[MHLO] Init MHLO slice like op patterns (llvm#1091)

See RFC: llvm#999

Co-authored-by: Bairen Yi [email protected]
Co-authored-by: Jiawei Wu [email protected]
Co-authored-by: Tianyou Guo [email protected]
Co-authored-by: Xu Yan [email protected]
Co-authored-by: Ziheng Jiang [email protected]

lib/Conversion/TorchToMhlo/CMakeLists.txt

@@ -2,6 +2,7 @@ add_mlir_conversion_library(TorchMLIRTorchToMhlo
   TorchToMhlo.cpp
   MhloLegalizeUtils.cpp
   BasicOp.cpp
+  SliceLikeOps.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${PROJECT_SOURCE_DIR}/include/torch-mlir/Conversion/TorchToMhlo

lib/Conversion/TorchToMhlo/PopulatePatterns.h

@@ -19,6 +19,10 @@ namespace torch_to_mhlo {
 void populateBasicOpPatternsAndLegality(TypeConverter &typeConverter,
                                         RewritePatternSet &patterns,
                                         ConversionTarget &target);
+void populateSliceLikeOpPatternsAndLegality(TypeConverter &typeConverter,
+                                        RewritePatternSet &patterns,
+                                        ConversionTarget &target);
+
 
 } // namespace torch_to_mhlo
 } // namespace torch

lib/Conversion/TorchToMhlo/SliceLikeOps.cpp

@@ -0,0 +1,249 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// Also available under a BSD-style license. See LICENSE.
+//
+//===----------------------------------------------------------------------===//
+
+#include "torch-mlir/Conversion/TorchToMhlo/TorchToMhlo.h"
+
+#include "../PassDetail.h"
+#include "./PopulatePatterns.h"
+#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
+#include "mlir/Dialect/Tensor/IR/Tensor.h"
+#include "mlir-hlo/Dialect/mhlo/IR/hlo_ops.h"
+#include "torch-mlir/Conversion/Utils/Utils.h"
+#include "torch-mlir/Dialect/Torch/IR/TorchDialect.h"
+#include "torch-mlir/Dialect/Torch/IR/TorchOps.h"
+#include "torch-mlir/Dialect/TorchConversion/IR/TorchConversionOps.h"
+
+using namespace mlir;
+using namespace mlir::torch;
+using namespace mlir::torch::Torch;
+
+#ifdef TORCH_MLIR_ENABLE_MHLO_TRUNC_DIMSIZE_TO_I32
+static constexpr size_t kMhloDimSizeBits = 32;
+#else
+static constexpr size_t kMhloDimSizeBits = 64;
+#endif
+
+namespace {
+
+SmallVector<Value, 4> getDimSizesOfTensor(
+    PatternRewriter& rewriter,
+    Operation* op,
+    Value value) {
+  auto valueTy = value.getType().dyn_cast<RankedTensorType>();
+  if (!valueTy) {
+    op->emitOpError("getDimSizesOfTensor(): the input is not a ranked tensor");
+    return {};
+  }
+
+  auto rank = valueTy.getRank();
+  if (rank == 0) {
+    return {};
+  }
+
+  SmallVector<Value, 4> dimSizes;
+  dimSizes.reserve(rank);
+  auto loc = op->getLoc();
+  for (auto d = 0; d < rank; ++d) {
+    dimSizes.emplace_back(rewriter.create<arith::IndexCastOp>(
+        loc,
+        rewriter.getIntegerType(kMhloDimSizeBits),
+        rewriter.create<tensor::DimOp>(loc, value, d)));
+  }
+  return dimSizes;
+}
+
+// A dimension index from torch.dialect might outside the range [0, dimSize].
+// The function is used to normalize the input index into the range.
+Value getNormalizedDimSizeInternal(
+    PatternRewriter& rewriter,
+    Operation* op,
+    Value index,
+    Value dimSize) {
+  auto loc = op->getLoc();
+  Value zero = rewriter.create<arith::ConstantOp>(
+      loc, rewriter.getIntegerAttr(rewriter.getI64Type(), 0));
+
+  // To normalize index into range [-dimSize, dimSize]
+  // index = min(max(-dimSize, index), dimSize)
+  auto negDimSize = rewriter.create<arith::SubIOp>(loc, zero, dimSize);
