1 //===- LoopSink.h - Loop Sink Pass ------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file provides the interface for the Loop Sink pass. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_TRANSFORMS_SCALAR_LOOPSINK_H 15 #define LLVM_TRANSFORMS_SCALAR_LOOPSINK_H 16 17 #include "llvm/Analysis/LoopInfo.h" 18 #include "llvm/IR/PassManager.h" 19 #include "llvm/Transforms/Scalar/LoopPassManager.h" 20 21 namespace llvm { 22 23 /// A pass that does profile-guided sinking of instructions into loops. 24 /// 25 /// This is a function pass as it shouldn't be composed into any kind of 26 /// unified loop pass pipeline. The goal of it is to sink code into loops that 27 /// is loop invariant but only required within the loop body when doing so 28 /// reduces the global expected dynamic frequency with which it executes. 29 /// A classic example is an extremely cold branch within a loop body. 30 /// 31 /// We do this as a separate pass so that during normal optimization all 32 /// invariant operations can be held outside the loop body to simplify 33 /// fundamental analyses and transforms of the loop. 34 class LoopSinkPass : public PassInfoMixin<LoopSinkPass> { 35 public: 36 PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM); 37 }; 38 } 39 40 #endif // LLVM_TRANSFORMS_SCALAR_LOOPSINK_H 41