llvm/mlir/lib/Dialect/Affine/Transforms/LoopUnroll.cpp

//===- LoopUnroll.cpp - Code to perform loop unrolling --------------------===//
//
// 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 loop unrolling.
//
//===----------------------------------------------------------------------===//

#include "mlir/Dialect/Affine/Passes.h"

#include "mlir/Dialect/Affine/Analysis/LoopAnalysis.h"
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/LoopUtils.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/IR/AffineExpr.h"
#include "mlir/IR/AffineMap.h"
#include "mlir/IR/Builders.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include <optional>

namespace mlir {
namespace affine {
#define GEN_PASS_DEF_AFFINELOOPUNROLL
#include "mlir/Dialect/Affine/Passes.h.inc"
} // namespace affine
} // namespace mlir

#define DEBUG_TYPE …

usingnamespacemlir;
usingnamespacemlir::affine;

namespace {

// TODO: this is really a test pass and should be moved out of dialect
// transforms.

/// Loop unrolling pass. Unrolls all innermost loops unless full unrolling and a
/// full unroll threshold was specified, in which case, fully unrolls all loops
/// with trip count less than the specified threshold. The latter is for testing
/// purposes, especially for testing outer loop unrolling.
struct LoopUnroll : public affine::impl::AffineLoopUnrollBase<LoopUnroll> { … };
} // namespace

/// Returns true if no other affine.for ops are nested within `op`.
static bool isInnermostAffineForOp(AffineForOp op) { … }

/// Gathers loops that have no affine.for's nested within.
static void gatherInnermostLoops(func::FuncOp f,
                                 SmallVectorImpl<AffineForOp> &loops) { … }

void LoopUnroll::runOnOperation() { … }

/// Unrolls a 'affine.for' op. Returns success if the loop was unrolled,
/// failure otherwise. The default unroll factor is 4.
LogicalResult LoopUnroll::runOnAffineForOp(AffineForOp forOp) { … }

std::unique_ptr<OperationPass<func::FuncOp>> mlir::affine::createLoopUnrollPass(
    int unrollFactor, bool unrollUpToFactor, bool unrollFull,
    const std::function<unsigned(AffineForOp)> &getUnrollFactor) { … }