lib/Target/Lanai/LanaiRegisterInfo.cpp

   1 //===-- LanaiRegisterInfo.cpp - Lanai Register Information ------*- C++ -*-===//
   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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the Lanai implementation of the TargetRegisterInfo class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "LanaiRegisterInfo.h"
  14 #include "LanaiAluCode.h"
  15 #include "LanaiCondCode.h"
  16 #include "LanaiFrameLowering.h"
  17 #include "LanaiInstrInfo.h"
  18 #include "llvm/ADT/BitVector.h"
  19 #include "llvm/ADT/STLExtras.h"
  20 #include "llvm/CodeGen/MachineFrameInfo.h"
  21 #include "llvm/CodeGen/MachineFunction.h"
  22 #include "llvm/CodeGen/MachineInstrBuilder.h"
  23 #include "llvm/CodeGen/RegisterScavenging.h"
  24 #include "llvm/CodeGen/TargetFrameLowering.h"
  25 #include "llvm/CodeGen/TargetInstrInfo.h"
  26 #include "llvm/IR/Function.h"
  27 #include "llvm/IR/Type.h"
  28 #include "llvm/Support/ErrorHandling.h"
  29
  30 #define GET_REGINFO_TARGET_DESC
  31 #include "LanaiGenRegisterInfo.inc"
  32
  33 using namespace llvm;
  34
  35 LanaiRegisterInfo::LanaiRegisterInfo() : LanaiGenRegisterInfo(Lanai::RCA) {}
  36
  37 const uint16_t *
  38 LanaiRegisterInfo::getCalleeSavedRegs(const MachineFunction * /*MF*/) const {
  39   return CSR_SaveList;
  40 }
  41
  42 BitVector LanaiRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
  43   BitVector Reserved(getNumRegs());
  44
  45   Reserved.set(Lanai::R0);
  46   Reserved.set(Lanai::R1);
  47   Reserved.set(Lanai::PC);
  48   Reserved.set(Lanai::R2);
  49   Reserved.set(Lanai::SP);
  50   Reserved.set(Lanai::R4);
  51   Reserved.set(Lanai::FP);
  52   Reserved.set(Lanai::R5);
  53   Reserved.set(Lanai::RR1);
  54   Reserved.set(Lanai::R10);
  55   Reserved.set(Lanai::RR2);
  56   Reserved.set(Lanai::R11);
  57   Reserved.set(Lanai::RCA);
  58   Reserved.set(Lanai::R15);
  59   if (hasBasePointer(MF))
  60     Reserved.set(getBaseRegister());
  61   return Reserved;
  62 }
  63
  64 bool LanaiRegisterInfo::requiresRegisterScavenging(
  65     const MachineFunction & /*MF*/) const {
  66   return true;
  67 }
  68
  69 bool LanaiRegisterInfo::trackLivenessAfterRegAlloc(
  70     const MachineFunction & /*MF*/) const {
  71   return true;
  72 }
  73
  74 static bool isALUArithLoOpcode(unsigned Opcode) {
  75   switch (Opcode) {
  76   case Lanai::ADD_I_LO:
  77   case Lanai::SUB_I_LO:
  78   case Lanai::ADD_F_I_LO:
  79   case Lanai::SUB_F_I_LO:
  80   case Lanai::ADDC_I_LO:
  81   case Lanai::SUBB_I_LO:
  82   case Lanai::ADDC_F_I_LO:
  83   case Lanai::SUBB_F_I_LO:
  84     return true;
  85   default:
  86     return false;
  87   }
  88 }
  89
  90 static unsigned getOppositeALULoOpcode(unsigned Opcode) {
  91   switch (Opcode) {
  92   case Lanai::ADD_I_LO:
  93     return Lanai::SUB_I_LO;
  94   case Lanai::SUB_I_LO:
  95     return Lanai::ADD_I_LO;
  96   case Lanai::ADD_F_I_LO:
  97     return Lanai::SUB_F_I_LO;
  98   case Lanai::SUB_F_I_LO:
  99     return Lanai::ADD_F_I_LO;
