lib/Target/Lanai/LanaiInstrInfo.cpp

   1 //===-- LanaiInstrInfo.cpp - Lanai Instruction 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 TargetInstrInfo class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "LanaiInstrInfo.h"
  14 #include "LanaiAluCode.h"
  15 #include "LanaiCondCode.h"
  16 #include "MCTargetDesc/LanaiBaseInfo.h"
  17 #include "llvm/ADT/STLExtras.h"
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineInstrBuilder.h"
  21 #include "llvm/CodeGen/MachineRegisterInfo.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/Support/TargetRegistry.h"
  24
  25 using namespace llvm;
  26
  27 #define GET_INSTRINFO_CTOR_DTOR
  28 #include "LanaiGenInstrInfo.inc"
  29
  30 LanaiInstrInfo::LanaiInstrInfo()
  31     : LanaiGenInstrInfo(Lanai::ADJCALLSTACKDOWN, Lanai::ADJCALLSTACKUP),
  32       RegisterInfo() {}
  33
  34 void LanaiInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
  35                                  MachineBasicBlock::iterator Position,
  36                                  const DebugLoc &DL,
  37                                  unsigned DestinationRegister,
  38                                  unsigned SourceRegister,
  39                                  bool KillSource) const {
  40   if (!Lanai::GPRRegClass.contains(DestinationRegister, SourceRegister)) {
  41     llvm_unreachable("Impossible reg-to-reg copy");
  42   }
  43
  44   BuildMI(MBB, Position, DL, get(Lanai::OR_I_LO), DestinationRegister)
  45       .addReg(SourceRegister, getKillRegState(KillSource))
  46       .addImm(0);
  47 }
  48
  49 void LanaiInstrInfo::storeRegToStackSlot(
  50     MachineBasicBlock &MBB, MachineBasicBlock::iterator Position,
  51     unsigned SourceRegister, bool IsKill, int FrameIndex,
  52     const TargetRegisterClass *RegisterClass,
  53     const TargetRegisterInfo * /*RegisterInfo*/) const {
  54   DebugLoc DL;
  55   if (Position != MBB.end()) {
  56     DL = Position->getDebugLoc();
  57   }
  58
  59   if (!Lanai::GPRRegClass.hasSubClassEq(RegisterClass)) {
  60     llvm_unreachable("Can't store this register to stack slot");
  61   }
  62   BuildMI(MBB, Position, DL, get(Lanai::SW_RI))
  63       .addReg(SourceRegister, getKillRegState(IsKill))
  64       .addFrameIndex(FrameIndex)
  65       .addImm(0)
  66       .addImm(LPAC::ADD);
  67 }
  68
  69 void LanaiInstrInfo::loadRegFromStackSlot(
  70     MachineBasicBlock &MBB, MachineBasicBlock::iterator Position,
  71     unsigned DestinationRegister, int FrameIndex,
  72     const TargetRegisterClass *RegisterClass,
  73     const TargetRegisterInfo * /*RegisterInfo*/) const {
  74   DebugLoc DL;
  75   if (Position != MBB.end()) {
  76     DL = Position->getDebugLoc();
  77   }
  78
  79   if (!Lanai::GPRRegClass.hasSubClassEq(RegisterClass)) {
  80     llvm_unreachable("Can't load this register from stack slot");
  81   }
  82   BuildMI(MBB, Position, DL, get(Lanai::LDW_RI), DestinationRegister)
  83       .addFrameIndex(FrameIndex)
  84       .addImm(0)
  85       .addImm(LPAC::ADD);
  86 }
  87
  88 bool LanaiInstrInfo::areMemAccessesTriviallyDisjoint(
  89     const MachineInstr &MIa, const MachineInstr &MIb,
  90     AliasAnalysis * /*AA*/) const {
  91   assert(MIa.mayLoadOrStore() && "MIa must be a load or store.");
  92   assert(MIb.mayLoadOrStore() && "MIb must be a load or store.");
  93
  94   if (MIa.hasUnmodeledSideEffects() || MIb.hasUnmodeledSideEffects() ||
  95       MIa.hasOrderedMemoryRef() || MIb.hasOrderedMemoryRef())
  96     return false;
  97
  98   // Retrieve the base register, offset from the base register and width. Width
  99   // is the size of memory that is being loaded/stored (e.g. 1, 2, 4).  If
 100   // base registers are identical, and the offset of a lower memory access +
 101   // the width doesn't overlap the offset of a higher memory access,
 102   // then the memory accesses are different.
