value...
    index = i;
    return true;
  }
  return false;
}
 
// Attempt to specialize unary or binary linalg.generic ops to named elementwise
// ops or linalg.elementwise.
//
// Example:
//   %0 = linalg.generic {
//       indexing_maps = [affine_map<(d0, d1) -> (d0, d1)>,
//                        affine_map<(d0, d1) -> (d0, d1)>],
//       iterator_types = ["parallel", "parallel"]
//     } ins(%In : tensor<?x?xf32>) outs(%Out : tensor<?x?xf32>) {
//     ^bb0(%in: f32, %out: f32):
//       %1 = math.exp %in : f32
//       linalg.yield %1 : f32
//     } -> tensor<?x?xf32>
//
// is specialized to
//   linalg.elementwise <exp> ...
//
// A named op is emitted instead for binary/ternary ops that still have a
// linalg.* named equivalent (e.g. linalg.add).
//
// Only the category op can carry non-identity indexing maps; these are
// transferred verbatim from the `genericOp`.
//
// In addition to the canonical forms used by the generalization path, this
// function can handle the following variations:
//
// 1) Swapped operands in binary ops (see the `areBinOpsSwapped` helper)
// 2) Unary generic ops with a binary body op (see the
//    `findIndexOfScalarOperand` helper)
static FailureOr<LinalgOp> specializeLinalgElementwise(RewriterBase &rewriter,
                                                       GenericOp genericOp,
                                                       bool emitCategoryOp) {
  bool hasNonIdentityMaps =
      !llvm::all_of(genericOp.getIndexingMapsArray(),
                    [](AffineMap map) { return map.isIdentity(); });
 
  // Early exit: Named ops cannot carry user-defined maps.
  if (hasNonIdentityMaps && !emitCategoryOp)
    return rewriter.notifyMatchFailure(
        genericOp,
        "non-identity indexing maps prevent specialization to named op");
 
  // Classify the generic op.
  bool isUnary = genericOp.getNumDpsInputs() == 1;
  bool isBinary = genericOp.getNumDpsInputs() == 2;
 
  // Will inspect the body operation to determine named op or elementwise kind.
  Operation *op = &genericOp.getBody()->front();
 
  // Detect variations from canonical forms.
  bool hasSwappedOperands = isBinary && areBinOpsSwapped(genericOp);
  int scalarOprIdx = -1;
  bool hasScalarOperand = isUnary && op->getNumOperands() == 2 &&
                          findIndexOfScalarOperand(genericOp, scalarOprIdx);
 
  // Helper to dispatch between named op and `linalg.elementwise`.
  // Lambdas with explicit template parameter list are a C++20 feature, hence
  // the dummy op object.
  auto replaceOp = [&](auto namedOp, ElementwiseKind kind,
                       bool mayHoistScalarOperand = true) -> LinalgOp {
    SmallVector<Value> inputs = genericOp.getDpsInputs();
    if (hasSwappedOperands)
      std::swap(inputs[0], inputs[1]);
 
    LinalgOp newOp;
    using NamedOpTy = decltype(namedOp);
    // A null named op means the op only has a category form; emit
    // `linalg.elementwise` regardless of the requested output form.
    if (!std::is_null_pointer_v<NamedOpTy>) {
      if constexpr (!std::is_null_pointer_v<NamedOpTy>)
        newOp = NamedOpTy::create(rewriter, genericOp.getLoc(), inputs,
                                  genericOp.getDpsInits(),
                                  ArrayRef<NamedAttribute>{});
    } else {
      SmallVector<AffineMap> indexingMaps = genericOp.getIndexingMapsArray();
      // Swap indexing maps, too.
      if (hasSwappedOperands)
        std::swap(indexingMaps[0], indexingMaps[1]);
 
      // Represent unary generic op as a binary `linalg.elementwise` with a
      // scalar operand and broadcasting map.
      if (hasScalarOperand && mayHoistScalarOperand) {
        // Adjust inputs and indexing maps accordingly.
        inputs.insert(inputs.begin() + scalarOprIdx,
                      op->getOperand(scalarOprIdx));
        auto scalarBroadcastMap =
            AffineMap::get(genericOp.getNumParallelLoops(), /*symbolCount=*/0,
                           rewriter.getContext());
        indexingMaps.insert(indexingMaps.begin() + scalarOprIdx,
                            scalarBroadcastMap);
      }
      newOp = ElementwiseOp::create(
          rewriter, genericOp.getLoc(), inputs, genericOp.getDpsInits(), kind,
          rewriter.getAffineMapArrayAttr(indexingMaps));
    }
 
    rewriter.replaceOp(genericOp, newOp);
    return newOp;
  };
 
