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torch-mlir/lib/Conversion/TorchToLinalg/Utils.cpp

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//===----------------------------------------------------------------------===//
//
// 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 "Utils.h"
#include "../PassDetail.h"
#include "PopulatePatterns.h"
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/ControlFlow/IR/ControlFlowOps.h"
#include "mlir/Dialect/Linalg/IR/Linalg.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Tensor/Utils/Utils.h"
#include "mlir/IR/Matchers.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/Torch/Utils/Utils.h"
using namespace mlir;
using namespace mlir::torch;
using namespace mlir::torch::Torch;
static SmallVector<OpFoldResult>
getIndexIntsAsOpFoldResult(OpBuilder &b, SmallVectorImpl<int64_t> &ints) {
return llvm::to_vector<4>(llvm::map_range(
ints, [&](int64_t val) -> OpFoldResult { return b.getIndexAttr(val); }));
}
// Helper function to get the padding tensor given the padding int values.
Value torch_to_linalg::getPaddedTensor(
Operation *op, OpBuilder &b, Value &input,
SmallVectorImpl<int64_t> &lowPaddingInts,
SmallVectorImpl<int64_t> &highPaddingInts, Value pad) {
Location loc = op->getLoc();
Type rankedTensorType =
tensor::PadOp::inferResultType(input.getType().cast<RankedTensorType>(),
lowPaddingInts, highPaddingInts);
SmallVector<OpFoldResult> lowPaddings =
getIndexIntsAsOpFoldResult(b, lowPaddingInts);
SmallVector<OpFoldResult> highPaddings =
getIndexIntsAsOpFoldResult(b, highPaddingInts);
Value paddedInput =
b.create<tensor::PadOp>(loc, rankedTensorType, input, /*low=*/lowPaddings,
/*high=*/highPaddings, pad);
return paddedInput;
}
// Helper function to get the padding tensor given the padding int values.
// It's assumed that the padding on the low end and high end are the same,
// and that zero padding is required.
Value torch_to_linalg::getZeroPaddedTensor(
Operation *op, OpBuilder &b, Value &input,
SmallVectorImpl<int64_t> &paddingInts) {
assert(input.getType().isa<RankedTensorType>() &&
"input must be RankedTensorType");
Location loc = op->getLoc();
Value c0 = b.create<arith::ConstantOp>(
loc,
b.getZeroAttr(input.getType().cast<RankedTensorType>().getElementType()));
return getPaddedTensor(op, b, input, paddingInts, paddingInts, c0);
}
// Helper function that adds dynamic padding to a tensor, ignoring unpaddedDims
// dimensions at the beginning. The high and low padding are the same, and the
// padding value is zero.
Value torch_to_linalg::getDynamicZeroPaddedTensor(
Operation *op, OpBuilder &b, Value &input, SmallVectorImpl<Value> &padding,
int unpaddedDims) {
assert(input.getType().isa<RankedTensorType>() &&
"input must be RankedTensorType");
unsigned int inRank = input.getType().cast<RankedTensorType>().getRank();
Location loc = op->getLoc();
SmallVector<Value> inputDims = getTensorSizes(b, loc, input);
Value c0 = b.create<arith::ConstantOp>(loc, b.getI64IntegerAttr(0));
SmallVector<Value> paddingIncludingUnchanged(unpaddedDims, c0);
paddingIncludingUnchanged.append(padding);
assert(unpaddedDims + padding.size() == inRank &&
"sum of unpaddedDims and padding.size() must equal to inputRank");
