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//===-- PPCFrameLowering.h - Define frame lowering for PowerPC --*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H
#define LLVM_LIB_TARGET_POWERPC_PPCFRAMELOWERING_H
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/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;
const unsigned CRSaveOffset;
/**
* Find register[s] that can be used in function prologue and epilogue
*
* Find register[s] that can be use as scratch register[s] in function
* prologue and epilogue to save various registers (Link Register, Base
* Pointer, etc.). Prefer R0/R12, if available. Otherwise choose whatever
* register[s] are available.
*
* This method will return true if it is able to find enough unique scratch
* registers (1 or 2 depending on the requirement). If it is unable to find
* enough available registers in the block, it will return false and set
* any passed output parameter that corresponds to a required unique register
* to PPC::NoRegister.
*
* \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[in] TwoUniqueRegsRequired Specify whether this basic block will
* require two unique scratch registers.
* \param[out] SR1 The scratch register to use
* \param[out] SR2 The second scratch register. If this pointer is not null
* the function will attempt to set it to an available
* register regardless of whether there is a hard requirement
* for two unique scratch registers.
* \return true if the required number of registers was found.
* false if the required number of scratch register weren't available.
* If either output parameter refers to a required scratch register
* that isn't available, it will be set to an invalid value.
*/
bool findScratchRegister(MachineBasicBlock *MBB,
bool UseAtEnd,
bool TwoUniqueRegsRequired = false,
Register *SR1 = nullptr,
Register *SR2 = nullptr) const;
bool twoUniqueScratchRegsRequired(MachineBasicBlock *MBB) const;
/**
* Create branch instruction for PPC::TCRETURN* (tail call return)
*
* \param[in] MBB that is terminated by PPC::TCRETURN*
*/
void createTailCallBranchInstr(MachineBasicBlock &MBB) const;
/**
* Check if the conditions are correct to allow for the stack update
* to be moved past the CSR save/restore code.
*/
bool stackUpdateCanBeMoved(MachineFunction &MF) const;
public:
PPCFrameLowering(const PPCSubtarget &STI);
/**
* Determine the frame layout and update the machine function.
*/
unsigned determineFrameLayoutAndUpdate(MachineFunction &MF,
bool UseEstimate = false) const;
/**
* Determine the frame layout but do not update the machine function.
* The MachineFunction object can be const in this case as it is not
* modified.
*/
unsigned determineFrameLayout(const MachineFunction &MF,
bool UseEstimate = false,
unsigned *NewMaxCallFrameSize = nullptr) 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;
void inlineStackProbe(MachineFunction &MF,
MachineBasicBlock &PrologMBB) 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,
ArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
/// This function will assign callee saved gprs to volatile vector registers
/// for prologue spills when applicable. It returns false if there are any
/// registers which were not spilled to volatile vector registers.
bool
assignCalleeSavedSpillSlots(MachineFunction &MF,
const TargetRegisterInfo *TRI,
std::vector<CalleeSavedInfo> &CSI) const override;
MachineBasicBlock::iterator
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const override;
bool
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
MutableArrayRef<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;
/// getFramePointerSaveOffset - Return the previous frame offset to save the
/// frame pointer.
unsigned getFramePointerSaveOffset() const;
/// getBasePointerSaveOffset - Return the previous frame offset to save the
/// base pointer.
unsigned getBasePointerSaveOffset() const;
/// 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
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