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 N->RemoveRegOperandsFromUseLists();
116 LeakDetector::addGarbageObject(N);
119 /// transferNodesFromList (MI) - When moving a range of instructions from one
120 /// MBB list to another, we need to update the parent pointers and the use/def
122 void ilist_traits<MachineInstr>::
123 transferNodesFromList(ilist_traits<MachineInstr> &fromList,
124 ilist_iterator<MachineInstr> first,
125 ilist_iterator<MachineInstr> last) {
126 assert(Parent->getParent() == fromList.Parent->getParent() &&
127 "MachineInstr parent mismatch!");
129 // Splice within the same MBB -> no change.
130 if (Parent == fromList.Parent) return;
132 // If splicing between two blocks within the same function, just update the
134 for (; first != last; ++first)
135 first->setParent(Parent);
138 void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
139 assert(!MI->getParent() && "MI is still in a block!");
140 Parent->getParent()->DeleteMachineInstr(MI);
143 MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
144 instr_iterator I = instr_begin(), E = instr_end();
145 while (I != E && I->isPHI())
147 assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
151 MachineBasicBlock::iterator
152 MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
154 while (I != E && (I->isPHI() || I->isLabel() || I->isDebugValue()))
156 // FIXME: This needs to change if we wish to bundle labels / dbg_values
157 // inside the bundle.
158 assert(!I->isInsideBundle() &&
159 "First non-phi / non-label instruction is inside a bundle!");
163 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
164 iterator B = begin(), E = end(), I = E;
165 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
167 while (I != E && !I->isTerminator())
172 MachineBasicBlock::const_iterator
173 MachineBasicBlock::getFirstTerminator() const {
174 const_iterator B = begin(), E = end(), I = E;
175 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
177 while (I != E && !I->isTerminator())
182 MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
183 instr_iterator B = instr_begin(), E = instr_end(), I = E;
184 while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
186 while (I != E && !I->isTerminator())
191 MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
192 // Skip over end-of-block dbg_value instructions.
193 instr_iterator B = instr_begin(), I = instr_end();
196 // Return instruction that starts a bundle.
197 if (I->isDebugValue() || I->isInsideBundle())
201 // The block is all debug values.
205 MachineBasicBlock::const_iterator
206 MachineBasicBlock::getLastNonDebugInstr() const {
207 // Skip over end-of-block dbg_value instructions.
208 const_instr_iterator B = instr_begin(), I = instr_end();
211 // Return instruction that starts a bundle.
212 if (I->isDebugValue() || I->isInsideBundle())
216 // The block is all debug values.
220 const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
221 // A block with a landing pad successor only has one other successor.
224 for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
225 if ((*I)->isLandingPad())
230 void MachineBasicBlock::dump() const {
234 StringRef MachineBasicBlock::getName() const {
235 if (const BasicBlock *LBB = getBasicBlock())
236 return LBB->getName();
241 void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const {
242 const MachineFunction *MF = getParent();
244 OS << "Can't print out MachineBasicBlock because parent MachineFunction"
250 OS << Indexes->getMBBStartIdx(this) << '\t';
252 OS << "BB#" << getNumber() << ": ";
254 const char *Comma = "";
255 if (const BasicBlock *LBB = getBasicBlock()) {
256 OS << Comma << "derived from LLVM BB ";
257 WriteAsOperand(OS, LBB, /*PrintType=*/false);
260 if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
261 if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
263 OS << Comma << "Align " << Alignment << " (" << (1u << Alignment)
270 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
271 if (!livein_empty()) {
272 if (Indexes) OS << '\t';
274 for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
275 OS << ' ' << PrintReg(*I, TRI);
278 // Print the preds of this block according to the CFG.
280 if (Indexes) OS << '\t';
281 OS << " Predecessors according to CFG:";
282 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
283 OS << " BB#" << (*PI)->getNumber();
287 for (const_instr_iterator I = instr_begin(); I != instr_end(); ++I) {
289 if (Indexes->hasIndex(I))
290 OS << Indexes->getInstructionIndex(I);
294 if (I->isInsideBundle())
296 I->print(OS, &getParent()->getTarget());
299 // Print the successors of this block according to the CFG.
