1 //===- Mips16InstrInfo.cpp - Mips16 Instruction Information ---------------===// 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 Mips16 implementation of the TargetInstrInfo class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "Mips16InstrInfo.h" 14 #include "llvm/ADT/BitVector.h" 15 #include "llvm/CodeGen/MachineBasicBlock.h" 16 #include "llvm/CodeGen/MachineFrameInfo.h" 17 #include "llvm/CodeGen/MachineFunction.h" 18 #include "llvm/CodeGen/MachineInstr.h" 19 #include "llvm/CodeGen/MachineInstrBuilder.h" 20 #include "llvm/CodeGen/MachineMemOperand.h" 21 #include "llvm/CodeGen/MachineOperand.h" 22 #include "llvm/CodeGen/RegisterScavenging.h" 23 #include "llvm/CodeGen/TargetRegisterInfo.h" 24 #include "llvm/IR/DebugLoc.h" 25 #include "llvm/MC/MCAsmInfo.h" 26 #include "llvm/Support/Debug.h" 27 #include "llvm/Support/ErrorHandling.h" 28 #include "llvm/Support/MathExtras.h" 29 #include "llvm/Support/raw_ostream.h" 30 #include <cassert> 31 #include <cctype> 32 #include <cstdint> 33 #include <cstdlib> 34 #include <cstring> 35 #include <iterator> 36 #include <vector> 37 38 using namespace llvm; 39 40 #define DEBUG_TYPE "mips16-instrinfo" 41 42 Mips16InstrInfo::Mips16InstrInfo(const MipsSubtarget &STI) 43 : MipsInstrInfo(STI, Mips::Bimm16) {} 44 45 const MipsRegisterInfo &Mips16InstrInfo::getRegisterInfo() const { 46 return RI; 47 } 48 49 /// isLoadFromStackSlot - If the specified machine instruction is a direct 50 /// load from a stack slot, return the virtual or physical register number of 51 /// the destination along with the FrameIndex of the loaded stack slot. If 52 /// not, return 0. This predicate must return 0 if the instruction has 53 /// any side effects other than loading from the stack slot. 54 unsigned Mips16InstrInfo::isLoadFromStackSlot(const MachineInstr &MI, 55 int &FrameIndex) const { 56 return 0; 57 } 58 59 /// isStoreToStackSlot - If the specified machine instruction is a direct 60 /// store to a stack slot, return the virtual or physical register number of 61 /// the source reg along with the FrameIndex of the loaded stack slot. If 62 /// not, return 0. This predicate must return 0 if the instruction has 63 /// any side effects other than storing to the stack slot. 64 unsigned Mips16InstrInfo::isStoreToStackSlot(const MachineInstr &MI, 65 int &FrameIndex) const { 66 return 0; 67 } 68 69 void Mips16InstrInfo::copyPhysReg(MachineBasicBlock &MBB, 70 MachineBasicBlock::iterator I, 71 const DebugLoc &DL, MCRegister DestReg, 72 MCRegister SrcReg, bool KillSrc) const { 73 unsigned Opc = 0; 74 75 if (Mips::CPU16RegsRegClass.contains(DestReg) && 76 Mips::GPR32RegClass.contains(SrcReg)) 77 Opc = Mips::MoveR3216; 78 else if (Mips::GPR32RegClass.contains(DestReg) && 79 Mips::CPU16RegsRegClass.contains(SrcReg)) 80 Opc = Mips::Move32R16; 81 else if ((SrcReg == Mips::HI0) && 82 (Mips::CPU16RegsRegClass.contains(DestReg))) 83 Opc = Mips::Mfhi16, SrcReg = 0; 84 else if ((SrcReg == Mips::LO0) && 85 (Mips::CPU16RegsRegClass.contains(DestReg))) 86 Opc = Mips::Mflo16, SrcReg = 0; 87 88 assert(Opc && "Cannot copy registers"); 89 90 MachineInstrBuilder MIB = BuildMI(MBB, I, DL, get(Opc)); 91 92 if (DestReg) 93 MIB.addReg(DestReg, RegState::Define); 94 95 if (SrcReg) 96 MIB.addReg(SrcReg, getKillRegState(KillSrc)); 97 } 98 99 std::optional<DestSourcePair> 100 Mips16InstrInfo::isCopyInstrImpl(const MachineInstr &MI) const { 101 if (MI.isMoveReg()) 102 return DestSourcePair{MI.getOperand(0), MI.getOperand(1)}; 103 return std::nullopt; 104 } 105 106 void Mips16InstrInfo::storeRegToStack(MachineBasicBlock &MBB, 107 MachineBasicBlock::iterator I, 108 Register SrcReg, bool isKill, int FI, 109 const TargetRegisterClass *RC, 110 const TargetRegisterInfo *TRI, 111 int64_t Offset) const { 112 DebugLoc DL; 113 if (I != MBB.end()) DL = I->getDebugLoc(); 114 MachineMemOperand *MMO = GetMemOperand(MBB, FI, MachineMemOperand::MOStore); 115 unsigned Opc = 0; 116 if (Mips::CPU16RegsRegClass.hasSubClassEq(RC)) 117 Opc = Mips::SwRxSpImmX16; 118 assert(Opc && "Register class not handled!"); 119 BuildMI(MBB, I, DL, get(Opc)).addReg(SrcReg, getKillRegState(isKill)). 120 addFrameIndex(FI).addImm(Offset) 121 .addMemOperand(MMO); 122 } 123 124 void Mips16InstrInfo::loadRegFromStack(MachineBasicBlock &MBB, 125 MachineBasicBlock::iterator I, 126 Register DestReg, int FI, 127 const TargetRegisterClass *RC, 128 const TargetRegisterInfo *TRI, 129 int64_t Offset) const { 130 DebugLoc DL; 131 if (I != MBB.end()) DL = I->getDebugLoc(); 132 MachineMemOperand *MMO = GetMemOperand(MBB, FI, MachineMemOperand::MOLoad); 133 unsigned Opc = 0; 134 135 if (Mips::CPU16RegsRegClass.hasSubClassEq(RC)) 136 Opc = Mips::LwRxSpImmX16; 137 assert(Opc && "Register class not handled!"); 138 BuildMI(MBB, I, DL, get(Opc), DestReg).addFrameIndex(FI).addImm(Offset) 139 .addMemOperand(MMO); 140 } 141 142 bool Mips16InstrInfo::expandPostRAPseudo(MachineInstr &MI) const { 143 MachineBasicBlock &MBB = *MI.getParent(); 144 switch (MI.getDesc().getOpcode()) { 145 default: 146 return false; 147 case Mips::RetRA16: 148 ExpandRetRA16(MBB, MI, Mips::JrcRa16); 149 break; 150 } 151 152 MBB.erase(MI.getIterator()); 153 return true; 154 } 155 156 /// GetOppositeBranchOpc - Return the inverse of the specified 157 /// opcode, e.g. turning BEQ to BNE. 158 unsigned Mips16InstrInfo::getOppositeBranchOpc(unsigned Opc) const { 159 switch (Opc) { 160 case Mips::BeqzRxImmX16: return Mips::BnezRxImmX16; 161 case Mips::BnezRxImmX16: return Mips::BeqzRxImmX16; 162 case Mips::BeqzRxImm16: return Mips::BnezRxImm16; 163 case Mips::BnezRxImm16: return Mips::BeqzRxImm16; 164 case Mips::BteqzT8CmpX16: return Mips::BtnezT8CmpX16; 165 case Mips::BteqzT8SltX16: return Mips::BtnezT8SltX16; 166 case Mips::BteqzT8SltiX16: return Mips::BtnezT8SltiX16; 167 case Mips::Btnez16: return Mips::Bteqz16; 