AffineOps.h | Explore in Territory

//===- AffineOps.h - MLIR Affine Operations -------------------------------===//
//
// 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 defines convenience types for working with Affine operations
// in the MLIR operation set.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_DIALECT_AFFINE_IR_AFFINEOPS_H
#define MLIR_DIALECT_AFFINE_IR_AFFINEOPS_H

#include "mlir/Dialect/Affine/IR/AffineMemoryOpInterfaces.h"
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/IR/AffineMap.h"
#include "mlir/IR/Builders.h"
#include "mlir/Interfaces/ControlFlowInterfaces.h"
#include "mlir/Interfaces/LoopLikeInterface.h"

namespace mlir {
namespace affine {

class AffineApplyOp;
class AffineBound;
class AffineMaxOp;
class AffineMinOp;
class AffineValueMap;

/// A utility function to check if a value is defined at the top level of an
/// op with trait `AffineScope` or is a region argument for such an op. A value
/// of index type defined at the top level is always a valid symbol for all its
/// uses.
bool isTopLevelValue(Value value);

/// A utility function to check if a value is defined at the top level of
/// `region` or is an argument of `region`. A value of index type defined at the
/// top level of a `AffineScope` region is always a valid symbol for all
/// uses in that region.
bool isTopLevelValue(Value value, Region *region);

/// Returns the closest region enclosing `op` that is held by an operation with
/// trait `AffineScope`; `nullptr` if there is no such region.
Region *getAffineScope(Operation *op);

/// AffineDmaStartOp starts a non-blocking DMA operation that transfers data
/// from a source memref to a destination memref. The source and destination
/// memref need not be of the same dimensionality, but need to have the same
/// elemental type. The operands include the source and destination memref's
/// each followed by its indices, size of the data transfer in terms of the
/// number of elements (of the elemental type of the memref), a tag memref with
/// its indices, and optionally at the end, a stride and a
/// number_of_elements_per_stride arguments. The tag location is used by an
/// AffineDmaWaitOp to check for completion. The indices of the source memref,
/// destination memref, and the tag memref have the same restrictions as any
/// affine.load/store. In particular, index for each memref dimension must be an
/// affine expression of loop induction variables and symbols.
/// The optional stride arguments should be of 'index' type, and specify a
/// stride for the slower memory space (memory space with a lower memory space
/// id), transferring chunks of number_of_elements_per_stride every stride until
/// %num_elements are transferred. Either both or no stride arguments should be
/// specified. The value of 'num_elements' must be a multiple of
/// 'number_of_elements_per_stride'. If the source and destination locations
/// overlap the behavior of this operation is not defined.
//
// For example, an AffineDmaStartOp operation that transfers 256 elements of a
// memref '%src' in memory space 0 at indices [%i + 3, %j] to memref '%dst' in
// memory space 1 at indices [%k + 7, %l], would be specified as follows:
//
//   %num_elements = arith.constant 256
//   %idx = arith.constant 0 : index
//   %tag = memref.alloc() : memref<1xi32, 4>
//   affine.dma_start %src[%i + 3, %j], %dst[%k + 7, %l], %tag[%idx],
//     %num_elements :
//       memref<40x128xf32, 0>, memref<2x1024xf32, 1>, memref<1xi32, 2>
//
//   If %stride and %num_elt_per_stride are specified, the DMA is expected to
//   transfer %num_elt_per_stride elements every %stride elements apart from
//   memory space 0 until %num_elements are transferred.
//
//   affine.dma_start %src[%i, %j], %dst[%k, %l], %tag[%idx], %num_elements,
//     %stride, %num_elt_per_stride : ...
//
// TODO: add additional operands to allow source and destination striding, and
// multiple stride levels (possibly using AffineMaps to specify multiple levels
// of striding).
class AffineDmaStartOp
    : public Op<AffineDmaStartOp, OpTrait::MemRefsNormalizable,
                OpTrait::VariadicOperands, OpTrait::ZeroResults,
                OpTrait::OpInvariants, AffineMapAccessInterface::Trait,
                MemoryEffectOpInterface::Trait> { … };