 103   const TargetRegisterInfo *TRI = &getRegisterInfo();
 104   const MachineOperand *BaseOpA = nullptr, *BaseOpB = nullptr;
 105   int64_t OffsetA = 0, OffsetB = 0;
 106   unsigned int WidthA = 0, WidthB = 0;
 107   if (getMemOperandWithOffsetWidth(MIa, BaseOpA, OffsetA, WidthA, TRI) &&
 108       getMemOperandWithOffsetWidth(MIb, BaseOpB, OffsetB, WidthB, TRI)) {
 109     if (BaseOpA->isIdenticalTo(*BaseOpB)) {
 110       int LowOffset = std::min(OffsetA, OffsetB);
 111       int HighOffset = std::max(OffsetA, OffsetB);
 112       int LowWidth = (LowOffset == OffsetA) ? WidthA : WidthB;
 113       if (LowOffset + LowWidth <= HighOffset)
 114         return true;
 115     }
 116   }
 117   return false;
 118 }
 119
 120 bool LanaiInstrInfo::expandPostRAPseudo(MachineInstr & /*MI*/) const {
 121   return false;
 122 }
 123
 124 static LPCC::CondCode getOppositeCondition(LPCC::CondCode CC) {
 125   switch (CC) {
 126   case LPCC::ICC_T: //  true
 127     return LPCC::ICC_F;
 128   case LPCC::ICC_F: //  false
 129     return LPCC::ICC_T;
 130   case LPCC::ICC_HI: //  high
 131     return LPCC::ICC_LS;
 132   case LPCC::ICC_LS: //  low or same
 133     return LPCC::ICC_HI;
 134   case LPCC::ICC_CC: //  carry cleared
 135     return LPCC::ICC_CS;
 136   case LPCC::ICC_CS: //  carry set
 137     return LPCC::ICC_CC;
 138   case LPCC::ICC_NE: //  not equal
 139     return LPCC::ICC_EQ;
 140   case LPCC::ICC_EQ: //  equal
 141     return LPCC::ICC_NE;
 142   case LPCC::ICC_VC: //  oVerflow cleared
 143     return LPCC::ICC_VS;
 144   case LPCC::ICC_VS: //  oVerflow set
 145     return LPCC::ICC_VC;
 146   case LPCC::ICC_PL: //  plus (note: 0 is "minus" too here)
 147     return LPCC::ICC_MI;
 148   case LPCC::ICC_MI: //  minus
 149     return LPCC::ICC_PL;
 150   case LPCC::ICC_GE: //  greater than or equal
 151     return LPCC::ICC_LT;
 152   case LPCC::ICC_LT: //  less than
 153     return LPCC::ICC_GE;
 154   case LPCC::ICC_GT: //  greater than
 155     return LPCC::ICC_LE;
 156   case LPCC::ICC_LE: //  less than or equal
 157     return LPCC::ICC_GT;
 158   default:
 159     llvm_unreachable("Invalid condtional code");
 160   }
 161 }
 162
 163 std::pair<unsigned, unsigned>
 164 LanaiInstrInfo::decomposeMachineOperandsTargetFlags(unsigned TF) const {
 165   return std::make_pair(TF, 0u);
 166 }
 167
 168 ArrayRef<std::pair<unsigned, const char *>>
 169 LanaiInstrInfo::getSerializableDirectMachineOperandTargetFlags() const {
 170   using namespace LanaiII;
 171   static const std::pair<unsigned, const char *> TargetFlags[] = {
 172       {MO_ABS_HI, "lanai-hi"},
 173       {MO_ABS_LO, "lanai-lo"},
 174       {MO_NO_FLAG, "lanai-nf"}};
 175   return makeArrayRef(TargetFlags);
 176 }
 177
 178 bool LanaiInstrInfo::analyzeCompare(const MachineInstr &MI, unsigned &SrcReg,
 179                                     unsigned &SrcReg2, int &CmpMask,
 180                                     int &CmpValue) const {
 181   switch (MI.getOpcode()) {
 182   default:
 183     break;
 184   case Lanai::SFSUB_F_RI_LO:
 185   case Lanai::SFSUB_F_RI_HI:
 186     SrcReg = MI.getOperand(0).getReg();
 187     SrcReg2 = 0;
 188     CmpMask = ~0;
 189     CmpValue = MI.getOperand(1).getImm();
 190     return true;
 191   case Lanai::SFSUB_F_RR:
 192     SrcReg = MI.getOperand(0).getReg();
 193     SrcReg2 = MI.getOperand(1).getReg();
 194     CmpMask = ~0;
 195     CmpValue = 0;
 196     return true;
 197   }
 198
 199   return false;
 200 }
 201
 202 // isRedundantFlagInstr - check whether the first instruction, whose only
 203 // purpose is to update flags, can be made redundant.