301 if (Indexes) OS << '\t';
302 OS << " Successors according to CFG:";
303 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
304 OS << " BB#" << (*SI)->getNumber();
309 void MachineBasicBlock::removeLiveIn(unsigned Reg) {
310 std::vector<unsigned>::iterator I =
311 std::find(LiveIns.begin(), LiveIns.end(), Reg);
312 assert(I != LiveIns.end() && "Not a live in!");
316 bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
317 livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
318 return I != livein_end();
321 void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
322 getParent()->splice(NewAfter, this);
325 void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
326 MachineFunction::iterator BBI = NewBefore;
327 getParent()->splice(++BBI, this);
330 void MachineBasicBlock::updateTerminator() {
331 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
332 // A block with no successors has no concerns with fall-through edges.
333 if (this->succ_empty()) return;
335 MachineBasicBlock *TBB = 0, *FBB = 0;
336 SmallVector<MachineOperand, 4> Cond;
337 DebugLoc dl; // FIXME: this is nowhere
338 bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond);
340 assert(!B && "UpdateTerminators requires analyzable predecessors!");
343 // The block has an unconditional branch. If its successor is now
344 // its layout successor, delete the branch.
345 if (isLayoutSuccessor(TBB))
346 TII->RemoveBranch(*this);
348 // The block has an unconditional fallthrough. If its successor is not
349 // its layout successor, insert a branch. First we have to locate the
350 // only non-landing-pad successor, as that is the fallthrough block.
351 for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
352 if ((*SI)->isLandingPad())
354 assert(!TBB && "Found more than one non-landing-pad successor!");
358 // If there is no non-landing-pad successor, the block has no
359 // fall-through edges to be concerned with.
363 // Finally update the unconditional successor to be reached via a branch
364 // if it would not be reached by fallthrough.
365 if (!isLayoutSuccessor(TBB))
366 TII->InsertBranch(*this, TBB, 0, Cond, dl);
370 // The block has a non-fallthrough conditional branch. If one of its
371 // successors is its layout successor, rewrite it to a fallthrough
372 // conditional branch.
373 if (isLayoutSuccessor(TBB)) {
374 if (TII->ReverseBranchCondition(Cond))
376 TII->RemoveBranch(*this);
377 TII->InsertBranch(*this, FBB, 0, Cond, dl);
378 } else if (isLayoutSuccessor(FBB)) {
379 TII->RemoveBranch(*this);
380 TII->InsertBranch(*this, TBB, 0, Cond, dl);
383 // The block has a fallthrough conditional branch.
384 MachineBasicBlock *MBBA = *succ_begin();
385 MachineBasicBlock *MBBB = *llvm::next(succ_begin());
386 if (MBBA == TBB) std::swap(MBBB, MBBA);
387 if (isLayoutSuccessor(TBB)) {
388 if (TII->ReverseBranchCondition(Cond)) {
389 // We can't reverse the condition, add an unconditional branch.
391 TII->InsertBranch(*this, MBBA, 0, Cond, dl);
394 TII->RemoveBranch(*this);
395 TII->InsertBranch(*this, MBBA, 0, Cond, dl);
396 } else if (!isLayoutSuccessor(MBBA)) {
397 TII->RemoveBranch(*this);
398 TII->InsertBranch(*this, TBB, MBBA, Cond, dl);
404 void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ, uint32_t weight) {
406 // If we see non-zero value for the first time it means we actually use Weight
407 // list, so we fill all Weights with 0's.
408 if (weight != 0 && Weights.empty())
409 Weights.resize(Successors.size());
411 if (weight != 0 || !Weights.empty())
412 Weights.push_back(weight);
414 Successors.push_back(succ);
415 succ->addPredecessor(this);
418 void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
419 succ->removePredecessor(this);
420 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
421 assert(I != Successors.end() && "Not a current successor!");
423 // If Weight list is empty it means we don't use it (disabled optimization).
424 if (!Weights.empty()) {
425 weight_iterator WI = getWeightIterator(I);
432 MachineBasicBlock::succ_iterator
433 MachineBasicBlock::removeSuccessor(succ_iterator I) {
434 assert(I != Successors.end() && "Not a current successor!");
436 // If Weight list is empty it means we don't use it (disabled optimization).
437 if (!Weights.empty()) {
438 weight_iterator WI = getWeightIterator(I);
442 (*I)->removePredecessor(this);
443 return Successors.erase(I);
446 void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
447 MachineBasicBlock *New) {
449 succ_iterator SI = std::find(Successors.begin(), Successors.end(), Old);
451 // If Weight list is empty it means we don't use it (disabled optimization).
452 if (!Weights.empty()) {
453 weight_iterator WI = getWeightIterator(SI);
457 // Update the successor information.
