FastISel.cpp revision 539f434334ae6cc5becba8b3099eb20ab7fe48dc
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/MachineInstrBuilder.h" 48#include "llvm/CodeGen/MachineModuleInfo.h" 49#include "llvm/CodeGen/MachineRegisterInfo.h" 50#include "llvm/CodeGen/DwarfWriter.h" 51#include "llvm/Analysis/DebugInfo.h" 52#include "llvm/Target/TargetData.h" 53#include "llvm/Target/TargetInstrInfo.h" 54#include "llvm/Target/TargetLowering.h" 55#include "llvm/Target/TargetMachine.h" 56#include "SelectionDAGBuild.h" 57using namespace llvm; 58 59unsigned FastISel::getRegForValue(Value *V) { 60 EVT RealVT = TLI.getValueType(V->getType(), /*AllowUnknown=*/true); 61 // Don't handle non-simple values in FastISel. 62 if (!RealVT.isSimple()) 63 return 0; 64 65 // Ignore illegal types. We must do this before looking up the value 66 // in ValueMap because Arguments are given virtual registers regardless 67 // of whether FastISel can handle them. 68 MVT VT = RealVT.getSimpleVT(); 69 if (!TLI.isTypeLegal(VT)) { 70 // Promote MVT::i1 to a legal type though, because it's common and easy. 71 if (VT == MVT::i1) 72 VT = TLI.getTypeToTransformTo(V->getContext(), VT).getSimpleVT(); 73 else 74 return 0; 75 } 76 77 // Look up the value to see if we already have a register for it. We 78 // cache values defined by Instructions across blocks, and other values 79 // only locally. This is because Instructions already have the SSA 80 // def-dominatess-use requirement enforced. 81 if (ValueMap.count(V)) 82 return ValueMap[V]; 83 unsigned Reg = LocalValueMap[V]; 84 if (Reg != 0) 85 return Reg; 86 87 if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 88 if (CI->getValue().getActiveBits() <= 64) 89 Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue()); 90 } else if (isa<AllocaInst>(V)) { 91 Reg = TargetMaterializeAlloca(cast<AllocaInst>(V)); 92 } else if (isa<ConstantPointerNull>(V)) { 93 // Translate this as an integer zero so that it can be 94 // local-CSE'd with actual integer zeros. 95 Reg = 96 getRegForValue(Constant::getNullValue(TD.getIntPtrType(V->getContext()))); 97 } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) { 98 Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF); 99 100 if (!Reg) { 101 const APFloat &Flt = CF->getValueAPF(); 102 EVT IntVT = TLI.getPointerTy(); 103 104 uint64_t x[2]; 105 uint32_t IntBitWidth = IntVT.getSizeInBits(); 106 bool isExact; 107 (void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true, 108 APFloat::rmTowardZero, &isExact); 109 if (isExact) { 110 APInt IntVal(IntBitWidth, 2, x); 111 112 unsigned IntegerReg = 113 getRegForValue(ConstantInt::get(V->getContext(), IntVal)); 114 if (IntegerReg != 0) 115 Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg); 116 } 117 } 118 } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { 119 if (!SelectOperator(CE, CE->getOpcode())) return 0; 120 Reg = LocalValueMap[CE]; 121 } else if (isa<UndefValue>(V)) { 122 Reg = createResultReg(TLI.getRegClassFor(VT)); 123 BuildMI(MBB, DL, TII.get(TargetInstrInfo::IMPLICIT_DEF), Reg); 124 } 125 126 // If target-independent code couldn't handle the value, give target-specific 127 // code a try. 128 if (!Reg && isa<Constant>(V)) 129 Reg = TargetMaterializeConstant(cast<Constant>(V)); 130 131 // Don't cache constant materializations in the general ValueMap. 132 // To do so would require tracking what uses they dominate. 133 if (Reg != 0) 134 LocalValueMap[V] = Reg; 135 return Reg; 136} 137 138unsigned FastISel::lookUpRegForValue(Value *V) { 139 // Look up the value to see if we already have a register for it. We 140 // cache values defined by Instructions across blocks, and other values 141 // only locally. This is because Instructions already have the SSA 142 // def-dominatess-use requirement enforced. 143 if (ValueMap.count(V)) 144 return ValueMap[V]; 145 return LocalValueMap[V]; 146} 147 148/// UpdateValueMap - Update the value map to include the new mapping for this 149/// instruction, or insert an extra copy to get the result in a previous 150/// determined register. 151/// NOTE: This is only necessary because we might select a block that uses 152/// a value before we select the block that defines the value. It might be 153/// possible to fix this by selecting blocks in reverse postorder. 