 204 // * SFSUB_F_RR can be made redundant by SUB_RI if the operands are the same.
 205 // * SFSUB_F_RI can be made redundant by SUB_I if the operands are the same.
 206 inline static bool isRedundantFlagInstr(MachineInstr *CmpI, unsigned SrcReg,
 207                                         unsigned SrcReg2, int ImmValue,
 208                                         MachineInstr *OI) {
 209   if (CmpI->getOpcode() == Lanai::SFSUB_F_RR &&
 210       OI->getOpcode() == Lanai::SUB_R &&
 211       ((OI->getOperand(1).getReg() == SrcReg &&
 212         OI->getOperand(2).getReg() == SrcReg2) ||
 213        (OI->getOperand(1).getReg() == SrcReg2 &&
 214         OI->getOperand(2).getReg() == SrcReg)))
 215     return true;
 216
 217   if (((CmpI->getOpcode() == Lanai::SFSUB_F_RI_LO &&
 218         OI->getOpcode() == Lanai::SUB_I_LO) ||
 219        (CmpI->getOpcode() == Lanai::SFSUB_F_RI_HI &&
 220         OI->getOpcode() == Lanai::SUB_I_HI)) &&
 221       OI->getOperand(1).getReg() == SrcReg &&
 222       OI->getOperand(2).getImm() == ImmValue)
 223     return true;
 224   return false;
 225 }
 226
 227 inline static unsigned flagSettingOpcodeVariant(unsigned OldOpcode) {
 228   switch (OldOpcode) {
 229   case Lanai::ADD_I_HI:
 230     return Lanai::ADD_F_I_HI;
 231   case Lanai::ADD_I_LO:
 232     return Lanai::ADD_F_I_LO;
 233   case Lanai::ADD_R:
 234     return Lanai::ADD_F_R;
 235   case Lanai::ADDC_I_HI:
 236     return Lanai::ADDC_F_I_HI;
 237   case Lanai::ADDC_I_LO:
 238     return Lanai::ADDC_F_I_LO;
 239   case Lanai::ADDC_R:
 240     return Lanai::ADDC_F_R;
 241   case Lanai::AND_I_HI:
 242     return Lanai::AND_F_I_HI;
 243   case Lanai::AND_I_LO:
 244     return Lanai::AND_F_I_LO;
 245   case Lanai::AND_R:
 246     return Lanai::AND_F_R;
 247   case Lanai::OR_I_HI:
 248     return Lanai::OR_F_I_HI;
 249   case Lanai::OR_I_LO:
 250     return Lanai::OR_F_I_LO;
 251   case Lanai::OR_R:
 252     return Lanai::OR_F_R;
 253   case Lanai::SL_I:
 254     return Lanai::SL_F_I;
 255   case Lanai::SRL_R:
 256     return Lanai::SRL_F_R;
 257   case Lanai::SA_I:
 258     return Lanai::SA_F_I;
 259   case Lanai::SRA_R:
 260     return Lanai::SRA_F_R;
 261   case Lanai::SUB_I_HI:
 262     return Lanai::SUB_F_I_HI;
 263   case Lanai::SUB_I_LO:
 264     return Lanai::SUB_F_I_LO;
 265   case Lanai::SUB_R:
 266     return Lanai::SUB_F_R;
 267   case Lanai::SUBB_I_HI:
 268     return Lanai::SUBB_F_I_HI;
 269   case Lanai::SUBB_I_LO:
 270     return Lanai::SUBB_F_I_LO;
 271   case Lanai::SUBB_R:
 272     return Lanai::SUBB_F_R;
 273   case Lanai::XOR_I_HI:
 274     return Lanai::XOR_F_I_HI;
 275   case Lanai::XOR_I_LO:
 276     return Lanai::XOR_F_I_LO;
 277   case Lanai::XOR_R:
 278     return Lanai::XOR_F_R;
 279   default:
 280     return Lanai::NOP;
 281   }
 282 }
 283
 284 bool LanaiInstrInfo::optimizeCompareInstr(
 285     MachineInstr &CmpInstr, unsigned SrcReg, unsigned SrcReg2, int /*CmpMask*/,
 286     int CmpValue, const MachineRegisterInfo *MRI) const {
 287   // Get the unique definition of SrcReg.
 288   MachineInstr *MI = MRI->getUniqueVRegDef(SrcReg);
 289   if (!MI)
 290     return false;
 291
 292   // Get ready to iterate backward from CmpInstr.
