torch-mlir/lib/RefBackend/TensorToMemref/LowerShapedResultsToMemref.cpp

376 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 "../PassDetail.h"
#include "npcomp/RefBackend/RefBackend.h"
#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
#include "mlir/Dialect/Linalg/IR/LinalgTypes.h"
#include "mlir/Dialect/SCF/SCF.h"
#include "mlir/Dialect/Shape/IR/Shape.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Pass/PassRegistry.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/InliningUtils.h"
#include "npcomp/Conversion/TCFToTCP/TCFToTCP.h"
#include "npcomp/Dialect/Refback/IR/RefbackOps.h"
#include "npcomp/Dialect/TCP/IR/TCPDialect.h"
#include "npcomp/Dialect/TCP/IR/TCPOps.h"
using namespace mlir;
using namespace mlir::NPCOMP;
static FailureOr<SmallVector<Value, 6>>
allocateResults(Operation *op, ConversionPatternRewriter &rewriter,
Location loc,
SmallVectorImpl<Value> *resultShapesOut = nullptr) {
// TODO: This is really fragile. Can we have a better story?
auto shapedResults = dyn_cast<refback::ShapedResultsOp>(op->getParentOp());
if (!shapedResults)
return rewriter.notifyMatchFailure(op, "parent not refback.shaped_results");
if (op->getResults() !=
shapedResults.getBody()->getTerminator()->getOperands())
return rewriter.notifyMatchFailure(
op, "only limited forms of refback.shaped_results allowed");
auto resultShapes = shapedResults.resultShapes();
SmallVector<Value, 6> results;
for (auto t : llvm::zip(op->getResults(), resultShapes)) {
auto result = std::get<0>(t);
auto resultShape = std::get<1>(t);
auto tensorType = result.getType().cast<RankedTensorType>();
auto memrefType =
MemRefType::get(tensorType.getShape(), tensorType.getElementType());
auto memref =
rewriter.create<refback::AllocMemRefOp>(loc, memrefType, resultShape);
results.push_back(memref);
}
if (resultShapesOut)
resultShapesOut->append(resultShapes.begin(), resultShapes.end());
return results;
}
namespace {
// TODO: Lower to a "buffer version" of tcp::BroadcastTo instead of directly to
// loops.
class LowerBroadcastToToLoopsPattern
: public OpConversionPattern<tcp::BroadcastToOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(tcp::BroadcastToOp op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
auto resultType = op.getType().cast<RankedTensorType>();
auto inputType = op.operand().getType().cast<RankedTensorType>();
SmallVector<Value, 6> resultShapes;
auto resultsOrFailure =
allocateResults(op, rewriter, op.getLoc(), &resultShapes);
if (failed(resultsOrFailure))
return failure();
Value resultMemref = (*resultsOrFailure)[0];
auto resultShape = resultShapes[0];
Value inputMemref = operands[0];
SmallVector<Value, 6> outputExtents;
for (int i = 0, e = resultType.getRank(); i < e; i++) {
Value dimIndex = rewriter.create<ConstantIndexOp>(op.getLoc(), i);
Value outputExtent = rewriter.create<shape::GetExtentOp>(
op.getLoc(), rewriter.getIndexType(), resultShape, dimIndex);
outputExtents.push_back(outputExtent);
}
int rankDiff = resultType.getRank() - inputType.getRank();
SmallVector<Value, 6> inputDimRequiresBroadcasting;
for (int i = 0, e = inputType.getRank(); i < e; i++) {
// Calculate the relevant extents.
Value inputExtent = rewriter.create<DimOp>(op.getLoc(), op.operand(), i);
inputDimRequiresBroadcasting.push_back(
rewriter.create<CmpIOp>(op.getLoc(), CmpIPredicate::ne, inputExtent,
outputExtents[rankDiff + i]));
}
{
OpBuilder::InsertionGuard guard(rewriter);
Value c0 = rewriter.create<ConstantIndexOp>(op.getLoc(), 0);
Value c1 = rewriter.create<ConstantIndexOp>(op.getLoc(), 1);
SmallVector<Value, 6> inductionVariables;
// Create the (perfectly nested) loops.
// Loop invariant: At the start of iteration `i`, the rewriter insertion
// point is inside `i` nested loops.
for (int i = 0, e = resultType.getRank(); i < e; i++) {
auto loop = rewriter.create<scf::ForOp>(
op.getLoc(), c0, outputExtents[i], c1, ValueRange({}));
Block *body = loop.getBody();
inductionVariables.push_back(body->getArgument(0));
// Leave the insertion point at the beginning of the body.
rewriter.setInsertionPointToStart(body);
}
// Create the inner loop body.
// When reading from the input, clamp any indices for dimensions that are
// being broadcast.