459 addSuccessor(New, weight);
462 void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
463 Predecessors.push_back(pred);
466 void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
467 pred_iterator I = std::find(Predecessors.begin(), Predecessors.end(), pred);
468 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
469 Predecessors.erase(I);
472 void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
476 while (!fromMBB->succ_empty()) {
477 MachineBasicBlock *Succ = *fromMBB->succ_begin();
481 // If Weight list is empty it means we don't use it (disabled optimization).
482 if (!fromMBB->Weights.empty())
483 weight = *fromMBB->Weights.begin();
485 addSuccessor(Succ, weight);
486 fromMBB->removeSuccessor(Succ);
491 MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
495 while (!fromMBB->succ_empty()) {
496 MachineBasicBlock *Succ = *fromMBB->succ_begin();
498 fromMBB->removeSuccessor(Succ);
500 // Fix up any PHI nodes in the successor.
501 for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
502 ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
503 for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
504 MachineOperand &MO = MI->getOperand(i);
505 if (MO.getMBB() == fromMBB)
511 bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
512 const_succ_iterator I = std::find(Successors.begin(), Successors.end(), MBB);
513 return I != Successors.end();
516 bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
517 MachineFunction::const_iterator I(this);
518 return llvm::next(I) == MachineFunction::const_iterator(MBB);
521 bool MachineBasicBlock::canFallThrough() {
522 MachineFunction::iterator Fallthrough = this;
524 // If FallthroughBlock is off the end of the function, it can't fall through.
525 if (Fallthrough == getParent()->end())
528 // If FallthroughBlock isn't a successor, no fallthrough is possible.
529 if (!isSuccessor(Fallthrough))
532 // Analyze the branches, if any, at the end of the block.
533 MachineBasicBlock *TBB = 0, *FBB = 0;
534 SmallVector<MachineOperand, 4> Cond;
535 const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
536 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) {
537 // If we couldn't analyze the branch, examine the last instruction.
538 // If the block doesn't end in a known control barrier, assume fallthrough
539 // is possible. The isPredicated check is needed because this code can be
540 // called during IfConversion, where an instruction which is normally a
541 // Barrier is predicated and thus no longer an actual control barrier.
542 return empty() || !back().isBarrier() || TII->isPredicated(&back());
545 // If there is no branch, control always falls through.
546 if (TBB == 0) return true;
548 // If there is some explicit branch to the fallthrough block, it can obviously
549 // reach, even though the branch should get folded to fall through implicitly.
550 if (MachineFunction::iterator(TBB) == Fallthrough ||
551 MachineFunction::iterator(FBB) == Fallthrough)
554 // If it's an unconditional branch to some block not the fall through, it
555 // doesn't fall through.
556 if (Cond.empty()) return false;
558 // Otherwise, if it is conditional and has no explicit false block, it falls
564 MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
565 MachineFunction *MF = getParent();
566 DebugLoc dl; // FIXME: this is nowhere
568 // We may need to update this's terminator, but we can't do that if
569 // AnalyzeBranch fails. If this uses a jump table, we won't touch it.
570 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
571 MachineBasicBlock *TBB = 0, *FBB = 0;
572 SmallVector<MachineOperand, 4> Cond;
573 if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
576 // Avoid bugpoint weirdness: A block may end with a conditional branch but
577 // jumps to the same MBB is either case. We have duplicate CFG edges in that
578 // case that we can't handle. Since this never happens in properly optimized
579 // code, just skip those edges.
580 if (TBB && TBB == FBB) {
581 DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
582 << getNumber() << '\n');
586 MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
587 MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
588 DEBUG(dbgs() << "Splitting critical edge:"
589 " BB#" << getNumber()
590 << " -- BB#" << NMBB->getNumber()
591 << " -- BB#" << Succ->getNumber() << '\n');
593 // On some targets like Mips, branches may kill virtual registers. Make sure
594 // that LiveVariables is properly updated after updateTerminator replaces the
596 LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();
598 // Collect a list of virtual registers killed by the terminators.
599 SmallVector<unsigned, 4> KilledRegs;
601 for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
603 MachineInstr *MI = I;
604 for (MachineInstr::mop_iterator OI = MI->operands_begin(),
605 OE = MI->operands_end(); OI != OE; ++OI) {
606 if (!OI->isReg() || OI->getReg() == 0 ||
607 !OI->isUse() || !OI->isKill() || OI->isUndef())
609 unsigned Reg = OI->getReg();
610 if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
611 LV->getVarInfo(Reg).removeKill(MI)) {
612 KilledRegs.push_back(Reg);
613 DEBUG(dbgs() << "Removing terminator kill: " << *MI);
614 OI->setIsKill(false);
619 ReplaceUsesOfBlockWith(Succ, NMBB);
622 // Insert unconditional "jump Succ" instruction in NMBB if necessary.