 293   MachineBasicBlock::iterator I = CmpInstr, E = MI,
 294                               B = CmpInstr.getParent()->begin();
 295
 296   // Early exit if CmpInstr is at the beginning of the BB.
 297   if (I == B)
 298     return false;
 299
 300   // There are two possible candidates which can be changed to set SR:
 301   // One is MI, the other is a SUB instruction.
 302   // * For SFSUB_F_RR(r1,r2), we are looking for SUB(r1,r2) or SUB(r2,r1).
 303   // * For SFSUB_F_RI(r1, CmpValue), we are looking for SUB(r1, CmpValue).
 304   MachineInstr *Sub = nullptr;
 305   if (SrcReg2 != 0)
 306     // MI is not a candidate to transform into a flag setting instruction.
 307     MI = nullptr;
 308   else if (MI->getParent() != CmpInstr.getParent() || CmpValue != 0) {
 309     // Conservatively refuse to convert an instruction which isn't in the same
 310     // BB as the comparison. Don't return if SFSUB_F_RI and CmpValue != 0 as Sub
 311     // may still be a candidate.
 312     if (CmpInstr.getOpcode() == Lanai::SFSUB_F_RI_LO)
 313       MI = nullptr;
 314     else
 315       return false;
 316   }
 317
 318   // Check that SR isn't set between the comparison instruction and the
 319   // instruction we want to change while searching for Sub.
 320   const TargetRegisterInfo *TRI = &getRegisterInfo();
 321   for (--I; I != E; --I) {
 322     const MachineInstr &Instr = *I;
 323
 324     if (Instr.modifiesRegister(Lanai::SR, TRI) ||
 325         Instr.readsRegister(Lanai::SR, TRI))
 326       // This instruction modifies or uses SR after the one we want to change.
 327       // We can't do this transformation.
 328       return false;
 329
 330     // Check whether CmpInstr can be made redundant by the current instruction.
 331     if (isRedundantFlagInstr(&CmpInstr, SrcReg, SrcReg2, CmpValue, &*I)) {
 332       Sub = &*I;
 333       break;
 334     }
 335
 336     // Don't search outside the containing basic block.
 337     if (I == B)
 338       return false;
 339   }
 340
 341   // Return false if no candidates exist.
 342   if (!MI && !Sub)
 343     return false;
 344
 345   // The single candidate is called MI.
 346   if (!MI)
 347     MI = Sub;
 348
 349   if (flagSettingOpcodeVariant(MI->getOpcode()) != Lanai::NOP) {
 350     bool isSafe = false;
 351
 352     SmallVector<std::pair<MachineOperand *, LPCC::CondCode>, 4>
 353         OperandsToUpdate;
 354     I = CmpInstr;
 355     E = CmpInstr.getParent()->end();
 356     while (!isSafe && ++I != E) {
 357       const MachineInstr &Instr = *I;
 358       for (unsigned IO = 0, EO = Instr.getNumOperands(); !isSafe && IO != EO;
 359            ++IO) {
 360         const MachineOperand &MO = Instr.getOperand(IO);
 361         if (MO.isRegMask() && MO.clobbersPhysReg(Lanai::SR)) {
 362           isSafe = true;
 363           break;
 364         }
 365         if (!MO.isReg() || MO.getReg() != Lanai::SR)
 366           continue;
 367         if (MO.isDef()) {
 368           isSafe = true;
 369           break;
 370         }
 371         // Condition code is after the operand before SR.
 372         LPCC::CondCode CC;
 373         CC = (LPCC::CondCode)Instr.getOperand(IO - 1).getImm();
 374
 375         if (Sub) {
 376           LPCC::CondCode NewCC = getOppositeCondition(CC);
 377           if (NewCC == LPCC::ICC_T)
 378             return false;
 379           // If we have SUB(r1, r2) and CMP(r2, r1), the condition code based on
 380           // CMP needs to be updated to be based on SUB.  Push the condition
 381           // code operands to OperandsToUpdate.  If it is safe to remove
 382           // CmpInstr, the condition code of these operands will be modified.
 383           if (SrcReg2 != 0 && Sub->getOperand(1).getReg() == SrcReg2 &&
 384               Sub->getOperand(2).getReg() == SrcReg) {
 385             OperandsToUpdate.push_back(
 386                 std::make_pair(&((*I).getOperand(IO - 1)), NewCC));
 387           }
 388         } else {
 389           // No Sub, so this is x = <op> y, z; cmp x, 0.