+  index = rewriter.create<arith::MaxSIOp>(loc, negDimSize, index);
+  index = rewriter.create<arith::MinSIOp>(loc, dimSize, index);
+
+  auto dimSizePlusIndex = rewriter.create<arith::AddIOp>(loc, dimSize, index);
+  auto indexPositive = rewriter.create<arith::CmpIOp>(
+      loc, arith::CmpIPredicate::sge, index, zero);
+  // get positive index: (index >=0) ? index: index + dimSize
+  return rewriter.create<arith::SelectOp>(
+      loc, indexPositive, index, dimSizePlusIndex);
+}
+
+Value getDynamicSliceInternal(
+    PatternRewriter& rewriter,
+    Operation* op,
+    Value input,
+    Value startIndex,
+    Value endIndex,
+    Value step,
+    size_t dimIndex,
+    ArrayRef<Value> dimSizes) {
+  auto loc = op->getLoc();
+  // startIndex & endIndex has been normailized into range [0, dSize]
+  Type intType = rewriter.getIntegerType(kMhloDimSizeBits);
+  Value zero = rewriter.create<arith::ConstantOp>(
+      loc, rewriter.getIntegerAttr(intType, 0));
+  Value one = rewriter.create<arith::ConstantOp>(
+      loc, rewriter.getIntegerAttr(intType, 1));
+
+  SmallVector<Value, 4> startIndices;
+  SmallVector<Value, 4> endIndices;
+  SmallVector<Value, 4> strides;
+
+  auto inputTy = input.getType().dyn_cast<RankedTensorType>();
+  size_t rank = inputTy.getRank();
+  startIndices.reserve(rank);
+  endIndices.reserve(rank);
+  strides.reserve(rank);
+
+  auto endIndexIsZero = rewriter.create<arith::CmpIOp>(
+      loc, arith::CmpIPredicate::eq, endIndex, zero);
+  endIndex = rewriter.create<arith::SelectOp>(
+      loc, endIndexIsZero, dimSizes[dimIndex], endIndex);
+
+  for (size_t r = 0; r < rank; ++r) {
+    if (r == dimIndex) {
+      startIndices.push_back(startIndex);
+      endIndices.push_back(endIndex);
+      strides.push_back(step);
+    } else {
+      startIndices.push_back(zero);
+      endIndices.push_back(dimSizes[r]);
+      strides.push_back(one);
+    }
+  }
+
+  auto startTensor =
+      rewriter.create<tensor::FromElementsOp>(loc, startIndices).getResult();
+  auto endTensor =
+      rewriter.create<tensor::FromElementsOp>(loc, endIndices).getResult();
+  auto stridesTensor =
+      rewriter.create<tensor::FromElementsOp>(loc, strides).getResult();
+
+  auto inputShape = inputTy.getShape();
+  SmallVector<int64_t, 4> sliceShape(inputShape.begin(), inputShape.end());
+  sliceShape[dimIndex] = ShapedType::kDynamicSize;
+  auto sliceoutputTy =
+      RankedTensorType::get(sliceShape, inputTy.getElementType());
+  return rewriter.create<mhlo::RealDynamicSliceOp>(
+      loc, sliceoutputTy, input, startTensor, endTensor, stridesTensor);
+}
+
+// Get a dynamic slice of the tensor from startIndex to endIndex with stride step
+// on the specifed dimension. The input startIndex(default to 0),
+// endIndex(default to dimSize), and step(default to 1) can be optional.
+Value getDynamicSlice(
+    PatternRewriter& rewriter,
+    Operation* op,
+    Value input,
+    llvm::Optional<Value> startIndexOpt,
+    llvm::Optional<Value> endIndexOpt,
+    llvm::Optional<Value> stepOpt,
+    int64_t dim) {
+  auto loc = op->getLoc();
+  auto inputTy = input.getType().dyn_cast<RankedTensorType>();
+  auto rank = inputTy.getRank();
+
+  dim = (dim + rank) % rank;
+  Value dimSize = rewriter.create<arith::IndexCastOp>(
+      loc,
+      rewriter.getI64Type(),
+      rewriter.create<tensor::DimOp>(loc, input, dim));
+
+  Value normStartIndex = startIndexOpt
+      ? getNormalizedDimSizeInternal(rewriter, op, *startIndexOpt, dimSize)
+      : rewriter.create<arith::ConstantOp>(
