1 //===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Collect the sequence of machine instructions for a basic block.
12 //===----------------------------------------------------------------------===//
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/CodeGen/SlotIndexes.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/Target/TargetRegisterInfo.h"
24 #include "llvm/Target/TargetData.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"
36 MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
37 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false),
42 MachineBasicBlock::~MachineBasicBlock() {
43 LeakDetector::removeGarbageObject(this);
46 /// getSymbol - Return the MCSymbol for this basic block.
48 MCSymbol *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()) + "_" +
58 raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
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.
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.
70 void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) {
71 MachineFunction &MF = *N->getParent();
72 N->Number = MF.addToMBBNumbering(N);
74 // Make sure the instructions have their operands in the reginfo lists.
75 MachineRegisterInfo &RegInfo = MF.getRegInfo();
76 for (MachineBasicBlock::instr_iterator
77 I = N->instr_begin(), E = N->instr_end(); I != E; ++I)
78 I->AddRegOperandsToUseLists(RegInfo);
80 LeakDetector::removeGarbageObject(N);
83 void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) {
84 N->getParent()->removeFromMBBNumbering(N->Number);
86 LeakDetector::addGarbageObject(N);
90 /// addNodeToList (MI) - When we add an instruction to a basic block
91 /// list, we update its parent pointer and add its operands from reg use/def
92 /// lists if appropriate.
93 void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
94 assert(N->getParent() == 0 && "machine instruction already in a basic block");
97 // Add the instruction's register operands to their corresponding
99 MachineFunction *MF = Parent->getParent();
100 N->AddRegOperandsToUseLists(MF->getRegInfo());
102 LeakDetector::removeGarbageObject(N);
105 /// removeNodeFromList (MI) - When we remove an instruction from a basic block
106 /// list, we update its parent pointer and remove its operands from reg use/def
107 /// lists if appropriate.
108 void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
109 assert(N->getParent() != 0 && "machine instruction not in a basic block");
111 // Remove from the use/def lists.
112 if (MachineFunction *MF = N->getParent()->getParent())
113 N->RemoveRegOperandsFromUseLists(MF->getRegInfo());
117 LeakDetector::addGarbageObject(N);
120 /// transferNodesFromList (MI) - When moving a range of instructions from one
121 /// MBB list to another, we need to update the parent pointers and the use/def
123 void ilist_traits<MachineInstr>::
124 transferNodesFromList(ilist_traits<MachineInstr> &fromList,
125 ilist_iterator<MachineInstr> first,
126 ilist_iterator<MachineInstr> last) {
127 assert(Parent->getParent() == fromList.Parent->getParent() &&
128 "MachineInstr parent mismatch!");
130 // Splice within the same MBB -> no change.
131 if (Parent == fromList.Parent) return;
133 // If splicing between two blocks within the same function, just update the
135 for (; first != last; ++first)
136 first->setParent(Parent);
139 void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
140 assert(!MI->getParent() && "MI is still in a block!");
141 Parent->getParent()->DeleteMachineInstr(MI);
144 MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
145 instr_iterator I = instr_begin(), E = instr_end();
146 while (I != E && I->isPHI())
148 assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
152 MachineBasicBlock::iterator
153 MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
155 while (I != E && (I->isPHI() || I->isLabel() || I->isDebugValue()))
157 // FIXME: This needs to change if we wish to bundle labels / dbg_values
158 // inside the bundle.
159 assert(!I->isInsideBundle() &&
160 "First non-phi / non-label instruction is inside a bundle!");
164 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
165 iterator B = begin(), E = end(), I = E;
166 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
168 while (I != E && !I->isTerminator())
173 MachineBasicBlock::const_iterator
174 MachineBasicBlock::getFirstTerminator() const {
175 const_iterator B = begin(), E = end(), I = E;
176 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
178 while (I != E && !I->isTerminator())
183 MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
184 instr_iterator B = instr_begin(), E = instr_end(), I = E;
185 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
187 while (I != E && !I->isTerminator())
192 MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
193 // Skip over end-of-block dbg_value instructions.
194 instr_iterator B = instr_begin(), I = instr_end();
197 // Return instruction that starts a bundle.
198 if (I->isDebugValue() || I->isInsideBundle())
202 // The block is all debug values.
206 MachineBasicBlock::const_iterator
207 MachineBasicBlock::getLastNonDebugInstr() const {
208 // Skip over end-of-block dbg_value instructions.
