MLIR  22.0.0git
LoopInvariantCodeMotion.cpp
Go to the documentation of this file.
1 //===- LoopInvariantCodeMotion.cpp - Code to perform loop fusion-----------===//
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 // This file implements loop invariant code motion.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "mlir/Transforms/Passes.h"
14 
15 #include "mlir/IR/PatternMatch.h"
18 
19 namespace mlir {
20 #define GEN_PASS_DEF_LOOPINVARIANTCODEMOTION
21 #define GEN_PASS_DEF_LOOPINVARIANTSUBSETHOISTING
22 #include "mlir/Transforms/Passes.h.inc"
23 } // namespace mlir
24 
25 using namespace mlir;
26 
27 namespace {
28 /// Loop invariant code motion (LICM) pass.
29 struct LoopInvariantCodeMotion
30  : public impl::LoopInvariantCodeMotionBase<LoopInvariantCodeMotion> {
31  void runOnOperation() override;
32 };
33 
34 struct LoopInvariantSubsetHoisting
35  : public impl::LoopInvariantSubsetHoistingBase<
36  LoopInvariantSubsetHoisting> {
37  void runOnOperation() override;
38 };
39 } // namespace
40 
41 void LoopInvariantCodeMotion::runOnOperation() {
42  // Walk through all loops in a function in innermost-loop-first order. This
43  // way, we first LICM from the inner loop, and place the ops in
44  // the outer loop, which in turn can be further LICM'ed.
45  getOperation()->walk(
46  [&](LoopLikeOpInterface loopLike) { moveLoopInvariantCode(loopLike); });
47 }
48 
49 void LoopInvariantSubsetHoisting::runOnOperation() {
50  IRRewriter rewriter(getOperation()->getContext());
51  // Walk through all loops in a function in innermost-loop-first order. This
52  // way, we first hoist from the inner loop, and place the ops in the outer
53  // loop, which in turn can be further hoisted from.
54  getOperation()->walk([&](LoopLikeOpInterface loopLike) {
55  (void)hoistLoopInvariantSubsets(rewriter, loopLike);
56  });
57 }
58 
59 std::unique_ptr<Pass> mlir::createLoopInvariantCodeMotionPass() {
60  return std::make_unique<LoopInvariantCodeMotion>();
61 }
62 
64  return std::make_unique<LoopInvariantSubsetHoisting>();
65 }
static MLIRContext * getContext(OpFoldResult val)
This class coordinates rewriting a piece of IR outside of a pattern rewrite, providing a way to keep ...
Definition: PatternMatch.h:774
Include the generated interface declarations.
LoopLikeOpInterface hoistLoopInvariantSubsets(RewriterBase &rewriter, LoopLikeOpInterface loopLike)
Hoist loop-invariant tensor subsets (subset extraction and subset insertion ops) from loop-like ops.
std::unique_ptr< Pass > createLoopInvariantCodeMotionPass()
Creates a loop invariant code motion pass that hoists loop invariant instructions out of the loop.
std::unique_ptr< Pass > createLoopInvariantSubsetHoistingPass()
Creates a pass that hoists loop-invariant subset ops.
size_t moveLoopInvariantCode(ArrayRef< Region * > regions, function_ref< bool(Value, Region *)> isDefinedOutsideRegion, function_ref< bool(Operation *, Region *)> shouldMoveOutOfRegion, function_ref< void(Operation *, Region *)> moveOutOfRegion)
Given a list of regions, perform loop-invariant code motion.