lib/Target/ARM/ARMFastISel.cpp

   1 //===-- ARMFastISel.cpp - ARM FastISel implementation ---------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines the ARM-specific support for the FastISel class. Some
  11 // of the target-specific code is generated by tablegen in the file
  12 // ARMGenFastISel.inc, which is #included here.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "ARM.h"
  17 #include "ARMBaseInstrInfo.h"
  18 #include "ARMRegisterInfo.h"
  19 #include "ARMTargetMachine.h"
  20 #include "ARMSubtarget.h"
  21 #include "llvm/CallingConv.h"
  22 #include "llvm/DerivedTypes.h"
  23 #include "llvm/GlobalVariable.h"
  24 #include "llvm/Instructions.h"
  25 #include "llvm/IntrinsicInst.h"
  26 #include "llvm/CodeGen/Analysis.h"
  27 #include "llvm/CodeGen/FastISel.h"
  28 #include "llvm/CodeGen/FunctionLoweringInfo.h"
  29 #include "llvm/CodeGen/MachineInstrBuilder.h"
  30 #include "llvm/CodeGen/MachineModuleInfo.h"
  31 #include "llvm/CodeGen/MachineConstantPool.h"
  32 #include "llvm/CodeGen/MachineFrameInfo.h"
  33 #include "llvm/CodeGen/MachineRegisterInfo.h"
  34 #include "llvm/Support/CallSite.h"
  35 #include "llvm/Support/CommandLine.h"
  36 #include "llvm/Support/ErrorHandling.h"
  37 #include "llvm/Support/GetElementPtrTypeIterator.h"
  38 #include "llvm/Target/TargetData.h"
  39 #include "llvm/Target/TargetInstrInfo.h"
  40 #include "llvm/Target/TargetLowering.h"
  41 #include "llvm/Target/TargetMachine.h"
  42 #include "llvm/Target/TargetOptions.h"
  43 using namespace llvm;
  44
  45 static cl::opt<bool>
  46 EnableARMFastISel("arm-fast-isel",
  47                   cl::desc("Turn on experimental ARM fast-isel support"),
  48                   cl::init(false), cl::Hidden);
  49
  50 namespace {
  51
  52 class ARMFastISel : public FastISel {
  53
  54   /// Subtarget - Keep a pointer to the ARMSubtarget around so that we can
  55   /// make the right decision when generating code for different targets.
  56   const ARMSubtarget *Subtarget;
  57   const TargetMachine &TM;
  58   const TargetInstrInfo &TII;
  59   const TargetLowering &TLI;
  60   const ARMFunctionInfo *AFI;
  61
  62   // FIXME: Remove this and replace it with queries.
  63   const TargetRegisterClass *FixedRC;
  64
  65   public:
  66     explicit ARMFastISel(FunctionLoweringInfo &funcInfo)
  67     : FastISel(funcInfo),
  68       TM(funcInfo.MF->getTarget()),
  69       TII(*TM.getInstrInfo()),
  70       TLI(*TM.getTargetLowering()) {
  71       Subtarget = &TM.getSubtarget<ARMSubtarget>();
  72       AFI = funcInfo.MF->getInfo<ARMFunctionInfo>();
  73       FixedRC = ARM::GPRRegisterClass;
  74     }
  75
  76     // Code from FastISel.cpp.
  77     virtual unsigned FastEmitInst_(unsigned MachineInstOpcode,
  78                                    const TargetRegisterClass *RC);
  79     virtual unsigned FastEmitInst_r(unsigned MachineInstOpcode,
  80                                     const TargetRegisterClass *RC,
  81                                     unsigned Op0, bool Op0IsKill);
  82     virtual unsigned FastEmitInst_rr(unsigned MachineInstOpcode,
  83                                      const TargetRegisterClass *RC,
  84                                      unsigned Op0, bool Op0IsKill,
  85                                      unsigned Op1, bool Op1IsKill);
  86     virtual unsigned FastEmitInst_ri(unsigned MachineInstOpcode,
  87                                      const TargetRegisterClass *RC,
  88                                      unsigned Op0, bool Op0IsKill,
  89                                      uint64_t Imm);
  90     virtual unsigned FastEmitInst_rf(unsigned MachineInstOpcode,
  91                                      const TargetRegisterClass *RC,
  92                                      unsigned Op0, bool Op0IsKill,
  93                                      const ConstantFP *FPImm);
  94     virtual unsigned FastEmitInst_i(unsigned MachineInstOpcode,
  95                                     const TargetRegisterClass *RC,
  96                                     uint64_t Imm);
  97     virtual unsigned FastEmitInst_rri(unsigned MachineInstOpcode,
  98                                       const TargetRegisterClass *RC,
  99                                       unsigned Op0, bool Op0IsKill,
 100                                       unsigned Op1, bool Op1IsKill,
 101                                       uint64_t Imm);
 102     virtual unsigned FastEmitInst_extractsubreg(MVT RetVT,
 103                                                 unsigned Op0, bool Op0IsKill,
 104                                                 uint32_t Idx);
 105
 106     // Backend specific FastISel code.