  // There are no named ops for these elementwise operations; can only emit the
  // category form.
  if (emitCategoryOp) {
    if (isa<math::ExpOp>(op))
      return replaceOp(nullptr, ElementwiseKind::exp);
    if (isa<math::AbsFOp>(op))
      return replaceOp(nullptr, ElementwiseKind::abs);
    if (isa<math::CeilOp>(op))
      return replaceOp(nullptr, ElementwiseKind::ceil);
    if (isa<math::FloorOp>(op))
      return replaceOp(nullptr, ElementwiseKind::floor);
    if (isa<arith::NegFOp>(op))
      return replaceOp(nullptr, ElementwiseKind::negf);
    if (auto divOp = dyn_cast<arith::DivFOp>(op)) {
      if (auto constOp = dyn_cast_if_present<arith::ConstantOp>(
              divOp.getLhs().getDefiningOp()))
        if (cast<FloatAttr>(constOp.getValue()).getValue().isExactlyValue(1.0))
          return replaceOp(nullptr, ElementwiseKind::reciprocal,
                           /*mayHoistScalarOperand=*/false);
    }
    if (isa<math::RoundOp>(op))
      return replaceOp(nullptr, ElementwiseKind::round);
    if (isa<math::SqrtOp>(op))
      return replaceOp(nullptr, ElementwiseKind::sqrt);
    if (isa<math::RsqrtOp>(op))
      return replaceOp(nullptr, ElementwiseKind::rsqrt);
    if (auto mulOp = dyn_cast<arith::MulFOp>(op);
        mulOp && mulOp.getLhs() == mulOp.getRhs())
      return replaceOp(nullptr, ElementwiseKind::square);
    if (isa<math::TanhOp>(op))
      return replaceOp(nullptr, ElementwiseKind::tanh);
    if (isa<math::ErfOp>(op))
      return replaceOp(nullptr, ElementwiseKind::erf);
    if (isa<math::SinOp>(op))
      return replaceOp(nullptr, ElementwiseKind::sin);
    if (isa<math::CosOp>(op))
      return replaceOp(nullptr, ElementwiseKind::cos);
    if (isa<math::TanOp>(op))
      return replaceOp(nullptr, ElementwiseKind::tan);
    if (isa<math::AcosOp>(op))
      return replaceOp(nullptr, ElementwiseKind::acos);
    if (isa<math::AcoshOp>(op))
      return replaceOp(nullptr, ElementwiseKind::acosh);
    if (isa<math::AsinOp>(op))
      return replaceOp(nullptr, ElementwiseKind::asin);
    if (isa<math::AsinhOp>(op))
      return replaceOp(nullptr, ElementwiseKind::asinh);
    if (isa<math::AtanOp>(op))
      return replaceOp(nullptr, ElementwiseKind::atan);
    if (isa<math::AtanhOp>(op))
      return replaceOp(nullptr, ElementwiseKind::atanh);
    if (isa<math::LogOp>(op))
      return replaceOp(nullptr, ElementwiseKind::log);
    if (isa<math::Log10Op>(op))
      return replaceOp(nullptr, ElementwiseKind::log10);
    if (isa<math::Log1pOp>(op))
      return replaceOp(nullptr, ElementwiseKind::log1p);
    if (isa<math::Log2Op>(op))
      return replaceOp(nullptr, ElementwiseKind::log2);
 
    // The remaining kinds are binary. A single-input generic can only be
    // represented as a binary elementwise if it has a scalar operand to hoist;
    // otherwise (e.g. a body reusing a block argument twice) it has no
    // category form.
    if (isUnary && !hasScalarOperand)
      return rewriter.notifyMatchFailure(
          genericOp, "unary elementwise operation cannot be specialized to a "
                     "category op");
 