209 const_instr_iterator B = instr_begin(), I = instr_end();
212 // Return instruction that starts a bundle.
213 if (I->isDebugValue() || I->isInsideBundle())
217 // The block is all debug values.
221 const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
222 // A block with a landing pad successor only has one other successor.
225 for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
226 if ((*I)->isLandingPad())
231 void MachineBasicBlock::dump() const {
235 StringRef MachineBasicBlock::getName() const {
236 if (const BasicBlock *LBB = getBasicBlock())
237 return LBB->getName();
242 /// Return a hopefully unique identifier for this block.
243 std::string MachineBasicBlock::getFullName() const {
246 Name = (getParent()->getFunction()->getName() + ":").str();
248 Name += getBasicBlock()->getName();
250 Name += (Twine("BB") + Twine(getNumber())).str();
254 void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const {
255 const MachineFunction *MF = getParent();
257 OS << "Can't print out MachineBasicBlock because parent MachineFunction"
263 OS << Indexes->getMBBStartIdx(this) << '\t';
265 OS << "BB#" << getNumber() << ": ";
267 const char *Comma = "";
268 if (const BasicBlock *LBB = getBasicBlock()) {
269 OS << Comma << "derived from LLVM BB ";
270 WriteAsOperand(OS, LBB, /*PrintType=*/false);
273 if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
274 if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
276 OS << Comma << "Align " << Alignment << " (" << (1u << Alignment)
281 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
282 if (!livein_empty()) {
283 if (Indexes) OS << '\t';
285 for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
286 OS << ' ' << PrintReg(*I, TRI);
289 // Print the preds of this block according to the CFG.
291 if (Indexes) OS << '\t';
292 OS << " Predecessors according to CFG:";
293 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
294 OS << " BB#" << (*PI)->getNumber();
298 for (const_instr_iterator I = instr_begin(); I != instr_end(); ++I) {
300 if (Indexes->hasIndex(I))
301 OS << Indexes->getInstructionIndex(I);
305 if (I->isInsideBundle())
307 I->print(OS, &getParent()->getTarget());
310 // Print the successors of this block according to the CFG.
312 if (Indexes) OS << '\t';
313 OS << " Successors according to CFG:";
314 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
315 OS << " BB#" << (*SI)->getNumber();
320 void MachineBasicBlock::removeLiveIn(unsigned Reg) {
321 std::vector<unsigned>::iterator I =
322 std::find(LiveIns.begin(), LiveIns.end(), Reg);
323 if (I != LiveIns.end())
327 bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
328 livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
329 return I != livein_end();
332 void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
333 getParent()->splice(NewAfter, this);
336 void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
337 MachineFunction::iterator BBI = NewBefore;
338 getParent()->splice(++BBI, this);
341 void MachineBasicBlock::updateTerminator() {
342 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
343 // A block with no successors has no concerns with fall-through edges.
344 if (this->succ_empty()) return;
346 MachineBasicBlock *TBB = 0, *FBB = 0;
347 SmallVector<MachineOperand, 4> Cond;
348 DebugLoc dl; // FIXME: this is nowhere
349 bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond);
351 assert(!B && "UpdateTerminators requires analyzable predecessors!");
354 // The block has an unconditional branch. If its successor is now
355 // its layout successor, delete the branch.
356 if (isLayoutSuccessor(TBB))
357 TII->RemoveBranch(*this);
359 // The block has an unconditional fallthrough. If its successor is not
360 // its layout successor, insert a branch. First we have to locate the
361 // only non-landing-pad successor, as that is the fallthrough block.
362 for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
363 if ((*SI)->isLandingPad())
365 assert(!TBB && "Found more than one non-landing-pad successor!");
369 // If there is no non-landing-pad successor, the block has no
370 // fall-through edges to be concerned with.
374 // Finally update the unconditional successor to be reached via a branch
375 // if it would not be reached by fallthrough.
376 if (!isLayoutSuccessor(TBB))
377 TII->InsertBranch(*this, TBB, 0, Cond, dl);
381 // The block has a non-fallthrough conditional branch. If one of its
382 // successors is its layout successor, rewrite it to a fallthrough
383 // conditional branch.
