1 //===- ARMTargetFrameLowering.h - Define frame lowering for ARM -*- 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_ARMFRAMELOWERING_H
10 #define LLVM_LIB_TARGET_ARM_ARMFRAMELOWERING_H
11 
12 #include "llvm/CodeGen/TargetFrameLowering.h"
13 #include "llvm/Support/TypeSize.h"
14 
15 namespace llvm {
16 
17 class ARMSubtarget;
18 class CalleeSavedInfo;
19 class MachineFunction;
20 
21 class ARMFrameLowering : public TargetFrameLowering {
22 protected:
23   const ARMSubtarget &STI;
24 
25 public:
26   explicit ARMFrameLowering(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 
33   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
34                                  MachineBasicBlock::iterator MI,
35                                  ArrayRef<CalleeSavedInfo> CSI,
36                                  const TargetRegisterInfo *TRI) const override;
37 
38   bool
39   restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
40                               MachineBasicBlock::iterator MI,
41                               MutableArrayRef<CalleeSavedInfo> CSI,
42                               const TargetRegisterInfo *TRI) const override;
43 
44   bool keepFramePointer(const MachineFunction &MF) const override;
45 
46   bool enableCalleeSaveSkip(const MachineFunction &MF) const override;
47 
48   bool hasFP(const MachineFunction &MF) const override;
49   bool isFPReserved(const MachineFunction &MF) const;
50   bool hasReservedCallFrame(const MachineFunction &MF) const override;
51   bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
52   StackOffset getFrameIndexReference(const MachineFunction &MF, int FI,
53                                      Register &FrameReg) const override;
54   int ResolveFrameIndexReference(const MachineFunction &MF, int FI,
55                                  Register &FrameReg, int SPAdj) const;
56 
57   void getCalleeSaves(const MachineFunction &MF,
58                       BitVector &SavedRegs) const override;
59   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
60                             RegScavenger *RS) const override;
61 
62   /// Update the IsRestored flag on LR if it is spilled, based on the return
63   /// instructions.
64   static void updateLRRestored(MachineFunction &MF);
65 
66   void processFunctionBeforeFrameFinalized(
67       MachineFunction &MF, RegScavenger *RS = nullptr) const override;
68 
69   void adjustForSegmentedStacks(MachineFunction &MF,
70                                 MachineBasicBlock &MBB) const override;
71 
72   /// Returns true if the target will correctly handle shrink wrapping.
73   bool enableShrinkWrapping(const MachineFunction &MF) const override;
74 
75   bool isProfitableForNoCSROpt(const Function &F) const override {
76     // The no-CSR optimisation is bad for code size on ARM, because we can save
77     // many registers with a single PUSH/POP pair.
78     return false;
79   }
80 
81   bool
82   assignCalleeSavedSpillSlots(MachineFunction &MF,
83                               const TargetRegisterInfo *TRI,
84                               std::vector<CalleeSavedInfo> &CSI) const override;
85 
86   const SpillSlot *
87   getCalleeSavedSpillSlots(unsigned &NumEntries) const override;
88 
89 private:
90   void emitPushInst(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
91                     ArrayRef<CalleeSavedInfo> CSI, unsigned StmOpc,
92                     unsigned StrOpc, bool NoGap, bool (*Func)(unsigned, bool),
93                     unsigned NumAlignedDPRCS2Regs, unsigned MIFlags = 0) const;
94   void emitPopInst(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
95                    MutableArrayRef<CalleeSavedInfo> CSI, unsigned LdmOpc,
96                    unsigned LdrOpc, bool isVarArg, bool NoGap,
97                    bool (*Func)(unsigned, bool),
98                    unsigned NumAlignedDPRCS2Regs) const;
99 
100   MachineBasicBlock::iterator
101   eliminateCallFramePseudoInstr(MachineFunction &MF,
102                                 MachineBasicBlock &MBB,
103                                 MachineBasicBlock::iterator MI) const override;
104 };
105 
106 } // end namespace llvm
107 
108 #endif // LLVM_LIB_TARGET_ARM_ARMFRAMELOWERING_H
109