 390           switch (CC) {
 391           case LPCC::ICC_EQ: // Z
 392           case LPCC::ICC_NE: // Z
 393           case LPCC::ICC_MI: // N
 394           case LPCC::ICC_PL: // N
 395           case LPCC::ICC_F:  // none
 396           case LPCC::ICC_T:  // none
 397             // SR can be used multiple times, we should continue.
 398             break;
 399           case LPCC::ICC_CS: // C
 400           case LPCC::ICC_CC: // C
 401           case LPCC::ICC_VS: // V
 402           case LPCC::ICC_VC: // V
 403           case LPCC::ICC_HI: // C Z
 404           case LPCC::ICC_LS: // C Z
 405           case LPCC::ICC_GE: // N V
 406           case LPCC::ICC_LT: // N V
 407           case LPCC::ICC_GT: // Z N V
 408           case LPCC::ICC_LE: // Z N V
 409             // The instruction uses the V bit or C bit which is not safe.
 410             return false;
 411           case LPCC::UNKNOWN:
 412             return false;
 413           }
 414         }
 415       }
 416     }
 417
 418     // If SR is not killed nor re-defined, we should check whether it is
 419     // live-out. If it is live-out, do not optimize.
 420     if (!isSafe) {
 421       MachineBasicBlock *MBB = CmpInstr.getParent();
 422       for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
 423                                             SE = MBB->succ_end();
 424            SI != SE; ++SI)
 425         if ((*SI)->isLiveIn(Lanai::SR))
 426           return false;
 427     }
 428
 429     // Toggle the optional operand to SR.
 430     MI->setDesc(get(flagSettingOpcodeVariant(MI->getOpcode())));
 431     MI->addRegisterDefined(Lanai::SR);
 432     CmpInstr.eraseFromParent();
 433     return true;
 434   }
 435
 436   return false;
 437 }
 438
 439 bool LanaiInstrInfo::analyzeSelect(const MachineInstr &MI,
 440                                    SmallVectorImpl<MachineOperand> &Cond,
 441                                    unsigned &TrueOp, unsigned &FalseOp,
 442                                    bool &Optimizable) const {
 443   assert(MI.getOpcode() == Lanai::SELECT && "unknown select instruction");
 444   // Select operands:
 445   // 0: Def.
 446   // 1: True use.
 447   // 2: False use.
 448   // 3: Condition code.
 449   TrueOp = 1;
 450   FalseOp = 2;
 451   Cond.push_back(MI.getOperand(3));
 452   Optimizable = true;
 453   return false;
 454 }
 455
 456 // Identify instructions that can be folded into a SELECT instruction, and
 457 // return the defining instruction.
 458 static MachineInstr *canFoldIntoSelect(unsigned Reg,
 459                                        const MachineRegisterInfo &MRI) {
 460   if (!Register::isVirtualRegister(Reg))
 461     return nullptr;
 462   if (!MRI.hasOneNonDBGUse(Reg))
 463     return nullptr;
 464   MachineInstr *MI = MRI.getVRegDef(Reg);
 465   if (!MI)
 466     return nullptr;
 467   // MI is folded into the SELECT by predicating it.
 468   if (!MI->isPredicable())
 469     return nullptr;
 470   // Check if MI has any non-dead defs or physreg uses. This also detects
 471   // predicated instructions which will be reading SR.
 472   for (unsigned i = 1, e = MI->getNumOperands(); i != e; ++i) {
 473     const MachineOperand &MO = MI->getOperand(i);
 474     // Reject frame index operands.
 475     if (MO.isFI() || MO.isCPI() || MO.isJTI())
 476       return nullptr;
 477     if (!MO.isReg())
 478       continue;
 479     // MI can't have any tied operands, that would conflict with predication.
 480     if (MO.isTied())
 481       return nullptr;
 482     if (Register::isPhysicalRegister(MO.getReg()))
 483       return nullptr;
 484     if (MO.isDef() && !MO.isDead())
 485       return nullptr;
 486   }
 487   bool DontMoveAcrossStores = true;
 488   if (!MI->isSafeToMove(/*AliasAnalysis=*/nullptr, DontMoveAcrossStores))
 489     return nullptr;
 490   return MI;
 491 }
 492
 493 MachineInstr *
 494 LanaiInstrInfo::optimizeSelect(MachineInstr &MI,
 495                                SmallPtrSetImpl<MachineInstr *> &SeenMIs,
 496                                bool /*PreferFalse*/) const {
 497   assert(MI.getOpcode() == Lanai::SELECT && "unknown select instruction");
 498   MachineRegisterInfo &MRI = MI.getParent()->getParent()->getRegInfo();
 499   MachineInstr *DefMI = canFoldIntoSelect(MI.getOperand(1).getReg(), MRI);
 500   bool Invert = !DefMI;
 501   if (!DefMI)
 502     DefMI = canFoldIntoSelect(MI.getOperand(2).getReg(), MRI);
 503   if (!DefMI)
 504     return nullptr;
 505
 506   // Find new register class to use.
