#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetInstrDesc.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Assembly/Writer.h"
return OS;
}
-/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
+/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
/// parent pointer of the MBB, the MBB numbering, and any instructions in the
/// MBB to be on the right operand list for registers.
///
// Make sure the instructions have their operands in the reginfo lists.
MachineRegisterInfo &RegInfo = MF.getRegInfo();
- for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I)
+ for (MachineBasicBlock::instr_iterator
+ I = N->instr_begin(), E = N->instr_end(); I != E; ++I)
I->AddRegOperandsToUseLists(RegInfo);
LeakDetector::removeGarbageObject(N);
void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
assert(N->getParent() == 0 && "machine instruction already in a basic block");
N->setParent(Parent);
-
+
// Add the instruction's register operands to their corresponding
// use/def lists.
MachineFunction *MF = Parent->getParent();
// Remove from the use/def lists.
N->RemoveRegOperandsFromUseLists();
-
+
N->setParent(0);
LeakDetector::addGarbageObject(N);
/// lists.
void ilist_traits<MachineInstr>::
transferNodesFromList(ilist_traits<MachineInstr> &fromList,
- MachineBasicBlock::iterator first,
- MachineBasicBlock::iterator last) {
+ ilist_iterator<MachineInstr> first,
+ ilist_iterator<MachineInstr> last) {
assert(Parent->getParent() == fromList.Parent->getParent() &&
"MachineInstr parent mismatch!");
}
MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
- iterator I = begin();
+ instr_iterator I = instr_begin();
while (I != end() && I->isPHI())
++I;
+ assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
+ return I;
+}
+
+MachineBasicBlock::iterator
+MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
+ while (I != end() && (I->isPHI() || I->isLabel() || I->isDebugValue()))
+ ++I;
+ // FIXME: This needs to change if we wish to bundle labels / dbg_values
+ // inside the bundle.
+ assert(!I->isInsideBundle() &&
+ "First non-phi / non-label instruction is inside a bundle!");
return I;
}
MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
iterator I = end();
- while (I != begin() && (--I)->getDesc().isTerminator())
+ while (I != begin() && ((--I)->isTerminator() || I->isDebugValue()))
; /*noop */
- if (I != end() && !I->getDesc().isTerminator()) ++I;
+ while (I != end() && !I->isTerminator())
+ ++I;
return I;
}
-void MachineBasicBlock::dump() const {
- print(dbgs());
+MachineBasicBlock::const_iterator
+MachineBasicBlock::getFirstTerminator() const {
+ const_iterator I = end();
+ while (I != begin() && ((--I)->isTerminator() || I->isDebugValue()))
+ ; /*noop */
+ while (I != end() && !I->isTerminator())
+ ++I;
+ return I;
}
-static inline void OutputReg(raw_ostream &os, unsigned RegNo,
- const TargetRegisterInfo *TRI = 0) {
- if (RegNo != 0 && TargetRegisterInfo::isPhysicalRegister(RegNo)) {
- if (TRI)
- os << " %" << TRI->get(RegNo).Name;
- else
- os << " %physreg" << RegNo;
- } else
- os << " %reg" << RegNo;
+MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
+ instr_iterator I = instr_end();
+ while (I != instr_begin() && ((--I)->isTerminator() || I->isDebugValue()))
+ ; /*noop */
+ while (I != instr_end() && !I->isTerminator())
+ ++I;
+ return I;
+}
+
+MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
+ // Skip over end-of-block dbg_value instructions.
+ instr_iterator B = instr_begin(), I = instr_end();
+ while (I != B) {
+ --I;
+ // Return instruction that starts a bundle.
+ if (I->isDebugValue() || I->isInsideBundle())
+ continue;
+ return I;
+ }
+ // The block is all debug values.
+ return end();
+}
+
+MachineBasicBlock::const_iterator
+MachineBasicBlock::getLastNonDebugInstr() const {
+ // Skip over end-of-block dbg_value instructions.
+ const_instr_iterator B = instr_begin(), I = instr_end();
+ while (I != B) {
+ --I;
+ // Return instruction that starts a bundle.
+ if (I->isDebugValue() || I->isInsideBundle())
+ continue;
+ return I;
+ }
+ // The block is all debug values.
+ return end();
+}
+
+const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
+ // A block with a landing pad successor only has one other successor.
