1 //===-- PPCFrameLowering.h - Define frame lowering for PowerPC --*- 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 // 10 //===----------------------------------------------------------------------===// 11 12 #ifndef LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H 13 #define LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H 14 15 #include "llvm/ADT/STLExtras.h" 16 #include "llvm/CodeGen/TargetFrameLowering.h" 17 #include "llvm/Target/TargetMachine.h" 18 19 namespace llvm { 20 class PPCSubtarget; 21 22 class PPCFrameLowering: public TargetFrameLowering { 23 const PPCSubtarget &Subtarget; 24 const unsigned ReturnSaveOffset; 25 const unsigned TOCSaveOffset; 26 const unsigned FramePointerSaveOffset; 27 const unsigned LinkageSize; 28 const unsigned BasePointerSaveOffset; 29 30 /** 31 * Find register[s] that can be used in function prologue and epilogue 32 * 33 * Find register[s] that can be use as scratch register[s] in function 34 * prologue and epilogue to save various registers (Link Register, Base 35 * Pointer, etc.). Prefer R0/R12, if available. Otherwise choose whatever 36 * register[s] are available. 37 * 38 * This method will return true if it is able to find enough unique scratch 39 * registers (1 or 2 depending on the requirement). If it is unable to find 40 * enough available registers in the block, it will return false and set 41 * any passed output parameter that corresponds to a required unique register 42 * to PPC::NoRegister. 43 * 44 * \param[in] MBB The machine basic block to find an available register for 45 * \param[in] UseAtEnd Specify whether the scratch register will be used at 46 * the end of the basic block (i.e., will the scratch 47 * register kill a register defined in the basic block) 48 * \param[in] TwoUniqueRegsRequired Specify whether this basic block will 49 * require two unique scratch registers. 50 * \param[out] SR1 The scratch register to use 51 * \param[out] SR2 The second scratch register. If this pointer is not null 52 * the function will attempt to set it to an available 53 * register regardless of whether there is a hard requirement 54 * for two unique scratch registers. 55 * \return true if the required number of registers was found. 56 * false if the required number of scratch register weren't available. 57 * If either output parameter refers to a required scratch register 58 * that isn't available, it will be set to an invalid value. 59 */ 60 bool findScratchRegister(MachineBasicBlock *MBB, 61 bool UseAtEnd, 62 bool TwoUniqueRegsRequired = false, 63 unsigned *SR1 = nullptr, 64 unsigned *SR2 = nullptr) const; 65 bool twoUniqueScratchRegsRequired(MachineBasicBlock *MBB) const; 66 67 /** 68 * Create branch instruction for PPC::TCRETURN* (tail call return) 69 * 70 * \param[in] MBB that is terminated by PPC::TCRETURN* 71 */ 72 void createTailCallBranchInstr(MachineBasicBlock &MBB) const; 73 74 /** 75 * Check if the conditions are correct to allow for the stack update 76 * to be moved past the CSR save/restore code. 77 */ 78 bool stackUpdateCanBeMoved(MachineFunction &MF) const; 79 80 public: 81 PPCFrameLowering(const PPCSubtarget &STI); 82 83 /** 84 * Determine the frame layout and update the machine function. 85 */ 86 unsigned determineFrameLayoutAndUpdate(MachineFunction &MF, 87 bool UseEstimate = false) const; 88 89 /** 90 * Determine the frame layout but do not update the machine function. 91 * The MachineFunction object can be const in this case as it is not 92 * modified. 93 */ 94 unsigned determineFrameLayout(const MachineFunction &MF, 95 bool UseEstimate = false, 96 unsigned *NewMaxCallFrameSize = nullptr) const; 97 98 /// emitProlog/emitEpilog - These methods insert prolog and epilog code into 99 /// the function. 100 void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override; 101 void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override; 102 103 bool hasFP(const MachineFunction &MF) const override; 104 bool needsFP(const MachineFunction &MF) const; 105 void replaceFPWithRealFP(MachineFunction &MF) const; 106 107 void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs, 108 RegScavenger *RS = nullptr) const override; 109 void processFunctionBeforeFrameFinalized(MachineFunction &MF, 110 RegScavenger *RS = nullptr) const override; 111 void addScavengingSpillSlot(MachineFunction &MF, RegScavenger *RS) const; 112 113 bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 114 MachineBasicBlock::iterator MI, 115 const std::vector<CalleeSavedInfo> &CSI, 116 const TargetRegisterInfo *TRI) const override; 117 /// This function will assign callee saved gprs to volatile vector registers 118 /// for prologue spills when applicable. It returns false if there are any 119 /// registers which were not spilled to volatile vector registers. 120 bool 121 assignCalleeSavedSpillSlots(MachineFunction &MF, 122 const TargetRegisterInfo *TRI, 123 std::vector<CalleeSavedInfo> &CSI) const override; 124 125 MachineBasicBlock::iterator 126 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, 127 MachineBasicBlock::iterator I) const override; 128 129 bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 130 MachineBasicBlock::iterator MI, 131 std::vector<CalleeSavedInfo> &CSI, 132 const TargetRegisterInfo *TRI) const override; 133 134 /// targetHandlesStackFrameRounding - Returns true if the target is 135 /// responsible for rounding up the stack frame (probably at emitPrologue 136 /// time). 137 bool targetHandlesStackFrameRounding() const override { return true; } 138 139 /// getReturnSaveOffset - Return the previous frame offset to save the 140 /// return address. 141 unsigned getReturnSaveOffset() const { return ReturnSaveOffset; } 142 143 /// getTOCSaveOffset - Return the previous frame offset to save the 144 /// TOC register -- 64-bit SVR4 ABI only. 145 unsigned getTOCSaveOffset() const { return TOCSaveOffset; } 146 147 /// getFramePointerSaveOffset - Return the previous frame offset to save the 148 /// frame pointer. 149 unsigned getFramePointerSaveOffset() const { return FramePointerSaveOffset; } 150 151 /// getBasePointerSaveOffset - Return the previous frame offset to save the 152 /// base pointer. 153 unsigned getBasePointerSaveOffset() const { return BasePointerSaveOffset; } 154 155 /// getLinkageSize - Return the size of the PowerPC ABI linkage area. 156 /// 157 unsigned getLinkageSize() const { return LinkageSize; } 158 159 const SpillSlot * 160 getCalleeSavedSpillSlots(unsigned &NumEntries) const override; 161 162 bool enableShrinkWrapping(const MachineFunction &MF) const override; 163 164 /// Methods used by shrink wrapping to determine if MBB can be used for the 165 /// function prologue/epilogue. 166 bool canUseAsPrologue(const MachineBasicBlock &MBB) const override; 167 bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override; 168 }; 169 } // End llvm namespace 170 171 #endif 172