 107     virtual bool TargetSelectInstruction(const Instruction *I);
 108
 109   #include "ARMGenFastISel.inc"
 110
 111     // Instruction selection routines.
 112     virtual bool ARMSelectLoad(const Instruction *I);
 113
 114     // Utility routines.
 115   private:
 116     bool ARMLoadAlloca(const Instruction *I);
 117     bool ARMComputeRegOffset(const Value *Obj, unsigned &Reg, int &Offset);
 118
 119     bool DefinesOptionalPredicate(MachineInstr *MI, bool *CPSR);
 120     const MachineInstrBuilder &AddOptionalDefs(const MachineInstrBuilder &MIB);
 121 };
 122
 123 } // end anonymous namespace
 124
 125 // #include "ARMGenCallingConv.inc"
 126
 127 // DefinesOptionalPredicate - This is different from DefinesPredicate in that
 128 // we don't care about implicit defs here, just places we'll need to add a
 129 // default CCReg argument. Sets CPSR if we're setting CPSR instead of CCR.
 130 bool ARMFastISel::DefinesOptionalPredicate(MachineInstr *MI, bool *CPSR) {
 131   const TargetInstrDesc &TID = MI->getDesc();
 132   if (!TID.hasOptionalDef())
 133     return false;
 134
 135   // Look to see if our OptionalDef is defining CPSR or CCR.
 136   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
 137     const MachineOperand &MO = MI->getOperand(i);
 138     if (!MO.isReg() || !MO.isDef()) continue;
 139     if (MO.getReg() == ARM::CPSR)
 140       *CPSR = true;
 141   }
 142   return true;
 143 }
 144
 145 // If the machine is predicable go ahead and add the predicate operands, if
 146 // it needs default CC operands add those.
 147 const MachineInstrBuilder &
 148 ARMFastISel::AddOptionalDefs(const MachineInstrBuilder &MIB) {
 149   MachineInstr *MI = &*MIB;
 150
 151   // Do we use a predicate?
 152   if (TII.isPredicable(MI))
 153     AddDefaultPred(MIB);
 154
 155   // Do we optionally set a predicate?  Preds is size > 0 iff the predicate
 156   // defines CPSR. All other OptionalDefines in ARM are the CCR register.
 157   bool CPSR = false;
 158   if (DefinesOptionalPredicate(MI, &CPSR)) {
 159     if (CPSR)
 160       AddDefaultT1CC(MIB);
 161     else
 162       AddDefaultCC(MIB);
 163   }
 164   return MIB;
 165 }
 166
 167 unsigned ARMFastISel::FastEmitInst_(unsigned MachineInstOpcode,
 168                                     const TargetRegisterClass* RC) {
 169   unsigned ResultReg = createResultReg(RC);
 170   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 171
 172   AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg));
 173   return ResultReg;
 174 }
 175
 176 unsigned ARMFastISel::FastEmitInst_r(unsigned MachineInstOpcode,
 177                                      const TargetRegisterClass *RC,
 178                                      unsigned Op0, bool Op0IsKill) {
 179   unsigned ResultReg = createResultReg(RC);
 180   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 181
 182   if (II.getNumDefs() >= 1)
 183     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 184                    .addReg(Op0, Op0IsKill * RegState::Kill));
 185   else {
 186     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 187                    .addReg(Op0, Op0IsKill * RegState::Kill));
 188     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 189                    TII.get(TargetOpcode::COPY), ResultReg)
 190                    .addReg(II.ImplicitDefs[0]));
 191   }
 192   return ResultReg;
 193 }
 194
 195 unsigned ARMFastISel::FastEmitInst_rr(unsigned MachineInstOpcode,
 196                                       const TargetRegisterClass *RC,
 197                                       unsigned Op0, bool Op0IsKill,
 198                                       unsigned Op1, bool Op1IsKill) {
 199   unsigned ResultReg = createResultReg(RC);
 200   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 201
 202   if (II.getNumDefs() >= 1)
 203     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 204                    .addReg(Op0, Op0IsKill * RegState::Kill)
 205                    .addReg(Op1, Op1IsKill * RegState::Kill));
 206   else {
 207     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 208                    .addReg(Op0, Op0IsKill * RegState::Kill)
 209                    .addReg(Op1, Op1IsKill * RegState::Kill));
 210     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 211                            TII.get(TargetOpcode::COPY), ResultReg)
 212                    .addReg(II.ImplicitDefs[0]));
 213   }
 214   return ResultReg;
 215 }
 216
 217 unsigned ARMFastISel::FastEmitInst_ri(unsigned MachineInstOpcode,
 218                                       const TargetRegisterClass *RC,
 219                                       unsigned Op0, bool Op0IsKill,
 220                                       uint64_t Imm) {
 221   unsigned ResultReg = createResultReg(RC);
 222   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 223
