LLVM  4.0.0
Thumb1FrameLowering.h
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1 //===-- Thumb1FrameLowering.h - Thumb1-specific frame info stuff --*- C++ -*-=//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
15 #define LLVM_LIB_TARGET_ARM_THUMB1FRAMELOWERING_H
16 
17 #include "ARMFrameLowering.h"
18 #include "Thumb1InstrInfo.h"
19 #include "ThumbRegisterInfo.h"
21 
22 namespace llvm {
23 
25 public:
26  explicit Thumb1FrameLowering(const ARMSubtarget &sti);
27 
28  /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
29  /// the function.
30  void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
31  void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
32 
35  const std::vector<CalleeSavedInfo> &CSI,
36  const TargetRegisterInfo *TRI) const override;
39  const std::vector<CalleeSavedInfo> &CSI,
40  const TargetRegisterInfo *TRI) const override;
41 
42  bool hasReservedCallFrame(const MachineFunction &MF) const override;
43 
46  MachineBasicBlock &MBB,
47  MachineBasicBlock::iterator MI) const override;
48 
49  /// Check whether or not the given \p MBB can be used as a epilogue
50  /// for the target.
51  /// The epilogue will be inserted before the first terminator of that block.
52  /// This method is used by the shrink-wrapping pass to decide if
53  /// \p MBB will be correctly handled by the target.
54  bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
55 
56  /// Disable shrink wrap as tBfar/BL will be used to adjust for long jumps.
57  bool enableShrinkWrapping(const MachineFunction &MF) const override {
58  return false;
59  }
60 
61 private:
62  /// Check if the frame lowering of \p MF needs a special fixup
63  /// code sequence for the epilogue.
64  /// Unlike T2 and ARM mode, the T1 pop instruction cannot restore
65  /// to LR, and we can't pop the value directly to the PC when
66  /// we need to update the SP after popping the value. So instead
67  /// we have to emit:
68  /// POP {r3}
69  /// ADD sp, #offset
70  /// BX r3
71  /// If this would clobber a return value, then generate this sequence instead:
72  /// MOV ip, r3
73  /// POP {r3}
74  /// ADD sp, #offset
75  /// MOV lr, r3
76  /// MOV r3, ip
77  /// BX lr
78  bool needPopSpecialFixUp(const MachineFunction &MF) const;
79 
80  /// Emit the special fixup code sequence for the epilogue.
81  /// \see needPopSpecialFixUp for more details.
82  /// \p DoIt, tells this method whether or not to actually insert
83  /// the code sequence in \p MBB. I.e., when \p DoIt is false,
84  /// \p MBB is left untouched.
85  /// \returns For \p DoIt == true: True when the emission succeeded
86  /// false otherwise. For \p DoIt == false: True when the emission
87  /// would have been possible, false otherwise.
88  bool emitPopSpecialFixUp(MachineBasicBlock &MBB, bool DoIt) const;
89 };
90 
91 } // End llvm namespace
92 
93 #endif
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override
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)
MachineBasicBlock * MBB
bool enableShrinkWrapping(const MachineFunction &MF) const override
Disable shrink wrap as tBfar/BL will be used to adjust for long jumps.
bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, const std::vector< CalleeSavedInfo > &CSI, const TargetRegisterInfo *TRI) const override
restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee saved registers and returns...
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.
IRTranslator LLVM IR MI
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, const std::vector< CalleeSavedInfo > &CSI, const TargetRegisterInfo *TRI) const override
spillCalleeSavedRegisters - Issues instruction(s) to spill all callee saved registers and returns tru...