for (auto pad = paddingIncludingUnchanged.begin();
pad < paddingIncludingUnchanged.end(); pad++)
*pad = castIntToIndex(b, loc, *pad);
Type elementType = input.getType().cast<RankedTensorType>().getElementType();
Type inputType =
RankedTensorType::get(makeShapeLLVMCompatible(llvm::ArrayRef<int64_t>(
SmallVector<int64_t>(inRank, kUnknownSize))),
elementType);
Value cf0 =
b.create<arith::ConstantOp>(loc, b.getFloatAttr(elementType, 0.0));
SmallVector<OpFoldResult> paddingValues =
getAsOpFoldResult(paddingIncludingUnchanged);
return b.create<tensor::PadOp>(loc, inputType, input, /*low=*/paddingValues,
/*high=*/paddingValues, cf0);
}
Value torch_to_linalg::getOutputDimForConvOps(OpBuilder &b, Location loc,
Value in, Value paddingInt,
Value dilationInt,
Value kernelSizeInt,
Value strideInt, bool ceilMode) {
Value c1 = b.create<arith::ConstantOp>(loc, b.getI64IntegerAttr(1));
Value c2 = b.create<arith::ConstantOp>(loc, b.getI64IntegerAttr(2));
Value doublePadding = b.create<arith::MulIOp>(loc, paddingInt, c2);
// in + 2 * padding
Value inAddDoublePadding =
b.create<arith::AddIOp>(loc, castIndexToInt64(b, loc, in), doublePadding);
// dilation * (kernelSize - 1)
Value kernelSizeSub1 = b.create<arith::SubIOp>(loc, kernelSizeInt, c1);
Value dilationTimesKernelSize =
b.create<arith::MulIOp>(loc, dilationInt, kernelSizeSub1);
Value temp =
b.create<arith::SubIOp>(loc, inAddDoublePadding, dilationTimesKernelSize);
Value dividend = b.create<arith::SubIOp>(loc, temp, c1);
Value division;
if (ceilMode)
division = b.create<arith::CeilDivSIOp>(loc, dividend, strideInt);
else
division = b.create<arith::FloorDivSIOp>(loc, dividend, strideInt);
Value out = b.create<arith::AddIOp>(loc, division, c1);
return castIntToIndex(b, loc, out);
}
Value torch_to_linalg::getOutputDimForConvTransposeOps(
OpBuilder &b, Location loc, Value in, Value paddingInt, Value dilationInt,
Value kernelSizeInt, Value strideInt, Value outputPaddingInt) {
Value c1 = b.create<arith::ConstantOp>(loc, b.getI64IntegerAttr(1));
Value c2 = b.create<arith::ConstantOp>(loc, b.getI64IntegerAttr(2));
// (in - 1) * stride
Value inStrided =
b.create<arith::SubIOp>(loc, castIndexToInt64(b, loc, in), c1);
inStrided = b.create<arith::MulIOp>(loc, inStrided, strideInt);
// 2 * padding
Value doublePadding = b.create<arith::MulIOp>(loc, paddingInt, c2);
// (kernelSize - 1) * dilation
Value kernelDilated = b.create<arith::SubIOp>(loc, kernelSizeInt, c1);
kernelDilated = b.create<arith::MulIOp>(loc, kernelDilated, dilationInt);
Value out = b.create<arith::SubIOp>(loc, inStrided, doublePadding);
out = b.create<arith::AddIOp>(loc, out, kernelDilated);
out = b.create<arith::AddIOp>(loc, out, outputPaddingInt);
out = b.create<arith::AddIOp>(loc, out, c1);
return castIntToIndex(b, loc, out);
}
Value torch_to_linalg::createReductionLinalgGeneric(
OpBuilder &b, Location loc, const ReductionOpInfo &opInfo, Value initElem,
function_ref<void(OpBuilder &, Location, ValueRange)> bodyBuild) {
auto inputType = opInfo.tensorOperand.getType().cast<RankedTensorType>();
// Get the result shape by obtaining the size of each
// dimension in the input tensor that is not getting reduced.