    // Boolean-typed `linalg.add` and `linalg.mul` require special handling.
    bool allBool = llvm::all_of(
        op->getOperands(), [](Value v) { return v.getType().isInteger(1); });
 
    if (isa<arith::AddFOp, arith::AddIOp, complex::AddOp>(op) ||
        (allBool && isa<arith::OrIOp>(op)))
      return replaceOp(nullptr, ElementwiseKind::add);
    if (isa<arith::SubIOp, arith::SubFOp, complex::SubOp>(op))
      return replaceOp(nullptr, ElementwiseKind::sub);
    if (isa<arith::MulIOp, arith::MulFOp, complex::MulOp>(op) ||
        (allBool && isa<arith::AndIOp>(op)))
      return replaceOp(nullptr, ElementwiseKind::mul);
    if (isa<arith::DivSIOp, arith::DivFOp, complex::DivOp>(op))
      return replaceOp(nullptr, ElementwiseKind::div);
    if (isa<arith::DivUIOp>(op))
      return replaceOp(nullptr, ElementwiseKind::div_unsigned);
    if (isa<arith::MaxSIOp, arith::MaximumFOp>(op))
      return replaceOp(nullptr, ElementwiseKind::max_signed);
    if (isa<arith::MinSIOp, arith::MinimumFOp>(op))
      return replaceOp(nullptr, ElementwiseKind::min_signed);
    if (isa<math::PowFOp>(op))
      return replaceOp(nullptr, ElementwiseKind::powf);
    // No named ops for unsigned maximum/minimum.
    if (isa<arith::MaxUIOp>(op))
      return replaceOp(nullptr, ElementwiseKind::max_unsigned);
    if (isa<arith::MinUIOp>(op))
      return replaceOp(nullptr, ElementwiseKind::min_unsigned);
  }
 
  return rewriter.notifyMatchFailure(
      genericOp,
      "elementwise operation cannot be specialized to named or category op");
}
 
//===----------------------------------------------------------------------===//
// Specialize linalg generic to matmul variants.
//===----------------------------------------------------------------------===//
/// Identifies linalg.generic that is essentially named op of the form:
//    ` linalg.{batch_}?matmul{_transpose_a | _transpose_b}? `
//
// It is possible that a linalg.generic may be implementing a matmul but not
// in a straight-forward way e.g. below is matrix multiply over some slice
// ```
//  %0 = linalg.generic {
//          indexing_maps = [affine_map<(d0, d1, d2) -> (3, d1, d0)>,
//                           affine_map<(d0, d1, d2) -> (d0, 5, d2)>,
//                           affine_map<(d0, d1, d2) -> (d2, d1, 13)>],
//          iterator_types = ["parallel", "parallel", "parallel"]}
//          ins(%A, %B : tensor<20x20x20xf32>,  tensor<20x20x20xf32>)
//          outs(%C : tensor<20x20x20xf32>) {
//             ^bb0(%a: f32, %b: f32, %c : f32):
//                %mul = arith.mulf %a, %b : f32
//                %add = arith.addf %mul, %c : f32
//                linalg.yield %add : f32
//       } -> tensor<20x20x20xf32>
// ```
// It is not possible to represent above as named op.
// e.g. linalg.batch_matmul(%A, %B :  tensor<20x20x20xf32>, ...) is
// not  the same as linalg.generic above.
namespace {
enum class IndexMatchResult {
  Match = 0,  // identity map.
  Transposed, // transposed map.
  Mismatch    // none of the above.
};
 
// Checks whether the input Affine `map` contains two consecutive dims that
// can be interpreted as accessing a 2D matrix. It is assumed that the row
// column dimension are adjacent axis (in this order) and start at
// `rowDimIdx` in the input map.
//
//  e.g. consider A matrix in `C[M,N] = A[M,K] * B[K,N]`. We will check
//  whether the map of A is identity (match), transposed, or something
//  completely different (mis-match). Similar for B and C.
static IndexMatchResult matchOperandMap(AffineMap map, unsigned rowDimIdx,
                                        unsigned expectedPosOfRowDim,
                                        unsigned expectedPosOfColDim) {
  // Get the matrix multiply indices. They are past the batch indices.
  auto exprOfRowDim = map.getResults()[rowDimIdx];
  auto exprOfColDim = map.getResults()[rowDimIdx + 1];
 
