221 lines · cpp
1//===-- Mips16ISelDAGToDAG.cpp - A Dag to Dag Inst Selector for Mips16 ----===//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-exception6//7//===----------------------------------------------------------------------===//8//9// Subclass of MipsDAGToDAGISel specialized for mips16.10//11//===----------------------------------------------------------------------===//12 13#include "Mips16ISelDAGToDAG.h"14#include "MCTargetDesc/MipsBaseInfo.h"15#include "Mips.h"16#include "MipsMachineFunction.h"17#include "MipsRegisterInfo.h"18#include "llvm/CodeGen/MachineFrameInfo.h"19#include "llvm/CodeGen/MachineFunction.h"20#include "llvm/CodeGen/MachineInstrBuilder.h"21#include "llvm/CodeGen/MachineRegisterInfo.h"22#include "llvm/CodeGen/SelectionDAGNodes.h"23#include "llvm/Target/TargetMachine.h"24using namespace llvm;25 26#define DEBUG_TYPE "mips-isel"27 28bool Mips16DAGToDAGISel::runOnMachineFunction(MachineFunction &MF) {29 Subtarget = &MF.getSubtarget<MipsSubtarget>();30 if (!Subtarget->inMips16Mode())31 return false;32 return MipsDAGToDAGISel::runOnMachineFunction(MF);33}34/// Select multiply instructions.35std::pair<SDNode *, SDNode *>36Mips16DAGToDAGISel::selectMULT(SDNode *N, unsigned Opc, const SDLoc &DL, EVT Ty,37 bool HasLo, bool HasHi) {38 SDNode *Lo = nullptr, *Hi = nullptr;39 SDNode *Mul = CurDAG->getMachineNode(Opc, DL, MVT::Glue, N->getOperand(0),40 N->getOperand(1));41 SDValue InGlue = SDValue(Mul, 0);42 43 if (HasLo) {44 unsigned Opcode = Mips::Mflo16;45 Lo = CurDAG->getMachineNode(Opcode, DL, Ty, MVT::Glue, InGlue);46 InGlue = SDValue(Lo, 1);47 }48 if (HasHi) {49 unsigned Opcode = Mips::Mfhi16;50 Hi = CurDAG->getMachineNode(Opcode, DL, Ty, InGlue);51 }52 return std::make_pair(Lo, Hi);53}54 55void Mips16DAGToDAGISel::initGlobalBaseReg(MachineFunction &MF) {56 MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();57 58 if (!MipsFI->globalBaseRegSet())59 return;60 61 MachineBasicBlock &MBB = MF.front();62 MachineBasicBlock::iterator I = MBB.begin();63 MachineRegisterInfo &RegInfo = MF.getRegInfo();64 const TargetInstrInfo &TII = *Subtarget->getInstrInfo();65 DebugLoc DL;66 Register V0, V1, V2, GlobalBaseReg = MipsFI->getGlobalBaseReg(MF);67 const TargetRegisterClass *RC = &Mips::CPU16RegsRegClass;68 69 V0 = RegInfo.createVirtualRegister(RC);70 V1 = RegInfo.createVirtualRegister(RC);71 V2 = RegInfo.createVirtualRegister(RC);72 73 74 BuildMI(MBB, I, DL, TII.get(Mips::LiRxImmX16), V0)75 .addExternalSymbol("_gp_disp", MipsII::MO_ABS_HI);76 BuildMI(MBB, I, DL, TII.get(Mips::AddiuRxPcImmX16), V1)77 .addExternalSymbol("_gp_disp", MipsII::MO_ABS_LO);78 79 BuildMI(MBB, I, DL, TII.get(Mips::SllX16), V2).addReg(V0).addImm(16);80 BuildMI(MBB, I, DL, TII.get(Mips::AdduRxRyRz16), GlobalBaseReg)81 .addReg(V1)82 .addReg(V2);83}84 85void Mips16DAGToDAGISel::processFunctionAfterISel(MachineFunction &MF) {86 initGlobalBaseReg(MF);87}88 89bool Mips16DAGToDAGISel::selectAddr(bool SPAllowed, SDValue Addr, SDValue &Base,90 SDValue &Offset) {91 SDLoc DL(Addr);92 EVT ValTy = Addr.getValueType();93 94 // if Address is FI, get the TargetFrameIndex.95 if (SPAllowed) {96 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {97 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);98 Offset = CurDAG->getTargetConstant(0, DL, ValTy);99 return true;100 }101 }102 // on PIC code Load GA103 if (Addr.getOpcode() == MipsISD::Wrapper) {104 Base = Addr.getOperand(0);105 Offset = Addr.getOperand(1);106 return true;107 }108 if (!TM.isPositionIndependent()) {109 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||110 Addr.getOpcode() == ISD::TargetGlobalAddress))111 return false;112 }113 // Addresses of the form FI+const or FI|const114 if (CurDAG->isBaseWithConstantOffset(Addr)) {115 auto *CN = cast<ConstantSDNode>(Addr.getOperand(1));116 if (isInt<16>(CN->getSExtValue())) {117 // If the first operand is a FI, get the TargetFI Node118 if (SPAllowed) {119 if (FrameIndexSDNode *FIN =120 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {121 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);122 Offset = CurDAG->getTargetConstant(CN->getZExtValue(), DL, ValTy);123 return true;124 }125 }126 127 Base = Addr.getOperand(0);128 Offset = CurDAG->getTargetConstant(CN->getZExtValue(), DL, ValTy);129 return true;130 }131 }132 // Operand is a result from an ADD.133 if (Addr.getOpcode() == ISD::ADD) {134 // When loading from constant pools, load the lower address part in135 // the instruction itself. Example, instead of:136 // lui $2, %hi($CPI1_0)137 // addiu $2, $2, %lo($CPI1_0)138 // lwc1 $f0, 0($2)139 // Generate:140 // lui $2, %hi($CPI1_0)141 // lwc1 $f0, %lo($CPI1_0)($2)142 if (Addr.getOperand(1).getOpcode() == MipsISD::Lo ||143 Addr.getOperand(1).getOpcode() == MipsISD::GPRel) {144 SDValue Opnd0 = Addr.getOperand(1).getOperand(0);145 if (isa<ConstantPoolSDNode>(Opnd0) || isa<GlobalAddressSDNode>(Opnd0) ||146 isa<JumpTableSDNode>(Opnd0)) {147 Base = Addr.getOperand(0);148 Offset = Opnd0;149 return true;150 }151 }152 }153 Base = Addr;154 Offset = CurDAG->getTargetConstant(0, DL, ValTy);155 return true;156}157 158bool Mips16DAGToDAGISel::selectAddr16(SDValue Addr, SDValue &Base,159 SDValue &Offset) {160 return selectAddr(false, Addr, Base, Offset);161}162 163bool Mips16DAGToDAGISel::selectAddr16SP(SDValue Addr, SDValue &Base,164 SDValue &Offset) {165 return selectAddr(true, Addr, Base, Offset);166}167 168/// Select instructions not customized! Used for169/// expanded, promoted and normal instructions170bool Mips16DAGToDAGISel::trySelect(SDNode *Node) {171 unsigned Opcode = Node->getOpcode();172 SDLoc DL(Node);173 174 ///175 // Instruction Selection not handled by the auto-generated176 // tablegen selection should be handled here.177 ///178 EVT NodeTy = Node->getValueType(0);179 unsigned MultOpc;180 181 switch (Opcode) {182 default:183 break;184 185 /// Mul with two results186 case ISD::SMUL_LOHI:187 case ISD::UMUL_LOHI: {188 MultOpc = (Opcode == ISD::UMUL_LOHI ? Mips::MultuRxRy16 : Mips::MultRxRy16);189 std::pair<SDNode *, SDNode *> LoHi =190 selectMULT(Node, MultOpc, DL, NodeTy, true, true);191 if (!SDValue(Node, 0).use_empty())192 ReplaceUses(SDValue(Node, 0), SDValue(LoHi.first, 0));193 194 if (!SDValue(Node, 1).use_empty())195 ReplaceUses(SDValue(Node, 1), SDValue(LoHi.second, 0));196 197 CurDAG->RemoveDeadNode(Node);198 return true;199 }200 201 case ISD::MULHS:202 case ISD::MULHU: {203 MultOpc = (Opcode == ISD::MULHU ? Mips::MultuRxRy16 : Mips::MultRxRy16);204 auto LoHi = selectMULT(Node, MultOpc, DL, NodeTy, false, true);205 ReplaceNode(Node, LoHi.second);206 return true;207 }208 }209 210 return false;211}212 213Mips16DAGToDAGISelLegacy::Mips16DAGToDAGISelLegacy(MipsTargetMachine &TM,214 CodeGenOptLevel OL)215 : MipsDAGToDAGISelLegacy(std::make_unique<Mips16DAGToDAGISel>(TM, OL)) {}216 217FunctionPass *llvm::createMips16ISelDag(MipsTargetMachine &TM,218 CodeGenOptLevel OptLevel) {219 return new Mips16DAGToDAGISelLegacy(TM, OptLevel);220}221