154unsigned FastISel::UpdateValueMap(Value* I, unsigned Reg) { 155 if (!isa<Instruction>(I)) { 156 LocalValueMap[I] = Reg; 157 return Reg; 158 } 159 160 unsigned &AssignedReg = ValueMap[I]; 161 if (AssignedReg == 0) 162 AssignedReg = Reg; 163 else if (Reg != AssignedReg) { 164 const TargetRegisterClass *RegClass = MRI.getRegClass(Reg); 165 TII.copyRegToReg(*MBB, MBB->end(), AssignedReg, 166 Reg, RegClass, RegClass); 167 } 168 return AssignedReg; 169} 170 171unsigned FastISel::getRegForGEPIndex(Value *Idx) { 172 unsigned IdxN = getRegForValue(Idx); 173 if (IdxN == 0) 174 // Unhandled operand. Halt "fast" selection and bail. 175 return 0; 176 177 // If the index is smaller or larger than intptr_t, truncate or extend it. 178 MVT PtrVT = TLI.getPointerTy(); 179 EVT IdxVT = EVT::getEVT(Idx->getType(), /*HandleUnknown=*/false); 180 if (IdxVT.bitsLT(PtrVT)) 181 IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::SIGN_EXTEND, IdxN); 182 else if (IdxVT.bitsGT(PtrVT)) 183 IdxN = FastEmit_r(IdxVT.getSimpleVT(), PtrVT, ISD::TRUNCATE, IdxN); 184 return IdxN; 185} 186 187/// SelectBinaryOp - Select and emit code for a binary operator instruction, 188/// which has an opcode which directly corresponds to the given ISD opcode. 189/// 190bool FastISel::SelectBinaryOp(User *I, ISD::NodeType ISDOpcode) { 191 EVT VT = EVT::getEVT(I->getType(), /*HandleUnknown=*/true); 192 if (VT == MVT::Other || !VT.isSimple()) 193 // Unhandled type. Halt "fast" selection and bail. 194 return false; 195 196 // We only handle legal types. For example, on x86-32 the instruction 197 // selector contains all of the 64-bit instructions from x86-64, 198 // under the assumption that i64 won't be used if the target doesn't 199 // support it. 200 if (!TLI.isTypeLegal(VT)) { 201 // MVT::i1 is special. Allow AND, OR, or XOR because they 202 // don't require additional zeroing, which makes them easy. 203 if (VT == MVT::i1 && 204 (ISDOpcode == ISD::AND || ISDOpcode == ISD::OR || 205 ISDOpcode == ISD::XOR)) 206 VT = TLI.getTypeToTransformTo(I->getContext(), VT); 207 else 208 return false; 209 } 210 211 unsigned Op0 = getRegForValue(I->getOperand(0)); 212 if (Op0 == 0) 213 // Unhandled operand. Halt "fast" selection and bail. 214 return false; 215 216 // Check if the second operand is a constant and handle it appropriately. 217 if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { 218 unsigned ResultReg = FastEmit_ri(VT.getSimpleVT(), VT.getSimpleVT(), 219 ISDOpcode, Op0, CI->getZExtValue()); 220 if (ResultReg != 0) { 221 // We successfully emitted code for the given LLVM Instruction. 222 UpdateValueMap(I, ResultReg); 223 return true; 224 } 225 } 226 227 // Check if the second operand is a constant float. 228 if (ConstantFP *CF = dyn_cast<ConstantFP>(I->getOperand(1))) { 229 unsigned ResultReg = FastEmit_rf(VT.getSimpleVT(), VT.getSimpleVT(), 230 ISDOpcode, Op0, CF); 231 if (ResultReg != 0) { 232 // We successfully emitted code for the given LLVM Instruction. 233 UpdateValueMap(I, ResultReg); 234 return true; 235 } 236 } 237 238 unsigned Op1 = getRegForValue(I->getOperand(1)); 239 if (Op1 == 0) 240 // Unhandled operand. Halt "fast" selection and bail. 241 return false; 242 243 // Now we have both operands in registers. Emit the instruction. 244 unsigned ResultReg = FastEmit_rr(VT.getSimpleVT(), VT.getSimpleVT(), 245 ISDOpcode, Op0, Op1); 246 if (ResultReg == 0) 247 // Target-specific code wasn't able to find a machine opcode for 248 // the given ISD opcode and type. Halt "fast" selection and bail. 249 return false; 250 251 // We successfully emitted code for the given LLVM Instruction. 252 UpdateValueMap(I, ResultReg); 253 return true; 254} 255 256bool FastISel::SelectGetElementPtr(User *I) { 257 unsigned N = getRegForValue(I->getOperand(0)); 258 if (N == 0) 259 // Unhandled operand. Halt "fast" selection and bail. 260 return false; 261 262 const Type *Ty = I->getOperand(0)->getType(); 263 MVT VT = TLI.getPointerTy(); 264 for (GetElementPtrInst::op_iterator OI = I->op_begin()+1, E = I->op_end(); 265 OI != E; ++OI) { 266 Value *Idx = *OI; 267 if (const StructType *StTy = dyn_cast<StructType>(Ty)) { 268 unsigned Field = cast<ConstantInt>(Idx)->getZExtValue(); 269 if (Field) { 270 // N = N + Offset 271 uint64_t Offs = TD.getStructLayout(StTy)->getElementOffset(Field); 272 // FIXME: This can be optimized by combining the add with a 273 // subsequent one. 274 N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT); 275 if (N == 0) 276 // Unhandled operand. Halt "fast" selection and bail. 277 return false; 278 } 279 Ty = StTy->getElementType(Field); 280 } else { 281 Ty = cast<SequentialType>(Ty)->getElementType(); 282 283 // If this is a constant subscript, handle it quickly. 