1 //===- LoopInvariantCodeMotionUtils.h - LICM Utils --------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef MLIR_TRANSFORMS_LOOPINVARIANTCODEMOTIONUTILS_H
10 #define MLIR_TRANSFORMS_LOOPINVARIANTCODEMOTIONUTILS_H
11 
12 #include "mlir/Support/LLVM.h"
13 
14 namespace mlir {
15 
16 class LoopLikeOpInterface;
17 class Operation;
18 class Region;
19 class RegionRange;
20 class Value;
21 
22 /// Given a list of regions, perform loop-invariant code motion. An operation is
23 /// loop-invariant if it depends only of values defined outside of the loop.
24 /// LICM moves these operations out of the loop body so that they are not
25 /// computed more than once.
26 ///
27 /// Example:
28 ///
29 /// ```mlir
30 /// affine.for %arg0 = 0 to 10 {
31 ///   affine.for %arg1 = 0 to 10 {
32 ///     %v0 = arith.addi %arg0, %arg0 : i32
33 ///     %v1 = arith.addi %v0, %arg1 : i32
34 ///   }
35 /// }
36 /// ```
37 ///
38 /// After LICM:
39 ///
40 /// ```mlir
41 /// affine.for %arg0 = 0 to 10 {
42 ///   %v0 = arith.addi %arg0, %arg0 : i32
43 ///   affine.for %arg1 = 0 to 10 {
44 ///     %v1 = arith.addi %v0, %arg1 : i32
45 ///   }
46 /// }
47 /// ```
48 ///
49 /// Users must supply three callbacks.
50 ///
51 /// - `isDefinedOutsideRegion` returns true if the given value is invariant with
52 ///   respect to the given region. A common implementation might be:
53 ///   `value.getParentRegion()->isProperAncestor(region)`.
54 /// - `shouldMoveOutOfRegion` returns true if the provided operation can be
55 ///   moved of the given region, e.g. if it is side-effect free.
56 /// - `moveOutOfRegion` moves the operation out of the given region. A common
57 ///   implementation might be: `op->moveBefore(region->getParentOp())`.
58 ///
59 /// An operation is moved if all of its operands satisfy
60 /// `isDefinedOutsideRegion` and it satisfies `shouldMoveOutOfRegion`.
61 ///
62 /// Returns the number of operations moved.
63 size_t moveLoopInvariantCode(
64     RegionRange regions,
65     function_ref<bool(Value, Region *)> isDefinedOutsideRegion,
66     function_ref<bool(Operation *, Region *)> shouldMoveOutOfRegion,
67     function_ref<void(Operation *, Region *)> moveOutOfRegion);
68 
69 /// Move side-effect free loop invariant code out of a loop-like op using
70 /// methods provided by the interface.
71 size_t moveLoopInvariantCode(LoopLikeOpInterface loopLike);
72 
73 } // end namespace mlir
74 
75 #endif // MLIR_TRANSFORMS_LOOPINVARIANTCODEMOTIONUTILS_H
76