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//===- TosaToSCF.cpp - Lowering Tosa to SCF Dialect -----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// These rewriters lower from the Tosa to the SCF dialect.
//
//===----------------------------------------------------------------------===//
#include "mlir/Conversion/TosaToSCF/TosaToSCF.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Tosa/IR/TosaOps.h"
#include "mlir/IR/IRMapping.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
using namespace mlir;
using namespace tosa;
static void inlineIfCase(Region &srcRegion, Region &dstRegion,
OperandRange operands, PatternRewriter &rewriter) {
rewriter.cloneRegionBefore(srcRegion, &dstRegion.front());
rewriter.eraseBlock(&dstRegion.back());
Block *headBlock = &dstRegion.front();
for (auto it : llvm::zip(headBlock->getArguments(), operands))
std::get<0>(it).replaceAllUsesWith(std::get<1>(it));
auto yield = cast<YieldOp>(headBlock->getTerminator());
rewriter.setInsertionPoint(yield);
rewriter.create<scf::YieldOp>(yield.getLoc(), yield.getInputs());
rewriter.eraseOp(yield);
headBlock->eraseArguments(0, headBlock->getNumArguments());
}
static void inlineWhileCase(Region &srcRegion, Region &dstRegion,
PatternRewriter &rewriter, bool isCond) {
rewriter.cloneRegionBefore(srcRegion, &dstRegion.back());
rewriter.eraseBlock(&dstRegion.back());
Block *headBlock = &dstRegion.front();
auto yield = cast<YieldOp>(headBlock->getTerminator());
rewriter.setInsertionPoint(yield);
if (isCond) {
auto condition =
rewriter.create<tensor::ExtractOp>(yield.getLoc(), yield.getOperand(0));
rewriter.create<scf::ConditionOp>(yield.getLoc(), condition,
headBlock->getArguments());
} else {
rewriter.setInsertionPoint(yield);
rewriter.create<scf::YieldOp>(yield.getLoc(), yield.getInputs());
}
rewriter.eraseOp(yield);
}
namespace {
class IfOpConverter : public OpRewritePattern<tosa::IfOp> {
public:
using OpRewritePattern<tosa::IfOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tosa::IfOp op,
PatternRewriter &rewriter) const final {
auto condition =
rewriter.create<tensor::ExtractOp>(op.getLoc(), op.getCond());
auto newIf = rewriter.create<scf::IfOp>(op.getLoc(), op.getResultTypes(),
condition, true);
inlineIfCase(op.getThenBranch(), newIf.getThenRegion(), op.getInputs(),
rewriter);
inlineIfCase(op.getElseBranch(), newIf.getElseRegion(), op.getInputs(),
rewriter);
rewriter.replaceOp(op, newIf.getResults());
return success();
}
};
class ScatterOpConverter : public OpRewritePattern<tosa::ScatterOp> {
static Value createTensorDim(OpBuilder &builder, Location loc, Value tensor,
int64_t dim) {
return builder.createOrFold<tensor::DimOp>(loc, tensor, dim);
}
static Value createIndexConst(OpBuilder &builder, Location loc,
int64_t value) {
return builder.create<arith::ConstantIndexOp>(loc, value);
}
public:
using OpRewritePattern<tosa::ScatterOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tosa::ScatterOp scatter,
PatternRewriter &rewriter) const final {
auto valuesIn = scatter.getValuesIn();
auto indices = scatter.getIndices();
auto input = scatter.getInput();
auto loc = scatter.getLoc();
// N, W, C are chosen to match the TOSA spec
auto dimN = createTensorDim(rewriter, loc, input, 0);
auto dimW = createTensorDim(rewriter, loc, input, 1);
auto dimC = createTensorDim(rewriter, loc, input, 2);
auto zero = createIndexConst(rewriter, loc, 0);
auto one = createIndexConst(rewriter, loc, 1);
// Loop bounds
auto lbs = llvm::SmallVector<Value>(2, zero);
auto steps = llvm::SmallVector<Value>(2, one);
auto ubs = llvm::SmallVector<Value>{{dimN, dimW}};
auto buildBody = [&](OpBuilder &builder, Location loc, ValueRange ivs,
ValueRange args) -> scf::ValueVector {
auto n = ivs[0];
// Read the index and cast it to index type
auto index = builder.create<tensor::ExtractOp>(loc, indices, ivs);
auto castIndex = builder.create<arith::IndexCastOp>(
loc, builder.getIndexType(), index);
// Offset, sizes, and strides for the input tensor
auto inputOffset = llvm::to_vector(ivs);
inputOffset.push_back(zero);
llvm::SmallVector<Value> sizes = {one, one, dimC};
llvm::SmallVector<Value> strides = {one, one, one};
auto slice = builder.create<tensor::ExtractSliceOp>(
loc, input, inputOffset, sizes, strides);
// Insert the slice into the output accumulator tensor.
llvm::SmallVector<Value> outputOffset = {n, castIndex, zero};
auto updated = builder.create<tensor::InsertSliceOp>(
loc, slice, args[0], outputOffset, sizes, strides);
return {updated};
};
auto loops = scf::buildLoopNest(rewriter, loc, lbs, ubs, steps,
ValueRange{valuesIn}, buildBody);
rewriter.replaceOp(scatter, loops.results);
return success();
}
};
class WhileOpConverter : public OpRewritePattern<tosa::WhileOp> {
public:
using OpRewritePattern<tosa::WhileOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tosa::WhileOp op,
PatternRewriter &rewriter) const final {
auto newWhile = rewriter.create<scf::WhileOp>(
op.getLoc(), op.getResultTypes(), op.getInputs());
rewriter.createBlock(&newWhile.getBefore());
rewriter.createBlock(&newWhile.getAfter());
inlineWhileCase(op.getCond(), newWhile.getBefore(), rewriter, true);
inlineWhileCase(op.getBody(), newWhile.getAfter(), rewriter, false);
rewriter.replaceOp(op, newWhile.getResults());
return success();
}
};
} // namespace
void mlir::tosa::populateTosaToSCFConversionPatterns(
RewritePatternSet *patterns) {
patterns->add<IfOpConverter, ScatterOpConverter, WhileOpConverter>(
patterns->getContext());
}
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