623 NMBB->addSuccessor(Succ);
624 if (!NMBB->isLayoutSuccessor(Succ)) {
626 MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl);
629 // Fix PHI nodes in Succ so they refer to NMBB instead of this
630 for (MachineBasicBlock::instr_iterator
631 i = Succ->instr_begin(),e = Succ->instr_end();
632 i != e && i->isPHI(); ++i)
633 for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
634 if (i->getOperand(ni+1).getMBB() == this)
635 i->getOperand(ni+1).setMBB(NMBB);
637 // Inherit live-ins from the successor
638 for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
639 E = Succ->livein_end(); I != E; ++I)
642 // Update LiveVariables.
643 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
645 // Restore kills of virtual registers that were killed by the terminators.
646 while (!KilledRegs.empty()) {
647 unsigned Reg = KilledRegs.pop_back_val();
648 for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
649 if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
651 if (TargetRegisterInfo::isVirtualRegister(Reg))
652 LV->getVarInfo(Reg).Kills.push_back(I);
653 DEBUG(dbgs() << "Restored terminator kill: " << *I);
657 // Update relevant live-through information.
658 LV->addNewBlock(NMBB, this, Succ);
661 if (MachineDominatorTree *MDT =
662 P->getAnalysisIfAvailable<MachineDominatorTree>()) {
663 // Update dominator information.
664 MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
666 bool IsNewIDom = true;
667 for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
669 MachineBasicBlock *PredBB = *PI;
672 if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
678 // We know "this" dominates the newly created basic block.
679 MachineDomTreeNode *NewDTNode = MDT->addNewBlock(NMBB, this);
681 // If all the other predecessors of "Succ" are dominated by "Succ" itself
682 // then the new block is the new immediate dominator of "Succ". Otherwise,
683 // the new block doesn't dominate anything.
685 MDT->changeImmediateDominator(SucccDTNode, NewDTNode);
688 if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
689 if (MachineLoop *TIL = MLI->getLoopFor(this)) {
690 // If one or the other blocks were not in a loop, the new block is not
691 // either, and thus LI doesn't need to be updated.
692 if (MachineLoop *DestLoop = MLI->getLoopFor(Succ)) {
693 if (TIL == DestLoop) {
694 // Both in the same loop, the NMBB joins loop.
695 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
696 } else if (TIL->contains(DestLoop)) {
697 // Edge from an outer loop to an inner loop. Add to the outer loop.
698 TIL->addBasicBlockToLoop(NMBB, MLI->getBase());
699 } else if (DestLoop->contains(TIL)) {
700 // Edge from an inner loop to an outer loop. Add to the outer loop.
701 DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
703 // Edge from two loops with no containment relation. Because these
704 // are natural loops, we know that the destination block must be the
705 // header of its loop (adding a branch into a loop elsewhere would
706 // create an irreducible loop).
707 assert(DestLoop->getHeader() == Succ &&
708 "Should not create irreducible loops!");
709 if (MachineLoop *P = DestLoop->getParentLoop())
710 P->addBasicBlockToLoop(NMBB, MLI->getBase());
718 MachineBasicBlock::iterator
719 MachineBasicBlock::erase(MachineBasicBlock::iterator I) {
721 MachineBasicBlock::iterator E = llvm::next(I);
722 return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
725 return Insts.erase(I.getInstrIterator());
728 MachineInstr *MachineBasicBlock::remove(MachineInstr *I) {
730 instr_iterator MII = llvm::next(I);
732 while (MII != E && MII->isInsideBundle()) {
733 MachineInstr *MI = &*MII++;
738 return Insts.remove(I);
741 void MachineBasicBlock::splice(MachineBasicBlock::iterator where,
742 MachineBasicBlock *Other,
743 MachineBasicBlock::iterator From) {
744 if (From->isBundle()) {
745 MachineBasicBlock::iterator To = llvm::next(From);
746 Insts.splice(where.getInstrIterator(), Other->Insts,
747 From.getInstrIterator(), To.getInstrIterator());
751 Insts.splice(where.getInstrIterator(), Other->Insts, From.getInstrIterator());
754 /// removeFromParent - This method unlinks 'this' from the containing function,
755 /// and returns it, but does not delete it.
