FastISel.cpp revision e7b4dec881fced628644b65eb90b9ff72dfc1fee
1//===-- FastISel.cpp - Implementation of the FastISel class ---------------===// 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 contains the implementation of the FastISel class. 11// 12// "Fast" instruction selection is designed to emit very poor code quickly. 13// Also, it is not designed to be able to do much lowering, so most illegal 14// types (e.g. i64 on 32-bit targets) and operations are not supported. It is 15// also not intended to be able to do much optimization, except in a few cases 16// where doing optimizations reduces overall compile time. For example, folding 17// constants into immediate fields is often done, because it's cheap and it 18// reduces the number of instructions later phases have to examine. 19// 20// "Fast" instruction selection is able to fail gracefully and transfer 21// control to the SelectionDAG selector for operations that it doesn't 22// support. In many cases, this allows us to avoid duplicating a lot of 23// the complicated lowering logic that SelectionDAG currently has. 24// 25// The intended use for "fast" instruction selection is "-O0" mode 26// compilation, where the quality of the generated code is irrelevant when 27// weighed against the speed at which the code can be generated. Also, 28// at -O0, the LLVM optimizers are not running, and this makes the 29// compile time of codegen a much higher portion of the overall compile 30// time. Despite its limitations, "fast" instruction selection is able to 31// handle enough code on its own to provide noticeable overall speedups 32// in -O0 compiles. 33// 34// Basic operations are supported in a target-independent way, by reading 35// the same instruction descriptions that the SelectionDAG selector reads, 36// and identifying simple arithmetic operations that can be directly selected 37// from simple operators. More complicated operations currently require 38// target-specific code. 39// 40//===----------------------------------------------------------------------===// 41 42#include "llvm/Function.h" 43#include "llvm/GlobalVariable.h" 44#include "llvm/Instructions.h" 45#include "llvm/IntrinsicInst.h" 46#include "llvm/CodeGen/FastISel.h" 47#include "llvm/CodeGen/FunctionLoweringInfo.h" 48#include "llvm/CodeGen/MachineInstrBuilder.h" 49#include "llvm/CodeGen/MachineModuleInfo.h" 50#include "llvm/CodeGen/MachineRegisterInfo.h" 51#include "llvm/Analysis/DebugInfo.h" 52#include "llvm/Analysis/Loads.h" 53#include "llvm/Target/TargetData.h" 54#include "llvm/Target/TargetInstrInfo.h" 55#include "llvm/Target/TargetLowering.h" 56#include "llvm/Target/TargetMachine.h" 57#include "llvm/Support/ErrorHandling.h" 58using namespace llvm; 59 60/// startNewBlock - Set the current block to which generated machine 61/// instructions will be appended, and clear the local CSE map. 62/// 63void FastISel::startNewBlock() { 64 LocalValueMap.clear(); 65 66 // Start out as null, meaining no local-value instructions have 67 // been emitted. 68 LastLocalValue = 0; 69 70 // Advance the last local value past any EH_LABEL instructions. 71 MachineBasicBlock::iterator 72 I = FuncInfo.MBB->begin(), E = FuncInfo.MBB->end(); 73 while (I != E && I->getOpcode() == TargetOpcode::EH_LABEL) { 74 LastLocalValue = I; 75 ++I; 76 } 77} 78 79bool FastISel::hasTrivialKill(const Value *V) const { 80 // Don't consider constants or arguments to have trivial kills. 81 const Instruction *I = dyn_cast<Instruction>(V); 82 if (!I) 83 return false; 84 85 // No-op casts are trivially coalesced by fast-isel. 86 if (const CastInst *Cast = dyn_cast<CastInst>(I)) 87 if (Cast->isNoopCast(TD.getIntPtrType(Cast->getContext())) && 88 !hasTrivialKill(Cast->getOperand(0))) 89 return false; 90 91 // Only instructions with a single use in the same basic block are considered 92 // to have trivial kills. 93 return I->hasOneUse() && 94 !(I->getOpcode() == Instruction::BitCast || 95 I->getOpcode() == Instruction::PtrToInt || 96 I->getOpcode() == Instruction::IntToPtr) && 97 cast<Instruction>(I->use_begin())->getParent() == I->getParent(); 98} 99 100unsigned FastISel::getRegForValue(const Value *V) { 101 EVT RealVT = TLI.getValueType(V->getType(), /*AllowUnknown=*/true); 102 // Don't handle non-simple values in FastISel. 103 if (!RealVT.isSimple()) 104 return 0; 105 106 // Ignore illegal types. We must do this before looking up the value 107 // in ValueMap because Arguments are given virtual registers regardless 108 // of whether FastISel can handle them. 109 MVT VT = RealVT.getSimpleVT(); 110 if (!TLI.isTypeLegal(VT)) { 111 // Promote MVT::i1 to a legal type though, because it's common and easy. 112 if (VT == MVT::i1) 113 VT = TLI.getTypeToTransformTo(V->getContext(), VT).getSimpleVT(); 114 else 115 return 0; 116 } 117 118 // Look up the value to see if we already have a register for it. We 119 // cache values defined by Instructions across blocks, and other values 120 // only locally. This is because Instructions already have the SSA 121 // def-dominates-use requirement enforced. 122 DenseMap<const Value *, unsigned>::iterator I = FuncInfo.ValueMap.find(V); 123 if (I != FuncInfo.ValueMap.end()) { 124 unsigned Reg = I->second; 125 return Reg; 126 } 127 unsigned Reg = LocalValueMap[V]; 128 if (Reg != 0) 129 return Reg; 130 131 // In bottom-up mode, just create the virtual register which will be used 132 // to hold the value. It will be materialized later. 