 224   if (II.getNumDefs() >= 1)
 225     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 226                    .addReg(Op0, Op0IsKill * RegState::Kill)
 227                    .addImm(Imm));
 228   else {
 229     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 230                    .addReg(Op0, Op0IsKill * RegState::Kill)
 231                    .addImm(Imm));
 232     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 233                            TII.get(TargetOpcode::COPY), ResultReg)
 234                    .addReg(II.ImplicitDefs[0]));
 235   }
 236   return ResultReg;
 237 }
 238
 239 unsigned ARMFastISel::FastEmitInst_rf(unsigned MachineInstOpcode,
 240                                       const TargetRegisterClass *RC,
 241                                       unsigned Op0, bool Op0IsKill,
 242                                       const ConstantFP *FPImm) {
 243   unsigned ResultReg = createResultReg(RC);
 244   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 245
 246   if (II.getNumDefs() >= 1)
 247     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 248                    .addReg(Op0, Op0IsKill * RegState::Kill)
 249                    .addFPImm(FPImm));
 250   else {
 251     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 252                    .addReg(Op0, Op0IsKill * RegState::Kill)
 253                    .addFPImm(FPImm));
 254     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 255                            TII.get(TargetOpcode::COPY), ResultReg)
 256                    .addReg(II.ImplicitDefs[0]));
 257   }
 258   return ResultReg;
 259 }
 260
 261 unsigned ARMFastISel::FastEmitInst_rri(unsigned MachineInstOpcode,
 262                                        const TargetRegisterClass *RC,
 263                                        unsigned Op0, bool Op0IsKill,
 264                                        unsigned Op1, bool Op1IsKill,
 265                                        uint64_t Imm) {
 266   unsigned ResultReg = createResultReg(RC);
 267   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 268
 269   if (II.getNumDefs() >= 1)
 270     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 271                    .addReg(Op0, Op0IsKill * RegState::Kill)
 272                    .addReg(Op1, Op1IsKill * RegState::Kill)
 273                    .addImm(Imm));
 274   else {
 275     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 276                    .addReg(Op0, Op0IsKill * RegState::Kill)
 277                    .addReg(Op1, Op1IsKill * RegState::Kill)
 278                    .addImm(Imm));
 279     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 280                            TII.get(TargetOpcode::COPY), ResultReg)
 281                    .addReg(II.ImplicitDefs[0]));
 282   }
 283   return ResultReg;
 284 }
 285
 286 unsigned ARMFastISel::FastEmitInst_i(unsigned MachineInstOpcode,
 287                                      const TargetRegisterClass *RC,
 288                                      uint64_t Imm) {
 289   unsigned ResultReg = createResultReg(RC);
 290   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 291
 292   if (II.getNumDefs() >= 1)
 293     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg)
 294                    .addImm(Imm));
 295   else {
 296     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
 297                    .addImm(Imm));
 298     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 299                            TII.get(TargetOpcode::COPY), ResultReg)
 300                    .addReg(II.ImplicitDefs[0]));
 301   }
 302   return ResultReg;
 303 }
 304
 305 unsigned ARMFastISel::FastEmitInst_extractsubreg(MVT RetVT,
 306                                                  unsigned Op0, bool Op0IsKill,
 307                                                  uint32_t Idx) {
 308   unsigned ResultReg = createResultReg(TLI.getRegClassFor(RetVT));
 309   assert(TargetRegisterInfo::isVirtualRegister(Op0) &&
 310          "Cannot yet extract from physregs");
 311   AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt,
 312                          DL, TII.get(TargetOpcode::COPY), ResultReg)
 313                  .addReg(Op0, getKillRegState(Op0IsKill), Idx));
 314   return ResultReg;
 315 }
 316
 317 // Computes the Reg+Offset to get to an object.
 318 bool ARMFastISel::ARMComputeRegOffset(const Value *Obj, unsigned &Reg,
 319                                       int &Offset) {
 320   // Some boilerplate from the X86 FastISel.
 321   const User *U = NULL;
 322   unsigned Opcode = Instruction::UserOp1;
 323   if (const Instruction *I = dyn_cast<Instruction>(Obj)) {
 324     // Don't walk into other basic blocks; it's possible we haven't
 325     // visited them yet, so the instructions may not yet be assigned
 326     // virtual registers.
