1//===- Thumb1FrameLowering.h - Thumb1-specific frame info stuff ---*- 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_TARGET_ARM_THUMB1FRAMELOWERING_H
10#define LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
11
12#include "ARMFrameLowering.h"
13
14namespace llvm {
15
16class ARMSubtarget;
17class MachineFunction;
18
19class Thumb1FrameLowering : public ARMFrameLowering {
20public:
21 explicit Thumb1FrameLowering(const ARMSubtarget &sti);
22
23 /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
24 /// the function.
25 void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
26 void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
27
28 bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
29 MachineBasicBlock::iterator MI,
30 ArrayRef<CalleeSavedInfo> CSI,
31 const TargetRegisterInfo *TRI) const override;
32 bool
33 restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
34 MachineBasicBlock::iterator MI,
35 MutableArrayRef<CalleeSavedInfo> CSI,
36 const TargetRegisterInfo *TRI) const override;
37
38 bool hasReservedCallFrame(const MachineFunction &MF) const override;
39
40 MachineBasicBlock::iterator
41 eliminateCallFramePseudoInstr(MachineFunction &MF,
42 MachineBasicBlock &MBB,
43 MachineBasicBlock::iterator MI) const override;
44
45 /// Check whether or not the given \p MBB can be used as a epilogue
46 /// for the target.
47 /// The epilogue will be inserted before the first terminator of that block.
48 /// This method is used by the shrink-wrapping pass to decide if
49 /// \p MBB will be correctly handled by the target.
50 bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
51
52 /// Disable shrink wrap as tBfar/BL will be used to adjust for long jumps.
53 bool enableShrinkWrapping(const MachineFunction &MF) const override {
54 return false;
55 }
56
57private:
58 /// Check if the frame lowering of \p MF needs a special fixup
59 /// code sequence for the epilogue.
60 /// Unlike T2 and ARM mode, the T1 pop instruction cannot restore
61 /// to LR, and we can't pop the value directly to the PC when
62 /// we need to update the SP after popping the value. So instead
63 /// we have to emit:
64 /// POP {r3}
65 /// ADD sp, #offset
66 /// BX r3
67 /// If this would clobber a return value, then generate this sequence instead:
68 /// MOV ip, r3
69 /// POP {r3}
70 /// ADD sp, #offset
71 /// MOV lr, r3
72 /// MOV r3, ip
73 /// BX lr
74 bool needPopSpecialFixUp(const MachineFunction &MF) const;
75
76 /// Emit the special fixup code sequence for the epilogue.
77 /// \see needPopSpecialFixUp for more details.
78 /// \p DoIt, tells this method whether or not to actually insert
79 /// the code sequence in \p MBB. I.e., when \p DoIt is false,
80 /// \p MBB is left untouched.
81 /// \returns For \p DoIt == true: True when the emission succeeded
82 /// false otherwise. For \p DoIt == false: True when the emission
83 /// would have been possible, false otherwise.
84 bool emitPopSpecialFixUp(MachineBasicBlock &MBB, bool DoIt) const;
85};
86
87} // end namespace llvm
88
89#endif // LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
90