133 if (isa<Instruction>(V) && 134 (!isa<AllocaInst>(V) || 135 !FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(V)))) 136 return FuncInfo.InitializeRegForValue(V); 137 138 SavePoint SaveInsertPt = enterLocalValueArea(); 139 140 // Materialize the value in a register. Emit any instructions in the 141 // local value area. 142 Reg = materializeRegForValue(V, VT); 143 144 leaveLocalValueArea(SaveInsertPt); 145 146 return Reg; 147} 148 149/// materializeRegForValue - Helper for getRegForVale. This function is 150/// called when the value isn't already available in a register and must 151/// be materialized with new instructions. 152unsigned FastISel::materializeRegForValue(const Value *V, MVT VT) { 153 unsigned Reg = 0; 154 155 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 156 if (CI->getValue().getActiveBits() <= 64) 157 Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue()); 158 } else if (isa<AllocaInst>(V)) { 159 Reg = TargetMaterializeAlloca(cast<AllocaInst>(V)); 160 } else if (isa<ConstantPointerNull>(V)) { 161 // Translate this as an integer zero so that it can be 162 // local-CSE'd with actual integer zeros. 163 Reg = 164 getRegForValue(Constant::getNullValue(TD.getIntPtrType(V->getContext()))); 165 } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) { 166 // Try to emit the constant directly. 167 Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF); 168 169 if (!Reg) { 170 // Try to emit the constant by using an integer constant with a cast. 171 const APFloat &Flt = CF->getValueAPF(); 172 EVT IntVT = TLI.getPointerTy(); 173 174 uint64_t x[2]; 175 uint32_t IntBitWidth = IntVT.getSizeInBits(); 176 bool isExact; 177 (void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true, 178 APFloat::rmTowardZero, &isExact); 179 if (isExact) { 180 APInt IntVal(IntBitWidth, 2, x); 181 182 unsigned IntegerReg = 183 getRegForValue(ConstantInt::get(V->getContext(), IntVal)); 184 if (IntegerReg != 0) 185 Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, 186 IntegerReg, /*Kill=*/false); 187 } 188 } 189 } else if (const Operator *Op = dyn_cast<Operator>(V)) { 190 if (!SelectOperator(Op, Op->getOpcode())) 191 if (!isa<Instruction>(Op) || 192 !TargetSelectInstruction(cast<Instruction>(Op))) 193 return 0; 194 Reg = lookUpRegForValue(Op); 195 } else if (isa<UndefValue>(V)) { 196 Reg = createResultReg(TLI.getRegClassFor(VT)); 197 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, 198 TII.get(TargetOpcode::IMPLICIT_DEF), Reg); 199 } 200 201 // If target-independent code couldn't handle the value, give target-specific 202 // code a try. 203 if (!Reg && isa<Constant>(V)) 204 Reg = TargetMaterializeConstant(cast<Constant>(V)); 205 206 // Don't cache constant materializations in the general ValueMap. 207 // To do so would require tracking what uses they dominate. 208 if (Reg != 0) { 209 LocalValueMap[V] = Reg; 210 LastLocalValue = MRI.getVRegDef(Reg); 211 } 212 return Reg; 213} 214 215unsigned FastISel::lookUpRegForValue(const Value *V) { 216 // Look up the value to see if we already have a register for it. We 217 // cache values defined by Instructions across blocks, and other values 218 // only locally. This is because Instructions already have the SSA 219 // def-dominates-use requirement enforced. 220 DenseMap<const Value *, unsigned>::iterator I = FuncInfo.ValueMap.find(V); 221 if (I != FuncInfo.ValueMap.end()) 222 return I->second; 223 return LocalValueMap[V]; 224} 225 226/// UpdateValueMap - Update the value map to include the new mapping for this 227/// instruction, or insert an extra copy to get the result in a previous 228/// determined register. 229/// NOTE: This is only necessary because we might select a block that uses 230/// a value before we select the block that defines the value. It might be 231/// possible to fix this by selecting blocks in reverse postorder. 232unsigned FastISel::UpdateValueMap(const Value *I, unsigned Reg) { 233 if (!isa<Instruction>(I)) { 234 LocalValueMap[I] = Reg; 235 return Reg; 236 } 237 238 unsigned &AssignedReg = FuncInfo.ValueMap[I]; 239 if (AssignedReg == 0) 240 // Use the new register. 241 AssignedReg = Reg; 242 else if (Reg != AssignedReg) { 243 // Arrange for uses of AssignedReg to be replaced by uses of Reg. 244 FuncInfo.RegFixups[AssignedReg] = Reg; 245 246 AssignedReg = Reg; 247 } 248 249 return AssignedReg; 250} 251 252std::pair<unsigned, bool> FastISel::getRegForGEPIndex(const Value *Idx) { 253 unsigned IdxN = getRegForValue(Idx); 254 if (IdxN == 0) 255 // Unhandled operand. Halt "fast" selection and bail. 256 return std::pair<unsigned, bool>(0, false); 257 258 bool IdxNIsKill = hasTrivialKill(Idx); 259 260 // If the index is smaller or larger than intptr_t, truncate or extend it. 261 MVT PtrVT = TLI.getPointerTy(); 262 EVT IdxVT = EVT::getEVT(Idx->getType(), /*HandleUnknown=*/false); 263 if (IdxVT.bitsLT(PtrVT)) { 264 IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::SIGN_EXTEND, 265 IdxN, IdxNIsKill); 266 IdxNIsKill = true; 267 } 268 else if (IdxVT.bitsGT(PtrVT)) { 269 IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::TRUNCATE, 270 IdxN, IdxNIsKill); 271 IdxNIsKill = true; 272 } 273 return std::pair<unsigned, bool>(IdxN, IdxNIsKill); 274} 275 276void FastISel::recomputeInsertPt() { 277 if (getLastLocalValue()) { 278 FuncInfo.InsertPt = getLastLocalValue(); 279 FuncInfo.MBB = FuncInfo.InsertPt->getParent(); 280 ++FuncInfo.InsertPt; 281 } else 282 FuncInfo.InsertPt = FuncInfo.MBB->getFirstNonPHI(); 283 284 // Now skip past any EH_LABELs, which must remain at the beginning. 