1 | //===- LoopSink.h - Loop Sink Pass ------------------------------*- 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 | // This file provides the interface for the Loop Sink pass. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_TRANSFORMS_SCALAR_LOOPSINK_H |
14 | #define LLVM_TRANSFORMS_SCALAR_LOOPSINK_H |
15 | |
16 | #include "llvm/IR/PassManager.h" |
17 | |
18 | namespace llvm { |
19 | |
20 | class Function; |
21 | |
22 | /// A pass that does profile-guided sinking of instructions into loops. |
23 | /// |
24 | /// This is a function pass as it shouldn't be composed into any kind of |
25 | /// unified loop pass pipeline. The goal of it is to sink code into loops that |
26 | /// is loop invariant but only required within the loop body when doing so |
27 | /// reduces the global expected dynamic frequency with which it executes. |
28 | /// A classic example is an extremely cold branch within a loop body. |
29 | /// |
30 | /// We do this as a separate pass so that during normal optimization all |
31 | /// invariant operations can be held outside the loop body to simplify |
32 | /// fundamental analyses and transforms of the loop. |
33 | class LoopSinkPass : public PassInfoMixin<LoopSinkPass> { |
34 | public: |
35 | PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM); |
36 | }; |
37 | } |
38 | |
39 | #endif // LLVM_TRANSFORMS_SCALAR_LOOPSINK_H |
40 | |