MachineBasicBlock.cpp revision 14152b480d09c7ca912af7c06d00b0ff3912e4f5
1//===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===// 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// Collect the sequence of machine instructions for a basic block. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/CodeGen/MachineBasicBlock.h" 15#include "llvm/BasicBlock.h" 16#include "llvm/CodeGen/LiveVariables.h" 17#include "llvm/CodeGen/MachineDominators.h" 18#include "llvm/CodeGen/MachineFunction.h" 19#include "llvm/CodeGen/MachineLoopInfo.h" 20#include "llvm/MC/MCAsmInfo.h" 21#include "llvm/MC/MCContext.h" 22#include "llvm/Target/TargetRegisterInfo.h" 23#include "llvm/Target/TargetData.h" 24#include "llvm/Target/TargetInstrDesc.h" 25#include "llvm/Target/TargetInstrInfo.h" 26#include "llvm/Target/TargetMachine.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/ADT/SmallString.h" 29#include "llvm/ADT/SmallPtrSet.h" 30#include "llvm/Support/Debug.h" 31#include "llvm/Support/LeakDetector.h" 32#include "llvm/Support/raw_ostream.h" 33#include <algorithm> 34using namespace llvm; 35 36MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb) 37 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false), 38 AddressTaken(false) { 39 Insts.Parent = this; 40} 41 42MachineBasicBlock::~MachineBasicBlock() { 43 LeakDetector::removeGarbageObject(this); 44} 45 46/// getSymbol - Return the MCSymbol for this basic block. 47/// 48MCSymbol *MachineBasicBlock::getSymbol() const { 49 const MachineFunction *MF = getParent(); 50 MCContext &Ctx = MF->getContext(); 51 const char *Prefix = Ctx.getAsmInfo().getPrivateGlobalPrefix(); 52 return Ctx.GetOrCreateSymbol(Twine(Prefix) + "BB" + 53 Twine(MF->getFunctionNumber()) + "_" + 54 Twine(getNumber())); 55} 56 57 58raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) { 59 MBB.print(OS); 60 return OS; 61} 62 63/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the 64/// parent pointer of the MBB, the MBB numbering, and any instructions in the 65/// MBB to be on the right operand list for registers. 66/// 67/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it 68/// gets the next available unique MBB number. If it is removed from a 69/// MachineFunction, it goes back to being #-1. 70void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) { 71 MachineFunction &MF = *N->getParent(); 72 N->Number = MF.addToMBBNumbering(N); 73 74 // Make sure the instructions have their operands in the reginfo lists. 75 MachineRegisterInfo &RegInfo = MF.getRegInfo(); 76 for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I) 77 I->AddRegOperandsToUseLists(RegInfo); 78 79 LeakDetector::removeGarbageObject(N); 80} 81 82void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) { 83 N->getParent()->removeFromMBBNumbering(N->Number); 84 N->Number = -1; 85 LeakDetector::addGarbageObject(N); 86} 87 88 89/// addNodeToList (MI) - When we add an instruction to a basic block 90/// list, we update its parent pointer and add its operands from reg use/def 91/// lists if appropriate. 92void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) { 93 assert(N->getParent() == 0 && "machine instruction already in a basic block"); 94 N->setParent(Parent); 95 96 // Add the instruction's register operands to their corresponding 97 // use/def lists. 98 MachineFunction *MF = Parent->getParent(); 99 N->AddRegOperandsToUseLists(MF->getRegInfo()); 100 101 LeakDetector::removeGarbageObject(N); 102} 103 104/// removeNodeFromList (MI) - When we remove an instruction from a basic block 105/// list, we update its parent pointer and remove its operands from reg use/def 106/// lists if appropriate. 107void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) { 108 assert(N->getParent() != 0 && "machine instruction not in a basic block"); 109 110 // Remove from the use/def lists. 111 N->RemoveRegOperandsFromUseLists(); 112 113 N->setParent(0); 114 115 LeakDetector::addGarbageObject(N); 116} 117 118/// transferNodesFromList (MI) - When moving a range of instructions from one 119/// MBB list to another, we need to update the parent pointers and the use/def 120/// lists. 121void ilist_traits<MachineInstr>:: 122transferNodesFromList(ilist_traits<MachineInstr> &fromList, 123 MachineBasicBlock::iterator first, 124 MachineBasicBlock::iterator last) { 125 assert(Parent->getParent() == fromList.Parent->getParent() && 126 "MachineInstr parent mismatch!"); 127 128 // Splice within the same MBB -> no change. 