// If `opInfo.keepDim` is true, the rank of the output tensor
// is kept the same as the rank of the input tensor, and the
// reduced dimensions are set to have size 1.
auto c1 = b.create<arith::ConstantIndexOp>(loc, /*value=*/1);
SmallVector<Value> resultShape;
for (int64_t i = 0; i < inputType.getRank(); i++) {
auto currentDimSize = b.create<tensor::DimOp>(loc, opInfo.tensorOperand, i);
if (!opInfo.dimSet.contains(i))
resultShape.push_back(currentDimSize);
else if (opInfo.keepDim)
resultShape.push_back(c1);
}
// Create the affine expressions that will be used to
// iterate over the input and output tensors.
// Here we also set the type of iterator: parallel or reduction.
SmallVector<AffineExpr> exprs;
SmallVector<utils::IteratorType> iteratorTypes;
SmallVector<AffineExpr> resultExprs;
for (auto size :
llvm::enumerate(makeShapeTorchCompatible(inputType.getShape()))) {
exprs.push_back(b.getAffineDimExpr(size.index()));
if (opInfo.dimSet.contains(size.index())) {
iteratorTypes.push_back(utils::IteratorType::reduction);
// If `opInfo.keepDim`, create affine map to the first element
// in the current dimension.
if (opInfo.keepDim)
resultExprs.push_back(b.getAffineConstantExpr(0));
} else {
iteratorTypes.push_back(utils::IteratorType::parallel);
resultExprs.push_back(b.getAffineDimExpr(size.index()));
}
}
auto indexingMaps = AffineMap::inferFromExprList({exprs, resultExprs});
Value accumulator =
createInitTensor(b, loc, resultShape, initElem.getType(), initElem);
return b
.create<linalg::GenericOp>(
loc, /*resultTensorTypes=*/accumulator.getType(),
/*inputs=*/opInfo.tensorOperand,
/*outputs=*/accumulator, indexingMaps, iteratorTypes, bodyBuild)
.getResult(0);
}
Value torch_to_linalg::createElementwiseLinalgGeneric(
OpBuilder &b, Location loc, ValueRange tensorOperands,
Type resultElementType,
function_ref<void(OpBuilder &, Location, ValueRange)> bodyBuild) {
// The overall error handling strategy here is best viewed by thinking about
// what happens for a single result dimension. This loop not structured that
// way because it is hard to create the affine maps for each operand unless
// we structure the loop to iterate over tensor operands as the outer loop
// instead of inner loop. This pseudocode gives better intuition:
// ```
// for each result dimension:
// for each tensor operand:
// if it doesn't even have high enough rank relative to the result:
// continue
// if it is a static size-1 along this result dimension:
// continue
// if this is the first tensor operand that didn't continue above:
// take its dimension size as the size of the non-broadcasted
// traversal along this dimension (this may include a dynamic size-1,
// **non-broadcasted** traversal unless if
// isAssumingStrictSymbolicShapes!)
// emit error check "if the size does not match the non-broadcasted
// traversal size along this dimension, error"
// ```
SmallVector<int64_t> operandRanks;
operandRanks.resize(tensorOperands.size());
llvm::transform(tensorOperands, operandRanks.begin(), [](Value tensor) {
return tensor.getType().dyn_cast<RankedTensorType>().getRank();
});
auto resultRankIt =
std::max_element(operandRanks.begin(), operandRanks.end());
assert(resultRankIt != operandRanks.end() && "Unable to get result rank.");
int64_t resultRank = *resultRankIt;
// Initialize the resultShape to all 1's, as a fallback in case
// all sizes along that result dimension are statically 1.
auto c1 = b.create<arith::ConstantIndexOp>(loc, /*value=*/1);
SmallVector<Value> resultShape(resultRank, c1);
SmallVector<AffineMap> indexingMaps;
bool elideDynamicBroadcastCheck = isAssumingStrictSymbolicShapes(b);
for (Value tensorOperand : tensorOperands) {
SmallVector<AffineExpr> exprs;
auto type = tensorOperand.getType().cast<RankedTensorType>();
for (auto size :
llvm::enumerate(makeShapeTorchCompatible(type.getShape()))) {
// If the size is statically known to be 1, we don't want any
// error guards to be spuriously emitted, since we are specifically
// allowing size-1 broadcasts in this case, as they correspond to a
// constant-0 indexing map.