 100   case Lanai::ADDC_I_LO:
 101     return Lanai::SUBB_I_LO;
 102   case Lanai::SUBB_I_LO:
 103     return Lanai::ADDC_I_LO;
 104   case Lanai::ADDC_F_I_LO:
 105     return Lanai::SUBB_F_I_LO;
 106   case Lanai::SUBB_F_I_LO:
 107     return Lanai::ADDC_F_I_LO;
 108   default:
 109     llvm_unreachable("Invalid ALU lo opcode");
 110   }
 111 }
 112
 113 static unsigned getRRMOpcodeVariant(unsigned Opcode) {
 114   switch (Opcode) {
 115   case Lanai::LDBs_RI:
 116     return Lanai::LDBs_RR;
 117   case Lanai::LDBz_RI:
 118     return Lanai::LDBz_RR;
 119   case Lanai::LDHs_RI:
 120     return Lanai::LDHs_RR;
 121   case Lanai::LDHz_RI:
 122     return Lanai::LDHz_RR;
 123   case Lanai::LDW_RI:
 124     return Lanai::LDW_RR;
 125   case Lanai::STB_RI:
 126     return Lanai::STB_RR;
 127   case Lanai::STH_RI:
 128     return Lanai::STH_RR;
 129   case Lanai::SW_RI:
 130     return Lanai::SW_RR;
 131   default:
 132     llvm_unreachable("Opcode has no RRM variant");
 133   }
 134 }
 135
 136 void LanaiRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 137                                             int SPAdj, unsigned FIOperandNum,
 138                                             RegScavenger *RS) const {
 139   assert(SPAdj == 0 && "Unexpected");
 140
 141   MachineInstr &MI = *II;
 142   MachineFunction &MF = *MI.getParent()->getParent();
 143   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
 144   const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
 145   bool HasFP = TFI->hasFP(MF);
 146   DebugLoc DL = MI.getDebugLoc();
 147
 148   int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
 149
 150   int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex) +
 151                MI.getOperand(FIOperandNum + 1).getImm();
 152
 153   // Addressable stack objects are addressed using neg. offsets from fp
 154   // or pos. offsets from sp/basepointer
 155   if (!HasFP || (needsStackRealignment(MF) && FrameIndex >= 0))
 156     Offset += MF.getFrameInfo().getStackSize();
 157
 158   unsigned FrameReg = getFrameRegister(MF);
 159   if (FrameIndex >= 0) {
 160     if (hasBasePointer(MF))
 161       FrameReg = getBaseRegister();
 162     else if (needsStackRealignment(MF))
 163       FrameReg = Lanai::SP;
 164   }
 165
 166   // Replace frame index with a frame pointer reference.
 167   // If the offset is small enough to fit in the immediate field, directly
 168   // encode it.
 169   // Otherwise scavenge a register and encode it into a MOVHI, OR_I_LO sequence.
 170   if ((isSPLSOpcode(MI.getOpcode()) && !isInt<10>(Offset)) ||
 171       !isInt<16>(Offset)) {
 172     assert(RS && "Register scavenging must be on");
 173     unsigned Reg = RS->FindUnusedReg(&Lanai::GPRRegClass);
 174     if (!Reg)
 175       Reg = RS->scavengeRegister(&Lanai::GPRRegClass, II, SPAdj);
 176     assert(Reg && "Register scavenger failed");
 177
 178     bool HasNegOffset = false;
 179     // ALU ops have unsigned immediate values. If the Offset is negative, we
 180     // negate it here and reverse the opcode later.
