Files
clang-p2996/mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorConversion.cpp
wren romano 5167c36ab4 [mlir][sparse] Misc code cleanup
Depends On D111763

Reviewed By: aartbik

Differential Revision: https://reviews.llvm.org/D111766
2021-10-13 16:39:29 -07:00

646 lines
25 KiB
C++

//===- SparseTensorConversion.cpp - Sparse tensor primitives conversion ---===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Convert sparse tensor primitives to calls into a runtime support library.
// Note that this is a current implementation choice to keep the conversion
// simple. In principle, these primitives could also be converted to actual
// elaborate IR code that implements the primitives on the selected sparse
// tensor storage schemes.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/Linalg/Utils/Utils.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/SCF/SCF.h"
#include "mlir/Dialect/SparseTensor/IR/SparseTensor.h"
#include "mlir/Dialect/SparseTensor/Transforms/Passes.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Transforms/DialectConversion.h"
using namespace mlir;
using namespace mlir::sparse_tensor;
namespace {
//===----------------------------------------------------------------------===//
// Helper methods.
//===----------------------------------------------------------------------===//
/// Returns internal type encoding for primary storage. Keep these
/// values consistent with the sparse runtime support library.
static unsigned getPrimaryTypeEncoding(Type tp) {
if (tp.isF64())
return 1;
if (tp.isF32())
return 2;
if (tp.isInteger(64))
return 3;
if (tp.isInteger(32))
return 4;
if (tp.isInteger(16))
return 5;
if (tp.isInteger(8))
return 6;
return 0;
}
/// Returns internal type encoding for overhead storage. Keep these
/// values consistent with the sparse runtime support library.
static unsigned getOverheadTypeEncoding(unsigned width) {
switch (width) {
default:
return 1;
case 32:
return 2;
case 16:
return 3;
case 8:
return 4;
}
}
/// Returns internal dimension level type encoding. Keep these
/// values consistent with the sparse runtime support library.
static unsigned
getDimLevelTypeEncoding(SparseTensorEncodingAttr::DimLevelType dlt) {
switch (dlt) {
case SparseTensorEncodingAttr::DimLevelType::Dense:
return 0;
case SparseTensorEncodingAttr::DimLevelType::Compressed:
return 1;
case SparseTensorEncodingAttr::DimLevelType::Singleton:
return 2;
}
llvm_unreachable("Unknown SparseTensorEncodingAttr::DimLevelType");
}
/// Generates a constant zero of the given type.
inline static Value constantZero(ConversionPatternRewriter &rewriter,
Location loc, Type t) {
return rewriter.create<arith::ConstantOp>(loc, t, rewriter.getZeroAttr(t));
}
/// Generates a constant of `index` type.
inline static Value constantIndex(ConversionPatternRewriter &rewriter,
Location loc, unsigned i) {
return rewriter.create<arith::ConstantIndexOp>(loc, i);
}
/// Generates a constant of `i64` type.
inline static Value constantI64(ConversionPatternRewriter &rewriter,
Location loc, int64_t i) {
return rewriter.create<arith::ConstantIntOp>(loc, i, 64);
}
/// Generates a constant of `i32` type.
inline static Value constantI32(ConversionPatternRewriter &rewriter,
Location loc, int32_t i) {
return rewriter.create<arith::ConstantIntOp>(loc, i, 32);
}
/// Returns integers of given width and values as a constant tensor.
/// We cast the static shape into a dynamic shape to ensure that the
/// method signature remains uniform across different tensor dimensions.
static Value getTensor(ConversionPatternRewriter &rewriter, unsigned width,
Location loc, ArrayRef<APInt> values) {
Type etp = rewriter.getIntegerType(width);
unsigned sz = values.size();
RankedTensorType tt1 = RankedTensorType::get({sz}, etp);
RankedTensorType tt2 = RankedTensorType::get({ShapedType::kDynamicSize}, etp);
auto elts = rewriter.create<arith::ConstantOp>(
loc, DenseElementsAttr::get(tt1, values));
return rewriter.create<tensor::CastOp>(loc, tt2, elts);
}
/// Returns a function reference (first hit also inserts into module). Sets
/// the "_emit_c_interface" on the function declaration when requested,
/// so that LLVM lowering generates a wrapper function that takes care
/// of ABI complications with passing in and returning MemRefs to C functions.