384 if (isLayoutSuccessor(TBB)) {
385 if (TII->ReverseBranchCondition(Cond))
387 TII->RemoveBranch(*this);
388 TII->InsertBranch(*this, FBB, 0, Cond, dl);
389 } else if (isLayoutSuccessor(FBB)) {
390 TII->RemoveBranch(*this);
391 TII->InsertBranch(*this, TBB, 0, Cond, dl);
394 // Walk through the successors and find the successor which is not
395 // a landing pad and is not the conditional branch destination (in TBB)
396 // as the fallthrough successor.
397 MachineBasicBlock *FallthroughBB = 0;
398 for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
399 if ((*SI)->isLandingPad() || *SI == TBB)
401 assert(!FallthroughBB && "Found more than one fallthrough successor.");
404 if (!FallthroughBB && canFallThrough()) {
405 // We fallthrough to the same basic block as the conditional jump
406 // targets. Remove the conditional jump, leaving unconditional
408 // FIXME: This does not seem like a reasonable pattern to support, but it
409 // has been seen in the wild coming out of degenerate ARM test cases.
410 TII->RemoveBranch(*this);
412 // Finally update the unconditional successor to be reached via a branch
413 // if it would not be reached by fallthrough.
414 if (!isLayoutSuccessor(TBB))
415 TII->InsertBranch(*this, TBB, 0, Cond, dl);
419 // The block has a fallthrough conditional branch.
420 if (isLayoutSuccessor(TBB)) {
421 if (TII->ReverseBranchCondition(Cond)) {
422 // We can't reverse the condition, add an unconditional branch.
424 TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl);
427 TII->RemoveBranch(*this);
428 TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl);
429 } else if (!isLayoutSuccessor(FallthroughBB)) {
430 TII->RemoveBranch(*this);
431 TII->InsertBranch(*this, TBB, FallthroughBB, Cond, dl);
437 void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ, uint32_t weight) {
439 // If we see non-zero value for the first time it means we actually use Weight
440 // list, so we fill all Weights with 0's.
441 if (weight != 0 && Weights.empty())
442 Weights.resize(Successors.size());
444 if (weight != 0 || !Weights.empty())
445 Weights.push_back(weight);
447 Successors.push_back(succ);
448 succ->addPredecessor(this);
451 void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
452 succ->removePredecessor(this);
453 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
454 assert(I != Successors.end() && "Not a current successor!");
456 // If Weight list is empty it means we don't use it (disabled optimization).
457 if (!Weights.empty()) {
458 weight_iterator WI = getWeightIterator(I);
465 MachineBasicBlock::succ_iterator
466 MachineBasicBlock::removeSuccessor(succ_iterator I) {
467 assert(I != Successors.end() && "Not a current successor!");
469 // If Weight list is empty it means we don't use it (disabled optimization).
470 if (!Weights.empty()) {
471 weight_iterator WI = getWeightIterator(I);
475 (*I)->removePredecessor(this);
476 return Successors.erase(I);
479 void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
480 MachineBasicBlock *New) {
484 succ_iterator E = succ_end();
485 succ_iterator NewI = E;
486 succ_iterator OldI = E;
487 for (succ_iterator I = succ_begin(); I != E; ++I) {
499 assert(OldI != E && "Old is not a successor of this block");
500 Old->removePredecessor(this);
502 // If New isn't already a successor, let it take Old's place.
504 New->addPredecessor(this);
509 // New is already a successor.
510 // Update its weight instead of adding a duplicate edge.
511 if (!Weights.empty()) {
512 weight_iterator OldWI = getWeightIterator(OldI);
513 *getWeightIterator(NewI) += *OldWI;
514 Weights.erase(OldWI);
516 Successors.erase(OldI);
519 void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
520 Predecessors.push_back(pred);
523 void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
524 pred_iterator I = std::find(Predecessors.begin(), Predecessors.end(), pred);
525 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
526 Predecessors.erase(I);
529 void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
533 while (!fromMBB->succ_empty()) {
534 MachineBasicBlock *Succ = *fromMBB->succ_begin();
538 // If Weight list is empty it means we don't use it (disabled optimization).
539 if (!fromMBB->Weights.empty())
540 weight = *fromMBB->Weights.begin();
542 addSuccessor(Succ, weight);
543 fromMBB->removeSuccessor(Succ);
548 MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
552 while (!fromMBB->succ_empty()) {
553 MachineBasicBlock *Succ = *fromMBB->succ_begin();
555 fromMBB->removeSuccessor(Succ);
557 // Fix up any PHI nodes in the successor.