/// AffineDmaWaitOp blocks until the completion of a DMA operation associated
/// with the tag element '%tag[%index]'. %tag is a memref, and %index has to be
/// an index with the same restrictions as any load/store index. In particular,
/// index for each memref dimension must be an affine expression of loop
/// induction variables and symbols. %num_elements is the number of elements
/// associated with the DMA operation. For example:
//
//   affine.dma_start %src[%i, %j], %dst[%k, %l], %tag[%index], %num_elements :
//     memref<2048xf32, 0>, memref<256xf32, 1>, memref<1xi32, 2>
//   ...
//   ...
//   affine.dma_wait %tag[%index], %num_elements : memref<1xi32, 2>
//
class AffineDmaWaitOp
    : public Op<AffineDmaWaitOp, OpTrait::MemRefsNormalizable,
                OpTrait::VariadicOperands, OpTrait::ZeroResults,
                OpTrait::OpInvariants, AffineMapAccessInterface::Trait> { … };

/// Returns true if the given Value can be used as a dimension id in the region
/// of the closest surrounding op that has the trait `AffineScope`.
bool isValidDim(Value value);

/// Returns true if the given Value can be used as a dimension id in `region`,
/// i.e., for all its uses in `region`.
bool isValidDim(Value value, Region *region);

/// Returns true if the given value can be used as a symbol in the region of the
/// closest surrounding op that has the trait `AffineScope`.
bool isValidSymbol(Value value);

/// Returns true if the given Value can be used as a symbol for `region`, i.e.,
/// for all its uses in `region`.
bool isValidSymbol(Value value, Region *region);

/// Parses dimension and symbol list. `numDims` is set to the number of
/// dimensions in the list parsed.
ParseResult parseDimAndSymbolList(OpAsmParser &parser,
                                  SmallVectorImpl<Value> &operands,
                                  unsigned &numDims);

/// Modifies both `map` and `operands` in-place so as to:
/// 1. drop duplicate operands
/// 2. drop unused dims and symbols from map
/// 3. promote valid symbols to symbolic operands in case they appeared as
///    dimensional operands
/// 4. propagate constant operands and drop them
void canonicalizeMapAndOperands(AffineMap *map,
                                SmallVectorImpl<Value> *operands);

/// Canonicalizes an integer set the same way canonicalizeMapAndOperands does
/// for affine maps.
void canonicalizeSetAndOperands(IntegerSet *set,
                                SmallVectorImpl<Value> *operands);

/// Returns a composed AffineApplyOp by composing `map` and `operands` with
/// other AffineApplyOps supplying those operands. The operands of the resulting
/// AffineApplyOp do not change the length of  AffineApplyOp chains.
AffineApplyOp makeComposedAffineApply(OpBuilder &b, Location loc, AffineMap map,
                                      ArrayRef<OpFoldResult> operands);
AffineApplyOp makeComposedAffineApply(OpBuilder &b, Location loc, AffineExpr e,
                                      ArrayRef<OpFoldResult> operands);

/// Constructs an AffineApplyOp that applies `map` to `operands` after composing
/// the map with the maps of any other AffineApplyOp supplying the operands,
/// then immediately attempts to fold it. If folding results in a constant
/// value, no ops are actually created. The `map` must be a single-result affine
/// map.
OpFoldResult makeComposedFoldedAffineApply(OpBuilder &b, Location loc,
                                           AffineMap map,
                                           ArrayRef<OpFoldResult> operands);
/// Variant of `makeComposedFoldedAffineApply` that applies to an expression.
OpFoldResult makeComposedFoldedAffineApply(OpBuilder &b, Location loc,
                                           AffineExpr expr,
                                           ArrayRef<OpFoldResult> operands);
/// Variant of `makeComposedFoldedAffineApply` suitable for multi-result maps.
/// Note that this may create as many affine.apply operations as the map has
/// results given that affine.apply must be single-result.
SmallVector<OpFoldResult> makeComposedFoldedMultiResultAffineApply(
    OpBuilder &b, Location loc, AffineMap map, ArrayRef<OpFoldResult> operands);

/// Returns an AffineMinOp obtained by composing `map` and `operands` with
/// AffineApplyOps supplying those operands.
AffineMinOp makeComposedAffineMin(OpBuilder &b, Location loc, AffineMap map,
                                  ArrayRef<OpFoldResult> operands);