756 MachineBasicBlock *MachineBasicBlock::removeFromParent() {
757 assert(getParent() && "Not embedded in a function!");
758 getParent()->remove(this);
763 /// eraseFromParent - This method unlinks 'this' from the containing function,
765 void MachineBasicBlock::eraseFromParent() {
766 assert(getParent() && "Not embedded in a function!");
767 getParent()->erase(this);
771 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
772 /// 'Old', change the code and CFG so that it branches to 'New' instead.
773 void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
774 MachineBasicBlock *New) {
775 assert(Old != New && "Cannot replace self with self!");
777 MachineBasicBlock::instr_iterator I = instr_end();
778 while (I != instr_begin()) {
780 if (!I->isTerminator()) break;
782 // Scan the operands of this machine instruction, replacing any uses of Old
784 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
785 if (I->getOperand(i).isMBB() &&
786 I->getOperand(i).getMBB() == Old)
787 I->getOperand(i).setMBB(New);
790 // Update the successor information.
791 replaceSuccessor(Old, New);
794 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
795 /// CFG to be inserted. If we have proven that MBB can only branch to DestA and
796 /// DestB, remove any other MBB successors from the CFG. DestA and DestB can be
799 /// Besides DestA and DestB, retain other edges leading to LandingPads
800 /// (currently there can be only one; we don't check or require that here).
801 /// Note it is possible that DestA and/or DestB are LandingPads.
802 bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
803 MachineBasicBlock *DestB,
805 // The values of DestA and DestB frequently come from a call to the
806 // 'TargetInstrInfo::AnalyzeBranch' method. We take our meaning of the initial
807 // values from there.
809 // 1. If both DestA and DestB are null, then the block ends with no branches
810 // (it falls through to its successor).
811 // 2. If DestA is set, DestB is null, and isCond is false, then the block ends
812 // with only an unconditional branch.
813 // 3. If DestA is set, DestB is null, and isCond is true, then the block ends
814 // with a conditional branch that falls through to a successor (DestB).
815 // 4. If DestA and DestB is set and isCond is true, then the block ends with a
816 // conditional branch followed by an unconditional branch. DestA is the
817 // 'true' destination and DestB is the 'false' destination.
819 bool Changed = false;
821 MachineFunction::iterator FallThru =
822 llvm::next(MachineFunction::iterator(this));
824 if (DestA == 0 && DestB == 0) {
825 // Block falls through to successor.
828 } else if (DestA != 0 && DestB == 0) {
830 // Block ends in conditional jump that falls through to successor.
833 assert(DestA && DestB && isCond &&
834 "CFG in a bad state. Cannot correct CFG edges");
837 // Remove superfluous edges. I.e., those which aren't destinations of this
838 // basic block, duplicate edges, or landing pads.
839 SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs;
840 MachineBasicBlock::succ_iterator SI = succ_begin();
841 while (SI != succ_end()) {
842 const MachineBasicBlock *MBB = *SI;
843 if (!SeenMBBs.insert(MBB) ||
844 (MBB != DestA && MBB != DestB && !MBB->isLandingPad())) {
845 // This is a superfluous edge, remove it.
846 SI = removeSuccessor(SI);
856 /// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
857 /// any DBG_VALUE instructions. Return UnknownLoc if there is none.
859 MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
861 instr_iterator E = instr_end();
865 // Skip debug declarations, we don't want a DebugLoc from them.
866 while (MBBI != E && MBBI->isDebugValue())
869 DL = MBBI->getDebugLoc();
873 /// getSuccWeight - Return weight of the edge from this block to MBB.
875 uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const {
879 const_succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
880 return *getWeightIterator(I);
883 /// getWeightIterator - Return wight iterator corresonding to the I successor
885 MachineBasicBlock::weight_iterator MachineBasicBlock::
886 getWeightIterator(MachineBasicBlock::succ_iterator I) {
887 assert(Weights.size() == Successors.size() && "Async weight list!");
888 size_t index = std::distance(Successors.begin(), I);
889 assert(index < Weights.size() && "Not a current successor!");
890 return Weights.begin() + index;
893 /// getWeightIterator - Return wight iterator corresonding to the I successor
895 MachineBasicBlock::const_weight_iterator MachineBasicBlock::
896 getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
897 assert(Weights.size() == Successors.size() && "Async weight list!");
898 const size_t index = std::distance(Successors.begin(), I);
899 assert(index < Weights.size() && "Not a current successor!");
900 return Weights.begin() + index;
903 void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
905 OS << "BB#" << MBB->getNumber();