SmallVector<Value, 6> inputIndices;
for (int i = 0, e = inputType.getRank(); i < e; i++) {
auto c0 = rewriter.create<ConstantIndexOp>(op.getLoc(), 0);
auto select = rewriter.create<SelectOp>(
op.getLoc(), inputDimRequiresBroadcasting[i], c0,
inductionVariables[rankDiff + i]);
inputIndices.push_back(select);
}
Value load =
rewriter.create<LoadOp>(op.getLoc(), inputMemref, inputIndices);
rewriter.create<StoreOp>(op.getLoc(), load, resultMemref,
inductionVariables);
}
rewriter.replaceOp(op, resultMemref);
return success();
}
};
} // namespace
static Value createLinalgBodyCalculationForElementwiseOp(Operation *op,
ValueRange bodyArgs,
OpBuilder &builder,
Location loc) {
if (isa<tcp::AddOp>(op))
return builder.create<AddFOp>(loc, bodyArgs[0], bodyArgs[1]);
if (isa<tcp::MaxOp>(op)) {
auto greater = builder.create<CmpFOp>(loc, CmpFPredicate::OGT, bodyArgs[0],
bodyArgs[1]);
return builder.create<SelectOp>(loc, greater, bodyArgs[0], bodyArgs[1]);
}
if (isa<tcp::ExpOp>(op))
return builder.create<ExpOp>(loc, bodyArgs[0]);
if (isa<tcp::TanhOp>(op))
return builder.create<TanhOp>(loc, bodyArgs[0]);
op->dump();
llvm::report_fatal_error("unhandled op (see dump above): linalg body "
"calculation for elementwise op");
}
static LogicalResult
matchAndRewriteElementwiseOp(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) {
Location loc = op->getLoc();
Value result = op->getResult(0);
auto resultsOrFailure = allocateResults(op, rewriter, loc);
if (failed(resultsOrFailure))
return failure();
auto results = *resultsOrFailure;
SmallVector<Value, 6> args;
args.append(operands.begin(), operands.end());
args.append(results.begin(), results.end());
size_t rank = result.getType().cast<RankedTensorType>().getRank();
SmallVector<StringRef, 6> iterators(rank, getParallelIteratorTypeName());
// TODO: Generalize this to other elementwise ops.
// All we need to do is to have a mapping of tcp.foo to scalar.foo.
// TODO: Should we just use linalg named ops for most of TCP?
// Doing so would make tcp very consistent, but also it would, at this early
// stage, make most non-trivial changes also require co-design with the
// linalg ODS generator, which would be a very slow process.
auto argsIn = operands.size();
auto argsOut = results.size();
SmallVector<AffineMap, 3> accesses(argsIn + argsOut,
rewriter.getMultiDimIdentityMap(rank));
rewriter.create<linalg::GenericOp>(
loc, /*inputs=*/operands, /*outputBuffers=*/results,
/*indexingMaps=*/accesses,
/*iteratorTypes=*/iterators,
/*bodyBuilder=*/
[&](OpBuilder &builder, Location loc, ValueRange regionArgs) {
auto scalarResult = createLinalgBodyCalculationForElementwiseOp(
op, regionArgs, builder, loc);
builder.create<linalg::YieldOp>(loc, ValueRange({scalarResult}));
});
rewriter.replaceOp(op, results);
return success();
}
namespace {
template <typename SourceOp>
class LowerElementwiseOp : public OpConversionPattern<SourceOp> {
public:
using OpConversionPattern<SourceOp>::OpConversionPattern;
LogicalResult
matchAndRewrite(SourceOp op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
return matchAndRewriteElementwiseOp(op, operands, rewriter);
}
};
} // namespace
namespace {
class LowerTcpMatmulOp : public OpConversionPattern<tcp::MatmulOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(tcp::MatmulOp op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
auto resultsOrFailure = allocateResults(op, rewriter, op.getLoc());
if (failed(resultsOrFailure))
return failure();
auto results = *resultsOrFailure;
auto c0 =
rewriter.create<ConstantOp>(op.getLoc(), rewriter.getF32FloatAttr(0.0));
rewriter.create<linalg::FillOp>(op.getLoc(), results[0], c0);
rewriter.create<linalg::MatmulOp>(op.getLoc(), operands, results);
rewriter.replaceOp(op, results);
return success();
}
};
} // namespace
namespace {
// TODO: Linalg and shape don't implement the inliner interface, which blocks us
// from using mlir::inlineRegion. Locally override it here.
class LocallyOverrideLegalityInlinerInterface : public InlinerInterface {
public:
using InlinerInterface::InlinerInterface;
bool isLegalToInline(Operation *op, Region *dest,
BlockAndValueMapping &valueMapping) const final {
return true;
}
bool isLegalToInline(Region *dest, Region *src,
BlockAndValueMapping &valueMapping) const final {
return true;
}
};
} // namespace
namespace {
// This pass is responsible for lowering regions wrapped by
// refback.shaped_results (which operate on tensors) to memrefs.
// This includes any ops potentially contained within them.
