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//===- Thumb1FrameLowering.h - Thumb1-specific frame info stuff ---*- C++ -*-=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
#define LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
#include "ARMFrameLowering.h"
namespace llvm {
class ARMSubtarget;
class MachineFunction;
class Thumb1FrameLowering : public ARMFrameLowering {
public:
explicit Thumb1FrameLowering(const ARMSubtarget &sti);
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
ArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
bool
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
MutableArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
bool hasReservedCallFrame(const MachineFunction &MF) const override;
MachineBasicBlock::iterator
eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const override;
/// Check whether or not the given \p MBB can be used as a epilogue
/// for the target.
/// The epilogue will be inserted before the first terminator of that block.
/// This method is used by the shrink-wrapping pass to decide if
/// \p MBB will be correctly handled by the target.
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
/// Disable shrink wrap as tBfar/BL will be used to adjust for long jumps.
bool enableShrinkWrapping(const MachineFunction &MF) const override {
return false;
}
private:
/// Check if the frame lowering of \p MF needs a special fixup
/// code sequence for the epilogue.
/// Unlike T2 and ARM mode, the T1 pop instruction cannot restore
/// to LR, and we can't pop the value directly to the PC when
/// we need to update the SP after popping the value. So instead
/// we have to emit:
/// POP {r3}
/// ADD sp, #offset
/// BX r3
/// If this would clobber a return value, then generate this sequence instead:
/// MOV ip, r3
/// POP {r3}
/// ADD sp, #offset
/// MOV lr, r3
/// MOV r3, ip
/// BX lr
bool needPopSpecialFixUp(const MachineFunction &MF) const;
/// Emit the special fixup code sequence for the epilogue.
/// \see needPopSpecialFixUp for more details.
/// \p DoIt, tells this method whether or not to actually insert
/// the code sequence in \p MBB. I.e., when \p DoIt is false,
/// \p MBB is left untouched.
/// \returns For \p DoIt == true: True when the emission succeeded
/// false otherwise. For \p DoIt == false: True when the emission
/// would have been possible, false otherwise.
bool emitPopSpecialFixUp(MachineBasicBlock &MBB, bool DoIt) const;
};
} // end namespace llvm
#endif // LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
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