558 for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
559 ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
560 for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
561 MachineOperand &MO = MI->getOperand(i);
562 if (MO.getMBB() == fromMBB)
568 bool MachineBasicBlock::isPredecessor(const MachineBasicBlock *MBB) const {
569 return std::find(pred_begin(), pred_end(), MBB) != pred_end();
572 bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
573 return std::find(succ_begin(), succ_end(), MBB) != succ_end();
576 bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
577 MachineFunction::const_iterator I(this);
578 return llvm::next(I) == MachineFunction::const_iterator(MBB);
581 bool MachineBasicBlock::canFallThrough() {
582 MachineFunction::iterator Fallthrough = this;
584 // If FallthroughBlock is off the end of the function, it can't fall through.
585 if (Fallthrough == getParent()->end())
588 // If FallthroughBlock isn't a successor, no fallthrough is possible.
589 if (!isSuccessor(Fallthrough))
592 // Analyze the branches, if any, at the end of the block.
593 MachineBasicBlock *TBB = 0, *FBB = 0;
594 SmallVector<MachineOperand, 4> Cond;
595 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
596 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) {
597 // If we couldn't analyze the branch, examine the last instruction.
598 // If the block doesn't end in a known control barrier, assume fallthrough
599 // is possible. The isPredicated check is needed because this code can be
600 // called during IfConversion, where an instruction which is normally a
601 // Barrier is predicated and thus no longer an actual control barrier.
602 return empty() || !back().isBarrier() || TII->isPredicated(&back());
605 // If there is no branch, control always falls through.
606 if (TBB == 0) return true;
608 // If there is some explicit branch to the fallthrough block, it can obviously
609 // reach, even though the branch should get folded to fall through implicitly.
610 if (MachineFunction::iterator(TBB) == Fallthrough ||
611 MachineFunction::iterator(FBB) == Fallthrough)
614 // If it's an unconditional branch to some block not the fall through, it
615 // doesn't fall through.
616 if (Cond.empty()) return false;
618 // Otherwise, if it is conditional and has no explicit false block, it falls
624 MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
625 // Splitting the critical edge to a landing pad block is non-trivial. Don't do
626 // it in this generic function.
627 if (Succ->isLandingPad())
630 MachineFunction *MF = getParent();
631 DebugLoc dl; // FIXME: this is nowhere
633 // We may need to update this's terminator, but we can't do that if
634 // AnalyzeBranch fails. If this uses a jump table, we won't touch it.
635 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
636 MachineBasicBlock *TBB = 0, *FBB = 0;
637 SmallVector<MachineOperand, 4> Cond;
638 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
641 // Avoid bugpoint weirdness: A block may end with a conditional branch but
642 // jumps to the same MBB is either case. We have duplicate CFG edges in that
643 // case that we can't handle. Since this never happens in properly optimized
644 // code, just skip those edges.
645 if (TBB && TBB == FBB) {
646 DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
647 << getNumber() << '\n');
651 MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
652 MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
653 DEBUG(dbgs() << "Splitting critical edge:"
654 " BB#" << getNumber()
655 << " -- BB#" << NMBB->getNumber()
656 << " -- BB#" << Succ->getNumber() << '\n');
658 // On some targets like Mips, branches may kill virtual registers. Make sure
659 // that LiveVariables is properly updated after updateTerminator replaces the
661 LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();
663 // Collect a list of virtual registers killed by the terminators.
664 SmallVector<unsigned, 4> KilledRegs;
666 for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
668 MachineInstr *MI = I;
669 for (MachineInstr::mop_iterator OI = MI->operands_begin(),
670 OE = MI->operands_end(); OI != OE; ++OI) {
671 if (!OI->isReg() || OI->getReg() == 0 ||
672 !OI->isUse() || !OI->isKill() || OI->isUndef())
674 unsigned Reg = OI->getReg();
675 if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
676 LV->getVarInfo(Reg).removeKill(MI)) {
677 KilledRegs.push_back(Reg);
678 DEBUG(dbgs() << "Removing terminator kill: " << *MI);
679 OI->setIsKill(false);
684 ReplaceUsesOfBlockWith(Succ, NMBB);
687 // Insert unconditional "jump Succ" instruction in NMBB if necessary.