// This is somewhat analogous to IREE's backend compilation of a single dispatch
// region, except that for now, we only allow a single op in the
// refback.shaped_results, and we don't have any notion of "backend" layered at
// all. Nor is it clear if we really want any of that here.
//
// The refback.shaped_results ops provide precisely the information needed to
// allocate output buffers when converting to memref.
// For now, this process eliminates the original refback.shaped_results op since
// we don't have any host/device distinction or other structure that would
// require retaining that sort of IR structure.
//
// TODO: Do "shape_of" resolution while still on tensors.
// Here we spew out tons of shape_of and rely on dim ops on descriptors to make
// it work. The key difference is that we need refback.shaped_results (or its
// successor / something it gets lowered to) to not be IsolatedFromAbove, and
// explicitly capture all input tensors along with their shapes. That allows
// shape_of ops on inputs to be trivially resolved. Unfortunately, this opens up
// the whole "dispatch region formation" can of worms like exists in IREE --
// once you have multiple ops inside a "dispatch region", you need to somehow
// lower them without allocating intermediate buffers.
//
// TODO: Don't hardcode the lowering for every op in this one pass.
class LowerShapedResultsToMemref
: public LowerShapedResultsToMemrefBase<LowerShapedResultsToMemref> {
void getDependentDialects(DialectRegistry &registry) const override {
// clang-format off
registry.insert<linalg::LinalgDialect,
scf::SCFDialect,
shape::ShapeDialect>();
// clang-format on
}
void runOnOperation() override {
auto func = getOperation();
auto *context = &getContext();
TypeConverter typeConverter;
typeConverter.addConversion([](Type type) { return type; });
typeConverter.addConversion([](RankedTensorType type) -> Type {
return MemRefType::get(type.getShape(), type.getElementType());
});
typeConverter.addSourceMaterialization([](OpBuilder &builder,
RankedTensorType type,
ValueRange inputs, Location loc) {
assert(inputs.size() == 1);
assert(inputs[0].getType().isa<MemRefType>());
return (Value)builder.create<refback::MemrefToTensorOp>(loc, type,
inputs[0]);
});
typeConverter.addTargetMaterialization([](OpBuilder &builder,
MemRefType type,
ValueRange inputs, Location loc) {
assert(inputs.size() == 1);
assert(inputs[0].getType().isa<RankedTensorType>());
return (Value)builder.create<refback::TensorToMemrefOp>(loc, type,
inputs[0]);
});
OwningRewritePatternList patterns;
ConversionTarget target(*context);
// The shaped results ops themselves. They have to be legal since we delete
// them later after the conversion process.
target.addLegalOp<refback::ShapedResultsOp>();
target.addLegalOp<refback::YieldOp>();
// All lowering to buffers involves refback.alloc_memref ops.
target.addLegalOp<refback::AllocMemRefOp>();
// The casting ops are introduced by the type converter, so we should mark
// them legal.
target.addLegalOp<refback::MemrefToTensorOp>();
target.addLegalOp<refback::TensorToMemrefOp>();
patterns.insert<LowerBroadcastToToLoopsPattern>(typeConverter, context);
target.addIllegalOp<tcp::BroadcastToOp>();
patterns
.insert<LowerElementwiseOp<tcp::AddOp>, LowerElementwiseOp<tcp::MaxOp>,
LowerElementwiseOp<tcp::ExpOp>,
LowerElementwiseOp<tcp::TanhOp>>(typeConverter, context);
target.addIllegalOp<tcp::AddOp, tcp::MaxOp>();
patterns.insert<LowerTcpMatmulOp>(typeConverter, context);
target.addIllegalOp<tcp::MatmulOp>();
target.addLegalDialect<linalg::LinalgDialect>();
target.addLegalDialect<StandardOpsDialect>();
target.addLegalDialect<scf::SCFDialect>();
target.addLegalOp<shape::GetExtentOp>();
SmallVector<Operation *, 6> shapedResultsOps;
func.walk(
[&](refback::ShapedResultsOp op) { shapedResultsOps.push_back(op); });
if (failed(applyFullConversion(shapedResultsOps, target, patterns)))
return signalPassFailure();
// Now inline the refback.shaped_results ops.
// This can't be done as part of the conversion since conversion visits
// ops in preorder, and we need the refback.shaped_results ops to be present
// so that inner ops can get their shape.
LocallyOverrideLegalityInlinerInterface interface(context);
for (Operation *shapedResultsOp : shapedResultsOps) {
auto op = cast<refback::ShapedResultsOp>(shapedResultsOp);
if (failed(inlineRegion(interface, &op.body(), op, ValueRange({}),
op.getResults(), /*inlineLoc=*/llvm::None,
/*shouldCloneInlinedRegion=*/false))) {
op.emitError() << "could not inline body";
return signalPassFailure();
}
op.erase();
}
}
};
} // namespace
std::unique_ptr<OperationPass<FuncOp>>
mlir::NPCOMP::createLowerShapedResultsToMemrefPass() {
return std::make_unique<LowerShapedResultsToMemref>();
}