 507   MachineOperand FalseReg = MI.getOperand(Invert ? 1 : 2);
 508   Register DestReg = MI.getOperand(0).getReg();
 509   const TargetRegisterClass *PreviousClass = MRI.getRegClass(FalseReg.getReg());
 510   if (!MRI.constrainRegClass(DestReg, PreviousClass))
 511     return nullptr;
 512
 513   // Create a new predicated version of DefMI.
 514   MachineInstrBuilder NewMI =
 515       BuildMI(*MI.getParent(), MI, MI.getDebugLoc(), DefMI->getDesc(), DestReg);
 516
 517   // Copy all the DefMI operands, excluding its (null) predicate.
 518   const MCInstrDesc &DefDesc = DefMI->getDesc();
 519   for (unsigned i = 1, e = DefDesc.getNumOperands();
 520        i != e && !DefDesc.OpInfo[i].isPredicate(); ++i)
 521     NewMI.add(DefMI->getOperand(i));
 522
 523   unsigned CondCode = MI.getOperand(3).getImm();
 524   if (Invert)
 525     NewMI.addImm(getOppositeCondition(LPCC::CondCode(CondCode)));
 526   else
 527     NewMI.addImm(CondCode);
 528   NewMI.copyImplicitOps(MI);
 529
 530   // The output register value when the predicate is false is an implicit
 531   // register operand tied to the first def.  The tie makes the register
 532   // allocator ensure the FalseReg is allocated the same register as operand 0.
 533   FalseReg.setImplicit();
 534   NewMI.add(FalseReg);
 535   NewMI->tieOperands(0, NewMI->getNumOperands() - 1);
 536
 537   // Update SeenMIs set: register newly created MI and erase removed DefMI.
 538   SeenMIs.insert(NewMI);
 539   SeenMIs.erase(DefMI);
 540
 541   // If MI is inside a loop, and DefMI is outside the loop, then kill flags on
 542   // DefMI would be invalid when transferred inside the loop.  Checking for a
 543   // loop is expensive, but at least remove kill flags if they are in different
 544   // BBs.
 545   if (DefMI->getParent() != MI.getParent())
 546     NewMI->clearKillInfo();
 547
 548   // The caller will erase MI, but not DefMI.
 549   DefMI->eraseFromParent();
 550   return NewMI;
 551 }
 552
 553 // The analyzeBranch function is used to examine conditional instructions and
 554 // remove unnecessary instructions. This method is used by BranchFolder and
 555 // IfConverter machine function passes to improve the CFG.
 556 // - TrueBlock is set to the destination if condition evaluates true (it is the
 557 //   nullptr if the destination is the fall-through branch);
 558 // - FalseBlock is set to the destination if condition evaluates to false (it
 559 //   is the nullptr if the branch is unconditional);
 560 // - condition is populated with machine operands needed to generate the branch
 561 //   to insert in insertBranch;
 562 // Returns: false if branch could successfully be analyzed.
 563 bool LanaiInstrInfo::analyzeBranch(MachineBasicBlock &MBB,
 564                                    MachineBasicBlock *&TrueBlock,
 565                                    MachineBasicBlock *&FalseBlock,
 566                                    SmallVectorImpl<MachineOperand> &Condition,
 567                                    bool AllowModify) const {
 568   // Iterator to current instruction being considered.
 569   MachineBasicBlock::iterator Instruction = MBB.end();
 570
 571   // Start from the bottom of the block and work up, examining the
 572   // terminator instructions.
 573   while (Instruction != MBB.begin()) {
 574     --Instruction;
 575
 576     // Skip over debug instructions.
 577     if (Instruction->isDebugInstr())
 578       continue;
 579
 580     // Working from the bottom, when we see a non-terminator
 581     // instruction, we're done.
 582     if (!isUnpredicatedTerminator(*Instruction))
 583       break;
 584
 585     // A terminator that isn't a branch can't easily be handled
 586     // by this analysis.
 587     if (!Instruction->isBranch())
 588       return true;
 589
 590     // Handle unconditional branches.
 591     if (Instruction->getOpcode() == Lanai::BT) {
 592       if (!AllowModify) {
 593         TrueBlock = Instruction->getOperand(0).getMBB();
 594         continue;
 595       }
 596
 597       // If the block has any instructions after a branch, delete them.
