llvm/mlir/lib/Conversion/AffineToStandard/AffineToStandard.cpp

//===- AffineToStandard.cpp - Lower affine constructs to primitives -------===//
//
// 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 lowers affine constructs (If and For statements, AffineApply
// operations) within a function into their standard If and For equivalent ops.
//
//===----------------------------------------------------------------------===//

#include "mlir/Conversion/AffineToStandard/AffineToStandard.h"

#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/Transforms/Transforms.h"
#include "mlir/Dialect/Affine/Utils.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/Vector/IR/VectorOps.h"
#include "mlir/IR/IRMapping.h"
#include "mlir/IR/IntegerSet.h"
#include "mlir/IR/MLIRContext.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/Passes.h"

namespace mlir {
#define GEN_PASS_DEF_CONVERTAFFINETOSTANDARD
#include "mlir/Conversion/Passes.h.inc"
} // namespace mlir

usingnamespacemlir;
usingnamespacemlir::affine;
usingnamespacemlir::vector;

/// Given a range of values, emit the code that reduces them with "min" or "max"
/// depending on the provided comparison predicate, sgt for max and slt for min.
///
/// Multiple values are scanned in a linear sequence.  This creates a data
/// dependences that wouldn't exist in a tree reduction, but is easier to
/// recognize as a reduction by the subsequent passes.
static Value buildMinMaxReductionSeq(Location loc,
                                     arith::CmpIPredicate predicate,
                                     ValueRange values, OpBuilder &builder) { … }

/// Emit instructions that correspond to computing the maximum value among the
/// values of a (potentially) multi-output affine map applied to `operands`.
static Value lowerAffineMapMax(OpBuilder &builder, Location loc, AffineMap map,
                               ValueRange operands) { … }

/// Emit instructions that correspond to computing the minimum value among the
/// values of a (potentially) multi-output affine map applied to `operands`.
static Value lowerAffineMapMin(OpBuilder &builder, Location loc, AffineMap map,
                               ValueRange operands) { … }

/// Emit instructions that correspond to the affine map in the upper bound
/// applied to the respective operands, and compute the minimum value across
/// the results.
Value mlir::lowerAffineUpperBound(AffineForOp op, OpBuilder &builder) { … }

/// Emit instructions that correspond to the affine map in the lower bound
/// applied to the respective operands, and compute the maximum value across
/// the results.
Value mlir::lowerAffineLowerBound(AffineForOp op, OpBuilder &builder) { … }

namespace {
class AffineMinLowering : public OpRewritePattern<AffineMinOp> { … };

class AffineMaxLowering : public OpRewritePattern<AffineMaxOp> { … };

/// Affine yields ops are removed.
class AffineYieldOpLowering : public OpRewritePattern<AffineYieldOp> { … };

class AffineForLowering : public OpRewritePattern<AffineForOp> { … };

/// Convert an `affine.parallel` (loop nest) operation into a `scf.parallel`
/// operation.
class AffineParallelLowering : public OpRewritePattern<AffineParallelOp> { … };

class AffineIfLowering : public OpRewritePattern<AffineIfOp> { … };

/// Convert an "affine.apply" operation into a sequence of arithmetic
/// operations using the StandardOps dialect.
class AffineApplyLowering : public OpRewritePattern<AffineApplyOp> { … };

/// Apply the affine map from an 'affine.load' operation to its operands, and
/// feed the results to a newly created 'memref.load' operation (which replaces
/// the original 'affine.load').
class AffineLoadLowering : public OpRewritePattern<AffineLoadOp> { … };

/// Apply the affine map from an 'affine.prefetch' operation to its operands,
/// and feed the results to a newly created 'memref.prefetch' operation (which
/// replaces the original 'affine.prefetch').
class AffinePrefetchLowering : public OpRewritePattern<AffinePrefetchOp> { … };

/// Apply the affine map from an 'affine.store' operation to its operands, and
/// feed the results to a newly created 'memref.store' operation (which replaces
/// the original 'affine.store').
class AffineStoreLowering : public OpRewritePattern<AffineStoreOp> { … };

/// Apply the affine maps from an 'affine.dma_start' operation to each of their
/// respective map operands, and feed the results to a newly created
/// 'memref.dma_start' operation (which replaces the original
/// 'affine.dma_start').
class AffineDmaStartLowering : public OpRewritePattern<AffineDmaStartOp> { … };

/// Apply the affine map from an 'affine.dma_wait' operation tag memref,
/// and feed the results to a newly created 'memref.dma_wait' operation (which
/// replaces the original 'affine.dma_wait').
class AffineDmaWaitLowering : public OpRewritePattern<AffineDmaWaitOp> { … };

/// Apply the affine map from an 'affine.vector_load' operation to its operands,
/// and feed the results to a newly created 'vector.load' operation (which
/// replaces the original 'affine.vector_load').
class AffineVectorLoadLowering : public OpRewritePattern<AffineVectorLoadOp> { … };

/// Apply the affine map from an 'affine.vector_store' operation to its
/// operands, and feed the results to a newly created 'vector.store' operation
/// (which replaces the original 'affine.vector_store').
class AffineVectorStoreLowering : public OpRewritePattern<AffineVectorStoreOp> { … };

} // namespace

void mlir::populateAffineToStdConversionPatterns(RewritePatternSet &patterns) { … }

void mlir::populateAffineToVectorConversionPatterns(
    RewritePatternSet &patterns) { … }

namespace {
class LowerAffinePass
    : public impl::ConvertAffineToStandardBase<LowerAffinePass> { … };
} // namespace

/// Lowers If and For operations within a function into their lower level CFG
/// equivalent blocks.
std::unique_ptr<Pass> mlir::createLowerAffinePass() { … }