129 if (Parent == fromList.Parent) return; 130 131 // If splicing between two blocks within the same function, just update the 132 // parent pointers. 133 for (; first != last; ++first) 134 first->setParent(Parent); 135} 136 137void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) { 138 assert(!MI->getParent() && "MI is still in a block!"); 139 Parent->getParent()->DeleteMachineInstr(MI); 140} 141 142MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() { 143 iterator I = end(); 144 while (I != begin() && (--I)->getDesc().isTerminator()) 145 ; /*noop */ 146 if (I != end() && !I->getDesc().isTerminator()) ++I; 147 return I; 148} 149 150void MachineBasicBlock::dump() const { 151 print(dbgs()); 152} 153 154static inline void OutputReg(raw_ostream &os, unsigned RegNo, 155 const TargetRegisterInfo *TRI = 0) { 156 if (RegNo != 0 && TargetRegisterInfo::isPhysicalRegister(RegNo)) { 157 if (TRI) 158 os << " %" << TRI->get(RegNo).Name; 159 else 160 os << " %physreg" << RegNo; 161 } else 162 os << " %reg" << RegNo; 163} 164 165StringRef MachineBasicBlock::getName() const { 166 if (const BasicBlock *LBB = getBasicBlock()) 167 return LBB->getName(); 168 else 169 return "(null)"; 170} 171 172void MachineBasicBlock::print(raw_ostream &OS) const { 173 const MachineFunction *MF = getParent(); 174 if (!MF) { 175 OS << "Can't print out MachineBasicBlock because parent MachineFunction" 176 << " is null\n"; 177 return; 178 } 179 180 if (Alignment) { OS << "Alignment " << Alignment << "\n"; } 181 182 OS << "BB#" << getNumber() << ": "; 183 184 const char *Comma = ""; 185 if (const BasicBlock *LBB = getBasicBlock()) { 186 OS << Comma << "derived from LLVM BB "; 187 WriteAsOperand(OS, LBB, /*PrintType=*/false); 188 Comma = ", "; 189 } 190 if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; } 191 if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; } 192 OS << '\n'; 193 194 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo(); 195 if (!livein_empty()) { 196 OS << " Live Ins:"; 197 for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I) 198 OutputReg(OS, *I, TRI); 199 OS << '\n'; 200 } 201 // Print the preds of this block according to the CFG. 202 if (!pred_empty()) { 203 OS << " Predecessors according to CFG:"; 204 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI) 205 OS << " BB#" << (*PI)->getNumber(); 206 OS << '\n'; 207 } 208 209 for (const_iterator I = begin(); I != end(); ++I) { 210 OS << '\t'; 211 I->print(OS, &getParent()->getTarget()); 212 } 213 214 // Print the successors of this block according to the CFG. 215 if (!succ_empty()) { 216 OS << " Successors according to CFG:"; 217 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) 218 OS << " BB#" << (*SI)->getNumber(); 219 OS << '\n'; 220 } 221} 222 223void MachineBasicBlock::removeLiveIn(unsigned Reg) { 224 std::vector<unsigned>::iterator I = 225 std::find(LiveIns.begin(), LiveIns.end(), Reg); 226 assert(I != LiveIns.end() && "Not a live in!"); 227 LiveIns.erase(I); 228} 229 230bool MachineBasicBlock::isLiveIn(unsigned Reg) const { 231 livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 232 return I != livein_end(); 233} 234 235void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) { 236 getParent()->splice(NewAfter, this); 237} 238 239void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) { 240 MachineFunction::iterator BBI = NewBefore; 241 getParent()->splice(++BBI, this); 242} 243 244void MachineBasicBlock::updateTerminator() { 245 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo(); 246 // A block with no successors has no concerns with fall-through edges. 247 if (this->succ_empty()) return; 248 249 MachineBasicBlock *TBB = 0, *FBB = 0; 250 SmallVector<MachineOperand, 4> Cond; 251 DebugLoc dl; // FIXME: this is nowhere 252 bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond); 253 (void) B; 254 assert(!B && "UpdateTerminators requires analyzable predecessors!"); 255 if (Cond.empty()) { 256 if (TBB) { 257 // The block has an unconditional branch. If its successor is now 258 // its layout successor, delete the branch. 259 if (isLayoutSuccessor(TBB)) 260 TII->RemoveBranch(*this); 261 } else { 262 // The block has an unconditional fallthrough. If its successor is not 263 // its layout successor, insert a branch. 