static FlatSymbolRefAttr getFunc(Operation *op, StringRef name,
TypeRange resultType, ValueRange operands,
bool emitCInterface = false) {
MLIRContext *context = op->getContext();
auto module = op->getParentOfType<ModuleOp>();
auto result = SymbolRefAttr::get(context, name);
auto func = module.lookupSymbol<FuncOp>(result.getAttr());
if (!func) {
OpBuilder moduleBuilder(module.getBodyRegion());
func = moduleBuilder.create<FuncOp>(
op->getLoc(), name,
FunctionType::get(context, operands.getTypes(), resultType));
func.setPrivate();
if (emitCInterface)
func->setAttr("llvm.emit_c_interface", UnitAttr::get(context));
}
return result;
}
/// Generates a call into the "swiss army knife" method of the sparse runtime
/// support library for materializing sparse tensors into the computation. The
/// method returns the call value and assigns the permutation to 'perm'.
static Value genNewCall(ConversionPatternRewriter &rewriter, Operation *op,
SparseTensorEncodingAttr &enc, uint32_t action,
Value &perm, Value ptr = Value()) {
Location loc = op->getLoc();
ShapedType resType = op->getResult(0).getType().cast<ShapedType>();
SmallVector<Value, 8> params;
// Sparsity annotations in tensor constant form.
SmallVector<APInt, 4> attrs;
unsigned sz = enc.getDimLevelType().size();
for (unsigned i = 0; i < sz; i++)
attrs.push_back(
APInt(8, getDimLevelTypeEncoding(enc.getDimLevelType()[i])));
params.push_back(getTensor(rewriter, 8, loc, attrs));
// Dimension sizes array of the enveloping *dense* tensor. Useful for either
// verification of external data, or for construction of internal data.
auto shape = resType.getShape();
SmallVector<APInt, 4> sizes;
for (unsigned i = 0; i < sz; i++) {
uint64_t s = shape[i] == ShapedType::kDynamicSize ? 0 : shape[i];
sizes.push_back(APInt(64, s));
}
params.push_back(getTensor(rewriter, 64, loc, sizes));
// Dimension order permutation array. This is the "identity" permutation by
// default, or otherwise the "reverse" permutation of a given ordering, so
// that indices can be mapped quickly to the right position.
SmallVector<APInt, 4> rev(sz);
if (AffineMap p = enc.getDimOrdering()) {
for (unsigned i = 0; i < sz; i++)
rev[p.getDimPosition(i)] = APInt(64, i);
} else {
for (unsigned i = 0; i < sz; i++)
rev[i] = APInt(64, i);
}
perm = getTensor(rewriter, 64, loc, rev);
params.push_back(perm);
// Secondary and primary types encoding.
unsigned secPtr = getOverheadTypeEncoding(enc.getPointerBitWidth());
unsigned secInd = getOverheadTypeEncoding(enc.getIndexBitWidth());
unsigned primary = getPrimaryTypeEncoding(resType.getElementType());
assert(primary);
params.push_back(constantI64(rewriter, loc, secPtr));
params.push_back(constantI64(rewriter, loc, secInd));
params.push_back(constantI64(rewriter, loc, primary));
// User action and pointer.
Type pTp = LLVM::LLVMPointerType::get(rewriter.getI8Type());
if (!ptr)
ptr = rewriter.create<LLVM::NullOp>(loc, pTp);
params.push_back(constantI32(rewriter, loc, action));
params.push_back(ptr);
// Generate the call to create new tensor.
StringRef name = "newSparseTensor";
auto call = rewriter.create<CallOp>(
loc, pTp, getFunc(op, name, pTp, params, /*emitCInterface=*/true),
params);
return call.getResult(0);
}
/// Generates the comparison `v != 0` where `v` is of numeric type `t`.
/// For floating types, we use the "unordered" comparator (i.e., returns
/// true if `v` is NaN).
static Value genIsNonzero(ConversionPatternRewriter &rewriter, Location loc,
Value v) {
Type t = v.getType();
Value zero = constantZero(rewriter, loc, t);
if (t.isa<FloatType>())
return rewriter.create<arith::CmpFOp>(loc, arith::CmpFPredicate::UNE, v,
zero);
if (t.isIntOrIndex())
return rewriter.create<arith::CmpIOp>(loc, arith::CmpIPredicate::ne, v,
zero);
llvm_unreachable("Unknown element type");
}
/// Generates the code to read the value from tensor[ivs], and conditionally
/// stores the indices ivs to the memory in ind. The generated code looks like
/// the following and the insertion point after this routine is inside the
/// if-then branch behind the assignment to ind. This is to ensure that the
/// addEltX call generated after is inside the if-then branch.