168 case Mips::BtnezX16: return Mips::BteqzX16; 169 case Mips::BtnezT8CmpiX16: return Mips::BteqzT8CmpiX16; 170 case Mips::BtnezT8SltuX16: return Mips::BteqzT8SltuX16; 171 case Mips::BtnezT8SltiuX16: return Mips::BteqzT8SltiuX16; 172 case Mips::Bteqz16: return Mips::Btnez16; 173 case Mips::BteqzX16: return Mips::BtnezX16; 174 case Mips::BteqzT8CmpiX16: return Mips::BtnezT8CmpiX16; 175 case Mips::BteqzT8SltuX16: return Mips::BtnezT8SltuX16; 176 case Mips::BteqzT8SltiuX16: return Mips::BtnezT8SltiuX16; 177 case Mips::BtnezT8CmpX16: return Mips::BteqzT8CmpX16; 178 case Mips::BtnezT8SltX16: return Mips::BteqzT8SltX16; 179 case Mips::BtnezT8SltiX16: return Mips::BteqzT8SltiX16; 180 } 181 llvm_unreachable("Illegal opcode!"); 182 } 183 184 static void addSaveRestoreRegs(MachineInstrBuilder &MIB, 185 ArrayRef<CalleeSavedInfo> CSI, 186 unsigned Flags = 0) { 187 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 188 // Add the callee-saved register as live-in. Do not add if the register is 189 // RA and return address is taken, because it has already been added in 190 // method MipsTargetLowering::lowerRETURNADDR. 191 // It's killed at the spill, unless the register is RA and return address 192 // is taken. 193 Register Reg = CSI[e-i-1].getReg(); 194 switch (Reg) { 195 case Mips::RA: 196 case Mips::S0: 197 case Mips::S1: 198 MIB.addReg(Reg, Flags); 199 break; 200 case Mips::S2: 201 break; 202 default: 203 llvm_unreachable("unexpected mips16 callee saved register"); 204 205 } 206 } 207 } 208 209 // Adjust SP by FrameSize bytes. Save RA, S0, S1 210 void Mips16InstrInfo::makeFrame(unsigned SP, int64_t FrameSize, 211 MachineBasicBlock &MBB, 212 MachineBasicBlock::iterator I) const { 213 DebugLoc DL; 214 MachineFunction &MF = *MBB.getParent(); 215 MachineFrameInfo &MFI = MF.getFrameInfo(); 216 const BitVector Reserved = RI.getReservedRegs(MF); 217 bool SaveS2 = Reserved[Mips::S2]; 218 MachineInstrBuilder MIB; 219 unsigned Opc = ((FrameSize <= 128) && !SaveS2)? Mips::Save16:Mips::SaveX16; 220 MIB = BuildMI(MBB, I, DL, get(Opc)); 221 const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo(); 222 addSaveRestoreRegs(MIB, CSI); 223 if (SaveS2) 224 MIB.addReg(Mips::S2); 225 if (isUInt<11>(FrameSize)) 226 MIB.addImm(FrameSize); 227 else { 228 int Base = 2040; // should create template function like isUInt that 229 // returns largest possible n bit unsigned integer 230 int64_t Remainder = FrameSize - Base; 231 MIB.addImm(Base); 232 if (isInt<16>(-Remainder)) 233 BuildAddiuSpImm(MBB, I, -Remainder); 234 else 235 adjustStackPtrBig(SP, -Remainder, MBB, I, Mips::V0, Mips::V1); 236 } 237 } 238 239 // Adjust SP by FrameSize bytes. Restore RA, S0, S1 240 void Mips16InstrInfo::restoreFrame(unsigned SP, int64_t FrameSize, 241 MachineBasicBlock &MBB, 242 MachineBasicBlock::iterator I) const { 243 DebugLoc DL = I != MBB.end() ? I->getDebugLoc() : DebugLoc(); 244 MachineFunction *MF = MBB.getParent(); 245 MachineFrameInfo &MFI = MF->getFrameInfo(); 246 const BitVector Reserved = RI.getReservedRegs(*MF); 247 bool SaveS2 = Reserved[Mips::S2]; 248 MachineInstrBuilder MIB; 249 unsigned Opc = ((FrameSize <= 128) && !SaveS2)? 