| //===-- AVRRegisterInfo.cpp - AVR Register Information --------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the AVR implementation of the TargetRegisterInfo class. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "AVRRegisterInfo.h" |
| |
| #include "llvm/ADT/BitVector.h" |
| #include "llvm/CodeGen/MachineFrameInfo.h" |
| #include "llvm/CodeGen/MachineFunction.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/CodeGen/TargetFrameLowering.h" |
| #include "llvm/IR/Function.h" |
| |
| #include "AVR.h" |
| #include "AVRInstrInfo.h" |
| #include "AVRMachineFunctionInfo.h" |
| #include "AVRTargetMachine.h" |
| #include "MCTargetDesc/AVRMCTargetDesc.h" |
| |
| #define GET_REGINFO_TARGET_DESC |
| #include "AVRGenRegisterInfo.inc" |
| |
| namespace llvm { |
| |
| AVRRegisterInfo::AVRRegisterInfo() : AVRGenRegisterInfo(0) {} |
| |
| const uint16_t * |
| AVRRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const { |
| const AVRMachineFunctionInfo *AFI = MF->getInfo<AVRMachineFunctionInfo>(); |
| const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>(); |
| if (STI.hasTinyEncoding()) |
| return AFI->isInterruptOrSignalHandler() ? CSR_InterruptsTiny_SaveList |
| : CSR_NormalTiny_SaveList; |
| else |
| return AFI->isInterruptOrSignalHandler() ? CSR_Interrupts_SaveList |
| : CSR_Normal_SaveList; |
| } |
| |
| const uint32_t * |
| AVRRegisterInfo::getCallPreservedMask(const MachineFunction &MF, |
| CallingConv::ID CC) const { |
| const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>(); |
| return STI.hasTinyEncoding() ? CSR_NormalTiny_RegMask : CSR_Normal_RegMask; |
| } |
| |
| BitVector AVRRegisterInfo::getReservedRegs(const MachineFunction &MF) const { |
| BitVector Reserved(getNumRegs()); |
| |
| // Reserve the intermediate result registers r1 and r2 |
| // The result of instructions like 'mul' is always stored here. |
| // R0/R1/R1R0 are always reserved on both avr and avrtiny. |
| Reserved.set(AVR::R0); |
| Reserved.set(AVR::R1); |
| Reserved.set(AVR::R1R0); |
| |
| // Reserve the stack pointer. |
| Reserved.set(AVR::SPL); |
| Reserved.set(AVR::SPH); |
| Reserved.set(AVR::SP); |
| |
| // Reserve R2~R17 only on avrtiny. |
| if (MF.getSubtarget<AVRSubtarget>().hasTinyEncoding()) { |
| // Reserve 8-bit registers R2~R15, Rtmp(R16) and Zero(R17). |
| for (unsigned Reg = AVR::R2; Reg <= AVR::R17; Reg++) |
| Reserved.set(Reg); |
| // Reserve 16-bit registers R3R2~R18R17. |
| for (unsigned Reg = AVR::R3R2; Reg <= AVR::R18R17; Reg++) |
| Reserved.set(Reg); |
| } |
| |
| // We tenatively reserve the frame pointer register r29:r28 because the |
| // function may require one, but we cannot tell until register allocation |
| // is complete, which can be too late. |
| // |
| // Instead we just unconditionally reserve the Y register. |
| // |
| // TODO: Write a pass to enumerate functions which reserved the Y register |
| // but didn't end up needing a frame pointer. In these, we can |
| // convert one or two of the spills inside to use the Y register. |
| Reserved.set(AVR::R28); |
| Reserved.set(AVR::R29); |
| Reserved.set(AVR::R29R28); |
| |
| return Reserved; |
| } |
| |
| const TargetRegisterClass * |
| AVRRegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC, |
| const MachineFunction &MF) const { |
| const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo(); |
| if (TRI->isTypeLegalForClass(*RC, MVT::i16)) { |
| return &AVR::DREGSRegClass; |
| } |
| |
| if (TRI->isTypeLegalForClass(*RC, MVT::i8)) { |
| return &AVR::GPR8RegClass; |
| } |
| |
| llvm_unreachable("Invalid register size"); |
| } |
| |
| /// Fold a frame offset shared between two add instructions into a single one. |
| static void foldFrameOffset(MachineBasicBlock::iterator &II, int &Offset, |