/// if (tensor[ivs]!=0) {
/// ind = ivs
static Value genIndexAndValueForDense(ConversionPatternRewriter &rewriter,
Location loc, Value tensor, Value ind,
ValueRange ivs) {
Value val = rewriter.create<tensor::ExtractOp>(loc, tensor, ivs);
Value cond = genIsNonzero(rewriter, loc, val);
scf::IfOp ifOp = rewriter.create<scf::IfOp>(loc, cond, /*else*/ false);
rewriter.setInsertionPointToStart(&ifOp.thenRegion().front());
unsigned i = 0;
for (auto iv : ivs) {
Value idx = constantIndex(rewriter, loc, i++);
rewriter.create<memref::StoreOp>(loc, iv, ind, idx);
}
return val;
}
/// Generates a call that adds one element to a coordinate scheme.
/// In particular, this generates code like the following:
/// val = a[i1,..,ik];
/// if val != 0
/// t->add(val, [i1,..,ik], [p1,..,pk]);
static void genAddEltCall(ConversionPatternRewriter &rewriter, Operation *op,
Type eltType, Value ptr, Value val, Value ind,
Value perm) {
Location loc = op->getLoc();
StringRef name;
if (eltType.isF64())
name = "addEltF64";
else if (eltType.isF32())
name = "addEltF32";
else if (eltType.isInteger(64))
name = "addEltI64";
else if (eltType.isInteger(32))
name = "addEltI32";
else if (eltType.isInteger(16))
name = "addEltI16";
else if (eltType.isInteger(8))
name = "addEltI8";
else
llvm_unreachable("Unknown element type");
SmallVector<Value, 8> params;
params.push_back(ptr);
params.push_back(val);
params.push_back(ind);
params.push_back(perm);
Type pTp = LLVM::LLVMPointerType::get(rewriter.getI8Type());
rewriter.create<CallOp>(
loc, pTp, getFunc(op, name, pTp, params, /*emitCInterface=*/true),
params);
}
/// If the tensor is a sparse constant, generates and returns the pair of
/// the constants for the indices and the values.
static Optional<std::pair<Value, Value>>
genSplitSparseConstant(ConversionPatternRewriter &rewriter, Location loc,
Value tensor) {
if (auto constOp = tensor.getDefiningOp<arith::ConstantOp>()) {
if (auto attr = constOp.value().dyn_cast<SparseElementsAttr>()) {
DenseElementsAttr indicesAttr = attr.getIndices();
Value indices = rewriter.create<arith::ConstantOp>(loc, indicesAttr);
DenseElementsAttr valuesAttr = attr.getValues();
Value values = rewriter.create<arith::ConstantOp>(loc, valuesAttr);
return std::make_pair(indices, values);
}
}
return {};
}
/// Generates the code to copy the index at indices[ivs] to ind, and return
/// the value at value[ivs].
static Value genIndexAndValueForSparse(ConversionPatternRewriter &rewriter,
Location loc, Value indices,
Value values, Value ind, ValueRange ivs,
unsigned rank) {
for (unsigned i = 0; i < rank; i++) {
Value idx = constantIndex(rewriter, loc, i);
Value val = rewriter.create<tensor::ExtractOp>(loc, indices,
ValueRange{ivs[0], idx});
val =
rewriter.create<arith::IndexCastOp>(loc, val, rewriter.getIndexType());
rewriter.create<memref::StoreOp>(loc, val, ind, idx);
}
return rewriter.create<tensor::ExtractOp>(loc, values, ivs[0]);
}
/// Generates code to stack-allocate a `memref<?xindex>` where the `?`
/// is the given `rank`. This array is intended to serve as a reusable
/// buffer for storing the indices of a single tensor element, to avoid
/// allocation in the body of loops.
static Value allocaIndices(ConversionPatternRewriter &rewriter, Location loc,
int64_t rank) {
auto indexTp = rewriter.getIndexType();
auto memTp = MemRefType::get({ShapedType::kDynamicSize}, indexTp);
Value arg = constantIndex(rewriter, loc, rank);
return rewriter.create<memref::AllocaOp>(loc, memTp, ValueRange{arg});
}
//===----------------------------------------------------------------------===//
// Conversion rules.
//===----------------------------------------------------------------------===//
/// Sparse conversion rule for returns.
class SparseReturnConverter : public OpConversionPattern<ReturnOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ReturnOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
rewriter.replaceOpWithNewOp<ReturnOp>(op, adaptor.getOperands());
return success();
}
};
/// Sparse conversion rule for dimension accesses.
class SparseTensorToDimSizeConverter
: public OpConversionPattern<tensor::DimOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(tensor::DimOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
auto enc = getSparseTensorEncoding(op.source().getType());
if (!enc)
return failure();
// Permute the dim index.