285 while (FuncInfo.InsertPt != FuncInfo.MBB->end() && 286 FuncInfo.InsertPt->getOpcode() == TargetOpcode::EH_LABEL) 287 ++FuncInfo.InsertPt; 288} 289 290FastISel::SavePoint FastISel::enterLocalValueArea() { 291 MachineBasicBlock::iterator OldInsertPt = FuncInfo.InsertPt; 292 DebugLoc OldDL = DL; 293 recomputeInsertPt(); 294 DL = DebugLoc(); 295 SavePoint SP = { OldInsertPt, OldDL }; 296 return SP; 297} 298 299void FastISel::leaveLocalValueArea(SavePoint OldInsertPt) { 300 if (FuncInfo.InsertPt != FuncInfo.MBB->begin()) 301 LastLocalValue = llvm::prior(FuncInfo.InsertPt); 302 303 // Restore the previous insert position. 304 FuncInfo.InsertPt = OldInsertPt.InsertPt; 305 DL = OldInsertPt.DL; 306} 307 308/// SelectBinaryOp - Select and emit code for a binary operator instruction, 309/// which has an opcode which directly corresponds to the given ISD opcode. 310/// 311bool FastISel::SelectBinaryOp(const User *I, unsigned ISDOpcode) { 312 EVT VT = EVT::getEVT(I->getType(), /*HandleUnknown=*/true); 313 if (VT == MVT::Other || !VT.isSimple()) 314 // Unhandled type. Halt "fast" selection and bail. 315 return false; 316 317 // We only handle legal types. For example, on x86-32 the instruction 318 // selector contains all of the 64-bit instructions from x86-64, 319 // under the assumption that i64 won't be used if the target doesn't 320 // support it. 321 if (!TLI.isTypeLegal(VT)) { 322 // MVT::i1 is special. Allow AND, OR, or XOR because they 323 // don't require additional zeroing, which makes them easy. 324 if (VT == MVT::i1 && 325 (ISDOpcode == ISD::AND || ISDOpcode == ISD::OR || 326 ISDOpcode == ISD::XOR)) 327 VT = TLI.getTypeToTransformTo(I->getContext(), VT); 328 else 329 return false; 330 } 331 332 unsigned Op0 = getRegForValue(I->getOperand(0)); 333 if (Op0 == 0) 334 // Unhandled operand. Halt "fast" selection and bail. 335 return false; 336 337 bool Op0IsKill = hasTrivialKill(I->getOperand(0)); 338 339 // Check if the second operand is a constant and handle it appropriately. 340 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { 341 unsigned ResultReg = FastEmit_ri(VT.getSimpleVT(), VT.getSimpleVT(), 342 ISDOpcode, Op0, Op0IsKill, 343 CI->getZExtValue()); 344 if (ResultReg != 0) { 345 // We successfully emitted code for the given LLVM Instruction. 346 UpdateValueMap(I, ResultReg); 347 return true; 348 } 349 } 350 351 // Check if the second operand is a constant float. 352 if (ConstantFP *CF = dyn_cast<ConstantFP>(I->getOperand(1))) { 353 unsigned ResultReg = FastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(), 354 ISDOpcode, Op0, Op0IsKill, CF); 355 if (ResultReg != 0) { 356 // We successfully emitted code for the given LLVM Instruction. 357 UpdateValueMap(I, ResultReg); 358 return true; 359 } 360 } 361 362 unsigned Op1 = getRegForValue(I->getOperand(1)); 363 if (Op1 == 0) 364 // Unhandled operand. Halt "fast" selection and bail. 365 return false; 366 367 bool Op1IsKill = hasTrivialKill(I->getOperand(1)); 368 369 // Now we have both operands in registers. Emit the instruction. 370 unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(), 371 ISDOpcode, 372 Op0, Op0IsKill, 373 Op1, Op1IsKill); 374 if (ResultReg == 0) 375 // Target-specific code wasn't able to find a machine opcode for 376 // the given ISD opcode and type. Halt "fast" selection and bail. 377 return false; 378 379 // We successfully emitted code for the given LLVM Instruction. 380 UpdateValueMap(I, ResultReg); 381 return true; 382} 383 384bool FastISel::SelectGetElementPtr(const User *I) { 385 unsigned N = getRegForValue(I->getOperand(0)); 386 if (N == 0) 387 // Unhandled operand. Halt "fast" selection and bail. 388 return false; 389 390 bool NIsKill = hasTrivialKill(I->getOperand(0)); 391 392 const Type *Ty = I->getOperand(0)->getType(); 393 MVT VT = TLI.getPointerTy(); 394 for (GetElementPtrInst::const_op_iterator OI = I->op_begin()+1, 395 E = I->op_end(); OI != E; ++OI) { 396 const Value *Idx = *OI; 397 if (const StructType *StTy = dyn_cast<StructType>(Ty)) { 398 unsigned Field = cast<ConstantInt>(Idx)->getZExtValue(); 399 if (Field) { 400 // N = N + Offset 401 uint64_t Offs = TD.getStructLayout(StTy)->getElementOffset(Field); 402 // FIXME: This can be optimized by combining the add with a 403 // subsequent one. 404 N = FastEmit_ri_(VT, ISD::ADD, N, NIsKill, Offs, VT); 405 if (N == 0) 406 // Unhandled operand. Halt "fast" selection and bail. 407 return false; 408 NIsKill = true; 409 } 410 Ty = StTy->getElementType(Field); 411 } else { 412 Ty = cast<SequentialType>(Ty)->getElementType(); 413 414 // If this is a constant subscript, handle it quickly. 415 if (const ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) { 416 if (CI->isZero()) continue; 417 uint64_t Offs = 418 TD.getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue(); 419 N = FastEmit_ri_(VT, ISD::ADD, N, NIsKill, Offs, VT); 420 if (N == 0) 421 // Unhandled operand. Halt "fast" selection and bail. 422 return false; 423 NIsKill = true; 424 continue; 425 } 426 427 // N = N + Idx * ElementSize; 428 uint64_t ElementSize = TD.getTypeAllocSize(Ty); 429 std::pair<unsigned, bool> Pair = getRegForGEPIndex(Idx); 430 unsigned IdxN = Pair.first; 431 bool IdxNIsKill = Pair.second; 432 if (IdxN == 0) 433 // Unhandled operand. Halt "fast" selection and bail. 434 return false; 435 436 if (ElementSize != 1) { 437 IdxN = FastEmit_ri_(VT, ISD::MUL, IdxN, IdxNIsKill, ElementSize, VT); 438 if (IdxN == 0) 439 // Unhandled operand. Halt "fast" selection and bail. 440 return false; 441 IdxNIsKill = true; 442 } 443 N = FastEmit_rr(VT, VT, ISD::ADD, N, NIsKill, IdxN, IdxNIsKill); 444 if (N == 0) 445 // Unhandled operand. Halt "fast" selection and bail. 446 return false; 447 } 448 } 449 450 // We successfully emitted code for the given LLVM Instruction. 