  // They should be pure dimension ids.
  if (exprOfRowDim.getKind() != AffineExprKind::DimId ||
      exprOfColDim.getKind() != AffineExprKind::DimId)
    return IndexMatchResult::Mismatch;
 
  auto posRowDim = cast<AffineDimExpr>(exprOfRowDim).getPosition();
  auto posColDim = cast<AffineDimExpr>(exprOfColDim).getPosition();
 
  if (expectedPosOfRowDim == posRowDim && expectedPosOfColDim == posColDim)
    return IndexMatchResult::Match;
 
  if (expectedPosOfRowDim == posColDim && expectedPosOfColDim == posRowDim)
    return IndexMatchResult::Transposed;
 
  return IndexMatchResult::Mismatch;
}
 
// Replaces genericOp with `NamedOpTy` op, supplied as a template arg.
// All the variants expressed as pseudo regular expression:
// `linalg.{batch_}?matmul` have same number of ins/out, so it's easy to
// stamp different versions.
// `castTy` is an optional type function that indicates whether (and which) cast
// attribute is needed for the named matmul op variant.
template <typename NamedOpTy>
static LinalgOp replaceWithMatmulVariant(RewriterBase &rewriter, GenericOp op,
                                         std::optional<TypeFn> castTy,
                                         ArrayRef<AffineMap> indexingMaps) {
  SmallVector<NamedAttribute> attributes;
  // Only explicitly specify the cast attribute for unsigned cast; signed is
  // the default for linalg.matmul/linalg.batch_matmul.
  if (castTy.has_value() && *castTy == TypeFn::cast_unsigned) {
    auto castAttr = rewriter.getNamedAttr(
        "cast", TypeFnAttr::get(rewriter.getContext(), *castTy));
    attributes.push_back(castAttr);
  }
 
  // Set the original generic's maps to preserve operand indexing semantics like
  // transposition.
  SmallVector<Attribute, 3> indexingMapsAttrVal =
      llvm::map_to_vector(indexingMaps, [](AffineMap map) -> Attribute {
        return AffineMapAttr::get(map);
      });
  auto indexingMapsAttr = rewriter.getNamedAttr(
      "indexing_maps", rewriter.getArrayAttr(indexingMapsAttrVal));
  attributes.push_back(indexingMapsAttr);
 
  LinalgOp namedOp = rewriter.replaceOpWithNewOp<NamedOpTy>(
      op, ValueRange{op.getDpsInputs()[0], op.getDpsInputs()[1]},
      ValueRange{op.getDpsInits()[0]}, attributes);
 
  return namedOp;
}
 
// Returns the cast type to use for a matmul-like named op. If the generic
// contains casts that cannot be represented (e.g. output casts or mixed
// signedness), return std::nullopt.
static std::optional<TypeFn> getCastTypeForMatmulLikeOp(GenericOp genericOp) {
  bool foundCastForMatmulOutput = false;
  SmallVector<TypeFn> castTyFns;
  genericOp.getBody()->walk([&](CastOpInterface castOp) {
    // Collect forward slice of the cast op to check if it is for the matmul
    // output.
    SetVector<Operation *> forwardSlice;
    getForwardSlice(castOp, &forwardSlice);
 
    // If there is no multiplication op in the forward slice, then this cast
    // op is for the matmul output. Cast ops on matmul output cannot be
    // expressed by the matmul op variant.
    if (!llvm::any_of(forwardSlice, [](Operation *op) {
          // We check explicitly for these multiplication ops in
          // `specializeLinalgContractions()` to infer matmul-like ops.
          return isa<arith::MulIOp, arith::MulFOp, complex::MulOp>(op);
        })) {
      foundCastForMatmulOutput = true;
      return WalkResult::interrupt();
    }
 
    // Determine the cast type.
    if (isa<arith::ExtUIOp, arith::UIToFPOp, arith::FPToUIOp>(castOp))
      castTyFns.push_back(TypeFn::cast_unsigned);
    else if (isa<arith::ExtSIOp, arith::SIToFPOp, arith::FPToSIOp>(castOp))
      castTyFns.push_back(TypeFn::cast_signed);
 
    return WalkResult::advance();
  });
 
  if (foundCastForMatmulOutput)
    return std::nullopt;
 
  if (!castTyFns.empty()) {
    // If there were multiple different cast types found, then we can't express
    // them using matmul-like ops. They only allow a single cast type for all
    // inputs.
    if (!llvm::all_equal(castTyFns))
      return std::nullopt;
    return castTyFns.front();
  }
 
