1 //===- MergedLoadStoreMotion.h - merge and hoist/sink load/stores ---------===//
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 //! \file
10 //! This pass performs merges of loads and stores on both sides of a
11 //  diamond (hammock). It hoists the loads and sinks the stores.
12 //
13 // The algorithm iteratively hoists two loads to the same address out of a
14 // diamond (hammock) and merges them into a single load in the header. Similar
15 // it sinks and merges two stores to the tail block (footer). The algorithm
16 // iterates over the instructions of one side of the diamond and attempts to
17 // find a matching load/store on the other side. It hoists / sinks when it
18 // thinks it safe to do so.  This optimization helps with eg. hiding load
19 // latencies, triggering if-conversion, and reducing static code size.
20 //
21 //===----------------------------------------------------------------------===//
22 
23 #ifndef LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
24 #define LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
25 
26 #include "llvm/IR/Module.h"
27 #include "llvm/IR/PassManager.h"
28 
29 namespace llvm {
30 struct MergedLoadStoreMotionOptions {
31   bool SplitFooterBB;
32   MergedLoadStoreMotionOptions(bool SplitFooterBB = false)
SplitFooterBBMergedLoadStoreMotionOptions33       : SplitFooterBB(SplitFooterBB) {}
34 
splitFooterBBMergedLoadStoreMotionOptions35   MergedLoadStoreMotionOptions &splitFooterBB(bool SFBB) {
36     SplitFooterBB = SFBB;
37     return *this;
38   }
39 };
40 
41 class MergedLoadStoreMotionPass
42     : public PassInfoMixin<MergedLoadStoreMotionPass> {
43   MergedLoadStoreMotionOptions Options;
44 
45 public:
MergedLoadStoreMotionPass()46   MergedLoadStoreMotionPass()
47       : MergedLoadStoreMotionPass(MergedLoadStoreMotionOptions()) {}
MergedLoadStoreMotionPass(const MergedLoadStoreMotionOptions & PassOptions)48   MergedLoadStoreMotionPass(const MergedLoadStoreMotionOptions &PassOptions)
49       : Options(PassOptions) {}
50   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
51 };
52 }
53 
54 #endif // LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
55