451 UpdateValueMap(I, N); 452 return true; 453} 454 455bool FastISel::SelectCall(const User *I) { 456 const Function *F = cast<CallInst>(I)->getCalledFunction(); 457 if (!F) return false; 458 459 // Handle selected intrinsic function calls. 460 unsigned IID = F->getIntrinsicID(); 461 switch (IID) { 462 default: break; 463 case Intrinsic::dbg_declare: { 464 const DbgDeclareInst *DI = cast<DbgDeclareInst>(I); 465 if (!DIVariable(DI->getVariable()).Verify() || 466 !FuncInfo.MF->getMMI().hasDebugInfo()) 467 return true; 468 469 const Value *Address = DI->getAddress(); 470 if (!Address) 471 return true; 472 if (isa<UndefValue>(Address)) 473 return true; 474 const AllocaInst *AI = dyn_cast<AllocaInst>(Address); 475 // Don't handle byval struct arguments or VLAs, for example. 476 if (!AI) 477 // Building the map above is target independent. Generating DBG_VALUE 478 // inline is target dependent; do this now. 479 (void)TargetSelectInstruction(cast<Instruction>(I)); 480 return true; 481 } 482 case Intrinsic::dbg_value: { 483 // This form of DBG_VALUE is target-independent. 484 const DbgValueInst *DI = cast<DbgValueInst>(I); 485 const TargetInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE); 486 const Value *V = DI->getValue(); 487 if (!V) { 488 // Currently the optimizer can produce this; insert an undef to 489 // help debugging. Probably the optimizer should not do this. 490 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 491 .addReg(0U).addImm(DI->getOffset()) 492 .addMetadata(DI->getVariable()); 493 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 494 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 495 .addImm(CI->getZExtValue()).addImm(DI->getOffset()) 496 .addMetadata(DI->getVariable()); 497 } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) { 498 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 499 .addFPImm(CF).addImm(DI->getOffset()) 500 .addMetadata(DI->getVariable()); 501 } else if (unsigned Reg = lookUpRegForValue(V)) { 502 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 503 .addReg(Reg, RegState::Debug).addImm(DI->getOffset()) 504 .addMetadata(DI->getVariable()); 505 } else { 506 // We can't yet handle anything else here because it would require 507 // generating code, thus altering codegen because of debug info. 508 // Insert an undef so we can see what we dropped. 509 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 510 .addReg(0U).addImm(DI->getOffset()) 511 .addMetadata(DI->getVariable()); 512 } 513 return true; 514 } 515 case Intrinsic::eh_exception: { 516 EVT VT = TLI.getValueType(I->getType()); 517 switch (TLI.getOperationAction(ISD::EXCEPTIONADDR, VT)) { 518 default: break; 519 case TargetLowering::Expand: { 520 assert(FuncInfo.MBB->isLandingPad() && 521 "Call to eh.exception not in landing pad!"); 522 unsigned Reg = TLI.getExceptionAddressRegister(); 523 const TargetRegisterClass *RC = TLI.getRegClassFor(VT); 524 unsigned ResultReg = createResultReg(RC); 525 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 526 ResultReg).addReg(Reg); 527 UpdateValueMap(I, ResultReg); 528 return true; 529 } 530 } 531 break; 532 } 533 case Intrinsic::eh_selector: { 534 EVT VT = TLI.getValueType(I->getType()); 535 switch (TLI.getOperationAction(ISD::EHSELECTION, VT)) { 536 default: break; 537 case TargetLowering::Expand: { 538 if (FuncInfo.MBB->isLandingPad()) 539 AddCatchInfo(*cast<CallInst>(I), &FuncInfo.MF->getMMI(), FuncInfo.MBB); 540 else { 541#ifndef NDEBUG 542 FuncInfo.CatchInfoLost.insert(cast<CallInst>(I)); 543#endif 544 // FIXME: Mark exception selector register as live in. Hack for PR1508. 545 unsigned Reg = TLI.getExceptionSelectorRegister(); 546 if (Reg) FuncInfo.MBB->addLiveIn(Reg); 547 } 548 549 unsigned Reg = TLI.getExceptionSelectorRegister(); 550 EVT SrcVT = TLI.getPointerTy(); 551 const TargetRegisterClass *RC = TLI.getRegClassFor(SrcVT); 552 unsigned ResultReg = createResultReg(RC); 553 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 554 ResultReg).addReg(Reg); 555 556 bool ResultRegIsKill = hasTrivialKill(I); 557 558 // Cast the register to the type of the selector. 559 if (SrcVT.bitsGT(MVT::i32)) 560 ResultReg = FastEmit_r(SrcVT.getSimpleVT(), MVT::i32, ISD::TRUNCATE, 561 ResultReg, ResultRegIsKill); 562 else if (SrcVT.bitsLT(MVT::i32)) 563 ResultReg = FastEmit_r(SrcVT.getSimpleVT(), MVT::i32, 564 ISD::SIGN_EXTEND, ResultReg, ResultRegIsKill); 565 if (ResultReg == 0) 566 // Unhandled operand. Halt "fast" selection and bail. 567 return false; 568 569 UpdateValueMap(I, ResultReg); 570 571 return true; 572 } 573 } 574 break; 575 } 576 } 577 578 // An arbitrary call. Bail. 579 return false; 580} 581 582bool FastISel::SelectCast(const User *I, unsigned Opcode) { 583 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 584 EVT DstVT = TLI.getValueType(I->getType()); 585 586 if (SrcVT == MVT::Other || !SrcVT.isSimple() || 587 DstVT == MVT::Other || !DstVT.isSimple()) 588 // Unhandled type. Halt "fast" selection and bail. 589 return false; 590 591 // Check if the destination type is legal. Or as a special case, 592 // it may be i1 if we're doing a truncate because that's 593 // easy and somewhat common. 