/// Constructs an AffineMinOp that computes a minimum across the results of
/// applying `map` to `operands`, then immediately attempts to fold it. If
/// folding results in a constant value, no ops are actually created.
OpFoldResult makeComposedFoldedAffineMin(OpBuilder &b, Location loc,
                                         AffineMap map,
                                         ArrayRef<OpFoldResult> operands);

/// Constructs an AffineMinOp that computes a maximum across the results of
/// applying `map` to `operands`, then immediately attempts to fold it. If
/// folding results in a constant value, no ops are actually created.
OpFoldResult makeComposedFoldedAffineMax(OpBuilder &b, Location loc,
                                         AffineMap map,
                                         ArrayRef<OpFoldResult> operands);

/// Given an affine map `map` and its input `operands`, this method composes
/// into `map`, maps of AffineApplyOps whose results are the values in
/// `operands`, iteratively until no more of `operands` are the result of an
/// AffineApplyOp. When this function returns, `map` becomes the composed affine
/// map, and each Value in `operands` is guaranteed to be either a loop IV or a
/// terminal symbol, i.e., a symbol defined at the top level or a block/function
/// argument.
void fullyComposeAffineMapAndOperands(AffineMap *map,
                                      SmallVectorImpl<Value> *operands);

} // namespace affine
} // namespace mlir

#include "mlir/Dialect/Affine/IR/AffineOpsDialect.h.inc"

#define GET_OP_CLASSES
#include "mlir/Dialect/Affine/IR/AffineOps.h.inc"

namespace mlir {
namespace affine {

/// Returns true if the provided value is the induction variable of an
/// AffineForOp.
bool isAffineForInductionVar(Value val);

/// Returns true if `val` is the induction variable of an AffineParallelOp.
bool isAffineParallelInductionVar(Value val);

/// Returns true if the provided value is the induction variable of an
/// AffineForOp or AffineParallelOp.
bool isAffineInductionVar(Value val);

/// Returns the loop parent of an induction variable. If the provided value is
/// not an induction variable, then return nullptr.
AffineForOp getForInductionVarOwner(Value val);

/// Returns true if the provided value is among the induction variables of an
/// AffineParallelOp.
AffineParallelOp getAffineParallelInductionVarOwner(Value val);

/// Extracts the induction variables from a list of AffineForOps and places them
/// in the output argument `ivs`.
void extractForInductionVars(ArrayRef<AffineForOp> forInsts,
                             SmallVectorImpl<Value> *ivs);

/// Extracts the induction variables from a list of either AffineForOp or
/// AffineParallelOp and places them in the output argument `ivs`.
void extractInductionVars(ArrayRef<Operation *> affineOps,
                          SmallVectorImpl<Value> &ivs);

/// Builds a perfect nest of affine.for loops, i.e., each loop except the
/// innermost one contains only another loop and a terminator. The loops iterate
/// from "lbs" to "ubs" with "steps". The body of the innermost loop is
/// populated by calling "bodyBuilderFn" and providing it with an OpBuilder, a
/// Location and a list of loop induction variables.
void buildAffineLoopNest(OpBuilder &builder, Location loc,
                         ArrayRef<int64_t> lbs, ArrayRef<int64_t> ubs,
                         ArrayRef<int64_t> steps,
                         function_ref<void(OpBuilder &, Location, ValueRange)>
                             bodyBuilderFn = nullptr);
void buildAffineLoopNest(OpBuilder &builder, Location loc, ValueRange lbs,
                         ValueRange ubs, ArrayRef<int64_t> steps,
                         function_ref<void(OpBuilder &, Location, ValueRange)>
                             bodyBuilderFn = nullptr);

/// AffineBound represents a lower or upper bound in the for operation.
/// This class does not own the underlying operands. Instead, it refers
/// to the operands stored in the AffineForOp. Its life span should not exceed
/// that of the for operation it refers to.
class AffineBound { … };

} // namespace affine
} // namespace mlir

#endif
llvm/mlir/include/mlir/Dialect/Affine/IR/AffineOps.h