+ if (succ_size() > 2)
+ return 0;
+ for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
+ if ((*I)->isLandingPad())
+ return *I;
+ return 0;
+}
+
+void MachineBasicBlock::dump() const {
+ print(dbgs());
}
StringRef MachineBasicBlock::getName() const {
return "(null)";
}
-void MachineBasicBlock::print(raw_ostream &OS) const {
+void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const {
const MachineFunction *MF = getParent();
if (!MF) {
OS << "Can't print out MachineBasicBlock because parent MachineFunction"
return;
}
- if (Alignment) { OS << "Alignment " << Alignment << "\n"; }
+ if (Indexes)
+ OS << Indexes->getMBBStartIdx(this) << '\t';
OS << "BB#" << getNumber() << ": ";
}
if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
+ if (Alignment) {
+ OS << Comma << "Align " << Alignment << " (" << (1u << Alignment)
+ << " bytes)";
+ Comma = ", ";
+ }
+
OS << '\n';
- const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
+ const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
if (!livein_empty()) {
+ if (Indexes) OS << '\t';
OS << " Live Ins:";
for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
- OutputReg(OS, *I, TRI);
+ OS << ' ' << PrintReg(*I, TRI);
OS << '\n';
}
// Print the preds of this block according to the CFG.
if (!pred_empty()) {
+ if (Indexes) OS << '\t';
OS << " Predecessors according to CFG:";
for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
OS << " BB#" << (*PI)->getNumber();
OS << '\n';
}
-
- for (const_iterator I = begin(); I != end(); ++I) {
+
+ for (const_instr_iterator I = instr_begin(); I != instr_end(); ++I) {
+ if (Indexes) {
+ if (Indexes->hasIndex(I))
+ OS << Indexes->getInstructionIndex(I);
+ OS << '\t';
+ }
OS << '\t';
+ if (I->isInsideBundle())
+ OS << " * ";
I->print(OS, &getParent()->getTarget());
}
// Print the successors of this block according to the CFG.
if (!succ_empty()) {
+ if (Indexes) OS << '\t';
OS << " Successors according to CFG:";
for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
OS << " BB#" << (*SI)->getNumber();
TII->RemoveBranch(*this);
} else {
// The block has an unconditional fallthrough. If its successor is not
- // its layout successor, insert a branch.
- TBB = *succ_begin();
+ // its layout successor, insert a branch. First we have to locate the
+ // only non-landing-pad successor, as that is the fallthrough block.
+ for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
+ if ((*SI)->isLandingPad())
+ continue;
+ assert(!TBB && "Found more than one non-landing-pad successor!");
+ TBB = *SI;
+ }
+
+ // If there is no non-landing-pad successor, the block has no
+ // fall-through edges to be concerned with.
+ if (!TBB)
+ return;
+
+ // Finally update the unconditional successor to be reached via a branch
+ // if it would not be reached by fallthrough.
if (!isLayoutSuccessor(TBB))
TII->InsertBranch(*this, TBB, 0, Cond, dl);
}
}
}
-void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
- Successors.push_back(succ);
- succ->addPredecessor(this);
-}
+void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ, uint32_t weight) {
+
+ // If we see non-zero value for the first time it means we actually use Weight
+ // list, so we fill all Weights with 0's.
+ if (weight != 0 && Weights.empty())
+ Weights.resize(Successors.size());
+
+ if (weight != 0 || !Weights.empty())
+ Weights.push_back(weight);
+
+ Successors.push_back(succ);
+ succ->addPredecessor(this);
+ }
void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
succ->removePredecessor(this);
succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
assert(I != Successors.end() && "Not a current successor!");
+
+ // If Weight list is empty it means we don't use it (disabled optimization).
+ if (!Weights.empty()) {
+ weight_iterator WI = getWeightIterator(I);
+ Weights.erase(WI);
+ }
+
Successors.erase(I);
}
-MachineBasicBlock::succ_iterator
+MachineBasicBlock::succ_iterator
MachineBasicBlock::removeSuccessor(succ_iterator I) {
assert(I != Successors.end() && "Not a current successor!");
+
+ // If Weight list is empty it means we don't use it (disabled optimization).
+ if (!Weights.empty()) {
+ weight_iterator WI = getWeightIterator(I);
+ Weights.erase(WI);
+ }
+
(*I)->removePredecessor(this);
return Successors.erase(I);
}
+void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
+ MachineBasicBlock *New) {
+ uint32_t weight = 0;
+ succ_iterator SI = std::find(Successors.begin(), Successors.end(), Old);
+
+ // If Weight list is empty it means we don't use it (disabled optimization).
+ if (!Weights.empty()) {
+ weight_iterator WI = getWeightIterator(SI);
+ weight = *WI;
+ }
+
+ // Update the successor information.
