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

360 lines
16 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "npcomp/Conversion/TorchToLinalg/TorchToLinalg.h"
#include "../PassDetail.h"
#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
#include "mlir/Dialect/Math/IR/Math.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h" // TODO: For `memref.dim`.
#include "mlir/Dialect/Traits.h"
#include "mlir/Transforms/DialectConversion.h"
#include "npcomp/Dialect/Torch/IR/TorchOps.h"
#include "npcomp/Dialect/Torch/IR/TorchUtils.h"
using namespace mlir;
using namespace mlir::NPCOMP;
using namespace mlir::NPCOMP::Torch;
// -----------------------------------------------------------------------------
// Patterns (as this grows, it should be organized into multiple files)
// -----------------------------------------------------------------------------
// This is going to eventually be O(#aten ops), which is in the 100s.
//
// Most of these patterns consist of:
// 1. Checking that the operand/result types and other static properties are
// good-enough to create a valid linalg op (such as operands being of
// ranks/dtypes acceptable to the linalg op).
// 2. Creating dynamic error guards, usually checking a predicate on the
// compatibility of operand shapes.
// 3. Creating init tensors for the computation op. Usually this involves
// reifying IR for a shape transfer function based on the operand shapes.
// 4. Creating a named linalg op to replace the original op.
//
// TODO: Use linalg OpDSL to autogenerate at least 1)/2)/3) such
// that these patterns become mostly mechanical associations of
// "aten.foo -> linalg.foo".
static LogicalResult verifyLinalgCompatibleTypes(Operation *op,
PatternRewriter &rewriter) {
// For now, use a small allowlist of types we don't reject.
// The main culprit in practice is an unknown dtype
// when RefineTypes isn't smart enough to propagate it everywhere.
// For tensors, we consider the post-conversion tensor type (this pass is
// doing a type conversion).
auto isValidLinalgType = [](Type type) {
if (auto tensor = type.dyn_cast<ValueTensorType>()) {
if (auto rankedTensor =
tensor.toBuiltinTensor().dyn_cast_or_null<RankedTensorType>()) {
if (BaseMemRefType::isValidElementType(rankedTensor.getElementType()))
return true;
}
}
if (type.isa<FloatType, IntegerType, IndexType>())
return true;
return false;
};
bool valid = llvm::all_of(op->getOperandTypes(), isValidLinalgType) &&
llvm::all_of(op->getResultTypes(), isValidLinalgType);
if (!valid)
return rewriter.notifyMatchFailure(op, "type cannot be lowered to linalg");
return success();
}
namespace {
class ConvertAtenMmOp : public OpConversionPattern<AtenMmOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(AtenMmOp op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
Location loc = op->getLoc();
Value lhs = operands[0];
Value rhs = operands[1];
// A user can write an errorneous program where `aten.mm` is in fact called
// with operands of invalid rank or dtype. We cannot convert to linalg in
// this case or we will get a verifier error, which corresponds to breaking
// of *internal* compiler invariants, and for a user manifests as a compiler
// crash in the worst case (such as we try to canonicalize/fold/print the
// invalid op before the verifier gets to see it -- also release builds of a
// mature copmiler usually have the verifier turned off for compile time
// reasons).
//
// The compiler cannot crash even if the user wrote an erroneous program!
if (failed(verifyLinalgCompatibleTypes(op, rewriter)))
return failure();
if (lhs.getType().cast<RankedTensorType>().getRank() != 2 ||
rhs.getType().cast<RankedTensorType>().getRank() != 2) {
return rewriter.notifyMatchFailure(
op, "expected both operands to aten.mm to be rank 2");
}
Value lhsDim0 = rewriter.create<memref::DimOp>(loc, lhs, 0);
Value lhsDim1 = rewriter.create<memref::DimOp>(loc, lhs, 1);
Value rhsDim0 = rewriter.create<memref::DimOp>(loc, rhs, 0);
Value rhsDim1 = rewriter.create<memref::DimOp>(loc, rhs, 1);
Value contractingDimEqual =
rewriter.create<CmpIOp>(loc, CmpIPredicate::eq, lhsDim1, rhsDim0);
rewriter.create<AssertOp>(
loc, contractingDimEqual,
rewriter.getStringAttr(
"mismatching contracting dimension for torch.aten.mm"));
Type newResultType = getTypeConverter()->convertType(op.getType());
Type elementType = newResultType.cast<TensorType>().getElementType();
Value initTensor = rewriter.create<linalg::InitTensorOp>(
loc, ValueRange{lhsDim0, rhsDim1}, elementType);
Value c0 =
rewriter.create<ConstantOp>(loc, FloatAttr::get(elementType, 0.0));
Value zeroFill =
rewriter.create<linalg::FillOp>(loc, initTensor, c0).getResult(0);
Value matmul = rewriter
.create<linalg::MatmulOp>(loc, zeroFill.getType(),
ValueRange{lhs, rhs}, zeroFill)
.getResult(0);
// When constructed with just dynamic sizes, InitTensorOp will have a result
// type which has all `?`'s for dimensions, which might not be the result
// type of `op`. The constraints on later linalg ops means that the result
// of the MatmulOp will have this type too. So cast it to the desired type
// so that in the end we have the original result type.