594 if (!TLI.isTypeLegal(DstVT)) 595 if (DstVT != MVT::i1 || Opcode != ISD::TRUNCATE) 596 // Unhandled type. Halt "fast" selection and bail. 597 return false; 598 599 // Check if the source operand is legal. Or as a special case, 600 // it may be i1 if we're doing zero-extension because that's 601 // easy and somewhat common. 602 if (!TLI.isTypeLegal(SrcVT)) 603 if (SrcVT != MVT::i1 || Opcode != ISD::ZERO_EXTEND) 604 // Unhandled type. Halt "fast" selection and bail. 605 return false; 606 607 unsigned InputReg = getRegForValue(I->getOperand(0)); 608 if (!InputReg) 609 // Unhandled operand. Halt "fast" selection and bail. 610 return false; 611 612 bool InputRegIsKill = hasTrivialKill(I->getOperand(0)); 613 614 // If the operand is i1, arrange for the high bits in the register to be zero. 615 if (SrcVT == MVT::i1) { 616 SrcVT = TLI.getTypeToTransformTo(I->getContext(), SrcVT); 617 InputReg = FastEmitZExtFromI1(SrcVT.getSimpleVT(), InputReg, InputRegIsKill); 618 if (!InputReg) 619 return false; 620 InputRegIsKill = true; 621 } 622 // If the result is i1, truncate to the target's type for i1 first. 623 if (DstVT == MVT::i1) 624 DstVT = TLI.getTypeToTransformTo(I->getContext(), DstVT); 625 626 unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(), 627 DstVT.getSimpleVT(), 628 Opcode, 629 InputReg, InputRegIsKill); 630 if (!ResultReg) 631 return false; 632 633 UpdateValueMap(I, ResultReg); 634 return true; 635} 636 637bool FastISel::SelectBitCast(const User *I) { 638 // If the bitcast doesn't change the type, just use the operand value. 639 if (I->getType() == I->getOperand(0)->getType()) { 640 unsigned Reg = getRegForValue(I->getOperand(0)); 641 if (Reg == 0) 642 return false; 643 UpdateValueMap(I, Reg); 644 return true; 645 } 646 647 // Bitcasts of other values become reg-reg copies or BIT_CONVERT operators. 648 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 649 EVT DstVT = TLI.getValueType(I->getType()); 650 651 if (SrcVT == MVT::Other || !SrcVT.isSimple() || 652 DstVT == MVT::Other || !DstVT.isSimple() || 653 !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT)) 654 // Unhandled type. Halt "fast" selection and bail. 655 return false; 656 657 unsigned Op0 = getRegForValue(I->getOperand(0)); 658 if (Op0 == 0) 659 // Unhandled operand. Halt "fast" selection and bail. 660 return false; 661 662 bool Op0IsKill = hasTrivialKill(I->getOperand(0)); 663 664 // First, try to perform the bitcast by inserting a reg-reg copy. 665 unsigned ResultReg = 0; 666 if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) { 667 TargetRegisterClass* SrcClass = TLI.getRegClassFor(SrcVT); 668 TargetRegisterClass* DstClass = TLI.getRegClassFor(DstVT); 669 // Don't attempt a cross-class copy. It will likely fail. 670 if (SrcClass == DstClass) { 671 ResultReg = createResultReg(DstClass); 672 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 673 ResultReg).addReg(Op0); 674 } 675 } 676 677 // If the reg-reg copy failed, select a BIT_CONVERT opcode. 678 if (!ResultReg) 679 ResultReg = FastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(), 680 ISD::BIT_CONVERT, Op0, Op0IsKill); 681 682 if (!ResultReg) 683 return false; 684 685 UpdateValueMap(I, ResultReg); 686 return true; 687} 688 689bool 690FastISel::SelectInstruction(const Instruction *I) { 691 // Just before the terminator instruction, insert instructions to 692 // feed PHI nodes in successor blocks. 693 if (isa<TerminatorInst>(I)) 694 if (!HandlePHINodesInSuccessorBlocks(I->getParent())) 695 return false; 696 697 DL = I->getDebugLoc(); 698 699 // First, try doing target-independent selection. 700 if (SelectOperator(I, I->getOpcode())) { 701 DL = DebugLoc(); 702 return true; 703 } 704 705 // Next, try calling the target to attempt to handle the instruction. 706 if (TargetSelectInstruction(I)) { 707 DL = DebugLoc(); 708 return true; 709 } 710 711 DL = DebugLoc(); 712 return false; 713} 714 715/// FastEmitBranch - Emit an unconditional branch to the given block, 716/// unless it is the immediate (fall-through) successor, and update 717/// the CFG. 718void 719FastISel::FastEmitBranch(MachineBasicBlock *MSucc, DebugLoc DL) { 720 if (FuncInfo.MBB->isLayoutSuccessor(MSucc)) { 721 // The unconditional fall-through case, which needs no instructions. 722 } else { 723 // The unconditional branch case. 724 TII.InsertBranch(*FuncInfo.MBB, MSucc, NULL, 725 SmallVector<MachineOperand, 0>(), DL); 726 } 727 FuncInfo.MBB->addSuccessor(MSucc); 728} 729 730/// SelectFNeg - Emit an FNeg operation. 731/// 732bool 733FastISel::SelectFNeg(const User *I) { 734 unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I)); 735 if (OpReg == 0) return false; 736 737 bool OpRegIsKill = hasTrivialKill(I); 738 739 // If the target has ISD::FNEG, use it. 740 EVT VT = TLI.getValueType(I->getType()); 741 unsigned ResultReg = FastEmit_r(VT.getSimpleVT(), VT.getSimpleVT(), 742 ISD::FNEG, OpReg, OpRegIsKill); 743 if (ResultReg != 0) { 744 UpdateValueMap(I, ResultReg); 745 return true; 746 } 747 748 // Bitcast the value to integer, twiddle the sign bit with xor, 749 // and then bitcast it back to floating-point. 