+ removeSuccessor(SI);
+ addSuccessor(New, weight);
+}
+
void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
Predecessors.push_back(pred);
}
void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
- std::vector<MachineBasicBlock *>::iterator I =
- std::find(Predecessors.begin(), Predecessors.end(), pred);
+ pred_iterator I = std::find(Predecessors.begin(), Predecessors.end(), pred);
assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
Predecessors.erase(I);
}
void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
if (this == fromMBB)
return;
-
+
while (!fromMBB->succ_empty()) {
MachineBasicBlock *Succ = *fromMBB->succ_begin();
- addSuccessor(Succ);
+ uint32_t weight = 0;
+
+
+ // If Weight list is empty it means we don't use it (disabled optimization).
+ if (!fromMBB->Weights.empty())
+ weight = *fromMBB->Weights.begin();
+
+ addSuccessor(Succ, weight);
fromMBB->removeSuccessor(Succ);
}
}
MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
if (this == fromMBB)
return;
-
+
while (!fromMBB->succ_empty()) {
MachineBasicBlock *Succ = *fromMBB->succ_begin();
addSuccessor(Succ);
fromMBB->removeSuccessor(Succ);
// Fix up any PHI nodes in the successor.
- for (MachineBasicBlock::iterator MI = Succ->begin(), ME = Succ->end();
- MI != ME && MI->isPHI(); ++MI)
+ for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
+ ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
MachineOperand &MO = MI->getOperand(i);
if (MO.getMBB() == fromMBB)
}
bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
- std::vector<MachineBasicBlock *>::const_iterator I =
- std::find(Successors.begin(), Successors.end(), MBB);
+ const_succ_iterator I = std::find(Successors.begin(), Successors.end(), MBB);
return I != Successors.end();
}
// Barrier is predicated and thus no longer an actual control barrier. This
// is over-conservative though, because if an instruction isn't actually
// predicated we could still treat it like a barrier.
- return empty() || !back().getDesc().isBarrier() ||
- back().getDesc().isPredicable();
+ return empty() || !back().isBarrier() ||
+ back().isPredicable();
}
// If there is no branch, control always falls through.
MachineFunction *MF = getParent();
DebugLoc dl; // FIXME: this is nowhere
- // We may need to update this's terminator, but we can't do that if AnalyzeBranch
- // fails. If this uses a jump table, we won't touch it.
+ // We may need to update this's terminator, but we can't do that if
+ // AnalyzeBranch fails. If this uses a jump table, we won't touch it.
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
return NULL;
+ // Avoid bugpoint weirdness: A block may end with a conditional branch but
+ // jumps to the same MBB is either case. We have duplicate CFG edges in that
+ // case that we can't handle. Since this never happens in properly optimized
+ // code, just skip those edges.
+ if (TBB && TBB == FBB) {
+ DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
+ << getNumber() << '\n');
+ return NULL;
+ }
+
MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
- DEBUG(dbgs() << "PHIElimination splitting critical edge:"
+ DEBUG(dbgs() << "Splitting critical edge:"
" BB#" << getNumber()
<< " -- BB#" << NMBB->getNumber()
<< " -- BB#" << Succ->getNumber() << '\n');
+ // On some targets like Mips, branches may kill virtual registers. Make sure
+ // that LiveVariables is properly updated after updateTerminator replaces the
+ // terminators.
+ LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();
+
+ // Collect a list of virtual registers killed by the terminators.
+ SmallVector<unsigned, 4> KilledRegs;
+ if (LV)
+ for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
+ I != E; ++I) {
+ MachineInstr *MI = I;
+ for (MachineInstr::mop_iterator OI = MI->operands_begin(),
+ OE = MI->operands_end(); OI != OE; ++OI) {
+ if (!OI->isReg() || !OI->isUse() || !OI->isKill() || OI->isUndef())
+ continue;
+ unsigned Reg = OI->getReg();
+ if (TargetRegisterInfo::isVirtualRegister(Reg) &&
+ LV->getVarInfo(Reg).removeKill(MI)) {
+ KilledRegs.push_back(Reg);
+ DEBUG(dbgs() << "Removing terminator kill: " << *MI);
+ OI->setIsKill(false);
+ }
+ }
+ }
+
ReplaceUsesOfBlockWith(Succ, NMBB);
updateTerminator();
}
// Fix PHI nodes in Succ so they refer to NMBB instead of this
- for (MachineBasicBlock::iterator i = Succ->begin(), e = Succ->end();
+ for (MachineBasicBlock::instr_iterator
+ i = Succ->instr_begin(),e = Succ->instr_end();
i != e && i->isPHI(); ++i)
for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
if (i->getOperand(ni+1).getMBB() == this)
i->getOperand(ni+1).setMBB(NMBB);
- if (LiveVariables *LV =
- P->getAnalysisIfAvailable<LiveVariables>())
+ // Inherit live-ins from the successor
+ for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
+ E = Succ->livein_end(); I != E; ++I)
+ NMBB->addLiveIn(*I);
+
+ // Update LiveVariables.
