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  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/ADT/STLFunctionalExtras.h"
  27. #include "llvm/IR/PassManager.h"
  28.  
  29. namespace llvm {
  30. class Function;
  31. struct MergedLoadStoreMotionOptions {
  32.   bool SplitFooterBB;
  33.   MergedLoadStoreMotionOptions(bool SplitFooterBB = false)
  34.       : SplitFooterBB(SplitFooterBB) {}
  35.  
  36.   MergedLoadStoreMotionOptions &splitFooterBB(bool SFBB) {
  37.     SplitFooterBB = SFBB;
  38.     return *this;
  39.   }
  40. };
  41.  
  42. class MergedLoadStoreMotionPass
  43.     : public PassInfoMixin<MergedLoadStoreMotionPass> {
  44.   MergedLoadStoreMotionOptions Options;
  45.  
  46. public:
  47.   MergedLoadStoreMotionPass()
  48.       : MergedLoadStoreMotionPass(MergedLoadStoreMotionOptions()) {}
  49.   MergedLoadStoreMotionPass(const MergedLoadStoreMotionOptions &PassOptions)
  50.       : Options(PassOptions) {}
  51.   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  52.   void printPipeline(raw_ostream &OS,
  53.                      function_ref<StringRef(StringRef)> MapClassName2PassName);
  54. };
  55. }
  56.  
  57. #endif // LLVM_TRANSFORMS_SCALAR_MERGEDLOADSTOREMOTION_H
  58.