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/MachineBasicBlock.h"
13 #include "llvm/CodeGen/TargetFrameLowering.h"
14 #include <vector>
15 
16 namespace llvm {
17 
18 class ARMSubtarget;
19 class CalleeSavedInfo;
20 class MachineFunction;
21 
22 class ARMFrameLowering : public TargetFrameLowering {
23 protected:
24   const ARMSubtarget &STI;
25 
26 public:
27   explicit ARMFrameLowering(const ARMSubtarget &sti);
28 
29   /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
30   /// the function.
31   void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
32   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
33 
34   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
35                                  MachineBasicBlock::iterator MI,
36                                  const std::vector<CalleeSavedInfo> &CSI,
37                                  const TargetRegisterInfo *TRI) const override;
38 
39   bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
40                                   MachineBasicBlock::iterator MI,
41                                   std::vector<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 hasReservedCallFrame(const MachineFunction &MF) const override;
50   bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
51   int getFrameIndexReference(const MachineFunction &MF, int FI,
52                              unsigned &FrameReg) const override;
53   int ResolveFrameIndexReference(const MachineFunction &MF, int FI,
54                                  unsigned &FrameReg, int SPAdj) const;
55 
56   void getCalleeSaves(const MachineFunction &MF,
57                       BitVector &SavedRegs) const override;
58   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
59                             RegScavenger *RS) const override;
60 
61   void adjustForSegmentedStacks(MachineFunction &MF,
62                                 MachineBasicBlock &MBB) const override;
63 
64   /// Returns true if the target will correctly handle shrink wrapping.
65   bool enableShrinkWrapping(const MachineFunction &MF) const override {
66     return true;
67   }
68   bool isProfitableForNoCSROpt(const Function &F) const override {
69     // The no-CSR optimisation is bad for code size on ARM, because we can save
70     // many registers with a single PUSH/POP pair.
71     return false;
72   }
73 
74 private:
75   void emitPushInst(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
76                     const std::vector<CalleeSavedInfo> &CSI, unsigned StmOpc,
77                     unsigned StrOpc, bool NoGap,
78                     bool(*Func)(unsigned, bool), unsigned NumAlignedDPRCS2Regs,
79                     unsigned MIFlags = 0) const;
80   void emitPopInst(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
81                    std::vector<CalleeSavedInfo> &CSI, unsigned LdmOpc,
82                    unsigned LdrOpc, bool isVarArg, bool NoGap,
83                    bool(*Func)(unsigned, bool),
84                    unsigned NumAlignedDPRCS2Regs) const;
85 
86   MachineBasicBlock::iterator
87   eliminateCallFramePseudoInstr(MachineFunction &MF,
88                                 MachineBasicBlock &MBB,
89                                 MachineBasicBlock::iterator MI) const override;
90 };
91 
92 } // end namespace llvm
93 
94 #endif // LLVM_LIB_TARGET_ARM_ARMFRAMELOWERING_H
95