264 TBB = *succ_begin(); 265 if (!isLayoutSuccessor(TBB)) 266 TII->InsertBranch(*this, TBB, 0, Cond, dl); 267 } 268 } else { 269 if (FBB) { 270 // The block has a non-fallthrough conditional branch. If one of its 271 // successors is its layout successor, rewrite it to a fallthrough 272 // conditional branch. 273 if (isLayoutSuccessor(TBB)) { 274 if (TII->ReverseBranchCondition(Cond)) 275 return; 276 TII->RemoveBranch(*this); 277 TII->InsertBranch(*this, FBB, 0, Cond, dl); 278 } else if (isLayoutSuccessor(FBB)) { 279 TII->RemoveBranch(*this); 280 TII->InsertBranch(*this, TBB, 0, Cond, dl); 281 } 282 } else { 283 // The block has a fallthrough conditional branch. 284 MachineBasicBlock *MBBA = *succ_begin(); 285 MachineBasicBlock *MBBB = *llvm::next(succ_begin()); 286 if (MBBA == TBB) std::swap(MBBB, MBBA); 287 if (isLayoutSuccessor(TBB)) { 288 if (TII->ReverseBranchCondition(Cond)) { 289 // We can't reverse the condition, add an unconditional branch. 290 Cond.clear(); 291 TII->InsertBranch(*this, MBBA, 0, Cond, dl); 292 return; 293 } 294 TII->RemoveBranch(*this); 295 TII->InsertBranch(*this, MBBA, 0, Cond, dl); 296 } else if (!isLayoutSuccessor(MBBA)) { 297 TII->RemoveBranch(*this); 298 TII->InsertBranch(*this, TBB, MBBA, Cond, dl); 299 } 300 } 301 } 302} 303 304void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) { 305 Successors.push_back(succ); 306 succ->addPredecessor(this); 307} 308 309void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) { 310 succ->removePredecessor(this); 311 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ); 312 assert(I != Successors.end() && "Not a current successor!"); 313 Successors.erase(I); 314} 315 316MachineBasicBlock::succ_iterator 317MachineBasicBlock::removeSuccessor(succ_iterator I) { 318 assert(I != Successors.end() && "Not a current successor!"); 319 (*I)->removePredecessor(this); 320 return Successors.erase(I); 321} 322 323void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) { 324 Predecessors.push_back(pred); 325} 326 327void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) { 328 std::vector<MachineBasicBlock *>::iterator I = 329 std::find(Predecessors.begin(), Predecessors.end(), pred); 330 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!"); 331 Predecessors.erase(I); 332} 333 334void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) { 335 if (this == fromMBB) 336 return; 337 338 while (!fromMBB->succ_empty()) { 339 MachineBasicBlock *Succ = *fromMBB->succ_begin(); 340 addSuccessor(Succ); 341 fromMBB->removeSuccessor(Succ); 342 } 343} 344 345void 346MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) { 347 if (this == fromMBB) 348 return; 349 350 while (!fromMBB->succ_empty()) { 351 MachineBasicBlock *Succ = *fromMBB->succ_begin(); 352 addSuccessor(Succ); 353 fromMBB->removeSuccessor(Succ); 354 355 // Fix up any PHI nodes in the successor. 356 for (MachineBasicBlock::iterator MI = Succ->begin(), ME = Succ->end(); 357 MI != ME && MI->isPHI(); ++MI) 358 for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) { 359 MachineOperand &MO = MI->getOperand(i); 360 if (MO.getMBB() == fromMBB) 361 MO.setMBB(this); 362 } 363 } 364} 365 366bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const { 367 std::vector<MachineBasicBlock *>::const_iterator I = 368 std::find(Successors.begin(), Successors.end(), MBB); 369 return I != Successors.end(); 370} 371 372bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const { 373 MachineFunction::const_iterator I(this); 374 return llvm::next(I) == MachineFunction::const_iterator(MBB); 375} 376 377bool MachineBasicBlock::canFallThrough() { 378 MachineFunction::iterator Fallthrough = this; 379 ++Fallthrough; 380 // If FallthroughBlock is off the end of the function, it can't fall through. 381 if (Fallthrough == getParent()->end()) 382 return false; 383 384 // If FallthroughBlock isn't a successor, no fallthrough is possible. 385 if (!isSuccessor(Fallthrough)) 386 return false; 387 388 // Analyze the branches, if any, at the end of the block. 389 MachineBasicBlock *TBB = 0, *FBB = 0; 390 SmallVector<MachineOperand, 4> Cond; 391 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo(); 392 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) { 393 // If we couldn't analyze the branch, examine the last instruction. 