if (size.value() == 1) {
exprs.push_back(b.getAffineConstantExpr(0));
continue;
}
// The rank of this operand might be smaller than the overall rank of
// the broadcast. Add an offset to correlate it to the correct
// dimension of the result.
auto resultDim = size.index() + (resultRank - type.getRank());
// The generated linalg op will now be iterating along the full size
// of this dimension. Record that fact.
exprs.push_back(b.getAffineDimExpr(resultDim));
// Now, we need to ensure that such iteration is not going to trigger
// undefined behavior, by doing appropriate checks against the current
// dimension size.
auto currentDimSize = getDimOp(b, loc, tensorOperand, size.index());
// If the result size of this dimension has so far only hit the
// statically-known-to-be-1 case above (i.e., we have not yet assigned a
// new Value to `resultShape[resultDim]`), then we have no other dynamic
// values to check against, and merely need to record the current
// dimension size.
if (resultShape[resultDim] == c1) {
resultShape[resultDim] = currentDimSize;
continue;
}
// We prohibit the size-1 dynamic broadcasting scenario, so just check
// for exact equality with the running result size.
// This is the check which protects against the undefined behavior of
// the generated linalg op in the case of iterating two operands with
// dimensions sizes that are expected to match.
if (!elideDynamicBroadcastCheck) {
auto equalToRunning =
b.create<arith::CmpIOp>(loc, arith::CmpIPredicate::eq,
resultShape[resultDim], currentDimSize);
b.create<cf::AssertOp>(loc, equalToRunning,
"mismatched size for broadcast");
}
}
indexingMaps.push_back(AffineMap::get(
/*dimCount=*/resultRank, /*symbolCount=*/0, exprs, b.getContext()));
}
SmallVector<utils::IteratorType> iteratorTypes(resultRank,
utils::IteratorType::parallel);
// Add the indexing map for the outs init tensor.
indexingMaps.push_back(b.getMultiDimIdentityMap(resultRank));
Value initTensor = b.create<tensor::EmptyOp>(
loc, getAsOpFoldResult(resultShape), resultElementType);
return b
.create<linalg::GenericOp>(loc,
/*resultTensorTypes=*/initTensor.getType(),
/*inputs=*/tensorOperands,
/*outputs=*/initTensor, indexingMaps,
iteratorTypes, bodyBuild)
.getResult(0);
}
// Broadcasts input tensor based on the broadcastToShape.
LogicalResult torch_to_linalg::broadcastToGivenShape(
Operation *op, PatternRewriter &rewriter, Value input,
SmallVector<Value> broadcastToShape, RankedTensorType broadcastType,
Value &result, SmallVector<bool> useBroadcastToShape) {
RankedTensorType inputType = input.getType().cast<RankedTensorType>();
int64_t inputRank = inputType.getRank();
int64_t outputRank = broadcastToShape.size();
ArrayRef<int64_t> outputShape = broadcastType.getShape();
SmallVector<int64_t> inputShape =
makeShapeTorchCompatible(inputType.getShape());
if (outputRank < inputRank) {
return rewriter.notifyMatchFailure(
op, "invalid shape: broadcastToShape size must not be smaller than the "
"size of the input shape");
}
Type elementType = inputType.getElementType();
Location loc = op->getLoc();
SmallVector<OpFoldResult> outShape;
bool elideDynamicBroadcastCheck = isAssumingStrictSymbolicShapes(rewriter);
// Vector indicating broadcasted status when assuming strict symbolic shapes.
SmallVector<bool> broadcastedStatus;
// Create affine map and shapes for tensor initialization.