Optional<int64_t> index = op.getConstantIndex();
if (!index.hasValue())
return failure();
int64_t idx = index.getValue();
if (AffineMap p = enc.getDimOrdering())
idx = p.getPermutedPosition(idx);
// Generate the call.
StringRef name = "sparseDimSize";
SmallVector<Value, 2> params;
params.push_back(adaptor.getOperands()[0]);
params.push_back(constantIndex(rewriter, op.getLoc(), idx));
rewriter.replaceOpWithNewOp<CallOp>(
op, resType, getFunc(op, name, resType, params), params);
return success();
}
};
/// Sparse conversion rule for the new operator.
class SparseTensorNewConverter : public OpConversionPattern<NewOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(NewOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
auto enc = getSparseTensorEncoding(resType);
if (!enc)
return failure();
Value perm;
rewriter.replaceOp(
op, genNewCall(rewriter, op, enc, 0, perm, adaptor.getOperands()[0]));
return success();
}
};
/// Sparse conversion rule for the convert operator.
class SparseTensorConvertConverter : public OpConversionPattern<ConvertOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ConvertOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
auto encDst = getSparseTensorEncoding(resType);
auto encSrc = getSparseTensorEncoding(op.source().getType());
auto src = adaptor.getOperands()[0];
if (encDst && encSrc) {
// This is a sparse => sparse conversion, which is handled as follows:
// t = src->toCOO(); ; src to COO in dst order
// dst = newSparseTensor(t)
// Using the coordinate scheme as an intermediate does not always
// yield the fastest conversion but avoids the need for a full
// O(N^2) conversion matrix.
Value perm;
Value coo = genNewCall(rewriter, op, encDst, 3, perm, src);
rewriter.replaceOp(op, genNewCall(rewriter, op, encDst, 1, perm, coo));
return success();
}
if (!encDst || encSrc) {
// TODO: sparse => dense
return failure();
}
// This is a dense => sparse conversion or a sparse constant in COO =>
// sparse conversion, which is handled as follows:
// t = newSparseCOO()
// ...code to fill the COO tensor t...
// s = newSparseTensor(t)
//
// To fill the COO tensor from a dense tensor:
// for i1 in dim1
// ..
// for ik in dimk
// val = a[i1,..,ik]
// if val != 0
// t->add(val, [i1,..,ik], [p1,..,pk])
//
// To fill the COO tensor from a sparse constant in COO format:
// for i in range(NNZ)
// val = values[i]
// [i1,..,ik] = indices[i]
// t->add(val, [i1,..,ik], [p1,..,pk])
//
// Note that the dense tensor traversal code is actually implemented
// using MLIR IR to avoid having to expose too much low-level
// memref traversal details to the runtime support library.
// Also note that the code below only generates the "new" ops and
// the loop-nest per se; whereas the entire body of the innermost
// loop is generated by genAddElt().
Location loc = op->getLoc();
ShapedType shape = resType.cast<ShapedType>();
Value perm;
Value ptr = genNewCall(rewriter, op, encDst, 2, perm);
Value ind = allocaIndices(rewriter, loc, shape.getRank());
SmallVector<Value> lo;
SmallVector<Value> hi;
SmallVector<Value> st;
Value zero = constantIndex(rewriter, loc, 0);
Value one = constantIndex(rewriter, loc, 1);
auto indicesValues = genSplitSparseConstant(rewriter, loc, src);
bool isCOOConstant = indicesValues.hasValue();
Value indices;
Value values;
if (isCOOConstant) {
indices = indicesValues->first;
values = indicesValues->second;
lo.push_back(zero);
hi.push_back(linalg::createOrFoldDimOp(rewriter, loc, values, 0));
st.push_back(one);
} else {
for (unsigned i = 0, rank = shape.getRank(); i < rank; i++) {
lo.push_back(zero);
hi.push_back(linalg::createOrFoldDimOp(rewriter, loc, src, i));
st.push_back(one);
}
}
Type eltType = shape.getElementType();
unsigned rank = shape.getRank();
scf::buildLoopNest(
rewriter, op.getLoc(), lo, hi, st, {},
[&](OpBuilder &builder, Location loc, ValueRange ivs,
ValueRange args) -> scf::ValueVector {
Value val;
if (isCOOConstant)
val = genIndexAndValueForSparse(rewriter, loc, indices, values, ind,
ivs, rank);
else
val = genIndexAndValueForDense(rewriter, loc, src, ind, ivs);
genAddEltCall(rewriter, op, eltType, ptr, val, ind, perm);
return {};
});
rewriter.replaceOp(op, genNewCall(rewriter, op, encDst, 1, perm, ptr));
return success();
}
};
/// Sparse conversion rule for the release operator.