rewriter.replaceOpWithNewOp<tensor::CastOp>(op, newResultType, matmul);
return success();
}
};
} // namespace
namespace {
// See comments at in convertMmOp and the heading for this section for general
// considerations. This function needs to be auto-generated.
class ConvertAtenLinearOp : public OpConversionPattern<AtenLinearOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(AtenLinearOp op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
AtenLinearOp::Adaptor adaptor(operands);
MLIRContext *context = op->getContext();
Location loc = op->getLoc();
Value input = adaptor.input();
Value weight = adaptor.weight();
Value bias = adaptor.bias();
// TODO: Handle the case of bias being None (bias is optional).
if (failed(verifyLinalgCompatibleTypes(op, rewriter)))
return failure();
auto inputType = input.getType().cast<RankedTensorType>();
auto weightType = weight.getType().cast<RankedTensorType>();
auto biasType = bias.getType().cast<RankedTensorType>();
// Only handle the case of rank 2 `input` for now.
// TODO: Insert the appropriate reshape to collapse any leading dimensions.
if (inputType.getRank() != 2 || weightType.getRank() != 2 ||
biasType.getRank() != 1) {
return rewriter.notifyMatchFailure(
op,
"expected both input and weight to be rank 2 and bias to be rank 1");
}
// TODO: Handle type promotion. What are ATen's promotion rules?
if (inputType.getElementType() != weightType.getElementType() ||
inputType.getElementType() != biasType.getElementType()) {
return rewriter.notifyMatchFailure(op, "unimplemented: type promotion");
}
// TODO: We can handle a static size 1 here at some complexity cost, but the
// dynamic case is not representable in linalg. We don't handle either for
// now. Biases are generally statically shaped for most models (since for
// inference they are constants, and for training they don't change shape
// typically), so this is not too constraining.
auto biasSize = bias.getType().cast<RankedTensorType>().getShape()[0];
if (biasSize == 1 || biasSize == ShapedType::kDynamicSize)
return rewriter.notifyMatchFailure(
op, "unimplemented: size-1 broadcasting for aten::LinearOp");
auto getDimOp = [&](Value v, int dimension) {
return rewriter.create<memref::DimOp>(loc, v, dimension);
};
Value inputDim0 = getDimOp(input, 0);
Value inputDim1 = getDimOp(input, 1);
Value weightDim0 = getDimOp(weight, 0);
Value weightDim1 = getDimOp(weight, 1);
Value biasDim0 = getDimOp(bias, 0);
Value contractingDimEqual =
rewriter.create<CmpIOp>(loc, CmpIPredicate::eq, inputDim1, weightDim1);
rewriter.create<AssertOp>(
loc, contractingDimEqual,
rewriter.getStringAttr(
"mismatching contracting dimension for aten.linear"));
// Here we take advantage of ruling out the size-1 case above.
// In the static-size-1 case, we will not emit this check at all.
Value biasSizeCorrect =
rewriter.create<CmpIOp>(loc, CmpIPredicate::eq, weightDim0, biasDim0);
rewriter.create<AssertOp>(
loc, biasSizeCorrect,
rewriter.getStringAttr("mismatching bias size for aten.linear"));
Value initTensor = rewriter.create<linalg::InitTensorOp>(
loc, ValueRange{inputDim0, weightDim0}, inputType.getElementType());
SmallVector<AffineMap> broadcastIndexingMaps = {
AffineMap::get(
/*dimCount=*/2, /*symbolCount=*/0, rewriter.getAffineDimExpr(1)),
rewriter.getMultiDimIdentityMap(2)};
SmallVector<StringRef> iteratorTypes(2, "parallel");
Value broadcasted =
rewriter
.create<linalg::GenericOp>(
loc, initTensor.getType(), bias, initTensor,
/*indexingMaps=*/broadcastIndexingMaps,
/*iteratorTypes=*/iteratorTypes,
[](OpBuilder &b, Location loc, ValueRange args) {
b.create<linalg::YieldOp>(loc, args[0]);
})
.getResult(0);
// We need a matmul with dimension ordering (N, K) * (M, K), so transpose
// the weights to fit into linalg::MatmulOp which is (N, K) * (K, M).
// TODO: This whole aten.linear lowering should eventually be generated from
// a single linalg ODS generator statement. Both the bias and matmul part.