SmallVector<AffineExpr> outExpr;
Value zero =
rewriter.create<arith::ConstantOp>(loc, rewriter.getI64IntegerAttr(0));
Value zeroIndex =
rewriter.create<arith::ConstantOp>(loc, rewriter.getIndexAttr(0));
Value oneIndex =
rewriter.create<arith::ConstantOp>(loc, rewriter.getIndexAttr(1));
size_t diff = outputRank - inputRank;
bool hasDynamicNumpyBroadcast = false;
for (size_t i = 0, e = outputRank; i < e; i++) {
Value shapeValue = broadcastToShape[i];
size_t j = i - diff;
bool isDynamic = i >= diff && inputShape[j] == kUnknownSize;
// Inherit static output shapes if present.
if (outputShape[i] != ShapedType::kDynamic) {
outShape.push_back(rewriter.getIndexAttr(outputShape[i]));
if (i < diff) {
if (outputShape[i] < 0) {
return rewriter.notifyMatchFailure(
op, "invalid shape: negative values not allowed in new broadcast "
"dimensions");
}
continue;
}
if (isDynamic) {
hasDynamicNumpyBroadcast = true;
} else if (inputShape[j] != outputShape[i] && inputShape[j] != 1) {
return rewriter.notifyMatchFailure(
op, "invalid shape: static mismatch in input and output broadcast "
"shapes");
}
// If strict symbolic shapes are assumed and the input shape is dynamic,
// we can assume that dim is not broadcasted.
broadcastedStatus.push_back(inputShape[j] != outputShape[i] &&
!isDynamic);
continue;
}
if (i < diff) {
if (!elideDynamicBroadcastCheck) {
Value isValid = rewriter.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::sge, shapeValue, zero);
rewriter.create<cf::AssertOp>(
loc, isValid,
rewriter.getStringAttr(
"negative values not allowed in new dimensions"));
}
outShape.push_back(castIntToIndex(rewriter, loc, shapeValue));
continue;
}
if (inputShape[j] == 1) {
// Broadcast singleton dimension
Value isNegative = rewriter.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::slt, shapeValue, zero);
Value select = rewriter.create<arith::SelectOp>(
loc, isNegative, oneIndex, castIntToIndex(rewriter, loc, shapeValue));
outShape.push_back(select);
broadcastedStatus.push_back(true);
continue;
}
// Case of dynamic input dimension wherein the shape to broadcast will
// yield us the dimension size of the output.
Value dim;
if (!useBroadcastToShape.empty() && useBroadcastToShape[j]) {
dim = castIntToIndex(rewriter, loc, broadcastToShape[i]);
if (isDynamic) {
hasDynamicNumpyBroadcast = true;
}
if (!elideDynamicBroadcastCheck) {
Value isValid = rewriter.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::sge, shapeValue, zero);
rewriter.create<cf::AssertOp>(
loc, isValid,
rewriter.getStringAttr(
"unimplemented: dynamic negative broadcast sizes"));
}
} else {
dim = getDimOp(rewriter, loc, input, j);
}
// We can safely assume this dimension is not broadcasted with strict
// symbols.
broadcastedStatus.push_back(false);
outShape.push_back(dim);
}
Value outTensor =
rewriter.create<tensor::EmptyOp>(loc, outShape, elementType);
// If we know there are no ? -> ? broadcasted dims, or we are assuming
// strict symbols, we can safely use standard linalg style broadcasting
// semantics.
if (!hasDynamicNumpyBroadcast || elideDynamicBroadcastCheck) {
// If no dims are broadcasted and the rank doesn't change, we can just fold
// the op away entirely.
if (!llvm::any_of(broadcastedStatus, [](bool b) { return b; }) &&
inputRank == outputRank) {
result = rewriter.create<tensor::CastOp>(loc, outTensor.getType(), input);
return success();
}
SmallVector<AffineExpr> inputExprs;
for (int64_t i = 0, e = inputRank; i < e; ++i) {
if (broadcastedStatus[i]) {
inputExprs.push_back(rewriter.getAffineConstantExpr(0));
continue;
}
inputExprs.push_back(rewriter.getAffineDimExpr(i + diff));
}
SmallVector<AffineMap> indexingMaps = {
AffineMap::get(outputRank, 0, inputExprs, rewriter.getContext()),
rewriter.getMultiDimIdentityMap(outputRank)};
SmallVector<utils::IteratorType> iteratorTypes(
outputRank, utils::IteratorType::parallel);
result = rewriter
.create<linalg::GenericOp>(
loc, outTensor.getType(), input, outTensor, indexingMaps,
iteratorTypes,
[&](OpBuilder &b, Location loc, ValueRange args) {
b.create<linalg::YieldOp>(loc, args[0]);
})
.getResult(0);
return success();
}
// Fall back to numpy-style dynamic broadcasting in the form of a single
// linalg op.