  // Default to signed cast for matmul-like ops.
  return TypeFn::cast_signed;
}
 
static FailureOr<LinalgOp> specializeLinalgMmt4D(RewriterBase &rewriter,
                                                 GenericOp genericOp,
                                                 std::optional<TypeFn> castTy,
                                                 ContractionDimensions &dims) {
  // Should all be rank 4 and dim 6
  auto indexingMaps = genericOp.getIndexingMapsArray();
  if (llvm::any_of(indexingMaps, [](AffineMap m) {
        return m.getResults().size() != 4 || m.getNumDims() != 6;
      }))
    return failure();
 
  auto aOuter = matchOperandMap(indexingMaps[0], 0, dims.m[0], dims.k[0]);
  auto aInner = matchOperandMap(indexingMaps[0], 2, dims.m[1], dims.k[1]);
 
  auto bOuter = matchOperandMap(indexingMaps[1], 0, dims.k[0], dims.n[0]);
  auto bInner = matchOperandMap(indexingMaps[1], 2, dims.k[1], dims.n[1]);
 
  auto cOuter = matchOperandMap(indexingMaps[2], 0, dims.m[0], dims.n[0]);
  auto cInner = matchOperandMap(indexingMaps[2], 2, dims.m[1], dims.n[1]);
 
  if (llvm::is_contained({aOuter, bOuter, cOuter}, IndexMatchResult::Mismatch))
    return failure();
  if (llvm::is_contained({aInner, bInner, cInner}, IndexMatchResult::Mismatch))
    return failure();
 
  SmallVector<AffineMap> namedOpMaps = {indexingMaps[0], indexingMaps[1],
                                        indexingMaps[2]};
 
  return replaceWithMatmulVariant<Mmt4DOp>(rewriter, genericOp, castTy,
                                           namedOpMaps);
}
 
static bool isSupportedContractionPair(Operation *first, Operation *second) {
  if (isa<arith::MulFOp>(first) && isa<arith::AddFOp>(second))
    return true;
  if (isa<arith::MulIOp>(first) && isa<arith::AddIOp>(second))
    return true;
  if (isa<complex::MulOp>(first) && isa<complex::AddOp>(second))
    return true;
  if (isa<arith::AndIOp>(first) && isa<arith::OrIOp>(second) &&
      first->getResult(0).getType().isInteger(1))
    return true;
 
  return false;
}
 
// Converts linalg.generic to named linalg.*matmul* where possible.
static FailureOr<LinalgOp> specializeLinalgContractions(RewriterBase &rewriter,
                                                        GenericOp genericOp,
                                                        bool emitCategoryOp) {
  if (genericOp.getNumDpsInputs() != 2 || genericOp.getNumDpsInits() != 1)
    return failure();
 
  // Early exit if not projected permutations.
  auto mapRange = genericOp.getIndexingMapsArray();
  if (llvm::any_of(mapRange,
                   [](AffineMap m) { return !m.isProjectedPermutation(); }))
    return failure();
 
  // Only contractions that can be represented by named linalg ops are
  // eligible for specialization:
  //   - mul + add    (floating-point, integer, complex)
  //   - and + or     (bool)
  if (!mlir::linalg::detail::isContractionBody(*genericOp.getBlock(),
                                               isSupportedContractionPair))
    return failure();
 
  // Determine the cast type for the named matmul op, or bail out if casts
  // cannot be represented by the named op.
  std::optional<TypeFn> castTy = getCastTypeForMatmulLikeOp(genericOp);
  if (!castTy)
    return rewriter.notifyMatchFailure(
        genericOp, "contains invalid cast ops for the named matmul op");
 
  // In case of category op, wider range of variants is supported.
  if (emitCategoryOp)
    return replaceWithMatmulVariant<ContractOp>(
        rewriter, genericOp, castTy, genericOp.getIndexingMapsArray());
 