 327     if (FuncInfo.MBBMap[I->getParent()] != FuncInfo.MBB)
 328       return false;
 329
 330     Opcode = I->getOpcode();
 331     U = I;
 332   } else if (const ConstantExpr *C = dyn_cast<ConstantExpr>(Obj)) {
 333     Opcode = C->getOpcode();
 334     U = C;
 335   }
 336
 337   if (const PointerType *Ty = dyn_cast<PointerType>(Obj->getType()))
 338     if (Ty->getAddressSpace() > 255)
 339       // Fast instruction selection doesn't support the special
 340       // address spaces.
 341       return false;
 342
 343   switch (Opcode) {
 344     default:
 345     //errs() << "Failing Opcode is: " << *Op1 << "\n";
 346     break;
 347     case Instruction::Alloca: {
 348       assert(false && "Alloca should have been handled earlier!");
 349       return false;
 350     }
 351   }
 352
 353   if (const GlobalValue *GV = dyn_cast<GlobalValue>(Obj)) {
 354     //errs() << "Failing GV is: " << GV << "\n";
 355     (void)GV;
 356     return false;
 357   }
 358
 359   // Try to get this in a register if nothing else has worked.
 360   Reg = getRegForValue(Obj);
 361   return Reg != 0;
 362 }
 363
 364 bool ARMFastISel::ARMLoadAlloca(const Instruction *I) {
 365   Value *Op0 = I->getOperand(0);
 366
 367   // Verify it's an alloca.
 368   const Instruction *Inst = dyn_cast<Instruction>(Op0);
 369   if (!Inst || Inst->getOpcode() != Instruction::Alloca) return false;
 370
 371   const AllocaInst *AI = cast<AllocaInst>(Op0);
 372   DenseMap<const AllocaInst*, int>::iterator SI =
 373     FuncInfo.StaticAllocaMap.find(AI);
 374
 375   if (SI != FuncInfo.StaticAllocaMap.end()) {
 376     unsigned ResultReg = createResultReg(FixedRC);
 377     TII.loadRegFromStackSlot(*FuncInfo.MBB, *FuncInfo.InsertPt,
 378                               ResultReg, SI->second, FixedRC,
 379                               TM.getRegisterInfo());
 380     UpdateValueMap(I, ResultReg);
 381     return true;
 382   }
 383
 384   return false;
 385 }
 386
 387 bool ARMFastISel::ARMSelectLoad(const Instruction *I) {
 388   // Our register and offset with innocuous defaults.
 389   unsigned Reg = 0;
 390   int Offset = 0;
 391
 392   // TODO: Think about using loadRegFromStackSlot() here when we can.
 393   if (ARMLoadAlloca(I))
 394     return true;
 395
 396   // See if we can handle this as Reg + Offset
 397   if (!ARMComputeRegOffset(I->getOperand(0), Reg, Offset))
 398     return false;
 399
 400   // Since the offset may be too large for the load instruction
 401   // get the reg+offset into a register.
 402   // TODO: Optimize this somewhat.
 403   ARMCC::CondCodes Pred = ARMCC::AL;
 404   unsigned PredReg = 0;
 405
 406   if (!AFI->isThumbFunction())
 407     emitARMRegPlusImmediate(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 408                             Reg, Reg, Offset, Pred, PredReg,
 409                             static_cast<const ARMBaseInstrInfo&>(TII));
 410   else {
 411     assert(AFI->isThumb2Function());
 412     emitT2RegPlusImmediate(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 413                            Reg, Reg, Offset, Pred, PredReg,
 414                            static_cast<const ARMBaseInstrInfo&>(TII));
 415   }
 416
 417   // FIXME: There is more than one register class in the world...
 418   // TODO: Verify the additions above work, otherwise we'll need to add the
 419   // offset instead of 0 and do all sorts of operand munging.
 420   unsigned ResultReg = createResultReg(FixedRC);
 421   unsigned Opc = AFI->isThumb2Function() ? ARM::tLDR : ARM::LDR;
 422   AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
 423                           TII.get(Opc), ResultReg)
 424                   .addReg(Reg).addReg(0).addImm(0));
 425   UpdateValueMap(I, ResultReg);
 426
 427   return true;
 428 }
 429
 430 bool ARMFastISel::TargetSelectInstruction(const Instruction *I) {
 431   // No Thumb-1 for now.
 432   if (AFI->isThumbFunction() && !AFI->isThumb2Function()) return false;
 433
 434   switch (I->getOpcode()) {
 435     case Instruction::Load:
 436       return ARMSelectLoad(I);
 437     default: break;
 438   }
 439   return false;
 440 }
 441
 442 namespace llvm {
 443   llvm::FastISel *ARM::createFastISel(FunctionLoweringInfo &funcInfo) {
 444     if (EnableARMFastISel) return new ARMFastISel(funcInfo);
 445     return 0;
 446   }
 447 }