include/llvm/Transforms/Scalar/LoopSink.h

   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