 181     if (Offset < 0) {
 182       HasNegOffset = true;
 183       Offset = -Offset;
 184     }
 185
 186     if (!isInt<16>(Offset)) {
 187       // Reg = hi(offset) | lo(offset)
 188       BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::MOVHI), Reg)
 189           .addImm(static_cast<uint32_t>(Offset) >> 16);
 190       BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::OR_I_LO), Reg)
 191           .addReg(Reg)
 192           .addImm(Offset & 0xffffU);
 193     } else {
 194       // Reg = mov(offset)
 195       BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::ADD_I_LO), Reg)
 196           .addImm(0)
 197           .addImm(Offset);
 198     }
 199     // Reg = FrameReg OP Reg
 200     if (MI.getOpcode() == Lanai::ADD_I_LO) {
 201       BuildMI(*MI.getParent(), II, DL,
 202               HasNegOffset ? TII->get(Lanai::SUB_R) : TII->get(Lanai::ADD_R),
 203               MI.getOperand(0).getReg())
 204           .addReg(FrameReg)
 205           .addReg(Reg)
 206           .addImm(LPCC::ICC_T);
 207       MI.eraseFromParent();
 208       return;
 209     }
 210     if (isSPLSOpcode(MI.getOpcode()) || isRMOpcode(MI.getOpcode())) {
 211       MI.setDesc(TII->get(getRRMOpcodeVariant(MI.getOpcode())));
 212       if (HasNegOffset) {
 213         // Change the ALU op (operand 3) from LPAC::ADD (the default) to
 214         // LPAC::SUB with the already negated offset.
 215         assert((MI.getOperand(3).getImm() == LPAC::ADD) &&
 216                "Unexpected ALU op in RRM instruction");
 217         MI.getOperand(3).setImm(LPAC::SUB);
 218       }
 219     } else
 220       llvm_unreachable("Unexpected opcode in frame index operation");
 221
 222     MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, /*isDef=*/false);
 223     MI.getOperand(FIOperandNum + 1)
 224         .ChangeToRegister(Reg, /*isDef=*/false, /*isImp=*/false,
 225                           /*isKill=*/true);
 226     return;
 227   }
 228
 229   // ALU arithmetic ops take unsigned immediates. If the offset is negative,
 230   // we replace the instruction with one that inverts the opcode and negates
 231   // the immediate.
 232   if ((Offset < 0) && isALUArithLoOpcode(MI.getOpcode())) {
 233     unsigned NewOpcode = getOppositeALULoOpcode(MI.getOpcode());
 234     // We know this is an ALU op, so we know the operands are as follows:
 235     // 0: destination register
 236     // 1: source register (frame register)
 237     // 2: immediate
 238     BuildMI(*MI.getParent(), II, DL, TII->get(NewOpcode),
 239             MI.getOperand(0).getReg())
 240         .addReg(FrameReg)
 241         .addImm(-Offset);
 242     MI.eraseFromParent();
 243   } else {
 244     MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, /*isDef=*/false);
 245     MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
 246   }
 247 }
 248
 249 bool LanaiRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
 250   const MachineFrameInfo &MFI = MF.getFrameInfo();
 251   // When we need stack realignment and there are dynamic allocas, we can't
 252   // reference off of the stack pointer, so we reserve a base pointer.
 253   if (needsStackRealignment(MF) && MFI.hasVarSizedObjects())
 254     return true;
 255
 256   return false;
 257 }
 258
 259 unsigned LanaiRegisterInfo::getRARegister() const { return Lanai::RCA; }
 260
 261 Register
 262 LanaiRegisterInfo::getFrameRegister(const MachineFunction & /*MF*/) const {
 263   return Lanai::FP;
 264 }
 265
 266 Register LanaiRegisterInfo::getBaseRegister() const { return Lanai::R14; }
 267
 268 const uint32_t *
 269 LanaiRegisterInfo::getCallPreservedMask(const MachineFunction & /*MF*/,
 270                                         CallingConv::ID /*CC*/) const {
 271   return CSR_RegMask;
 272 }