  // Further checks for named variants.
  //
  // Linalg generic contraction can be across multiple axis e.g.
  // ```
  //      linalg.generic
  //           {indexing_maps = [affine_map<(m, n, k1, k2) -> (m, k1, k2)>,
  //                             affine_map<(m, n, k1, k2) -> (k2, k1, n)>,
  //                             affine_map<(m, n, k1, k2) -> (m, n)>],
  //           iterator_types = ["parallel", "parallel",
  //                             "reduction", "reduction"]}
  //           ins(%A, %B : tensor<10x20x30xf32>, tensor<30x20x40xf32>)
  //           outs(%C : tensor<10x40xf32>) {
  //           ^bb0(%a: f32, %b: f32, %c: f32):
  //                 %1 = arith.mulf %a, %b : f32
  //                 %2 = arith.addf %c, %1 : f32
  //                 linalg.yield %2 : f32
  //      } -> tensor<10x40xf32>
  //  ```
  //  In above contraction, there are two reduction dimensions {k1, k2}
  //  and although a valid linalg contraction, it is not a named-op
  //  matrix multiply kind. Therefore, reject multi-dim reduction.
  auto res = inferContractionDims(genericOp);
  if (!succeeded(res))
    return failure();
  auto dims = *res;
  if (dims.m.size() == 2 && dims.n.size() == 2 && dims.k.size() == 2)
    return specializeLinalgMmt4D(rewriter, genericOp, castTy, dims);
  if (dims.m.size() != 1 || dims.n.size() != 1 || dims.k.size() != 1)
    return failure();
 
  // Check rank of operands
  auto indexingMaps = genericOp.getIndexingMapsArray();
  if (llvm::any_of(indexingMaps, [&dims](AffineMap m) {
        return m.getResults().size() !=
               dims.batch.size() + 2 /* any two of {m,n,k} */;
      }))
    return failure();
 
  auto numOfBatchDims = dims.batch.size();
  if (indexingMaps[0].getNumDims() != numOfBatchDims + 3)
    return failure();
 
  if (numOfBatchDims) {
    // Each operand in a linalg generic contraction  could express different
    // permutations for its batch dimension. But for named op it must be
    // identity since separate maps are not specified.
    if (llvm::any_of(indexingMaps, [numOfBatchDims](AffineMap m) {
          for (unsigned i = 0; i < numOfBatchDims; ++i) {
            auto expr = m.getResults()[i];
            if (expr.getKind() != AffineExprKind::DimId ||
                cast<AffineDimExpr>(expr).getPosition() != i)
              return true;
          }
          return false;
        }))
      return failure();
  }
 
  auto a =
      matchOperandMap(indexingMaps[0], numOfBatchDims, dims.m[0], dims.k[0]);
  auto b =
      matchOperandMap(indexingMaps[1], numOfBatchDims, dims.k[0], dims.n[0]);
  auto c =
      matchOperandMap(indexingMaps[2], numOfBatchDims, dims.m[0], dims.n[0]);
 
  if (llvm::is_contained({a, b, c}, IndexMatchResult::Mismatch))
    return failure();
 
  // Build indexing maps for the named op in its canonical dimension ordering
  auto *ctx = genericOp.getContext();
  unsigned numLoopDims = numOfBatchDims + 3;
  unsigned mIdx = numOfBatchDims;
  unsigned nIdx = mIdx + 1;
  unsigned kIdx = mIdx + 2;
 
  // TODO: add support for indexing_maps with broadcasts.
  auto makeMap = [&](IndexMatchResult match, unsigned rowIdx, unsigned colIdx) {
    SmallVector<unsigned> tensorDims;
    for (unsigned i = 0; i < numOfBatchDims; ++i)
      tensorDims.push_back(i);
    if (match == IndexMatchResult::Transposed)
      llvm::append_values(tensorDims, colIdx, rowIdx);
    else
      llvm::append_values(tensorDims, rowIdx, colIdx);
    return AffineMap::getMultiDimMapWithTargets(numLoopDims, tensorDims, ctx);
  };
 
  auto mapA = makeMap(a, mIdx, kIdx);
  auto mapB = makeMap(b, kIdx, nIdx);
  auto mapC = makeMap(c, mIdx, nIdx);
 
  SmallVector<AffineMap> namedOpMaps = {mapA, mapB, mapC};
 
  // Codegen the different matmul variants.
  if (numOfBatchDims) {
    return replaceWithMatmulVariant<BatchMatmulOp>(rewriter, genericOp, castTy,
                                                   namedOpMaps);
  }
  return replaceWithMatmulVariant<MatmulOp>(rewriter, genericOp, castTy,
                                            namedOpMaps);
}
 