SmallVector<AffineMap> transposeIndexingMaps = {
AffineMap::get(
/*dimCount=*/2, /*symbolCount=*/0,
{rewriter.getAffineDimExpr(1), rewriter.getAffineDimExpr(0)},
context),
rewriter.getMultiDimIdentityMap(2)};
Value transposedWeightInitTensor = rewriter.create<linalg::InitTensorOp>(
loc, ValueRange{weightDim1, weightDim0}, weightType.getElementType());
Value transposedWeights =
rewriter
.create<linalg::GenericOp>(
loc, transposedWeightInitTensor.getType(), weight,
transposedWeightInitTensor,
/*indexingMaps=*/transposeIndexingMaps,
/*iteratorTypes=*/iteratorTypes,
[](OpBuilder &b, Location loc, ValueRange args) {
b.create<linalg::YieldOp>(loc, args[0]);
})
.getResult(0);
Value matmul = rewriter
.create<linalg::MatmulOp>(
loc, broadcasted.getType(),
ValueRange{input, transposedWeights}, broadcasted)
.getResult(0);
Type newResultType = getTypeConverter()->convertType(op.getType());
rewriter.replaceOpWithNewOp<tensor::CastOp>(op, newResultType, matmul);
return success();
}
};
} // namespace
static Value createScalarRelu(OpBuilder &b, Location loc, ValueRange args) {
Type elementType = args[0].getType();
// TODO: Add support for integer types.
assert(elementType.isa<::mlir::FloatType>() &&
"Only support float case for relu");
Value constZero = b.create<ConstantOp>(loc, FloatAttr::get(elementType, 0.0));
Value pred = b.create<CmpFOp>(loc, CmpFPredicate::UGT, args[0], constZero);
return b.create<SelectOp>(loc, pred, args[0], constZero);
}
namespace {
// Converts a unary op. There is no implicit broadcasting behavior, so these can
// be trivially lowered to linalg.
// TODO: For binary ops, we will need a "linalg.generic-like" op that models
// N-ary broadcasting and allows us to do multiversioning techniques for
// lowering to linalg. We can trivially handle this as through that
// abstraction instead.
struct ConvertUnaryOp : ConversionPattern {
ConvertUnaryOp(TypeConverter &typeConverter, MLIRContext *context)
: ConversionPattern(typeConverter, MatchAnyOpTypeTag(), /*benefit=*/1,
context) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
if (!isa<AtenTanhOp>(op) && !isa<AtenReluOp>(op))
return rewriter.notifyMatchFailure(op, "not a unary op");
if (failed(verifyLinalgCompatibleTypes(op, rewriter)))
return failure();
Value operand = operands[0];
auto type = getTypeConverter()
->convertType(op->getResult(0).getType())
.cast<RankedTensorType>();
auto rank = type.getRank();
SmallVector<StringRef> iteratorTypes(rank, "parallel");
SmallVector<AffineMap> indexingMaps = {
rewriter.getMultiDimIdentityMap(rank),
rewriter.getMultiDimIdentityMap(rank)};
rewriter.replaceOpWithNewOp<linalg::GenericOp>(
op, type, operand, operand,
/*indexingMaps=*/indexingMaps,
/*iteratorTypes=*/iteratorTypes,
[&](OpBuilder &b, Location loc, ValueRange args) {
Value result;
if (isa<AtenTanhOp>(op))
result = b.create<math::TanhOp>(loc, args[0]);
else if (isa<AtenReluOp>(op))
result = createScalarRelu(b, loc, args);
b.create<linalg::YieldOp>(loc, result);
});
return success();
}
};
} // namespace
// -----------------------------------------------------------------------------
// The pass
// -----------------------------------------------------------------------------
namespace {
class ConvertTorchToLinalg
: public ConvertTorchToLinalgBase<ConvertTorchToLinalg> {
public:
void getDependentDialects(DialectRegistry &registry) const override {
registry.insert<linalg::LinalgDialect>();
registry.insert<memref::MemRefDialect>();
registry.insert<math::MathDialect>();
registry.insert<StandardOpsDialect>();
registry.insert<tensor::TensorDialect>();
}
void runOnOperation() override {
MLIRContext *context = &getContext();
ConversionTarget target(*context);
target.addLegalDialect<linalg::LinalgDialect, StandardOpsDialect,
memref::MemRefDialect, math::MathDialect,
tensor::TensorDialect>();
TypeConverter typeConverter;
typeConverter.addConversion([](Type type) { return type; });
setupValueTensorToBuiltinTensorConversion(target, typeConverter);
RewritePatternSet patterns(context);
target.addIllegalOp<AtenMmOp>();
patterns.add<ConvertAtenMmOp>(typeConverter, context);
target.addIllegalOp<AtenLinearOp>();
patterns.add<ConvertAtenLinearOp>(typeConverter, context);
target.addIllegalOp<AtenTanhOp>();
patterns.add<ConvertUnaryOp>(typeConverter, context);
if (failed(applyPartialConversion(getOperation(), target,
std::move(patterns))))
return signalPassFailure();
}
};
} // namespace
std::unique_ptr<OperationPass<FuncOp>>
mlir::NPCOMP::createConvertTorchToLinalgPass() {
return std::make_unique<ConvertTorchToLinalg>();
}