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//===-- PPCFrameLowering.h - Define frame lowering for PowerPC --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H
#define LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H
#include "PPC.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetMachine.h"
namespace llvm {
class PPCSubtarget;
class PPCFrameLowering: public TargetFrameLowering {
const PPCSubtarget &Subtarget;
const unsigned ReturnSaveOffset;
const unsigned TOCSaveOffset;
const unsigned FramePointerSaveOffset;
const unsigned LinkageSize;
const unsigned BasePointerSaveOffset;
/**
* \brief Find a register that can be used in function prologue and epilogue
*
* Find a register that can be use as the scratch register in function
* prologue and epilogue to save various registers (Link Register, Base
* Pointer, etc.). Prefer R0, if it is available. If it is not available,
* then choose a different register.
*
* This method will return true if an available register was found (including
* R0). If no available registers are found, the method returns false and sets
* ScratchRegister to R0, as per the recommendation in the ABI.
*
* \param[in] MBB The machine basic block to find an available register for
* \param[in] UseAtEnd Specify whether the scratch register will be used at
* the end of the basic block (i.e., will the scratch
* register kill a register defined in the basic block)
* \param[out] ScratchRegister The scratch register to use
* \return true if a scratch register was found. false of a scratch register
* was not found and R0 is being used as the default.
*/
bool findScratchRegister(MachineBasicBlock *MBB,
bool UseAtEnd,
unsigned *ScratchRegister) const;
public:
PPCFrameLowering(const PPCSubtarget &STI);
unsigned determineFrameLayout(MachineFunction &MF,
bool UpdateMF = true,
bool UseEstimate = false) const;
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;
bool needsFP(const MachineFunction &MF) const;
void replaceFPWithRealFP(MachineFunction &MF) const;
void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
RegScavenger *RS = nullptr) const override;
void processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS = nullptr) const override;
void addScavengingSpillSlot(MachineFunction &MF, RegScavenger *RS) const;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const override;
void eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const override;
bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const override;
/// targetHandlesStackFrameRounding - Returns true if the target is
/// responsible for rounding up the stack frame (probably at emitPrologue
/// time).
bool targetHandlesStackFrameRounding() const override { return true; }
/// getReturnSaveOffset - Return the previous frame offset to save the
/// return address.
unsigned getReturnSaveOffset() const { return ReturnSaveOffset; }
/// getTOCSaveOffset - Return the previous frame offset to save the
/// TOC register -- 64-bit SVR4 ABI only.
unsigned getTOCSaveOffset() const { return TOCSaveOffset; }
/// getFramePointerSaveOffset - Return the previous frame offset to save the
/// frame pointer.
unsigned getFramePointerSaveOffset() const { return FramePointerSaveOffset; }
/// getBasePointerSaveOffset - Return the previous frame offset to save the
/// base pointer.
unsigned getBasePointerSaveOffset() const { return BasePointerSaveOffset; }
/// getLinkageSize - Return the size of the PowerPC ABI linkage area.
///
unsigned getLinkageSize() const { return LinkageSize; }
const SpillSlot *
getCalleeSavedSpillSlots(unsigned &NumEntries) const override;
bool enableShrinkWrapping(const MachineFunction &MF) const override;
/// Methods used by shrink wrapping to determine if MBB can be used for the
/// function prologue/epilogue.
bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
};
} // End llvm namespace
#endif