class SparseTensorReleaseConverter : public OpConversionPattern<ReleaseOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ReleaseOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
StringRef name = "delSparseTensor";
TypeRange none;
rewriter.create<CallOp>(op.getLoc(), none,
getFunc(op, name, none, adaptor.getOperands()),
adaptor.getOperands());
rewriter.eraseOp(op);
return success();
}
};
/// Sparse conversion rule for pointer accesses.
class SparseTensorToPointersConverter
: public OpConversionPattern<ToPointersOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ToPointersOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
Type eltType = resType.cast<ShapedType>().getElementType();
StringRef name;
if (eltType.isIndex())
name = "sparsePointers"; // 64-bit, but its own name for unique signature
else if (eltType.isInteger(64))
name = "sparsePointers64";
else if (eltType.isInteger(32))
name = "sparsePointers32";
else if (eltType.isInteger(16))
name = "sparsePointers16";
else if (eltType.isInteger(8))
name = "sparsePointers8";
else
return failure();
rewriter.replaceOpWithNewOp<CallOp>(op, resType,
getFunc(op, name, resType,
adaptor.getOperands(),
/*emitCInterface=*/true),
adaptor.getOperands());
return success();
}
};
/// Sparse conversion rule for index accesses.
class SparseTensorToIndicesConverter : public OpConversionPattern<ToIndicesOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ToIndicesOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
Type eltType = resType.cast<ShapedType>().getElementType();
StringRef name;
if (eltType.isIndex())
name = "sparseIndices"; // 64-bit, but its own name for unique signature
else if (eltType.isInteger(64))
name = "sparseIndices64";
else if (eltType.isInteger(32))
name = "sparseIndices32";
else if (eltType.isInteger(16))
name = "sparseIndices16";
else if (eltType.isInteger(8))
name = "sparseIndices8";
else
return failure();
rewriter.replaceOpWithNewOp<CallOp>(op, resType,
getFunc(op, name, resType,
adaptor.getOperands(),
/*emitCInterface=*/true),
adaptor.getOperands());
return success();
}
};
/// Sparse conversion rule for value accesses.
class SparseTensorToValuesConverter : public OpConversionPattern<ToValuesOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(ToValuesOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type resType = op.getType();
Type eltType = resType.cast<ShapedType>().getElementType();
StringRef name;
if (eltType.isF64())
name = "sparseValuesF64";
else if (eltType.isF32())
name = "sparseValuesF32";
else if (eltType.isInteger(64))
name = "sparseValuesI64";
else if (eltType.isInteger(32))
name = "sparseValuesI32";
else if (eltType.isInteger(16))
name = "sparseValuesI16";
else if (eltType.isInteger(8))
name = "sparseValuesI8";
else
return failure();
rewriter.replaceOpWithNewOp<CallOp>(op, resType,
getFunc(op, name, resType,
adaptor.getOperands(),
/*emitCInterface=*/true),
adaptor.getOperands());
return success();
}
};
/// Sparse conversion rule for tensor reconstruction.
class SparseTensorToTensorConverter : public OpConversionPattern<ToTensorOp> {
public:
using OpConversionPattern::OpConversionPattern;
LogicalResult
// Simply fold the operator into the pointer to the sparse storage scheme.
matchAndRewrite(ToTensorOp op, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
// Check that all arguments of the tensor reconstruction operators are calls
// into the support library that query exactly the same opaque pointer.
Value ptr;
for (Value op : adaptor.getOperands()) {
if (auto call = op.getDefiningOp<CallOp>()) {
Value arg = call.getOperand(0);
if (!arg.getType().isa<LLVM::LLVMPointerType>())
return failure();
if (!ptr)
ptr = arg;
else if (arg != ptr)
return failure();
}
}
// If a single opaque pointer is found, perform the folding.
if (!ptr)
return failure();
rewriter.replaceOp(op, ptr);
return success();
}
};
} // namespace
//===----------------------------------------------------------------------===//
// Public method for populating conversion rules.
//===----------------------------------------------------------------------===//
/// Populates the given patterns list with conversion rules required for
/// the sparsification of linear algebra operations.
void mlir::populateSparseTensorConversionPatterns(TypeConverter &typeConverter,
RewritePatternSet &patterns) {
patterns.add<SparseReturnConverter, SparseTensorToDimSizeConverter,
SparseTensorNewConverter, SparseTensorConvertConverter,
SparseTensorReleaseConverter, SparseTensorToPointersConverter,
SparseTensorToIndicesConverter, SparseTensorToValuesConverter,
SparseTensorToTensorConverter>(typeConverter,
patterns.getContext());
}