750 if (VT.getSizeInBits() > 64) return false; 751 EVT IntVT = EVT::getIntegerVT(I->getContext(), VT.getSizeInBits()); 752 if (!TLI.isTypeLegal(IntVT)) 753 return false; 754 755 unsigned IntReg = FastEmit_r(VT.getSimpleVT(), IntVT.getSimpleVT(), 756 ISD::BIT_CONVERT, OpReg, OpRegIsKill); 757 if (IntReg == 0) 758 return false; 759 760 unsigned IntResultReg = FastEmit_ri_(IntVT.getSimpleVT(), ISD::XOR, 761 IntReg, /*Kill=*/true, 762 UINT64_C(1) << (VT.getSizeInBits()-1), 763 IntVT.getSimpleVT()); 764 if (IntResultReg == 0) 765 return false; 766 767 ResultReg = FastEmit_r(IntVT.getSimpleVT(), VT.getSimpleVT(), 768 ISD::BIT_CONVERT, IntResultReg, /*Kill=*/true); 769 if (ResultReg == 0) 770 return false; 771 772 UpdateValueMap(I, ResultReg); 773 return true; 774} 775 776bool 777FastISel::SelectOperator(const User *I, unsigned Opcode) { 778 switch (Opcode) { 779 case Instruction::Add: 780 return SelectBinaryOp(I, ISD::ADD); 781 case Instruction::FAdd: 782 return SelectBinaryOp(I, ISD::FADD); 783 case Instruction::Sub: 784 return SelectBinaryOp(I, ISD::SUB); 785 case Instruction::FSub: 786 // FNeg is currently represented in LLVM IR as a special case of FSub. 787 if (BinaryOperator::isFNeg(I)) 788 return SelectFNeg(I); 789 return SelectBinaryOp(I, ISD::FSUB); 790 case Instruction::Mul: 791 return SelectBinaryOp(I, ISD::MUL); 792 case Instruction::FMul: 793 return SelectBinaryOp(I, ISD::FMUL); 794 case Instruction::SDiv: 795 return SelectBinaryOp(I, ISD::SDIV); 796 case Instruction::UDiv: 797 return SelectBinaryOp(I, ISD::UDIV); 798 case Instruction::FDiv: 799 return SelectBinaryOp(I, ISD::FDIV); 800 case Instruction::SRem: 801 return SelectBinaryOp(I, ISD::SREM); 802 case Instruction::URem: 803 return SelectBinaryOp(I, ISD::UREM); 804 case Instruction::FRem: 805 return SelectBinaryOp(I, ISD::FREM); 806 case Instruction::Shl: 807 return SelectBinaryOp(I, ISD::SHL); 808 case Instruction::LShr: 809 return SelectBinaryOp(I, ISD::SRL); 810 case Instruction::AShr: 811 return SelectBinaryOp(I, ISD::SRA); 812 case Instruction::And: 813 return SelectBinaryOp(I, ISD::AND); 814 case Instruction::Or: 815 return SelectBinaryOp(I, ISD::OR); 816 case Instruction::Xor: 817 return SelectBinaryOp(I, ISD::XOR); 818 819 case Instruction::GetElementPtr: 820 return SelectGetElementPtr(I); 821 822 case Instruction::Br: { 823 const BranchInst *BI = cast<BranchInst>(I); 824 825 if (BI->isUnconditional()) { 826 const BasicBlock *LLVMSucc = BI->getSuccessor(0); 827 MachineBasicBlock *MSucc = FuncInfo.MBBMap[LLVMSucc]; 828 FastEmitBranch(MSucc, BI->getDebugLoc()); 829 return true; 830 } 831 832 // Conditional branches are not handed yet. 833 // Halt "fast" selection and bail. 834 return false; 835 } 836 837 case Instruction::Unreachable: 838 // Nothing to emit. 839 return true; 840 841 case Instruction::Alloca: 842 // FunctionLowering has the static-sized case covered. 843 if (FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(I))) 844 return true; 845 846 // Dynamic-sized alloca is not handled yet. 847 return false; 848 849 case Instruction::Call: 850 return SelectCall(I); 851 852 case Instruction::BitCast: 853 return SelectBitCast(I); 854 855 case Instruction::FPToSI: 856 return SelectCast(I, ISD::FP_TO_SINT); 857 case Instruction::ZExt: 858 return SelectCast(I, ISD::ZERO_EXTEND); 859 case Instruction::SExt: 860 return SelectCast(I, ISD::SIGN_EXTEND); 861 case Instruction::Trunc: 862 return SelectCast(I, ISD::TRUNCATE); 863 case Instruction::SIToFP: 864 return SelectCast(I, ISD::SINT_TO_FP); 865 866 case Instruction::IntToPtr: // Deliberate fall-through. 867 case Instruction::PtrToInt: { 868 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 869 EVT DstVT = TLI.getValueType(I->getType()); 870 if (DstVT.bitsGT(SrcVT)) 871 return SelectCast(I, ISD::ZERO_EXTEND); 872 if (DstVT.bitsLT(SrcVT)) 873 return SelectCast(I, ISD::TRUNCATE); 874 unsigned Reg = getRegForValue(I->getOperand(0)); 875 if (Reg == 0) return false; 876 UpdateValueMap(I, Reg); 877 return true; 878 } 879 880 case Instruction::PHI: 881 llvm_unreachable("FastISel shouldn't visit PHI nodes!"); 882 883 default: 884 // Unhandled instruction. Halt "fast" selection and bail. 885 return false; 886 } 887} 888 889FastISel::FastISel(FunctionLoweringInfo &funcInfo) 890 : FuncInfo(funcInfo), 891 MRI(FuncInfo.MF->getRegInfo()), 892 MFI(*FuncInfo.MF->getFrameInfo()), 893 MCP(*FuncInfo.MF->getConstantPool()), 894 TM(FuncInfo.MF->getTarget()), 895 TD(*TM.getTargetData()), 896 TII(*TM.getInstrInfo()), 897 TLI(*TM.getTargetLowering()), 898 TRI(*TM.getRegisterInfo()) { 899} 900 901FastISel::~FastISel() {} 902 903unsigned FastISel::FastEmit_(MVT, MVT, 904 unsigned) { 905 return 0; 906} 907 908unsigned FastISel::FastEmit_r(MVT, MVT, 909 unsigned, 910 unsigned /*Op0*/, bool /*Op0IsKill*/) { 911 return 0; 912} 913 914unsigned FastISel::FastEmit_rr(MVT, MVT, 915 unsigned, 916 unsigned /*Op0*/, bool /*Op0IsKill*/, 917 unsigned /*Op1*/, bool /*Op1IsKill*/) { 918 return 0; 919} 920 921unsigned FastISel::FastEmit_i(MVT, MVT, unsigned, uint64_t /*Imm*/) { 922 return 0; 923} 924 925unsigned FastISel::FastEmit_f(MVT, MVT, 926 unsigned, const ConstantFP * /*FPImm*/) { 927 return 0; 928} 929 930unsigned FastISel::FastEmit_ri(MVT, MVT, 931 unsigned, 932 unsigned /*Op0*/, bool /*Op0IsKill*/, 933 uint64_t /*Imm*/) { 934 return 0; 935} 936 937unsigned FastISel::FastEmit_rf(MVT, MVT, 938 unsigned, 939 unsigned /*Op0*/, bool /*Op0IsKill*/, 940 const ConstantFP * /*FPImm*/) { 941 return 0; 942} 943 944unsigned FastISel::FastEmit_rri(MVT, MVT, 945 unsigned, 946 unsigned /*Op0*/, bool /*Op0IsKill*/, 947 unsigned /*Op1*/, bool /*Op1IsKill*/, 948 uint64_t /*Imm*/) { 949 return 0; 950} 951 952/// FastEmit_ri_ - This method is a wrapper of FastEmit_ri. It first tries 953/// to emit an instruction with an immediate operand using FastEmit_ri. 954/// If that fails, it materializes the immediate into a register and try 955/// FastEmit_rr instead. 