| Register DstReg) { |
| MachineInstr &MI = *II; |
| int Opcode = MI.getOpcode(); |
| |
| // Don't bother trying if the next instruction is not an add or a sub. |
| if ((Opcode != AVR::SUBIWRdK) && (Opcode != AVR::ADIWRdK)) { |
| return; |
| } |
| |
| // Check that DstReg matches with next instruction, otherwise the instruction |
| // is not related to stack address manipulation. |
| if (DstReg != MI.getOperand(0).getReg()) { |
| return; |
| } |
| |
| // Add the offset in the next instruction to our offset. |
| switch (Opcode) { |
| case AVR::SUBIWRdK: |
| Offset += -MI.getOperand(2).getImm(); |
| break; |
| case AVR::ADIWRdK: |
| Offset += MI.getOperand(2).getImm(); |
| break; |
| } |
| |
| // Finally remove the instruction. |
| II++; |
| MI.eraseFromParent(); |
| } |
| |
| bool AVRRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II, |
| int SPAdj, unsigned FIOperandNum, |
| RegScavenger *RS) const { |
| assert(SPAdj == 0 && "Unexpected SPAdj value"); |
| |
| MachineInstr &MI = *II; |
| DebugLoc dl = MI.getDebugLoc(); |
| MachineBasicBlock &MBB = *MI.getParent(); |
| const MachineFunction &MF = *MBB.getParent(); |
| const AVRTargetMachine &TM = (const AVRTargetMachine &)MF.getTarget(); |
| const TargetInstrInfo &TII = *TM.getSubtargetImpl()->getInstrInfo(); |
| const MachineFrameInfo &MFI = MF.getFrameInfo(); |
| const TargetFrameLowering *TFI = TM.getSubtargetImpl()->getFrameLowering(); |
| const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>(); |
| int FrameIndex = MI.getOperand(FIOperandNum).getIndex(); |
| int Offset = MFI.getObjectOffset(FrameIndex); |
| |
| // Add one to the offset because SP points to an empty slot. |
| Offset += MFI.getStackSize() - TFI->getOffsetOfLocalArea() + 1; |
| // Fold incoming offset. |
| Offset += MI.getOperand(FIOperandNum + 1).getImm(); |
| |
| // This is actually "load effective address" of the stack slot |
| // instruction. We have only two-address instructions, thus we need to |
| // expand it into move + add. |
| if (MI.getOpcode() == AVR::FRMIDX) { |
| Register DstReg = MI.getOperand(0).getReg(); |
| assert(DstReg != AVR::R29R28 && "Dest reg cannot be the frame pointer"); |
| |
| // Copy the frame pointer. |
| if (STI.hasMOVW()) { |
| BuildMI(MBB, MI, dl, TII.get(AVR::MOVWRdRr), DstReg) |
| .addReg(AVR::R29R28); |
| } else { |
| Register DstLoReg, DstHiReg; |
| splitReg(DstReg, DstLoReg, DstHiReg); |
| BuildMI(MBB, MI, dl, TII.get(AVR::MOVRdRr), DstLoReg) |
| .addReg(AVR::R28); |
| BuildMI(MBB, MI, dl, TII.get(AVR::MOVRdRr), DstHiReg) |
| .addReg(AVR::R29); |
| } |
| |
| assert(Offset > 0 && "Invalid offset"); |
| |
| // We need to materialize the offset via an add instruction. |
| unsigned Opcode; |
| |
| II++; // Skip over the FRMIDX instruction. |
| |
| // Generally, to load a frame address two add instructions are emitted that |
| // could get folded into a single one: |
| // movw r31:r30, r29:r28 |
| // adiw r31:r30, 29 |
| // adiw r31:r30, 16 |
| // to: |
| // movw r31:r30, r29:r28 |
| // adiw r31:r30, 45 |
| if (II != MBB.end()) |
| foldFrameOffset(II, Offset, DstReg); |
| |
| // Select the best opcode based on DstReg and the offset size. |
| switch (DstReg) { |
| case AVR::R25R24: |
| case AVR::R27R26: |
| case AVR::R31R30: { |
| if (isUInt<6>(Offset) && STI.hasADDSUBIW()) { |
| Opcode = AVR::ADIWRdK; |
| break; |
| } |
| [[fallthrough]]; |
| } |
| default: { |
| // This opcode will get expanded into a pair of subi/sbci. |
| Opcode = AVR::SUBIWRdK; |
| Offset = -Offset; |
| break; |
| } |
| } |
| |
| MachineInstr *New = BuildMI(MBB, II, dl, TII.get(Opcode), DstReg) |
| .addReg(DstReg, RegState::Kill) |
| .addImm(Offset); |
| New->getOperand(3).setIsDead(); |
| |
| MI.eraseFromParent(); // remove FRMIDX |