284 if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) { 285 if (CI->getZExtValue() == 0) continue; 286 uint64_t Offs = 287 TD.getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue(); 288 N = FastEmit_ri_(VT, ISD::ADD, N, Offs, VT); 289 if (N == 0) 290 // Unhandled operand. Halt "fast" selection and bail. 291 return false; 292 continue; 293 } 294 295 // N = N + Idx * ElementSize; 296 uint64_t ElementSize = TD.getTypeAllocSize(Ty); 297 unsigned IdxN = getRegForGEPIndex(Idx); 298 if (IdxN == 0) 299 // Unhandled operand. Halt "fast" selection and bail. 300 return false; 301 302 if (ElementSize != 1) { 303 IdxN = FastEmit_ri_(VT, ISD::MUL, IdxN, ElementSize, VT); 304 if (IdxN == 0) 305 // Unhandled operand. Halt "fast" selection and bail. 306 return false; 307 } 308 N = FastEmit_rr(VT, VT, ISD::ADD, N, IdxN); 309 if (N == 0) 310 // Unhandled operand. Halt "fast" selection and bail. 311 return false; 312 } 313 } 314 315 // We successfully emitted code for the given LLVM Instruction. 316 UpdateValueMap(I, N); 317 return true; 318} 319 320bool FastISel::SelectCall(User *I) { 321 Function *F = cast<CallInst>(I)->getCalledFunction(); 322 if (!F) return false; 323 324 unsigned IID = F->getIntrinsicID(); 325 switch (IID) { 326 default: break; 327 case Intrinsic::dbg_stoppoint: { 328 DbgStopPointInst *SPI = cast<DbgStopPointInst>(I); 329 if (isValidDebugInfoIntrinsic(*SPI, CodeGenOpt::None)) 330 setCurDebugLoc(ExtractDebugLocation(*SPI, MF.getDebugLocInfo())); 331 return true; 332 } 333 case Intrinsic::dbg_region_start: { 334 DbgRegionStartInst *RSI = cast<DbgRegionStartInst>(I); 335 if (isValidDebugInfoIntrinsic(*RSI, CodeGenOpt::None) && DW 336 && DW->ShouldEmitDwarfDebug()) { 337 unsigned ID = 338 DW->RecordRegionStart(RSI->getContext()); 339 const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL); 340 BuildMI(MBB, DL, II).addImm(ID); 341 } 342 return true; 343 } 344 case Intrinsic::dbg_region_end: { 345 DbgRegionEndInst *REI = cast<DbgRegionEndInst>(I); 346 if (isValidDebugInfoIntrinsic(*REI, CodeGenOpt::None) && DW 347 && DW->ShouldEmitDwarfDebug()) { 348 unsigned ID = 0; 349 DISubprogram Subprogram(REI->getContext()); 350 if (isInlinedFnEnd(*REI, MF.getFunction())) { 351 // This is end of an inlined function. 352 const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL); 353 ID = DW->RecordInlinedFnEnd(Subprogram); 354 if (ID) 355 // Returned ID is 0 if this is unbalanced "end of inlined 356 // scope". This could happen if optimizer eats dbg intrinsics 357 // or "beginning of inlined scope" is not recoginized due to 358 // missing location info. In such cases, ignore this region.end. 359 BuildMI(MBB, DL, II).addImm(ID); 360 } else { 361 const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL); 362 ID = DW->RecordRegionEnd(REI->getContext()); 363 BuildMI(MBB, DL, II).addImm(ID); 364 } 365 } 366 return true; 367 } 368 case Intrinsic::dbg_func_start: { 369 DbgFuncStartInst *FSI = cast<DbgFuncStartInst>(I); 370 if (!isValidDebugInfoIntrinsic(*FSI, CodeGenOpt::None) || !DW 371 || !DW->ShouldEmitDwarfDebug()) 372 return true; 373 374 if (isInlinedFnStart(*FSI, MF.getFunction())) { 375 // This is a beginning of an inlined function. 376 377 // If llvm.dbg.func.start is seen in a new block before any 378 // llvm.dbg.stoppoint intrinsic then the location info is unknown. 379 // FIXME : Why DebugLoc is reset at the beginning of each block ? 380 DebugLoc PrevLoc = DL; 381 if (PrevLoc.isUnknown()) 382 return true; 383 // Record the source line. 384 setCurDebugLoc(ExtractDebugLocation(*FSI, MF.getDebugLocInfo())); 385 386 DebugLocTuple PrevLocTpl = MF.getDebugLocTuple(PrevLoc); 387 DISubprogram SP(FSI->getSubprogram()); 388 unsigned LabelID = DW->RecordInlinedFnStart(SP, 389 DICompileUnit(PrevLocTpl.CompileUnit), 390 PrevLocTpl.Line, 391 PrevLocTpl.Col); 392 const TargetInstrDesc &II = TII.get(TargetInstrInfo::DBG_LABEL); 393 BuildMI(MBB, DL, II).addImm(LabelID); 394 return true; 395 } 396 397 // This is a beginning of a new function. 