250 Mips::Restore16:Mips::RestoreX16; 251 252 if (!isUInt<11>(FrameSize)) { 253 unsigned Base = 2040; 254 int64_t Remainder = FrameSize - Base; 255 FrameSize = Base; // should create template function like isUInt that 256 // returns largest possible n bit unsigned integer 257 258 if (isInt<16>(Remainder)) 259 BuildAddiuSpImm(MBB, I, Remainder); 260 else 261 adjustStackPtrBig(SP, Remainder, MBB, I, Mips::A0, Mips::A1); 262 } 263 MIB = BuildMI(MBB, I, DL, get(Opc)); 264 const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo(); 265 addSaveRestoreRegs(MIB, CSI, RegState::Define); 266 if (SaveS2) 267 MIB.addReg(Mips::S2, RegState::Define); 268 MIB.addImm(FrameSize); 269 } 270 271 // Adjust SP by Amount bytes where bytes can be up to 32bit number. 272 // This can only be called at times that we know that there is at least one free 273 // register. 274 // This is clearly safe at prologue and epilogue. 275 void Mips16InstrInfo::adjustStackPtrBig(unsigned SP, int64_t Amount, 276 MachineBasicBlock &MBB, 277 MachineBasicBlock::iterator I, 278 unsigned Reg1, unsigned Reg2) const { 279 DebugLoc DL; 280 // 281 // li reg1, constant 282 // move reg2, sp 283 // add reg1, reg1, reg2 284 // move sp, reg1 285 // 286 // 287 MachineInstrBuilder MIB1 = BuildMI(MBB, I, DL, get(Mips::LwConstant32), Reg1); 288 MIB1.addImm(Amount).addImm(-1); 289 MachineInstrBuilder MIB2 = BuildMI(MBB, I, DL, get(Mips::MoveR3216), Reg2); 290 MIB2.addReg(Mips::SP, RegState::Kill); 291 MachineInstrBuilder MIB3 = BuildMI(MBB, I, DL, get(Mips::AdduRxRyRz16), Reg1); 292 MIB3.addReg(Reg1); 293 MIB3.addReg(Reg2, RegState::Kill); 294 MachineInstrBuilder MIB4 = BuildMI(MBB, I, DL, get(Mips::Move32R16), 295 Mips::SP); 296 MIB4.addReg(Reg1, RegState::Kill); 297 } 298 299 void Mips16InstrInfo::adjustStackPtrBigUnrestricted( 300 unsigned SP, int64_t Amount, MachineBasicBlock &MBB, 301 MachineBasicBlock::iterator I) const { 302 llvm_unreachable("adjust stack pointer amount exceeded"); 303 } 304 305 /// Adjust SP by Amount bytes. 306 void Mips16InstrInfo::adjustStackPtr(unsigned SP, int64_t Amount, 307 MachineBasicBlock &MBB, 308 MachineBasicBlock::iterator I) const { 309 if (Amount == 0) 310 return; 311 312 if (isInt<16>(Amount)) // need to change to addiu sp, ....and isInt<16> 313 BuildAddiuSpImm(MBB, I, Amount); 314 else 315 adjustStackPtrBigUnrestricted(SP, Amount, MBB, I); 316 } 317 318 /// This function generates the sequence of instructions needed to get the 319 /// result of adding register REG and immediate IMM. 320 unsigned Mips16InstrInfo::loadImmediate(unsigned FrameReg, int64_t Imm, 321 MachineBasicBlock &MBB, 322 MachineBasicBlock::iterator II, 323 const