| |
| return false; |
| } |
| |
| // On most AVRs, we can use an offset up to 62 for load/store with |
| // displacement (63 for byte values, 62 for word values). However, the |
| // "reduced tiny" cores don't support load/store with displacement. So for |
| // them, we force an offset of 0 meaning that any positive offset will require |
| // adjusting the frame pointer. |
| int MaxOffset = STI.hasTinyEncoding() ? 0 : 62; |
| |
| // If the offset is too big we have to adjust and restore the frame pointer |
| // to materialize a valid load/store with displacement. |
| //: TODO: consider using only one adiw/sbiw chain for more than one frame |
| //: index |
| if (Offset > MaxOffset) { |
| unsigned AddOpc = AVR::ADIWRdK, SubOpc = AVR::SBIWRdK; |
| int AddOffset = Offset - MaxOffset; |
| |
| // For huge offsets where adiw/sbiw cannot be used use a pair of subi/sbci. |
| if ((Offset - MaxOffset) > 63 || !STI.hasADDSUBIW()) { |
| AddOpc = AVR::SUBIWRdK; |
| SubOpc = AVR::SUBIWRdK; |
| AddOffset = -AddOffset; |
| } |
| |
| // It is possible that the spiller places this frame instruction in between |
| // a compare and branch, invalidating the contents of SREG set by the |
| // compare instruction because of the add/sub pairs. Conservatively save and |
| // restore SREG before and after each add/sub pair. |
| BuildMI(MBB, II, dl, TII.get(AVR::INRdA), STI.getTmpRegister()) |
| .addImm(STI.getIORegSREG()); |
| |
| MachineInstr *New = BuildMI(MBB, II, dl, TII.get(AddOpc), AVR::R29R28) |
| .addReg(AVR::R29R28, RegState::Kill) |
| .addImm(AddOffset); |
| New->getOperand(3).setIsDead(); |
| |
| // Restore SREG. |
| BuildMI(MBB, std::next(II), dl, TII.get(AVR::OUTARr)) |
| .addImm(STI.getIORegSREG()) |
| .addReg(STI.getTmpRegister(), RegState::Kill); |
| |
| // No need to set SREG as dead here otherwise if the next instruction is a |
| // cond branch it will be using a dead register. |
| BuildMI(MBB, std::next(II), dl, TII.get(SubOpc), AVR::R29R28) |
| .addReg(AVR::R29R28, RegState::Kill) |
| .addImm(Offset - MaxOffset); |
| |
| Offset = MaxOffset; |
| } |
| |
| MI.getOperand(FIOperandNum).ChangeToRegister(AVR::R29R28, false); |
| assert(isUInt<6>(Offset) && "Offset is out of range"); |
| MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset); |
| return false; |
| } |
| |
| Register AVRRegisterInfo::getFrameRegister(const MachineFunction &MF) const { |
| const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering(); |
| if (TFI->hasFP(MF)) { |
| // The Y pointer register |
| return AVR::R28; |
| } |
| |
| return AVR::SP; |
| } |
| |
| const TargetRegisterClass * |
| AVRRegisterInfo::getPointerRegClass(const MachineFunction &MF, |
| unsigned Kind) const { |
| // FIXME: Currently we're using avr-gcc as reference, so we restrict |
| // ptrs to Y and Z regs. Though avr-gcc has buggy implementation |
| // of memory constraint, so we can fix it and bit avr-gcc here ;-) |
| return &AVR::PTRDISPREGSRegClass; |
| } |
| |
| void AVRRegisterInfo::splitReg(Register Reg, Register &LoReg, |
| Register &HiReg) const { |
| assert(AVR::DREGSRegClass.contains(Reg) && "can only split 16-bit registers"); |
| |
| LoReg = getSubReg(Reg, AVR::sub_lo); |
| HiReg = getSubReg(Reg, AVR::sub_hi); |
| } |
| |
| bool AVRRegisterInfo::shouldCoalesce( |
| MachineInstr *MI, const TargetRegisterClass *SrcRC, unsigned SubReg, |
| const TargetRegisterClass *DstRC, unsigned DstSubReg, |
| const TargetRegisterClass *NewRC, LiveIntervals &LIS) const { |
| if (this->getRegClass(AVR::PTRDISPREGSRegClassID)->hasSubClassEq(NewRC)) { |
| return false; |
| } |
| |
| return TargetRegisterInfo::shouldCoalesce(MI, SrcRC, SubReg, DstRC, DstSubReg, |
| NewRC, LIS); |
| } |
| |
| } // end of namespace llvm |