 598       while (std::next(Instruction) != MBB.end()) {
 599         std::next(Instruction)->eraseFromParent();
 600       }
 601
 602       Condition.clear();
 603       FalseBlock = nullptr;
 604
 605       // Delete the jump if it's equivalent to a fall-through.
 606       if (MBB.isLayoutSuccessor(Instruction->getOperand(0).getMBB())) {
 607         TrueBlock = nullptr;
 608         Instruction->eraseFromParent();
 609         Instruction = MBB.end();
 610         continue;
 611       }
 612
 613       // TrueBlock is used to indicate the unconditional destination.
 614       TrueBlock = Instruction->getOperand(0).getMBB();
 615       continue;
 616     }
 617
 618     // Handle conditional branches
 619     unsigned Opcode = Instruction->getOpcode();
 620     if (Opcode != Lanai::BRCC)
 621       return true; // Unknown opcode.
 622
 623     // Multiple conditional branches are not handled here so only proceed if
 624     // there are no conditions enqueued.
 625     if (Condition.empty()) {
 626       LPCC::CondCode BranchCond =
 627           static_cast<LPCC::CondCode>(Instruction->getOperand(1).getImm());
 628
 629       // TrueBlock is the target of the previously seen unconditional branch.
 630       FalseBlock = TrueBlock;
 631       TrueBlock = Instruction->getOperand(0).getMBB();
 632       Condition.push_back(MachineOperand::CreateImm(BranchCond));
 633       continue;
 634     }
 635
 636     // Multiple conditional branches are not handled.
 637     return true;
 638   }
 639
 640   // Return false indicating branch successfully analyzed.
 641   return false;
 642 }
 643
 644 // reverseBranchCondition - Reverses the branch condition of the specified
 645 // condition list, returning false on success and true if it cannot be
 646 // reversed.
 647 bool LanaiInstrInfo::reverseBranchCondition(
 648     SmallVectorImpl<llvm::MachineOperand> &Condition) const {
 649   assert((Condition.size() == 1) &&
 650          "Lanai branch conditions should have one component.");
 651
 652   LPCC::CondCode BranchCond =
 653       static_cast<LPCC::CondCode>(Condition[0].getImm());
 654   Condition[0].setImm(getOppositeCondition(BranchCond));
 655   return false;
 656 }
 657
 658 // Insert the branch with condition specified in condition and given targets
 659 // (TrueBlock and FalseBlock). This function returns the number of machine
 660 // instructions inserted.
 661 unsigned LanaiInstrInfo::insertBranch(MachineBasicBlock &MBB,
 662                                       MachineBasicBlock *TrueBlock,
 663                                       MachineBasicBlock *FalseBlock,
 664                                       ArrayRef<MachineOperand> Condition,
 665                                       const DebugLoc &DL,
 666                                       int *BytesAdded) const {
 667   // Shouldn't be a fall through.
 668   assert(TrueBlock && "insertBranch must not be told to insert a fallthrough");
 669   assert(!BytesAdded && "code size not handled");
 670
 671   // If condition is empty then an unconditional branch is being inserted.
 672   if (Condition.empty()) {
 673     assert(!FalseBlock && "Unconditional branch with multiple successors!");
 674     BuildMI(&MBB, DL, get(Lanai::BT)).addMBB(TrueBlock);
 675     return 1;
 676   }
 677
 678   // Else a conditional branch is inserted.
 679   assert((Condition.size() == 1) &&
 680          "Lanai branch conditions should have one component.");
 681   unsigned ConditionalCode = Condition[0].getImm();
 682   BuildMI(&MBB, DL, get(Lanai::BRCC)).addMBB(TrueBlock).addImm(ConditionalCode);
 683
 684   // If no false block, then false behavior is fall through and no branch needs
 685   // to be inserted.
 686   if (!FalseBlock)
 687     return 1;
 688
 689   BuildMI(&MBB, DL, get(Lanai::BT)).addMBB(FalseBlock);
 690   return 2;
 691 }
 692
 693 unsigned LanaiInstrInfo::removeBranch(MachineBasicBlock &MBB,
 694                                       int *BytesRemoved) const {
 695   assert(!BytesRemoved && "code size not handled");
 696
 697   MachineBasicBlock::iterator Instruction = MBB.end();
 698   unsigned Count = 0;
 699
 700   while (Instruction != MBB.begin()) {
 701     --Instruction;
 702     if (Instruction->isDebugInstr())
 703       continue;
 704     if (Instruction->getOpcode() != Lanai::BT &&
 705         Instruction->getOpcode() != Lanai::BRCC) {
 706       break;
 707     }
 708
 709     // Remove the branch.
