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/Analysis/LoopInfo.h" 17 #include "llvm/IR/PassManager.h" 18 #include "llvm/Transforms/Scalar/LoopPassManager.h" 19 20 namespace llvm { 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