include/llvm/CodeGen/MachineLoopUtils.h

   1 //=- MachineLoopUtils.h - Helper functions for manipulating loops -*- 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 #ifndef LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H
  10 #define LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H
  11
  12 namespace llvm {
  13 class MachineBasicBlock;
  14 class MachineRegisterInfo;
  15 class TargetInstrInfo;
  16
  17 enum LoopPeelDirection {
  18   LPD_Front, ///< Peel the first iteration of the loop.
  19   LPD_Back   ///< Peel the last iteration of the loop.
  20 };
  21
  22 /// Peels a single block loop. Loop must have two successors, one of which
  23 /// must be itself. Similarly it must have two predecessors, one of which must
  24 /// be itself.
  25 ///
  26 /// The loop block is copied and inserted into the CFG such that two copies of
  27 /// the loop follow on from each other. The copy is inserted either before or
  28 /// after the loop based on Direction.
  29 ///
  30 /// Phis are updated and an unconditional branch inserted at the end of the
  31 /// clone so as to execute a single iteration.
  32 ///
  33 /// The trip count of Loop is not updated.
  34 MachineBasicBlock *PeelSingleBlockLoop(LoopPeelDirection Direction,
  35                                        MachineBasicBlock *Loop,
  36                                        MachineRegisterInfo &MRI,
  37                                        const TargetInstrInfo *TII);
  38
  39 } // namespace llvm
  40
  41 #endif // LLVM_LIB_CODEGEN_MACHINELOOPUTILS_H