DebugLoc &DL, 324 unsigned &NewImm) const { 325 // 326 // given original instruction is: 327 // Instr rx, T[offset] where offset is too big. 328 // 329 // lo = offset & 0xFFFF 330 // hi = ((offset >> 16) + (lo >> 15)) & 0xFFFF; 331 // 332 // let T = temporary register 333 // li T, hi 334 // shl T, 16 335 // add T, Rx, T 336 // 337 RegScavenger rs; 338 int32_t lo = Imm & 0xFFFF; 339 NewImm = lo; 340 int Reg =0; 341 int SpReg = 0; 342 343 rs.enterBasicBlock(MBB); 344 rs.forward(II); 345 // 346 // We need to know which registers can be used, in the case where there 347 // are not enough free registers. We exclude all registers that 348 // are used in the instruction that we are helping. 349 // // Consider all allocatable registers in the register class initially 350 BitVector Candidates = 351 RI.getAllocatableSet 352 (*II->getParent()->getParent(), &Mips::CPU16RegsRegClass); 353 // Exclude all the registers being used by the instruction. 354 for (unsigned i = 0, e = II->getNumOperands(); i != e; ++i) { 355 MachineOperand &MO = II->getOperand(i); 356 if (MO.isReg() && MO.getReg() != 0 && !MO.isDef() && 357 !MO.getReg().isVirtual()) 358 Candidates.reset(MO.getReg()); 359 } 360 361 // If the same register was used and defined in an instruction, then 362 // it will not be in the list of candidates. 363 // 364 // we need to analyze the instruction that we are helping. 365 // we need to know if it defines register x but register x is not 366 // present as an operand of the instruction. this tells 367 // whether the register is live before the instruction. if it's not 368 // then we don't need to save it in case there are no free registers. 369 int DefReg = 0; 370 for (unsigned i = 0, e = II->getNumOperands(); i != e; ++i) { 371 MachineOperand &MO = II->getOperand(i); 372 if (MO.isReg() && MO.isDef()) { 373 DefReg = MO.getReg(); 374 break; 375 } 376 } 377 378 BitVector Available = rs.getRegsAvailable(&Mips::CPU16RegsRegClass); 379 Available &= Candidates; 380 // 381 // we use T0 for the first register, if we need to save something away. 382 // we use T1 for the second register, if we need to save something away. 383 // 384 unsigned FirstRegSaved =0, SecondRegSaved=0; 385 unsigned FirstRegSavedTo = 0, SecondRegSavedTo = 0; 386 387 Reg = Available.find_first(); 388 389 if (Reg == -1) { 390 Reg = Candidates.find_first(); 391 Candidates.reset(Reg); 392 if (DefReg != Reg) { 393 FirstRegSaved = Reg; 394 FirstRegSavedTo = Mips::T0; 395 copyPhysReg(MBB, II, DL, FirstRegSavedTo, FirstRegSaved, true); 396 } 397 } 398 else 399 Available.reset(Reg); 400 BuildMI(MBB, II, DL, get(Mips::LwConstant32), Reg).addImm(Imm).addImm(-1); 401 NewImm = 0; 402 if (FrameReg == Mips::SP) { 403 SpReg = Available.find_first(); 404 if (SpReg == -1) { 405 SpReg = Candidates.find_first(); 406 // Candidates.reset(SpReg); // not really needed 407 if (DefReg!