956unsigned FastISel::FastEmit_ri_(MVT VT, unsigned Opcode, 957 unsigned Op0, bool Op0IsKill, 958 uint64_t Imm, MVT ImmType) { 959 // First check if immediate type is legal. If not, we can't use the ri form. 960 unsigned ResultReg = FastEmit_ri(VT, VT, Opcode, Op0, Op0IsKill, Imm); 961 if (ResultReg != 0) 962 return ResultReg; 963 unsigned MaterialReg = FastEmit_i(ImmType, ImmType, ISD::Constant, Imm); 964 if (MaterialReg == 0) 965 return 0; 966 return FastEmit_rr(VT, VT, Opcode, 967 Op0, Op0IsKill, 968 MaterialReg, /*Kill=*/true); 969} 970 971/// FastEmit_rf_ - This method is a wrapper of FastEmit_ri. It first tries 972/// to emit an instruction with a floating-point immediate operand using 973/// FastEmit_rf. If that fails, it materializes the immediate into a register 974/// and try FastEmit_rr instead. 975unsigned FastISel::FastEmit_rf_(MVT VT, unsigned Opcode, 976 unsigned Op0, bool Op0IsKill, 977 const ConstantFP *FPImm, MVT ImmType) { 978 // First check if immediate type is legal. If not, we can't use the rf form. 979 unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, Op0IsKill, FPImm); 980 if (ResultReg != 0) 981 return ResultReg; 982 983 // Materialize the constant in a register. 984 unsigned MaterialReg = FastEmit_f(ImmType, ImmType, ISD::ConstantFP, FPImm); 985 if (MaterialReg == 0) { 986 // If the target doesn't have a way to directly enter a floating-point 987 // value into a register, use an alternate approach. 988 // TODO: The current approach only supports floating-point constants 989 // that can be constructed by conversion from integer values. This should 990 // be replaced by code that creates a load from a constant-pool entry, 991 // which will require some target-specific work. 992 const APFloat &Flt = FPImm->getValueAPF(); 993 EVT IntVT = TLI.getPointerTy(); 994 995 uint64_t x[2]; 996 uint32_t IntBitWidth = IntVT.getSizeInBits(); 997 bool isExact; 998 (void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true, 999 APFloat::rmTowardZero, &isExact); 1000 if (!isExact) 1001 return 0; 1002 APInt IntVal(IntBitWidth, 2, x); 1003 1004 unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(), 1005 ISD::Constant, IntVal.getZExtValue()); 1006 if (IntegerReg == 0) 1007 return 0; 1008 MaterialReg = FastEmit_r(IntVT.getSimpleVT(), VT, 1009 ISD::SINT_TO_FP, IntegerReg, /*Kill=*/true); 1010 if (MaterialReg == 0) 1011 return 0; 1012 } 1013 return FastEmit_rr(VT, VT, Opcode, 1014 Op0, Op0IsKill, 1015 MaterialReg, /*Kill=*/true); 1016} 1017 1018unsigned FastISel::createResultReg(const TargetRegisterClass* RC) { 1019 return MRI.createVirtualRegister(RC); 1020} 1021 1022unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode, 1023 const TargetRegisterClass* RC) { 1024 unsigned ResultReg = createResultReg(RC); 1025 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1026 1027 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg); 1028 return ResultReg; 1029} 1030 1031unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode, 1032 const TargetRegisterClass *RC, 1033 unsigned Op0, bool Op0IsKill) { 1034 unsigned ResultReg = createResultReg(RC); 1035 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1036 1037 if (II.getNumDefs() >= 1) 1038 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg) 1039 .addReg(Op0, Op0IsKill * RegState::Kill); 1040 else { 1041 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 1042 .addReg(Op0, Op0IsKill * RegState::Kill); 1043 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1044 ResultReg).addReg(II.ImplicitDefs[0]); 1045 } 1046 1047 return ResultReg; 1048} 1049 1050unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode, 1051 const TargetRegisterClass *RC, 1052 unsigned Op0, bool Op0IsKill, 1053 unsigned Op1, bool Op1IsKill) { 1054 unsigned ResultReg = createResultReg(RC); 1055 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1056 1057 if (II.getNumDefs() >= 1) 1058 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg) 1059 .addReg(Op0, Op0IsKill * RegState::Kill) 1060 .addReg(Op1, Op1IsKill * RegState::Kill); 1061 else { 1062 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 1063 .addReg(Op0, Op0IsKill * RegState::Kill) 1064 .addReg(Op1, Op1IsKill * RegState::Kill); 1065 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1066 ResultReg).addReg(II.ImplicitDefs[0]); 1067 } 1068 return ResultReg; 1069} 1070 1071unsigned FastISel::FastEmitInst_ri(unsigned MachineInstOpcode, 1072 const TargetRegisterClass *RC, 1073 unsigned Op0, bool Op0IsKill, 1074 uint64_t Imm) { 1075 unsigned ResultReg = createResultReg(RC); 1076 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1077 1078 if (II.getNumDefs() >= 1) 1079 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg) 1080 .addReg(Op0, Op0IsKill * RegState::Kill) 1081 .addImm(Imm); 1082 else { 1083 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 1084 .addReg(Op0, Op0IsKill * RegState::Kill) 1085 .addImm(Imm); 1086 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1087 ResultReg).addReg(II.ImplicitDefs[0]); 1088 } 1089 return ResultReg; 1090} 1091 1092unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode, 1093 const TargetRegisterClass *RC, 1094 unsigned Op0, bool Op0IsKill, 1095 const ConstantFP *FPImm) { 1096 unsigned ResultReg = createResultReg(RC); 1097 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1098 1099 if (II.getNumDefs() >= 1) 1100 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg) 1101 .addReg(Op0, Op0IsKill * RegState::Kill) 1102 .addFPImm(FPImm); 1103 else { 1104 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 