SmallVector<AffineMap> indexingMaps = {
rewriter.getMultiDimIdentityMap(outputRank)};
SmallVector<utils::IteratorType> iteratorTypes(outputRank,
utils::IteratorType::parallel);
result = rewriter
.create<linalg::GenericOp>(
loc, outTensor.getType(), ValueRange(), outTensor,
indexingMaps, iteratorTypes,
[&](OpBuilder &b, Location loc, ValueRange args) {
// `loopIndices` contains IV of the linalg loops which
// would be used to extract values from the input tensor
// later on.
SmallVector<Value> loopIndices;
for (size_t i = 0, e = outputRank; i < e; ++i) {
if (i < diff)
continue;
loopIndices.push_back(b.create<linalg::IndexOp>(loc, i));
}
// `inputIndicesToExtract` contains i-th linalg loop IV if
// the i-th input dimension is not 1, else it contains a
// zero index.
SmallVector<Value> inputIndicesToExtract;
for (size_t i = 0, n = inputRank; i < n; i++) {
if (inputShape[i] == 1) {
inputIndicesToExtract.push_back(zeroIndex);
} else {
Value inputDim = getDimOp(b, loc, input, i);
Value isEqual = b.create<arith::CmpIOp>(
loc, arith::CmpIPredicate::eq, inputDim, oneIndex);
Value select = rewriter.create<arith::SelectOp>(
loc, isEqual, zeroIndex, loopIndices[i]);
inputIndicesToExtract.push_back(select);
}
}
// Extract and yield the value from input tensor at
// `inputIndicesToExtract` indices.
Value result = b.create<tensor::ExtractOp>(
loc, input, inputIndicesToExtract);
b.create<linalg::YieldOp>(loc, result);
})
.getResult(0);
return success();
}
Value torch_to_linalg::removeSizeInformation(OpBuilder &b, Location loc,
Value tensor) {
auto tensorType = tensor.getType().cast<RankedTensorType>();
auto rank = tensorType.getRank();
SmallVector<int64_t> unknownSizes(rank, kUnknownSize);
return b.create<tensor::CastOp>(
loc, tensorType.clone(makeShapeLLVMCompatible(unknownSizes)), tensor);
}
Value torch_to_linalg::convertTensorToElementType(OpBuilder &b, Location loc,
Value tensor,
Type elementType) {
auto dtypePromoteBody = [&](OpBuilder &builder, Location loc,
ValueRange payloadArgs) {
Value elem =
convertScalarToDtype(builder, loc, payloadArgs[0], elementType);
builder.create<linalg::YieldOp>(loc, elem);
};
return torch_to_linalg::createElementwiseLinalgGeneric(
b, loc, {tensor}, elementType, dtypePromoteBody);
}
FailureOr<Type> torch_to_linalg::getBackendTypeForScalarType(
MLIRContext *context, torch_upstream::ScalarType dtypeInt) {
FailureOr<Type> maybeType =
getTypeForScalarType(context, (torch_upstream::ScalarType)dtypeInt);
if (failed(maybeType)) {
return failure();
}
Type type = *maybeType;
// The linalg-on-tensors backend currently expects integers to be signless.
if (auto intType = type.dyn_cast<IntegerType>()) {
type = IntegerType::get(context, intType.getWidth(), IntegerType::Signless);
}
return type;
}
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