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//===- M68kFrameLowering.h - Define frame lowering for M68k -*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file contains the M68k declaration of TargetFrameLowering class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_M68K_M68KFRAMELOWERING_H
#define LLVM_LIB_TARGET_M68K_M68KFRAMELOWERING_H
#include "M68k.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
namespace llvm {
class MachineInstrBuilder;
class MCCFIInstruction;
class M68kSubtarget;
class M68kRegisterInfo;
struct Align;
class M68kFrameLowering : public TargetFrameLowering {
// Cached subtarget predicates.
const M68kSubtarget &STI;
const TargetInstrInfo &TII;
const M68kRegisterInfo *TRI;
/// Stack slot size in bytes.
unsigned SlotSize;
unsigned StackPtr;
/// If we're forcing a stack realignment we can't rely on just the frame
/// info, we need to know the ABI stack alignment as well in case we have a
/// call out. Otherwise just make sure we have some alignment - we'll go
/// with the minimum SlotSize.
uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
/// Adjusts the stack pointer using LEA, SUB, or ADD.
MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
const DebugLoc &DL, int64_t Offset,
bool InEpilogue) const;
/// Aligns the stack pointer by ANDing it with -MaxAlign.
void BuildStackAlignAND(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
unsigned Reg, uint64_t MaxAlign) const;
/// Wraps up getting a CFI index and building a MachineInstr for it.
void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
const DebugLoc &DL, const MCCFIInstruction &CFIInst) const;
void emitPrologueCalleeSavedFrameMoves(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
const DebugLoc &DL) const;
unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
public:
explicit M68kFrameLowering(const M68kSubtarget &sti, Align Alignment);
static const M68kFrameLowering *create(const M68kSubtarget &ST);
/// This method is called during prolog/epilog code insertion to eliminate
/// call frame setup and destroy pseudo instructions (but only if the Target
/// is using them). It is responsible for eliminating these instructions,
/// replacing them with concrete instructions. This method need only be
/// implemented if using call frame setup/destroy pseudo instructions.
/// Returns an iterator pointing to the instruction after the replaced one.
MachineBasicBlock::iterator
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const override;
/// Insert prolog code into the function.
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
/// Insert epilog code into the function.
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
/// This method determines which of the registers reported by
/// TargetRegisterInfo::getCalleeSavedRegs() should actually get saved.
/// The default implementation checks populates the \p SavedRegs bitset with
/// all registers which are modified in the function, targets may override
/// this function to save additional registers.
/// This method also sets up the register scavenger ensuring there is a free
/// register or a frameindex available.
void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
RegScavenger *RS = nullptr) const override;
/// Allows target to override spill slot assignment logic. If implemented,
/// assignCalleeSavedSpillSlots() should assign frame slots to all CSI
/// entries and return true. If this method returns false, spill slots will
/// be assigned using generic implementation. assignCalleeSavedSpillSlots()
/// may add, delete or rearrange elements of CSI.
bool
assignCalleeSavedSpillSlots(MachineFunction &MF,
const TargetRegisterInfo *TRI,
std::vector<CalleeSavedInfo> &CSI) const override;
/// Issues instruction(s) to spill all callee saved registers and returns
/// true if it isn't possible / profitable to do so by issuing a series of
/// store instructions via storeRegToStackSlot(). Returns false otherwise.
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
ArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
/// Issues instruction(s) to restore all callee saved registers and returns
/// true if it isn't possible / profitable to do so by issuing a series of
/// load instructions via loadRegToStackSlot(). Returns false otherwise.
bool
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
MutableArrayRef<CalleeSavedInfo> CSI,
const TargetRegisterInfo *TRI) const override;
/// Return true if the specified function should have a dedicated frame
/// pointer register. This is true if the function has variable sized
/// allocas, if it needs dynamic stack realignment, if frame pointer
/// elimination is disabled, or if the frame address is taken.
bool hasFP(const MachineFunction &MF) const override;
/// Under normal circumstances, when a frame pointer is not required, we
/// reserve argument space for call sites in the function immediately on
/// entry to the current function. This eliminates the need for add/sub sp
/// brackets around call sites. Returns true if the call frame is included as
/// part of the stack frame.
bool hasReservedCallFrame(const MachineFunction &MF) const override;
/// If there is a reserved call frame, the call frame pseudos can be
/// simplified. Having a FP, as in the default implementation, is not
/// sufficient here since we can't always use it. Use a more nuanced
/// condition.
bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
// Do we need to perform FI resolution for this function. Normally, this is
// required only when the function has any stack objects. However, FI
// resolution actually has another job, not apparent from the title - it
// resolves callframe setup/destroy that were not simplified earlier.
//
// So, this is required for M68k functions that have push sequences even
// when there are no stack objects.
bool needsFrameIndexResolution(const MachineFunction &MF) const override;
/// This method should return the base register and offset used to reference
/// a frame index location. The offset is returned directly, and the base
/// register is returned via FrameReg.
StackOffset getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const override;
/// Check the instruction before/after the passed instruction. If
/// it is an ADD/SUB/LEA instruction it is deleted argument and the
/// stack adjustment is returned as a positive value for ADD/LEA and
/// a negative for SUB.
int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
bool doMergeWithPrevious) const;
/// Emit a series of instructions to increment / decrement the stack
/// pointer by a constant value.
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
int64_t NumBytes, bool InEpilogue) const;
};
} // namespace llvm
#endif
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