1105 .addReg(Op0, Op0IsKill * RegState::Kill) 1106 .addFPImm(FPImm); 1107 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1108 ResultReg).addReg(II.ImplicitDefs[0]); 1109 } 1110 return ResultReg; 1111} 1112 1113unsigned FastISel::FastEmitInst_rri(unsigned MachineInstOpcode, 1114 const TargetRegisterClass *RC, 1115 unsigned Op0, bool Op0IsKill, 1116 unsigned Op1, bool Op1IsKill, 1117 uint64_t Imm) { 1118 unsigned ResultReg = createResultReg(RC); 1119 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1120 1121 if (II.getNumDefs() >= 1) 1122 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg) 1123 .addReg(Op0, Op0IsKill * RegState::Kill) 1124 .addReg(Op1, Op1IsKill * RegState::Kill) 1125 .addImm(Imm); 1126 else { 1127 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II) 1128 .addReg(Op0, Op0IsKill * RegState::Kill) 1129 .addReg(Op1, Op1IsKill * RegState::Kill) 1130 .addImm(Imm); 1131 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1132 ResultReg).addReg(II.ImplicitDefs[0]); 1133 } 1134 return ResultReg; 1135} 1136 1137unsigned FastISel::FastEmitInst_i(unsigned MachineInstOpcode, 1138 const TargetRegisterClass *RC, 1139 uint64_t Imm) { 1140 unsigned ResultReg = createResultReg(RC); 1141 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1142 1143 if (II.getNumDefs() >= 1) 1144 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, ResultReg).addImm(Imm); 1145 else { 1146 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II).addImm(Imm); 1147 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(TargetOpcode::COPY), 1148 ResultReg).addReg(II.ImplicitDefs[0]); 1149 } 1150 return ResultReg; 1151} 1152 1153unsigned FastISel::FastEmitInst_extractsubreg(MVT RetVT, 1154 unsigned Op0, bool Op0IsKill, 1155 uint32_t Idx) { 1156 unsigned ResultReg = createResultReg(TLI.getRegClassFor(RetVT)); 1157 assert(TargetRegisterInfo::isVirtualRegister(Op0) && 1158 "Cannot yet extract from physregs"); 1159 BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, 1160 DL, TII.get(TargetOpcode::COPY), ResultReg) 1161 .addReg(Op0, getKillRegState(Op0IsKill), Idx); 1162 return ResultReg; 1163} 1164 1165/// FastEmitZExtFromI1 - Emit MachineInstrs to compute the value of Op 1166/// with all but the least significant bit set to zero. 1167unsigned FastISel::FastEmitZExtFromI1(MVT VT, unsigned Op0, bool Op0IsKill) { 1168 return FastEmit_ri(VT, VT, ISD::AND, Op0, Op0IsKill, 1); 1169} 1170 1171/// HandlePHINodesInSuccessorBlocks - Handle PHI nodes in successor blocks. 1172/// Emit code to ensure constants are copied into registers when needed. 1173/// Remember the virtual registers that need to be added to the Machine PHI 1174/// nodes as input. We cannot just directly add them, because expansion 1175/// might result in multiple MBB's for one BB. As such, the start of the 1176/// BB might correspond to a different MBB than the end. 1177bool FastISel::HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) { 1178 const TerminatorInst *TI = LLVMBB->getTerminator(); 1179 1180 SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled; 1181 unsigned OrigNumPHINodesToUpdate = FuncInfo.PHINodesToUpdate.size(); 1182 1183 // Check successor nodes' PHI nodes that expect a constant to be available 1184 // from this block. 1185 for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) { 1186 const BasicBlock *SuccBB = TI->getSuccessor(succ); 1187 if (!isa<PHINode>(SuccBB->begin())) continue; 1188 MachineBasicBlock *SuccMBB = FuncInfo.MBBMap[SuccBB]; 1189 1190 // If this terminator has multiple identical successors (common for 1191 // switches), only handle each succ once. 1192 if (!SuccsHandled.insert(SuccMBB)) continue; 1193 1194 MachineBasicBlock::iterator MBBI = SuccMBB->begin(); 1195 1196 // At this point we know that there is a 1-1 correspondence between LLVM PHI 1197 // nodes and Machine PHI nodes, but the incoming operands have not been 1198 // emitted yet. 1199 for (BasicBlock::const_iterator I = SuccBB->begin(); 1200 const PHINode *PN = dyn_cast<PHINode>(I); ++I) { 1201 1202 // Ignore dead phi's. 1203 if (PN->use_empty()) continue; 1204 1205 // Only handle legal types. Two interesting things to note here. First, 1206 // by bailing out early, we may leave behind some dead instructions, 1207 // since SelectionDAG's HandlePHINodesInSuccessorBlocks will insert its 1208 // own moves. Second, this check is necessary becuase FastISel doesn't 1209 // use CreateRegs to create registers, so it always creates 1210 // exactly one register for each non-void instruction. 1211 EVT VT = TLI.getValueType(PN->getType(), /*AllowUnknown=*/true); 1212 if (VT == MVT::Other || !TLI.isTypeLegal(VT)) { 1213 // Promote MVT::i1. 1214 if (VT == MVT::i1) 1215 VT = TLI.getTypeToTransformTo(LLVMBB->getContext(), VT); 1216 else { 1217 FuncInfo.PHINodesToUpdate.resize(OrigNumPHINodesToUpdate); 1218 return false; 1219 } 1220 } 1221 1222 const Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB); 1223 1224 // Set the DebugLoc for the copy. Prefer the location of the operand 1225 // if there is one; use the location of the PHI otherwise. 1226 DL = PN->getDebugLoc(); 1227 if (const Instruction *Inst = dyn_cast<Instruction>(PHIOp)) 1228 DL = Inst->getDebugLoc(); 1229 1230 unsigned Reg = getRegForValue(PHIOp); 1231 if (Reg == 0) { 1232 FuncInfo.PHINodesToUpdate.resize(OrigNumPHINodesToUpdate); 1233 return false; 1234 } 1235 FuncInfo.PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg)); 1236 DL = DebugLoc(); 1237 } 1238 } 1239 1240 return true; 1241} 1242