688 NMBB->addSuccessor(Succ);
689 if (!NMBB->isLayoutSuccessor(Succ)) {
691 MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl);
694 // Fix PHI nodes in Succ so they refer to NMBB instead of this
695 for (MachineBasicBlock::instr_iterator
696 i = Succ->instr_begin(),e = Succ->instr_end();
697 i != e && i->isPHI(); ++i)
698 for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
699 if (i->getOperand(ni+1).getMBB() == this)
700 i->getOperand(ni+1).setMBB(NMBB);
702 // Inherit live-ins from the successor
703 for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
704 E = Succ->livein_end(); I != E; ++I)
707 // Update LiveVariables.
708 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
710 // Restore kills of virtual registers that were killed by the terminators.
711 while (!KilledRegs.empty()) {
712 unsigned Reg = KilledRegs.pop_back_val();
713 for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
714 if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
716 if (TargetRegisterInfo::isVirtualRegister(Reg))
717 LV->getVarInfo(Reg).Kills.push_back(I);
718 DEBUG(dbgs() << "Restored terminator kill: " << *I);
722 // Update relevant live-through information.
723 LV->addNewBlock(NMBB, this, Succ);
726 if (MachineDominatorTree *MDT =
727 P->getAnalysisIfAvailable<MachineDominatorTree>()) {
728 // Update dominator information.
729 MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
731 bool IsNewIDom = true;
732 for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
734 MachineBasicBlock *PredBB = *PI;
737 if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
743 // We know "this" dominates the newly created basic block.
744 MachineDomTreeNode *NewDTNode = MDT->addNewBlock(NMBB, this);
746 // If all the other predecessors of "Succ" are dominated by "Succ" itself
747 // then the new block is the new immediate dominator of "Succ". Otherwise,
748 // the new block doesn't dominate anything.
750 MDT->changeImmediateDominator(SucccDTNode, NewDTNode);
753 if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
754 if (MachineLoop *TIL = MLI->getLoopFor(this)) {
755 // If one or the other blocks were not in a loop, the new block is not
756 // either, and thus LI doesn't need to be updated.
757 if (MachineLoop *DestLoop = MLI->getLoopFor(Succ)) {
758 if (TIL == DestLoop) {
759 // Both in the same loop, the NMBB joins loop.
760 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
761 } else if (TIL->contains(DestLoop)) {
762 // Edge from an outer loop to an inner loop. Add to the outer loop.
763 TIL->addBasicBlockToLoop(NMBB, MLI->getBase());
764 } else if (DestLoop->contains(TIL)) {
765 // Edge from an inner loop to an outer loop. Add to the outer loop.
766 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
768 // Edge from two loops with no containment relation. Because these
769 // are natural loops, we know that the destination block must be the
770 // header of its loop (adding a branch into a loop elsewhere would
771 // create an irreducible loop).
772 assert(DestLoop->getHeader() == Succ &&
773 "Should not create irreducible loops!");
774 if (MachineLoop *P = DestLoop->getParentLoop())
775 P->addBasicBlockToLoop(NMBB, MLI->getBase());
783 MachineBasicBlock::iterator
784 MachineBasicBlock::erase(MachineBasicBlock::iterator I) {
786 MachineBasicBlock::iterator E = llvm::next(I);
787 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
790 return Insts.erase(I.getInstrIterator());
793 MachineInstr *MachineBasicBlock::remove(MachineInstr *I) {
795 instr_iterator MII = llvm::next(I);
797 while (MII != E && MII->isInsideBundle()) {
798 MachineInstr *MI = &*MII++;
803 return Insts.remove(I);
806 void MachineBasicBlock::splice(MachineBasicBlock::iterator where,
807 MachineBasicBlock *Other,
808 MachineBasicBlock::iterator From) {
809 if (From->isBundle()) {
810 MachineBasicBlock::iterator To = llvm::next(From);
811 Insts.splice(where.getInstrIterator(), Other->Insts,
812 From.getInstrIterator(), To.getInstrIterator());
816 Insts.splice(where.getInstrIterator(), Other->Insts, From.getInstrIterator());
819 /// removeFromParent - This method unlinks 'this' from the containing function,
820 /// and returns it, but does not delete it.