398 MF.setDefaultDebugLoc(ExtractDebugLocation(*FSI, MF.getDebugLocInfo())); 399 400 // llvm.dbg.func_start also defines beginning of function scope. 401 DW->RecordRegionStart(FSI->getSubprogram()); 402 return true; 403 } 404 case Intrinsic::dbg_declare: { 405 DbgDeclareInst *DI = cast<DbgDeclareInst>(I); 406 if (!isValidDebugInfoIntrinsic(*DI, CodeGenOpt::None) || !DW 407 || !DW->ShouldEmitDwarfDebug()) 408 return true; 409 410 Value *Address = DI->getAddress(); 411 if (BitCastInst *BCI = dyn_cast<BitCastInst>(Address)) 412 Address = BCI->getOperand(0); 413 AllocaInst *AI = dyn_cast<AllocaInst>(Address); 414 // Don't handle byval struct arguments or VLAs, for example. 415 if (!AI) break; 416 DenseMap<const AllocaInst*, int>::iterator SI = 417 StaticAllocaMap.find(AI); 418 if (SI == StaticAllocaMap.end()) break; // VLAs. 419 int FI = SI->second; 420 if (MMI) { 421 MetadataContext &TheMetadata = AI->getContext().getMetadata(); 422 unsigned MDDbgKind = TheMetadata.getMDKind("dbg"); 423 MDNode *AllocaLocation = 424 dyn_cast_or_null<MDNode>(TheMetadata.getMD(MDDbgKind, AI)); 425 if (AllocaLocation) 426 MMI->setVariableDbgInfo(DI->getVariable(), AllocaLocation, FI); 427 } 428 DW->RecordVariable(DI->getVariable(), FI); 429 return true; 430 } 431 case Intrinsic::eh_exception: { 432 EVT VT = TLI.getValueType(I->getType()); 433 switch (TLI.getOperationAction(ISD::EXCEPTIONADDR, VT)) { 434 default: break; 435 case TargetLowering::Expand: { 436 assert(MBB->isLandingPad() && "Call to eh.exception not in landing pad!"); 437 unsigned Reg = TLI.getExceptionAddressRegister(); 438 const TargetRegisterClass *RC = TLI.getRegClassFor(VT); 439 unsigned ResultReg = createResultReg(RC); 440 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 441 Reg, RC, RC); 442 assert(InsertedCopy && "Can't copy address registers!"); 443 InsertedCopy = InsertedCopy; 444 UpdateValueMap(I, ResultReg); 445 return true; 446 } 447 } 448 break; 449 } 450 case Intrinsic::eh_selector_i32: 451 case Intrinsic::eh_selector_i64: { 452 EVT VT = TLI.getValueType(I->getType()); 453 switch (TLI.getOperationAction(ISD::EHSELECTION, VT)) { 454 default: break; 455 case TargetLowering::Expand: { 456 EVT VT = (IID == Intrinsic::eh_selector_i32 ? 457 MVT::i32 : MVT::i64); 458 459 if (MMI) { 460 if (MBB->isLandingPad()) 461 AddCatchInfo(*cast<CallInst>(I), MMI, MBB); 462 else { 463#ifndef NDEBUG 464 CatchInfoLost.insert(cast<CallInst>(I)); 465#endif 466 // FIXME: Mark exception selector register as live in. Hack for PR1508. 467 unsigned Reg = TLI.getExceptionSelectorRegister(); 468 if (Reg) MBB->addLiveIn(Reg); 469 } 470 471 unsigned Reg = TLI.getExceptionSelectorRegister(); 472 const TargetRegisterClass *RC = TLI.getRegClassFor(VT); 473 unsigned ResultReg = createResultReg(RC); 474 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 475 Reg, RC, RC); 476 assert(InsertedCopy && "Can't copy address registers!"); 477 InsertedCopy = InsertedCopy; 478 UpdateValueMap(I, ResultReg); 479 } else { 480 unsigned ResultReg = 481 getRegForValue(Constant::getNullValue(I->getType())); 482 UpdateValueMap(I, ResultReg); 483 } 484 return true; 485 } 486 } 487 break; 488 } 489 } 490 return false; 491} 492 493bool FastISel::SelectCast(User *I, ISD::NodeType Opcode) { 494 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 495 EVT DstVT = TLI.getValueType(I->getType()); 496 497 if (SrcVT == MVT::Other || !SrcVT.isSimple() || 498 DstVT == MVT::Other || !DstVT.isSimple()) 499 // Unhandled type. Halt "fast" selection and bail. 500 return false; 501 502 // Check if the destination type is legal. Or as a special case, 503 // it may be i1 if we're doing a truncate because that's 504 // easy and somewhat common. 505 if (!TLI.isTypeLegal(DstVT)) 506 if (DstVT != MVT::i1 || Opcode != ISD::TRUNCATE) 507 // Unhandled type. Halt "fast" selection and bail. 508 return false; 509 510 // Check if the source operand is legal. Or as a special case, 511 // it may be i1 if we're doing zero-extension because that's 512 // easy and somewhat common. 