+            loc, rewriter.getIntegerAttr(rewriter.getI64Type(), 0));
+  Value normEndIndex = endIndexOpt
+      ? getNormalizedDimSizeInternal(rewriter, op, *endIndexOpt, dimSize)
+      : dimSize;
+  Value step = stepOpt
+      ? *stepOpt
+      : rewriter.create<arith::ConstantOp>(
+            loc, rewriter.getIntegerAttr(rewriter.getI64Type(), 1));
+
+#ifdef TORCH_MLIR_ENABLE_MHLO_TRUNC_DIMSIZE_TO_I32
+  auto i32Type = rewriter.getIntegerType(kMhloDimSizeBits);
+  normStartIndex =
+      rewriter.create<arith::TruncIOp>(loc, i32Type, normStartIndex);
+  normEndIndex =
+      rewriter.create<arith::TruncIOp>(loc, i32Type, normEndIndex);
+  step = rewriter.create<arith::TruncIOp>(loc, i32Type, step);
+#endif
+  auto dimSizes = getDimSizesOfTensor(rewriter, op, input);
+
+  return getDynamicSliceInternal(
+      rewriter, op, input, normStartIndex, normEndIndex, step, dim, dimSizes);
+}
+
+template <typename AtenOpT>
+class ConvertAtenOp : public OpConversionPattern<AtenOpT> {
+public:
+  using OpConversionPattern<AtenOpT>::OpConversionPattern;
+  using OpAdaptor = typename AtenOpT::Adaptor;
+  LogicalResult
+  matchAndRewrite(AtenOpT op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override;
+};
+
+template <>
+LogicalResult ConvertAtenOp<AtenSliceTensorOp>::matchAndRewrite(
+    AtenSliceTensorOp op,
+    OpAdaptor adaptor,
+    ConversionPatternRewriter& rewriter) const {
+  auto self = adaptor.self();
+  auto selfTy = self.getType().template cast<RankedTensorType>();
+  if (!selfTy)
+    return op.emitError("Only ranked tensor types supported in MHLO Rsub");
+  int64_t dim;
+  if (!matchPattern(op.dim(), m_TorchConstantInt(&dim)))
+    return rewriter.notifyMatchFailure(
+        op, "Only constant dim is currently supported");
+
+  auto getOptionalVal = [&](Value val) -> llvm::Optional<Value> {
+    if (val.getType().isa<Torch::NoneType>()) {
+      return llvm::None;
+    } else {
+      return val;
+    }
+  };
+
+  llvm::Optional<Value> start = getOptionalVal(adaptor.start());
+  llvm::Optional<Value> end = getOptionalVal(adaptor.end());
+  llvm::Optional<Value> step = getOptionalVal(adaptor.step());
+
+  Value sliced =
+      getDynamicSlice(rewriter, op, self, start, end, step, dim);
+  rewriter.replaceOpWithNewOp<mhlo::ConvertOp>(
+      op, getTypeConverter()->convertType(op.getType()), sliced);
+
+  return success();
+}
+} // namespace
+
+void mlir::torch::torch_to_mhlo::populateSliceLikeOpPatternsAndLegality(
+    TypeConverter &typeConverter, RewritePatternSet &patterns,
+    ConversionTarget &target) {
+  MLIRContext *context = patterns.getContext();
+
+#define INSERT_ATENOP_PATTERN(AtenOp)                                          \
+  target.addIllegalOp<AtenOp>();                                               \
+  patterns.add<ConvertAtenOp<AtenOp>>(typeConverter, context);
+  INSERT_ATENOP_PATTERN(AtenSliceTensorOp);
+#undef INSERT_ATENOP_PATTERN
+
+}

lib/Conversion/TorchToMhlo/TorchToMhlo.cpp

@@ -51,6 +51,9 @@ class ConvertTorchToMhlo : public ConvertTorchToMhloBase<ConvertTorchToMhlo> {
 
     torch_to_mhlo::populateBasicOpPatternsAndLegality(typeConverter, patterns,
                                                       target);
+    torch_to_mhlo::populateSliceLikeOpPatternsAndLegality(typeConverter, patterns,
+                                                      target);
+
     if (failed(applyPartialConversion(getOperation(), target,
                                       std::move(patterns)))) {
       return signalPassFailure();