821 MachineBasicBlock *MachineBasicBlock::removeFromParent() {
822 assert(getParent() && "Not embedded in a function!");
823 getParent()->remove(this);
828 /// eraseFromParent - This method unlinks 'this' from the containing function,
830 void MachineBasicBlock::eraseFromParent() {
831 assert(getParent() && "Not embedded in a function!");
832 getParent()->erase(this);
836 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
837 /// 'Old', change the code and CFG so that it branches to 'New' instead.
838 void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
839 MachineBasicBlock *New) {
840 assert(Old != New && "Cannot replace self with self!");
842 MachineBasicBlock::instr_iterator I = instr_end();
843 while (I != instr_begin()) {
845 if (!I->isTerminator()) break;
847 // Scan the operands of this machine instruction, replacing any uses of Old
849 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
850 if (I->getOperand(i).isMBB() &&
851 I->getOperand(i).getMBB() == Old)
852 I->getOperand(i).setMBB(New);
855 // Update the successor information.
856 replaceSuccessor(Old, New);
859 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
860 /// CFG to be inserted. If we have proven that MBB can only branch to DestA and
861 /// DestB, remove any other MBB successors from the CFG. DestA and DestB can be
864 /// Besides DestA and DestB, retain other edges leading to LandingPads
865 /// (currently there can be only one; we don't check or require that here).
866 /// Note it is possible that DestA and/or DestB are LandingPads.
867 bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
868 MachineBasicBlock *DestB,
870 // The values of DestA and DestB frequently come from a call to the
871 // 'TargetInstrInfo::AnalyzeBranch' method. We take our meaning of the initial
872 // values from there.
874 // 1. If both DestA and DestB are null, then the block ends with no branches
875 // (it falls through to its successor).
876 // 2. If DestA is set, DestB is null, and isCond is false, then the block ends
877 // with only an unconditional branch.
878 // 3. If DestA is set, DestB is null, and isCond is true, then the block ends
879 // with a conditional branch that falls through to a successor (DestB).
880 // 4. If DestA and DestB is set and isCond is true, then the block ends with a
881 // conditional branch followed by an unconditional branch. DestA is the
882 // 'true' destination and DestB is the 'false' destination.
884 bool Changed = false;
886 MachineFunction::iterator FallThru =
887 llvm::next(MachineFunction::iterator(this));
889 if (DestA == 0 && DestB == 0) {
890 // Block falls through to successor.
893 } else if (DestA != 0 && DestB == 0) {
895 // Block ends in conditional jump that falls through to successor.
898 assert(DestA && DestB && isCond &&
899 "CFG in a bad state. Cannot correct CFG edges");
902 // Remove superfluous edges. I.e., those which aren't destinations of this
903 // basic block, duplicate edges, or landing pads.
904 SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs;
905 MachineBasicBlock::succ_iterator SI = succ_begin();
906 while (SI != succ_end()) {
907 const MachineBasicBlock *MBB = *SI;
908 if (!SeenMBBs.insert(MBB) ||
909 (MBB != DestA && MBB != DestB && !MBB->isLandingPad())) {
910 // This is a superfluous edge, remove it.
911 SI = removeSuccessor(SI);
921 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
922 /// any DBG_VALUE instructions. Return UnknownLoc if there is none.
924 MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
926 instr_iterator E = instr_end();
930 // Skip debug declarations, we don't want a DebugLoc from them.
931 while (MBBI != E && MBBI->isDebugValue())
934 DL = MBBI->getDebugLoc();
938 /// getSuccWeight - Return weight of the edge from this block to MBB.
940 uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const {
944 const_succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
945 return *getWeightIterator(I);
948 /// getWeightIterator - Return wight iterator corresonding to the I successor
950 MachineBasicBlock::weight_iterator MachineBasicBlock::
951 getWeightIterator(MachineBasicBlock::succ_iterator I) {
952 assert(Weights.size() == Successors.size() && "Async weight list!");
953 size_t index = std::distance(Successors.begin(), I);
954 assert(index < Weights.size() && "Not a current successor!");
955 return Weights.begin() + index;
958 /// getWeightIterator - Return wight iterator corresonding to the I successor
960 MachineBasicBlock::const_weight_iterator MachineBasicBlock::
961 getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
962 assert(Weights.size() == Successors.size() && "Async weight list!");
963 const size_t index = std::distance(Successors.begin(), I);
964 assert(index < Weights.size() && "Not a current successor!");
965 return Weights.begin() + index;
968 void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
970 OS << "BB#" << MBB->getNumber();