513 if (!TLI.isTypeLegal(SrcVT)) 514 if (SrcVT != MVT::i1 || Opcode != ISD::ZERO_EXTEND) 515 // Unhandled type. Halt "fast" selection and bail. 516 return false; 517 518 unsigned InputReg = getRegForValue(I->getOperand(0)); 519 if (!InputReg) 520 // Unhandled operand. Halt "fast" selection and bail. 521 return false; 522 523 // If the operand is i1, arrange for the high bits in the register to be zero. 524 if (SrcVT == MVT::i1) { 525 SrcVT = TLI.getTypeToTransformTo(I->getContext(), SrcVT); 526 InputReg = FastEmitZExtFromI1(SrcVT.getSimpleVT(), InputReg); 527 if (!InputReg) 528 return false; 529 } 530 // If the result is i1, truncate to the target's type for i1 first. 531 if (DstVT == MVT::i1) 532 DstVT = TLI.getTypeToTransformTo(I->getContext(), DstVT); 533 534 unsigned ResultReg = FastEmit_r(SrcVT.getSimpleVT(), 535 DstVT.getSimpleVT(), 536 Opcode, 537 InputReg); 538 if (!ResultReg) 539 return false; 540 541 UpdateValueMap(I, ResultReg); 542 return true; 543} 544 545bool FastISel::SelectBitCast(User *I) { 546 // If the bitcast doesn't change the type, just use the operand value. 547 if (I->getType() == I->getOperand(0)->getType()) { 548 unsigned Reg = getRegForValue(I->getOperand(0)); 549 if (Reg == 0) 550 return false; 551 UpdateValueMap(I, Reg); 552 return true; 553 } 554 555 // Bitcasts of other values become reg-reg copies or BIT_CONVERT operators. 556 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 557 EVT DstVT = TLI.getValueType(I->getType()); 558 559 if (SrcVT == MVT::Other || !SrcVT.isSimple() || 560 DstVT == MVT::Other || !DstVT.isSimple() || 561 !TLI.isTypeLegal(SrcVT) || !TLI.isTypeLegal(DstVT)) 562 // Unhandled type. Halt "fast" selection and bail. 563 return false; 564 565 unsigned Op0 = getRegForValue(I->getOperand(0)); 566 if (Op0 == 0) 567 // Unhandled operand. Halt "fast" selection and bail. 568 return false; 569 570 // First, try to perform the bitcast by inserting a reg-reg copy. 571 unsigned ResultReg = 0; 572 if (SrcVT.getSimpleVT() == DstVT.getSimpleVT()) { 573 TargetRegisterClass* SrcClass = TLI.getRegClassFor(SrcVT); 574 TargetRegisterClass* DstClass = TLI.getRegClassFor(DstVT); 575 ResultReg = createResultReg(DstClass); 576 577 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 578 Op0, DstClass, SrcClass); 579 if (!InsertedCopy) 580 ResultReg = 0; 581 } 582 583 // If the reg-reg copy failed, select a BIT_CONVERT opcode. 584 if (!ResultReg) 585 ResultReg = FastEmit_r(SrcVT.getSimpleVT(), DstVT.getSimpleVT(), 586 ISD::BIT_CONVERT, Op0); 587 588 if (!ResultReg) 589 return false; 590 591 UpdateValueMap(I, ResultReg); 592 return true; 593} 594 595bool 596FastISel::SelectInstruction(Instruction *I) { 597 return SelectOperator(I, I->getOpcode()); 598} 599 600/// FastEmitBranch - Emit an unconditional branch to the given block, 601/// unless it is the immediate (fall-through) successor, and update 602/// the CFG. 603void 604FastISel::FastEmitBranch(MachineBasicBlock *MSucc) { 605 MachineFunction::iterator NextMBB = 606 next(MachineFunction::iterator(MBB)); 607 608 if (MBB->isLayoutSuccessor(MSucc)) { 609 // The unconditional fall-through case, which needs no instructions. 610 } else { 611 // The unconditional branch case. 612 TII.InsertBranch(*MBB, MSucc, NULL, SmallVector<MachineOperand, 0>()); 613 } 614 MBB->addSuccessor(MSucc); 615} 616 617/// SelectFNeg - Emit an FNeg operation. 618/// 619bool 620FastISel::SelectFNeg(User *I) { 621 unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I)); 622 if (OpReg == 0) return false; 623 624 // If the target has ISD::FNEG, use it. 625 EVT VT = TLI.getValueType(I->getType()); 626 unsigned ResultReg = FastEmit_r(VT.getSimpleVT(), VT.getSimpleVT(), 627 ISD::FNEG, OpReg); 628 if (ResultReg != 0) { 629 UpdateValueMap(I, ResultReg); 630 return true; 631 } 632 633 // Bitcast the value to integer, twiddle the sign bit with xor, 634 // and then bitcast it back to floating-point. 