xref: /llvm-project/mlir/lib/Transforms/LoopInvariantCodeMotion.cpp (revision 039b969b32b64b64123dce30dd28ec4e343d893f)
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 "PassDetail.h"
14 #include "mlir/Interfaces/LoopLikeInterface.h"
15 #include "mlir/Transforms/LoopInvariantCodeMotionUtils.h"
16 #include "mlir/Transforms/Passes.h"
17 #include "mlir/Transforms/SideEffectUtils.h"
18 
19 using namespace mlir;
20 
21 namespace {
22 /// Loop invariant code motion (LICM) pass.
23 struct LoopInvariantCodeMotion
24     : public LoopInvariantCodeMotionBase<LoopInvariantCodeMotion> {
25   void runOnOperation() override;
26 };
27 } // namespace
28 
29 void LoopInvariantCodeMotion::runOnOperation() {
30   // Walk through all loops in a function in innermost-loop-first order. This
31   // way, we first LICM from the inner loop, and place the ops in
32   // the outer loop, which in turn can be further LICM'ed.
33   getOperation()->walk(
34       [&](LoopLikeOpInterface loopLike) { moveLoopInvariantCode(loopLike); });
35 }
36 
37 std::unique_ptr<Pass> mlir::createLoopInvariantCodeMotionPass() {
38   return std::make_unique<LoopInvariantCodeMotion>();
39 }
40