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Thumb1FrameLowering.h
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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 
14 namespace llvm {
15 
16 class ARMSubtarget;
17 class MachineFunction;
18 
20 public:
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 
31  const TargetRegisterInfo *TRI) const override;
32  bool
36  const TargetRegisterInfo *TRI) const override;
37 
38  bool hasReservedCallFrame(const MachineFunction &MF) const override;
39 
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 
57 private:
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
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override
This class represents lattice values for constants.
Definition: AllocatorList.h:23
unsigned const TargetRegisterInfo * TRI
MachineBasicBlock::iterator eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const override
This method is called during prolog/epilog code insertion to eliminate call frame setup and destroy p...
Thumb1FrameLowering(const ARMSubtarget &sti)
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
bool enableShrinkWrapping(const MachineFunction &MF) const override
Disable shrink wrap as tBfar/BL will be used to adjust for long jumps.
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:298
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, ArrayRef< CalleeSavedInfo > CSI, const TargetRegisterInfo *TRI) const override
spillCalleeSavedRegisters - Issues instruction(s) to spill all callee saved registers and returns tru...
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override
Check whether or not the given MBB can be used as a epilogue for the target.
bool hasReservedCallFrame(const MachineFunction &MF) const override
hasReservedCallFrame - Under normal circumstances, when a frame pointer is not required, we reserve argument space for call sites in the function immediately on entry to the current function.
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override
emitProlog/emitEpilog - These methods insert prolog and epilog code into the function.
bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, MutableArrayRef< CalleeSavedInfo > CSI, const TargetRegisterInfo *TRI) const override
restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee saved registers and returns...
IRTranslator LLVM IR MI