635 if (VT.getSizeInBits() > 64) return false; 636 EVT IntVT = EVT::getIntegerVT(I->getContext(), VT.getSizeInBits()); 637 if (!TLI.isTypeLegal(IntVT)) 638 return false; 639 640 unsigned IntReg = FastEmit_r(VT.getSimpleVT(), IntVT.getSimpleVT(), 641 ISD::BIT_CONVERT, OpReg); 642 if (IntReg == 0) 643 return false; 644 645 unsigned IntResultReg = FastEmit_ri_(IntVT.getSimpleVT(), ISD::XOR, IntReg, 646 UINT64_C(1) << (VT.getSizeInBits()-1), 647 IntVT.getSimpleVT()); 648 if (IntResultReg == 0) 649 return false; 650 651 ResultReg = FastEmit_r(IntVT.getSimpleVT(), VT.getSimpleVT(), 652 ISD::BIT_CONVERT, IntResultReg); 653 if (ResultReg == 0) 654 return false; 655 656 UpdateValueMap(I, ResultReg); 657 return true; 658} 659 660bool 661FastISel::SelectOperator(User *I, unsigned Opcode) { 662 switch (Opcode) { 663 case Instruction::Add: 664 return SelectBinaryOp(I, ISD::ADD); 665 case Instruction::FAdd: 666 return SelectBinaryOp(I, ISD::FADD); 667 case Instruction::Sub: 668 return SelectBinaryOp(I, ISD::SUB); 669 case Instruction::FSub: 670 // FNeg is currently represented in LLVM IR as a special case of FSub. 671 if (BinaryOperator::isFNeg(I)) 672 return SelectFNeg(I); 673 return SelectBinaryOp(I, ISD::FSUB); 674 case Instruction::Mul: 675 return SelectBinaryOp(I, ISD::MUL); 676 case Instruction::FMul: 677 return SelectBinaryOp(I, ISD::FMUL); 678 case Instruction::SDiv: 679 return SelectBinaryOp(I, ISD::SDIV); 680 case Instruction::UDiv: 681 return SelectBinaryOp(I, ISD::UDIV); 682 case Instruction::FDiv: 683 return SelectBinaryOp(I, ISD::FDIV); 684 case Instruction::SRem: 685 return SelectBinaryOp(I, ISD::SREM); 686 case Instruction::URem: 687 return SelectBinaryOp(I, ISD::UREM); 688 case Instruction::FRem: 689 return SelectBinaryOp(I, ISD::FREM); 690 case Instruction::Shl: 691 return SelectBinaryOp(I, ISD::SHL); 692 case Instruction::LShr: 693 return SelectBinaryOp(I, ISD::SRL); 694 case Instruction::AShr: 695 return SelectBinaryOp(I, ISD::SRA); 696 case Instruction::And: 697 return SelectBinaryOp(I, ISD::AND); 698 case Instruction::Or: 699 return SelectBinaryOp(I, ISD::OR); 700 case Instruction::Xor: 701 return SelectBinaryOp(I, ISD::XOR); 702 703 case Instruction::GetElementPtr: 704 return SelectGetElementPtr(I); 705 706 case Instruction::Br: { 707 BranchInst *BI = cast<BranchInst>(I); 708 709 if (BI->isUnconditional()) { 710 BasicBlock *LLVMSucc = BI->getSuccessor(0); 711 MachineBasicBlock *MSucc = MBBMap[LLVMSucc]; 712 FastEmitBranch(MSucc); 713 return true; 714 } 715 716 // Conditional branches are not handed yet. 717 // Halt "fast" selection and bail. 718 return false; 719 } 720 721 case Instruction::Unreachable: 722 // Nothing to emit. 723 return true; 724 725 case Instruction::PHI: 726 // PHI nodes are already emitted. 727 return true; 728 729 case Instruction::Alloca: 730 // FunctionLowering has the static-sized case covered. 731 if (StaticAllocaMap.count(cast<AllocaInst>(I))) 732 return true; 733 734 // Dynamic-sized alloca is not handled yet. 735 return false; 736 737 case Instruction::Call: 738 return SelectCall(I); 739 740 case Instruction::BitCast: 741 return SelectBitCast(I); 742 743 case Instruction::FPToSI: 744 return SelectCast(I, ISD::FP_TO_SINT); 745 case Instruction::ZExt: 746 return SelectCast(I, ISD::ZERO_EXTEND); 747 case Instruction::SExt: 748 return SelectCast(I, ISD::SIGN_EXTEND); 749 case Instruction::Trunc: 750 return SelectCast(I, ISD::TRUNCATE); 751 case Instruction::SIToFP: 752 return SelectCast(I, ISD::SINT_TO_FP); 753 754 case Instruction::IntToPtr: // Deliberate fall-through. 755 case Instruction::PtrToInt: { 756 EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()); 757 EVT DstVT = TLI.getValueType(I->getType()); 758 if (DstVT.bitsGT(SrcVT)) 759 return SelectCast(I, ISD::ZERO_EXTEND); 760 if (DstVT.bitsLT(SrcVT)) 761 return SelectCast(I, ISD::TRUNCATE); 762 unsigned Reg = getRegForValue(I->getOperand(0)); 763 if (Reg == 0) return false; 764 UpdateValueMap(I, Reg); 765 return true; 766 } 767 768 default: 769 // Unhandled instruction. Halt "fast" selection and bail. 770 return false; 771 } 772} 773 774FastISel::FastISel(MachineFunction &mf, 775 MachineModuleInfo *mmi, 776 DwarfWriter *dw, 777 DenseMap<const Value *, unsigned> &vm, 778 DenseMap<const BasicBlock *, MachineBasicBlock *> &bm, 779 DenseMap<const AllocaInst *, int> &am 780#ifndef NDEBUG 781 , SmallSet<Instruction*, 8> &cil 782#endif 783 ) 784 : MBB(0), 785 ValueMap(vm), 786 MBBMap(bm), 787 StaticAllocaMap(am), 788#ifndef NDEBUG 789 CatchInfoLost(cil), 790#endif 791 MF(mf), 792 MMI(mmi), 793 DW(dw), 794 MRI(MF.getRegInfo()), 795 MFI(*MF.getFrameInfo()), 