/// Utility to specialize a `genericOp` with a convolution op of type `ConvOpTy`
/// with `dilations` and `strides`.
template <typename ConvOpTy>
static FailureOr<LinalgOp>
specializeToConvOp(RewriterBase &rewriter, GenericOp genericOp,
                   ArrayRef<int64_t> dilations, ArrayRef<int64_t> strides) {
  SmallVector<Value> inputs = genericOp.getDpsInputs();
  ValueRange outputs = genericOp.getDpsInits();
  SmallVector<Type> resultTypes = genericOp.hasPureTensorSemantics()
                                      ? TypeRange(ValueRange(outputs))
                                      : TypeRange{};
  LinalgOp namedOp;
  // Ops with no dilations and no strides.
  if constexpr (std::is_same_v<ConvOpTy, linalg::Conv1DOp> ||
                std::is_same_v<ConvOpTy, linalg::Conv2DOp> ||
                std::is_same_v<ConvOpTy, linalg::Conv3DOp>) {
    namedOp = rewriter.replaceOpWithNewOp<ConvOpTy>(genericOp, resultTypes,
                                                    inputs, outputs);
  } else {
    Attribute stridesAttr = rewriter.getI64TensorAttr(strides);
    Attribute dilationsAttr = rewriter.getI64TensorAttr(dilations);
    namedOp = rewriter.replaceOpWithNewOp<ConvOpTy>(
        genericOp, resultTypes, inputs, outputs, stridesAttr, dilationsAttr);
  }
  return namedOp;
}
 
/// Converts linalg.generic to named linalg.*conv/pooling* where possible.
static FailureOr<LinalgOp> specializeLinalgConvolutions(RewriterBase &rewriter,
                                                        GenericOp genericOp) {
#define CONV_OP_SPECIALIZER(ConvOpTy)                                          \
  if (std::optional<DilationsAndStrides> convParams =                          \
          matchConvolutionOpOfType<ConvOpTy>(genericOp))                       \
    return specializeToConvOp<ConvOpTy>(                                       \
        rewriter, genericOp, convParams->dilations, convParams->strides);      \
  // -----------------------------
  // Convolution ops.
  // -----------------------------
  CONV_OP_SPECIALIZER(linalg::Conv1DOp);
  CONV_OP_SPECIALIZER(linalg::Conv1DNwcWcfOp);
  CONV_OP_SPECIALIZER(linalg::Conv1DNcwFcwOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwcHwcfOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwcHwcfQOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwcFhwcOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwcFhwcQOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNchwFchwOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNchwFchwQOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNgchwFgchwOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNgchwGfchwOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNgchwGfchwQOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwgcGfhwcOp);
  CONV_OP_SPECIALIZER(linalg::Conv2DNhwgcGfhwcQOp);
  CONV_OP_SPECIALIZER(linalg::Conv3DOp);
  CONV_OP_SPECIALIZER(linalg::Conv3DNdhwcDhwcfOp);
  CONV_OP_SPECIALIZER(linalg::Conv3DNdhwcDhwcfQOp);
  CONV_OP_SPECIALIZER(linalg::Conv3DNcdhwFcdhwOp);
  // -----------------------------
  // Depthwise Convolution ops.
  // -----------------------------
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv1DNcwCwOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv1DNwcWcOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv1DNwcWcmOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv2DNchwChwOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv2DNhwcHwcOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv2DNhwcHwcQOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv2DNhwcHwcmOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv2DNhwcHwcmQOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv3DNdhwcDhwcOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv3DNcdhwCdhwOp);
  CONV_OP_SPECIALIZER(linalg::DepthwiseConv3DNdhwcDhwcmOp);
  // -----------------------------
  // Pooling ops.
  // -----------------------------
  CONV_OP_SPECIALIZER(linalg::PoolingNhwcMaxOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNhwcMinOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNhwcSumOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNhwcMaxUnsignedOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNhwcMinUnsignedOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNchwSumOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNchwMaxOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNwcSumOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNcwSumOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNwcMaxOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNwcMaxUnsignedOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNcwMaxOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNwcMinOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNwcMinUnsignedOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNdhwcSumOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNdhwcMaxOp);
  CONV_OP_SPECIALIZER(linalg::PoolingNdhwcMinOp);
#undef CONV_OP_SPECIALIZER
  return failure();
}
 
