llvm-project/mlir/lib/Dialect/Affine/Transforms/AffineExpandIndexOpsAsAffine.cpp
Jacques Pienaar 09dfc5713d
[mlir] Enable decoupling two kinds of greedy behavior. (#104649)
The greedy rewriter is used in many different flows and it has a lot of
convenience (work list management, debugging actions, tracing, etc). But
it combines two kinds of greedy behavior 1) how ops are matched, 2)
folding wherever it can.

These are independent forms of greedy and leads to inefficiency. E.g.,
cases where one need to create different phases in lowering and is
required to applying patterns in specific order split across different
passes. Using the driver one ends up needlessly retrying folding/having
multiple rounds of folding attempts, where one final run would have
sufficed.

Of course folks can locally avoid this behavior by just building their
own, but this is also a common requested feature that folks keep on
working around locally in suboptimal ways.

For downstream users, there should be no behavioral change. Updating
from the deprecated should just be a find and replace (e.g., `find ./
-type f -exec sed -i
's|applyPatternsAndFoldGreedily|applyPatternsGreedily|g' {} \;` variety)
as the API arguments hasn't changed between the two.
2024-12-20 08:15:48 -08:00

98 lines
3.5 KiB
C++

//===- AffineExpandIndexOpsAsAffine.cpp - Expand index ops to apply pass --===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements a pass to expand affine index ops into one or more more
// fundamental operations.
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Affine/Passes.h"
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/Transforms/Transforms.h"
#include "mlir/Dialect/Affine/Utils.h"
#include "mlir/Dialect/Arith/Utils/Utils.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
namespace mlir {
namespace affine {
#define GEN_PASS_DEF_AFFINEEXPANDINDEXOPSASAFFINE
#include "mlir/Dialect/Affine/Passes.h.inc"
} // namespace affine
} // namespace mlir
using namespace mlir;
using namespace mlir::affine;
namespace {
/// Lowers `affine.delinearize_index` into a sequence of division and remainder
/// operations.
struct LowerDelinearizeIndexOps
: public OpRewritePattern<AffineDelinearizeIndexOp> {
using OpRewritePattern<AffineDelinearizeIndexOp>::OpRewritePattern;
LogicalResult matchAndRewrite(AffineDelinearizeIndexOp op,
PatternRewriter &rewriter) const override {
FailureOr<SmallVector<Value>> multiIndex =
delinearizeIndex(rewriter, op->getLoc(), op.getLinearIndex(),
op.getEffectiveBasis(), /*hasOuterBound=*/false);
if (failed(multiIndex))
return failure();
rewriter.replaceOp(op, *multiIndex);
return success();
}
};
/// Lowers `affine.linearize_index` into a sequence of multiplications and
/// additions.
struct LowerLinearizeIndexOps final : OpRewritePattern<AffineLinearizeIndexOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(AffineLinearizeIndexOp op,
PatternRewriter &rewriter) const override {
// Should be folded away, included here for safety.
if (op.getMultiIndex().empty()) {
rewriter.replaceOpWithNewOp<arith::ConstantIndexOp>(op, 0);
return success();
}
SmallVector<OpFoldResult> multiIndex =
getAsOpFoldResult(op.getMultiIndex());
OpFoldResult linearIndex =
linearizeIndex(rewriter, op.getLoc(), multiIndex, op.getMixedBasis());
Value linearIndexValue =
getValueOrCreateConstantIntOp(rewriter, op.getLoc(), linearIndex);
rewriter.replaceOp(op, linearIndexValue);
return success();
}
};
class ExpandAffineIndexOpsAsAffinePass
: public affine::impl::AffineExpandIndexOpsAsAffineBase<
ExpandAffineIndexOpsAsAffinePass> {
public:
ExpandAffineIndexOpsAsAffinePass() = default;
void runOnOperation() override {
MLIRContext *context = &getContext();
RewritePatternSet patterns(context);
populateAffineExpandIndexOpsAsAffinePatterns(patterns);
if (failed(applyPatternsGreedily(getOperation(), std::move(patterns))))
return signalPassFailure();
}
};
} // namespace
void mlir::affine::populateAffineExpandIndexOpsAsAffinePatterns(
RewritePatternSet &patterns) {
patterns.insert<LowerDelinearizeIndexOps, LowerLinearizeIndexOps>(
patterns.getContext());
}
std::unique_ptr<Pass> mlir::affine::createAffineExpandIndexOpsAsAffinePass() {
return std::make_unique<ExpandAffineIndexOpsAsAffinePass>();
}