 710     Instruction->eraseFromParent();
 711     Instruction = MBB.end();
 712     ++Count;
 713   }
 714
 715   return Count;
 716 }
 717
 718 unsigned LanaiInstrInfo::isLoadFromStackSlot(const MachineInstr &MI,
 719                                              int &FrameIndex) const {
 720   if (MI.getOpcode() == Lanai::LDW_RI)
 721     if (MI.getOperand(1).isFI() && MI.getOperand(2).isImm() &&
 722         MI.getOperand(2).getImm() == 0) {
 723       FrameIndex = MI.getOperand(1).getIndex();
 724       return MI.getOperand(0).getReg();
 725     }
 726   return 0;
 727 }
 728
 729 unsigned LanaiInstrInfo::isLoadFromStackSlotPostFE(const MachineInstr &MI,
 730                                                    int &FrameIndex) const {
 731   if (MI.getOpcode() == Lanai::LDW_RI) {
 732     unsigned Reg;
 733     if ((Reg = isLoadFromStackSlot(MI, FrameIndex)))
 734       return Reg;
 735     // Check for post-frame index elimination operations
 736     SmallVector<const MachineMemOperand *, 1> Accesses;
 737     if (hasLoadFromStackSlot(MI, Accesses)){
 738       FrameIndex =
 739           cast<FixedStackPseudoSourceValue>(Accesses.front()->getPseudoValue())
 740               ->getFrameIndex();
 741       return 1;
 742     }
 743   }
 744   return 0;
 745 }
 746
 747 unsigned LanaiInstrInfo::isStoreToStackSlot(const MachineInstr &MI,
 748                                             int &FrameIndex) const {
 749   if (MI.getOpcode() == Lanai::SW_RI)
 750     if (MI.getOperand(0).isFI() && MI.getOperand(1).isImm() &&
 751         MI.getOperand(1).getImm() == 0) {
 752       FrameIndex = MI.getOperand(0).getIndex();
 753       return MI.getOperand(2).getReg();
 754     }
 755   return 0;
 756 }
 757
 758 bool LanaiInstrInfo::getMemOperandWithOffsetWidth(
 759     const MachineInstr &LdSt, const MachineOperand *&BaseOp, int64_t &Offset,
 760     unsigned &Width, const TargetRegisterInfo * /*TRI*/) const {
 761   // Handle only loads/stores with base register followed by immediate offset
 762   // and with add as ALU op.
 763   if (LdSt.getNumOperands() != 4)
 764     return false;
 765   if (!LdSt.getOperand(1).isReg() || !LdSt.getOperand(2).isImm() ||
 766       !(LdSt.getOperand(3).isImm() && LdSt.getOperand(3).getImm() == LPAC::ADD))
 767     return false;
 768
 769   switch (LdSt.getOpcode()) {
 770   default:
 771     return false;
 772   case Lanai::LDW_RI:
 773   case Lanai::LDW_RR:
 774   case Lanai::SW_RR:
 775   case Lanai::SW_RI:
 776     Width = 4;
 777     break;
 778   case Lanai::LDHs_RI:
 779   case Lanai::LDHz_RI:
 780   case Lanai::STH_RI:
 781     Width = 2;
 782     break;
 783   case Lanai::LDBs_RI:
 784   case Lanai::LDBz_RI:
 785   case Lanai::STB_RI:
 786     Width = 1;
 787     break;
 788   }
 789
 790   BaseOp = &LdSt.getOperand(1);
 791   Offset = LdSt.getOperand(2).getImm();
 792   assert(BaseOp->isReg() && "getMemOperandWithOffset only supports base "
 793                             "operands of type register.");
 794   return true;
 795 }
 796
 797 bool LanaiInstrInfo::getMemOperandWithOffset(const MachineInstr &LdSt,
 798                                         const MachineOperand *&BaseOp,
 799                                         int64_t &Offset,
 800                                         const TargetRegisterInfo *TRI) const {
 801   switch (LdSt.getOpcode()) {
 802   default:
 803     return false;
 804   case Lanai::LDW_RI:
 805   case Lanai::LDW_RR:
 806   case Lanai::SW_RR:
 807   case Lanai::SW_RI:
 808   case Lanai::LDHs_RI:
 809   case Lanai::LDHz_RI:
 810   case Lanai::STH_RI:
 811   case Lanai::LDBs_RI:
 812   case Lanai::LDBz_RI:
 813     unsigned Width;
 814     return getMemOperandWithOffsetWidth(LdSt, BaseOp, Offset, Width, TRI);
 815   }
 816 }