= SpReg) { 408 SecondRegSaved = SpReg; 409 SecondRegSavedTo = Mips::T1; 410 } 411 if (SecondRegSaved) 412 copyPhysReg(MBB, II, DL, SecondRegSavedTo, SecondRegSaved, true); 413 } 414 else 415 Available.reset(SpReg); 416 copyPhysReg(MBB, II, DL, SpReg, Mips::SP, false); 417 BuildMI(MBB, II, DL, get(Mips::AdduRxRyRz16), Reg) 418 .addReg(SpReg, RegState::Kill) 419 .addReg(Reg); 420 } 421 else 422 BuildMI(MBB, II, DL, get(Mips:: AdduRxRyRz16), Reg).addReg(FrameReg) 423 .addReg(Reg, RegState::Kill); 424 if (FirstRegSaved || SecondRegSaved) { 425 II = std::next(II); 426 if (FirstRegSaved) 427 copyPhysReg(MBB, II, DL, FirstRegSaved, FirstRegSavedTo, true); 428 if (SecondRegSaved) 429 copyPhysReg(MBB, II, DL, SecondRegSaved, SecondRegSavedTo, true); 430 } 431 return Reg; 432 } 433 434 unsigned Mips16InstrInfo::getAnalyzableBrOpc(unsigned Opc) const { 435 return (Opc == Mips::BeqzRxImmX16 || Opc == Mips::BimmX16 || 436 Opc == Mips::Bimm16 || 437 Opc == Mips::Bteqz16 || Opc == Mips::Btnez16 || 438 Opc == Mips::BeqzRxImm16 || Opc == Mips::BnezRxImm16 || 439 Opc == Mips::BnezRxImmX16 || Opc == Mips::BteqzX16 || 440 Opc == Mips::BteqzT8CmpX16 || Opc == Mips::BteqzT8CmpiX16 || 441 Opc == Mips::BteqzT8SltX16 || Opc == Mips::BteqzT8SltuX16 || 442 Opc == Mips::BteqzT8SltiX16 || Opc == Mips::BteqzT8SltiuX16 || 443 Opc == Mips::BtnezX16 || Opc == Mips::BtnezT8CmpX16 || 444 Opc == Mips::BtnezT8CmpiX16 || Opc == Mips::BtnezT8SltX16 || 445 Opc == Mips::BtnezT8SltuX16 || Opc == Mips::BtnezT8SltiX16 || 446 Opc == Mips::BtnezT8SltiuX16 ) ? Opc : 0; 447 } 448 449 void Mips16InstrInfo::ExpandRetRA16(MachineBasicBlock &MBB, 450 MachineBasicBlock::iterator I, 451 unsigned Opc) const { 452 BuildMI(MBB, I, I->getDebugLoc(), get(Opc)); 453 } 454 455 const MCInstrDesc &Mips16InstrInfo::AddiuSpImm(int64_t Imm) const { 456 if (validSpImm8(Imm)) 457 return get(Mips::AddiuSpImm16); 458 else 459 return get(Mips::AddiuSpImmX16); 460 } 461 462 void Mips16InstrInfo::BuildAddiuSpImm 463 (MachineBasicBlock &MBB, MachineBasicBlock::iterator I, int64_t Imm) const { 464 DebugLoc DL; 465 BuildMI(MBB, I, DL, AddiuSpImm(Imm)).addImm(Imm); 466 } 467 468 const MipsInstrInfo *llvm::createMips16InstrInfo(const MipsSubtarget &STI) { 469 return new Mips16InstrInfo(STI); 470 } 471 472 bool Mips16InstrInfo::validImmediate(unsigned Opcode, unsigned Reg, 473 int64_t Amount) { 474 switch (Opcode) { 475 case Mips::LbRxRyOffMemX16: 476 case Mips::LbuRxRyOffMemX16: 477 case Mips::LhRxRyOffMemX16: 478 case Mips::LhuRxRyOffMemX16: 479 case Mips::SbRxRyOffMemX16: 480 case Mips::ShRxRyOffMemX16: 481 case Mips::LwRxRyOffMemX16: 482 case Mips::SwRxRyOffMemX16: 483 case Mips::SwRxSpImmX16: 484 case Mips::LwRxSpImmX16: 485 return isInt<16>(Amount); 486 case Mips::AddiuRxRyOffMemX16: 487 if ((Reg == Mips::PC) || (Reg == Mips::SP)) 488 return isInt<16>(Amount); 489 return isInt<15>(Amount); 490 } 491 llvm_unreachable("unexpected Opcode in validImmediate"); 492 } 493