} // namespace
 
//===----------------------------------------------------------------------===//
// Categorize linalg generic to named op where possible.
//===----------------------------------------------------------------------===//
FailureOr<LinalgOp> mlir::linalg::specializeGenericOp(
    RewriterBase &rewriter, GenericOp genericOp,
    const GenericOpSpecializationOptions &options) {
  // Elementwise - e.g. exp, add
  if (isaElemwiseSingleUnaryOpInterface(genericOp, options.emitCategoryOps) ||
      isaElemwiseSingleBinaryOpInterface(genericOp, options.emitCategoryOps)) {
    return specializeLinalgElementwise(rewriter, genericOp,
                                       options.emitCategoryOps);
  }
 
  // Contraction - e.g. matmul
  if (isaContractionOpInterface(genericOp)) {
    return specializeLinalgContractions(rewriter, genericOp,
                                        options.emitCategoryOps);
  }
 
  // Early exit in case of category specialization.
  // TODO: Remove when matches for other ops account for both named and
  // category.
  if (options.emitCategoryOps)
    return rewriter.notifyMatchFailure(
        genericOp, "no matching category op specialization");
 
  // Copy
  if (isaCopyOpInterface(genericOp)) {
    LinalgOp namedOp = rewriter.replaceOpWithNewOp<CopyOp>(
        genericOp, genericOp.getDpsInputs()[0], genericOp.getDpsInits()[0]);
    return namedOp;
  }
 
  // Fill
  if (std::optional<Value> fillValue = isaFillOpInterface(genericOp)) {
    // Always use the detected fill value, regardless of pattern
    LinalgOp namedOp = rewriter.replaceOpWithNewOp<FillOp>(
        genericOp, *fillValue, genericOp.getDpsInits()[0]);
    return namedOp;
  }
 
  // Broadcast
  std::optional<SmallVector<int64_t>> equivalentToBroadcast =
      isaBroadcastOpInterface(genericOp);
  if (equivalentToBroadcast) {
    auto dims = *equivalentToBroadcast;
    LinalgOp namedOp = rewriter.replaceOpWithNewOp<BroadcastOp>(
        genericOp, genericOp.getDpsInputs()[0], genericOp.getDpsInits()[0],
        dims);
    return namedOp;
  }
 
  // Transpose
  std::optional<SmallVector<int64_t>> equivalentToTranspose =
      isaTransposeOpInterface(genericOp);
  if (equivalentToTranspose) {
    auto permutation = *equivalentToTranspose;
    LinalgOp namedOp = rewriter.replaceOpWithNewOp<TransposeOp>(
        genericOp, genericOp.getDpsInputs()[0], genericOp.getDpsInits()[0],
        permutation);
    return namedOp;
  }
 
  // Convolution - e.g. *conv/pooling*
  if (isaConvolutionOpInterface(genericOp))
    return specializeLinalgConvolutions(rewriter, genericOp);
 
  return rewriter.notifyMatchFailure(genericOp,
                                     "no matching named op specialization");
}
 
namespace {
struct LinalgSpecializeGenericOpsPass
    : public impl::LinalgSpecializeGenericOpsPassBase<
          LinalgSpecializeGenericOpsPass> {
 
  using impl::LinalgSpecializeGenericOpsPassBase<
      LinalgSpecializeGenericOpsPass>::LinalgSpecializeGenericOpsPassBase;
  void runOnOperation() override;
};
} // namespace
 
void LinalgSpecializeGenericOpsPass::runOnOperation() {
  RewritePatternSet patterns(&getContext());
  populateLinalgGenericOpsSpecializationPatterns(patterns);
  populateDecomposeProjectedPermutationPatterns(patterns);
 
  if (failed(applyPatternsGreedily(getOperation(), std::move(patterns))))
    signalPassFailure();
}
 
void mlir::linalg::populateLinalgGenericOpsSpecializationPatterns(
    RewritePatternSet &patterns,
    const GenericOpSpecializationOptions &options) {
  patterns.add<LinalgSpecializationPattern>(patterns.getContext(), options);
}