394 // If the block doesn't end in a known control barrier, assume fallthrough 395 // is possible. The isPredicable check is needed because this code can be 396 // called during IfConversion, where an instruction which is normally a 397 // Barrier is predicated and thus no longer an actual control barrier. This 398 // is over-conservative though, because if an instruction isn't actually 399 // predicated we could still treat it like a barrier. 400 return empty() || !back().getDesc().isBarrier() || 401 back().getDesc().isPredicable(); 402 } 403 404 // If there is no branch, control always falls through. 405 if (TBB == 0) return true; 406 407 // If there is some explicit branch to the fallthrough block, it can obviously 408 // reach, even though the branch should get folded to fall through implicitly. 409 if (MachineFunction::iterator(TBB) == Fallthrough || 410 MachineFunction::iterator(FBB) == Fallthrough) 411 return true; 412 413 // If it's an unconditional branch to some block not the fall through, it 414 // doesn't fall through. 415 if (Cond.empty()) return false; 416 417 // Otherwise, if it is conditional and has no explicit false block, it falls 418 // through. 419 return FBB == 0; 420} 421 422MachineBasicBlock * 423MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) { 424 MachineFunction *MF = getParent(); 425 DebugLoc dl; // FIXME: this is nowhere 426 427 // We may need to update this's terminator, but we can't do that if AnalyzeBranch 428 // fails. If this uses a jump table, we won't touch it. 429 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); 430 MachineBasicBlock *TBB = 0, *FBB = 0; 431 SmallVector<MachineOperand, 4> Cond; 432 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) 433 return NULL; 434 435 MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock(); 436 MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB); 437 DEBUG(dbgs() << "PHIElimination splitting critical edge:" 438 " BB#" << getNumber() 439 << " -- BB#" << NMBB->getNumber() 440 << " -- BB#" << Succ->getNumber() << '\n'); 441 442 ReplaceUsesOfBlockWith(Succ, NMBB); 443 updateTerminator(); 444 445 // Insert unconditional "jump Succ" instruction in NMBB if necessary. 446 NMBB->addSuccessor(Succ); 447 if (!NMBB->isLayoutSuccessor(Succ)) { 448 Cond.clear(); 449 MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl); 450 } 451 452 // Fix PHI nodes in Succ so they refer to NMBB instead of this 453 for (MachineBasicBlock::iterator i = Succ->begin(), e = Succ->end(); 454 i != e && i->isPHI(); ++i) 455 for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2) 456 if (i->getOperand(ni+1).getMBB() == this) 457 i->getOperand(ni+1).setMBB(NMBB); 458 459 if (LiveVariables *LV = 460 P->getAnalysisIfAvailable<LiveVariables>()) 461 LV->addNewBlock(NMBB, this, Succ); 462 463 if (MachineDominatorTree *MDT = 464 P->getAnalysisIfAvailable<MachineDominatorTree>()) 465 MDT->addNewBlock(NMBB, this); 466 467 if (MachineLoopInfo *MLI = 468 P->getAnalysisIfAvailable<MachineLoopInfo>()) 469 if (MachineLoop *TIL = MLI->getLoopFor(this)) { 470 // If one or the other blocks were not in a loop, the new block is not 471 // either, and thus LI doesn't need to be updated. 472 if (MachineLoop *DestLoop = MLI->getLoopFor(Succ)) { 473 if (TIL == DestLoop) { 474 // Both in the same loop, the NMBB joins loop. 475 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase()); 476 } else if (TIL->contains(DestLoop)) { 477 // Edge from an outer loop to an inner loop. Add to the outer loop. 478 TIL->addBasicBlockToLoop(NMBB, MLI->getBase()); 479 } else if (DestLoop->contains(TIL)) { 480 // Edge from an inner loop to an outer loop. Add to the outer loop. 481 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase()); 482 } else { 483 // Edge from two loops with no containment relation. Because these 484 // are natural loops, we know that the destination block must be the 485 // header of its loop (adding a branch into a loop elsewhere would 486 // create an irreducible loop). 