796 MCP(*MF.getConstantPool()), 797 TM(MF.getTarget()), 798 TD(*TM.getTargetData()), 799 TII(*TM.getInstrInfo()), 800 TLI(*TM.getTargetLowering()) { 801} 802 803FastISel::~FastISel() {} 804 805unsigned FastISel::FastEmit_(MVT, MVT, 806 ISD::NodeType) { 807 return 0; 808} 809 810unsigned FastISel::FastEmit_r(MVT, MVT, 811 ISD::NodeType, unsigned /*Op0*/) { 812 return 0; 813} 814 815unsigned FastISel::FastEmit_rr(MVT, MVT, 816 ISD::NodeType, unsigned /*Op0*/, 817 unsigned /*Op0*/) { 818 return 0; 819} 820 821unsigned FastISel::FastEmit_i(MVT, MVT, ISD::NodeType, uint64_t /*Imm*/) { 822 return 0; 823} 824 825unsigned FastISel::FastEmit_f(MVT, MVT, 826 ISD::NodeType, ConstantFP * /*FPImm*/) { 827 return 0; 828} 829 830unsigned FastISel::FastEmit_ri(MVT, MVT, 831 ISD::NodeType, unsigned /*Op0*/, 832 uint64_t /*Imm*/) { 833 return 0; 834} 835 836unsigned FastISel::FastEmit_rf(MVT, MVT, 837 ISD::NodeType, unsigned /*Op0*/, 838 ConstantFP * /*FPImm*/) { 839 return 0; 840} 841 842unsigned FastISel::FastEmit_rri(MVT, MVT, 843 ISD::NodeType, 844 unsigned /*Op0*/, unsigned /*Op1*/, 845 uint64_t /*Imm*/) { 846 return 0; 847} 848 849/// FastEmit_ri_ - This method is a wrapper of FastEmit_ri. It first tries 850/// to emit an instruction with an immediate operand using FastEmit_ri. 851/// If that fails, it materializes the immediate into a register and try 852/// FastEmit_rr instead. 853unsigned FastISel::FastEmit_ri_(MVT VT, ISD::NodeType Opcode, 854 unsigned Op0, uint64_t Imm, 855 MVT ImmType) { 856 // First check if immediate type is legal. If not, we can't use the ri form. 857 unsigned ResultReg = FastEmit_ri(VT, VT, Opcode, Op0, Imm); 858 if (ResultReg != 0) 859 return ResultReg; 860 unsigned MaterialReg = FastEmit_i(ImmType, ImmType, ISD::Constant, Imm); 861 if (MaterialReg == 0) 862 return 0; 863 return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg); 864} 865 866/// FastEmit_rf_ - This method is a wrapper of FastEmit_ri. It first tries 867/// to emit an instruction with a floating-point immediate operand using 868/// FastEmit_rf. If that fails, it materializes the immediate into a register 869/// and try FastEmit_rr instead. 870unsigned FastISel::FastEmit_rf_(MVT VT, ISD::NodeType Opcode, 871 unsigned Op0, ConstantFP *FPImm, 872 MVT ImmType) { 873 // First check if immediate type is legal. If not, we can't use the rf form. 874 unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, FPImm); 875 if (ResultReg != 0) 876 return ResultReg; 877 878 // Materialize the constant in a register. 879 unsigned MaterialReg = FastEmit_f(ImmType, ImmType, ISD::ConstantFP, FPImm); 880 if (MaterialReg == 0) { 881 // If the target doesn't have a way to directly enter a floating-point 882 // value into a register, use an alternate approach. 883 // TODO: The current approach only supports floating-point constants 884 // that can be constructed by conversion from integer values. This should 885 // be replaced by code that creates a load from a constant-pool entry, 886 // which will require some target-specific work. 887 const APFloat &Flt = FPImm->getValueAPF(); 888 EVT IntVT = TLI.getPointerTy(); 889 890 uint64_t x[2]; 891 uint32_t IntBitWidth = IntVT.getSizeInBits(); 892 bool isExact; 893 (void) Flt.convertToInteger(x, IntBitWidth, /*isSigned=*/true, 894 APFloat::rmTowardZero, &isExact); 895 if (!isExact) 896 return 0; 897 APInt IntVal(IntBitWidth, 2, x); 898 899 unsigned IntegerReg = FastEmit_i(IntVT.getSimpleVT(), IntVT.getSimpleVT(), 900 ISD::Constant, IntVal.getZExtValue()); 901 if (IntegerReg == 0) 902 return 0; 903 MaterialReg = FastEmit_r(IntVT.getSimpleVT(), VT, 904 ISD::SINT_TO_FP, IntegerReg); 905 if (MaterialReg == 0) 906 return 0; 907 } 908 return FastEmit_rr(VT, VT, Opcode, Op0, MaterialReg); 909} 910 911unsigned FastISel::createResultReg(const TargetRegisterClass* RC) { 912 return MRI.createVirtualRegister(RC); 913} 914 915unsigned FastISel::FastEmitInst_(unsigned MachineInstOpcode, 916 const TargetRegisterClass* RC) { 917 unsigned ResultReg = createResultReg(RC); 918 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 919 920 BuildMI(MBB, DL, II, ResultReg); 921 return ResultReg; 922} 923 924unsigned FastISel::FastEmitInst_r(unsigned MachineInstOpcode, 925 const TargetRegisterClass *RC, 926 unsigned Op0) { 927 unsigned ResultReg = createResultReg(RC); 928 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 929 930 if (II.getNumDefs() >= 1) 931 BuildMI(MBB, DL, II, ResultReg).addReg(Op0); 932 else { 933 BuildMI(MBB, DL, II).addReg(Op0); 934 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 935 II.ImplicitDefs[0], RC, RC); 936 if (!InsertedCopy) 937 ResultReg = 0; 938 } 939 940 return ResultReg; 941} 942 943unsigned FastISel::FastEmitInst_rr(unsigned MachineInstOpcode, 944 const TargetRegisterClass *RC, 945 unsigned Op0, unsigned Op1) { 946 unsigned ResultReg = createResultReg(RC); 947 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 948 949 if (II.getNumDefs() >= 1) 950 BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addReg(Op1); 951 else { 952 BuildMI(MBB, DL, II).addReg(Op0).addReg(Op1); 953 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 954 II.ImplicitDefs[0], RC, RC); 955 if (!InsertedCopy) 956 ResultReg = 0; 957 } 958 return ResultReg; 959} 960 961unsigned FastISel::FastEmitInst_ri(unsigned MachineInstOpcode, 962 const TargetRegisterClass *RC, 963 unsigned Op0, uint64_t Imm) { 964 unsigned ResultReg = createResultReg(RC); 965 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 966 967 if (II.getNumDefs() >= 1) 968 BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addImm(Imm); 969 else { 970 BuildMI(MBB, DL, II).addReg(Op0).addImm(Imm); 971 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 972 II.ImplicitDefs[0], RC, RC); 973 if (!InsertedCopy) 974 ResultReg = 0; 975 } 976 return ResultReg; 977} 978 979unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode, 980 const TargetRegisterClass *RC, 981 unsigned Op0, ConstantFP *FPImm) { 982 unsigned ResultReg = createResultReg(RC); 983 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 984 985 if (II.getNumDefs() >= 1) 986 BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addFPImm(FPImm); 987 else { 988 BuildMI(MBB, DL, II).addReg(Op0).addFPImm(FPImm); 989 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 990 II.ImplicitDefs[0], RC, RC); 991 if (!InsertedCopy) 992 ResultReg = 0; 993 } 994 return ResultReg; 995} 996 997unsigned FastISel::FastEmitInst_rri(unsigned MachineInstOpcode, 998 const TargetRegisterClass *RC, 999 unsigned Op0, unsigned Op1, uint64_t Imm) { 1000 unsigned ResultReg = createResultReg(RC); 1001 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1002 1003 if (II.getNumDefs() >= 1) 1004 BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addReg(Op1).addImm(Imm); 1005 else { 1006 BuildMI(MBB, DL, II).addReg(Op0).addReg(Op1).addImm(Imm); 1007 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 1008 II.ImplicitDefs[0], RC, RC); 1009 if (!InsertedCopy) 1010 ResultReg = 0; 1011 } 1012 return ResultReg; 1013} 1014 1015unsigned FastISel::FastEmitInst_i(unsigned MachineInstOpcode, 1016 const TargetRegisterClass *RC, 1017 uint64_t Imm) { 1018 unsigned ResultReg = createResultReg(RC); 1019 const TargetInstrDesc &II = TII.get(MachineInstOpcode); 1020 1021 if (II.getNumDefs() >= 1) 1022 BuildMI(MBB, DL, II, ResultReg).addImm(Imm); 1023 else { 1024 BuildMI(MBB, DL, II).addImm(Imm); 1025 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 1026 II.ImplicitDefs[0], RC, RC); 1027 if (!InsertedCopy) 1028 ResultReg = 0; 1029 } 1030 return ResultReg; 1031} 1032 1033unsigned FastISel::FastEmitInst_extractsubreg(MVT RetVT, 1034 unsigned Op0, uint32_t Idx) { 1035 const TargetRegisterClass* RC = MRI.getRegClass(Op0); 1036 1037 unsigned ResultReg = createResultReg(TLI.getRegClassFor(RetVT)); 1038 const TargetInstrDesc &II = TII.get(TargetInstrInfo::EXTRACT_SUBREG); 1039 1040 if (II.getNumDefs() >= 1) 1041 BuildMI(MBB, DL, II, ResultReg).addReg(Op0).addImm(Idx); 1042 else { 1043 BuildMI(MBB, DL, II).addReg(Op0).addImm(Idx); 1044 bool InsertedCopy = TII.copyRegToReg(*MBB, MBB->end(), ResultReg, 1045 II.ImplicitDefs[0], RC, RC); 1046 if (!InsertedCopy) 1047 ResultReg = 0; 1048 } 1049 return ResultReg; 1050} 1051 1052/// FastEmitZExtFromI1 - Emit MachineInstrs to compute the value of Op 1053/// with all but the least significant bit set to zero. 1054unsigned FastISel::FastEmitZExtFromI1(MVT VT, unsigned Op) { 1055 return FastEmit_ri(VT, VT, ISD::AND, Op, 1); 1056} 1057