MLIR  19.0.0git
LoopInvariantCodeMotion.cpp
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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"
19 
20 namespace mlir {
21 #define GEN_PASS_DEF_LOOPINVARIANTCODEMOTION
22 #define GEN_PASS_DEF_LOOPINVARIANTSUBSETHOISTING
23 #include "mlir/Transforms/Passes.h.inc"
24 } // namespace mlir
25 
26 using namespace mlir;
27 
28 namespace {
29 /// Loop invariant code motion (LICM) pass.
30 struct LoopInvariantCodeMotion
31  : public impl::LoopInvariantCodeMotionBase<LoopInvariantCodeMotion> {
32  void runOnOperation() override;
33 };
34 
35 struct LoopInvariantSubsetHoisting
36  : public impl::LoopInvariantSubsetHoistingBase<
37  LoopInvariantSubsetHoisting> {
38  void runOnOperation() override;
39 };
40 } // namespace
41 
42 void LoopInvariantCodeMotion::runOnOperation() {
43  // Walk through all loops in a function in innermost-loop-first order. This
44  // way, we first LICM from the inner loop, and place the ops in
45  // the outer loop, which in turn can be further LICM'ed.
46  getOperation()->walk(
47  [&](LoopLikeOpInterface loopLike) { moveLoopInvariantCode(loopLike); });
48 }
49 
50 void LoopInvariantSubsetHoisting::runOnOperation() {
51  IRRewriter rewriter(getOperation()->getContext());
52  // Walk through all loops in a function in innermost-loop-first order. This
53  // way, we first hoist from the inner loop, and place the ops in the outer
54  // loop, which in turn can be further hoisted from.
55  getOperation()->walk([&](LoopLikeOpInterface loopLike) {
56  (void)hoistLoopInvariantSubsets(rewriter, loopLike);
57  });
58 }
59 
60 std::unique_ptr<Pass> mlir::createLoopInvariantCodeMotionPass() {
61  return std::make_unique<LoopInvariantCodeMotion>();
62 }
63 
65  return std::make_unique<LoopInvariantSubsetHoisting>();
66 }
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:766
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.