487 assert(DestLoop->getHeader() == Succ && 488 "Should not create irreducible loops!"); 489 if (MachineLoop *P = DestLoop->getParentLoop()) 490 P->addBasicBlockToLoop(NMBB, MLI->getBase()); 491 } 492 } 493 } 494 495 return NMBB; 496} 497 498/// removeFromParent - This method unlinks 'this' from the containing function, 499/// and returns it, but does not delete it. 500MachineBasicBlock *MachineBasicBlock::removeFromParent() { 501 assert(getParent() && "Not embedded in a function!"); 502 getParent()->remove(this); 503 return this; 504} 505 506 507/// eraseFromParent - This method unlinks 'this' from the containing function, 508/// and deletes it. 509void MachineBasicBlock::eraseFromParent() { 510 assert(getParent() && "Not embedded in a function!"); 511 getParent()->erase(this); 512} 513 514 515/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 516/// 'Old', change the code and CFG so that it branches to 'New' instead. 517void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old, 518 MachineBasicBlock *New) { 519 assert(Old != New && "Cannot replace self with self!"); 520 521 MachineBasicBlock::iterator I = end(); 522 while (I != begin()) { 523 --I; 524 if (!I->getDesc().isTerminator()) break; 525 526 // Scan the operands of this machine instruction, replacing any uses of Old 527 // with New. 528 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 529 if (I->getOperand(i).isMBB() && 530 I->getOperand(i).getMBB() == Old) 531 I->getOperand(i).setMBB(New); 532 } 533 534 // Update the successor information. 535 removeSuccessor(Old); 536 addSuccessor(New); 537} 538 539/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the 540/// CFG to be inserted. If we have proven that MBB can only branch to DestA and 541/// DestB, remove any other MBB successors from the CFG. DestA and DestB can be 542/// null. 543/// 544/// Besides DestA and DestB, retain other edges leading to LandingPads 545/// (currently there can be only one; we don't check or require that here). 546/// Note it is possible that DestA and/or DestB are LandingPads. 547bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA, 548 MachineBasicBlock *DestB, 549 bool isCond) { 550 // The values of DestA and DestB frequently come from a call to the 551 // 'TargetInstrInfo::AnalyzeBranch' method. We take our meaning of the initial 552 // values from there. 553 // 554 // 1. If both DestA and DestB are null, then the block ends with no branches 555 // (it falls through to its successor). 556 // 2. If DestA is set, DestB is null, and isCond is false, then the block ends 557 // with only an unconditional branch. 558 // 3. If DestA is set, DestB is null, and isCond is true, then the block ends 559 // with a conditional branch that falls through to a successor (DestB). 560 // 4. If DestA and DestB is set and isCond is true, then the block ends with a 561 // conditional branch followed by an unconditional branch. DestA is the 562 // 'true' destination and DestB is the 'false' destination. 563 564 bool Changed = false; 565 566 MachineFunction::iterator FallThru = 567 llvm::next(MachineFunction::iterator(this)); 568 569 if (DestA == 0 && DestB == 0) { 570 // Block falls through to successor. 571 DestA = FallThru; 572 DestB = FallThru; 573 } else if (DestA != 0 && DestB == 0) { 574 if (isCond) 575 // Block ends in conditional jump that falls through to successor. 576 DestB = FallThru; 577 } else { 578 assert(DestA && DestB && isCond && 579 "CFG in a bad state. Cannot correct CFG edges"); 580 } 581 582 // Remove superfluous edges. I.e., those which aren't destinations of this 583 // basic block, duplicate edges, or landing pads. 584 SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs; 585 MachineBasicBlock::succ_iterator SI = succ_begin(); 586 while (SI != succ_end()) { 587 const MachineBasicBlock *MBB = *SI; 588 if (!SeenMBBs.insert(MBB) || 589 (MBB != DestA && MBB != DestB && !MBB->isLandingPad())) { 590 // This is a superfluous edge, remove it. 591 SI = removeSuccessor(SI); 592 Changed = true; 593 } else { 594 ++SI; 595 } 596 } 597 598 return Changed; 599} 600 601/// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping 602/// any DBG_VALUE instructions. Return UnknownLoc if there is none. 603DebugLoc 604MachineBasicBlock::findDebugLoc(MachineBasicBlock::iterator &MBBI) { 605 DebugLoc DL; 606 MachineBasicBlock::iterator E = end(); 607 if (MBBI != E) { 608 // Skip debug declarations, we don't want a DebugLoc from them. 609 MachineBasicBlock::iterator MBBI2 = MBBI; 610 while (MBBI2 != E && MBBI2->isDebugValue()) 611 MBBI2++; 612 if (MBBI2 != E) 613 DL = MBBI2->getDebugLoc(); 614 } 615 return DL; 616} 617 618void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB, 619 bool t) { 620 OS << "BB#" << MBB->getNumber(); 621} 622 623