+ if (LV) {
+ // Restore kills of virtual registers that were killed by the terminators.
+ while (!KilledRegs.empty()) {
+ unsigned Reg = KilledRegs.pop_back_val();
+ for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
+ if (!(--I)->addRegisterKilled(Reg, NULL, /* addIfNotFound= */ false))
+ continue;
+ LV->getVarInfo(Reg).Kills.push_back(I);
+ DEBUG(dbgs() << "Restored terminator kill: " << *I);
+ break;
+ }
+ }
+ // Update relevant live-through information.
LV->addNewBlock(NMBB, this, Succ);
+ }
if (MachineDominatorTree *MDT =
- P->getAnalysisIfAvailable<MachineDominatorTree>())
- MDT->addNewBlock(NMBB, this);
+ P->getAnalysisIfAvailable<MachineDominatorTree>()) {
+ // Update dominator information.
+ MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
+
+ bool IsNewIDom = true;
+ for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
+ PI != E; ++PI) {
+ MachineBasicBlock *PredBB = *PI;
+ if (PredBB == NMBB)
+ continue;
+ if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
+ IsNewIDom = false;
+ break;
+ }
+ }
+
+ // We know "this" dominates the newly created basic block.
+ MachineDomTreeNode *NewDTNode = MDT->addNewBlock(NMBB, this);
+
+ // If all the other predecessors of "Succ" are dominated by "Succ" itself
+ // then the new block is the new immediate dominator of "Succ". Otherwise,
+ // the new block doesn't dominate anything.
+ if (IsNewIDom)
+ MDT->changeImmediateDominator(SucccDTNode, NewDTNode);
+ }
- if (MachineLoopInfo *MLI =
- P->getAnalysisIfAvailable<MachineLoopInfo>())
+ if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
if (MachineLoop *TIL = MLI->getLoopFor(this)) {
// If one or the other blocks were not in a loop, the new block is not
// either, and thus LI doesn't need to be updated.
return NMBB;
}
+MachineBasicBlock::iterator
+MachineBasicBlock::erase(MachineBasicBlock::iterator I) {
+ if (I->isBundle()) {
+ MachineBasicBlock::iterator E = llvm::next(I);
+ return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
+ }
+
+ return Insts.erase(I.getInstrIterator());
+}
+
+MachineInstr *MachineBasicBlock::remove(MachineInstr *I) {
+ if (I->isBundle()) {
+ MachineBasicBlock::instr_iterator MII = I; ++MII;
+ while (MII != end() && MII->isInsideBundle()) {
+ MachineInstr *MI = &*MII++;
+ Insts.remove(MI);
+ }
+ }
+
+ return Insts.remove(I);
+}
+
+void MachineBasicBlock::splice(MachineBasicBlock::iterator where,
+ MachineBasicBlock *Other,
+ MachineBasicBlock::iterator From) {
+ if (From->isBundle()) {
+ MachineBasicBlock::iterator To = llvm::next(From);
+ Insts.splice(where.getInstrIterator(), Other->Insts,
+ From.getInstrIterator(), To.getInstrIterator());
+ return;
+ }
+
+ Insts.splice(where.getInstrIterator(), Other->Insts, From.getInstrIterator());
+}
+
/// removeFromParent - This method unlinks 'this' from the containing function,
/// and returns it, but does not delete it.
MachineBasicBlock *MachineBasicBlock::removeFromParent() {
MachineBasicBlock *New) {
assert(Old != New && "Cannot replace self with self!");
- MachineBasicBlock::iterator I = end();
- while (I != begin()) {
+ MachineBasicBlock::instr_iterator I = instr_end();
+ while (I != instr_begin()) {
--I;
- if (!I->getDesc().isTerminator()) break;
+ if (!I->isTerminator()) break;
// Scan the operands of this machine instruction, replacing any uses of Old
// with New.
}
// Update the successor information.
- removeSuccessor(Old);
- addSuccessor(New);
+ replaceSuccessor(Old, New);
}
/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
/// CFG to be inserted. If we have proven that MBB can only branch to DestA and
/// DestB, remove any other MBB successors from the CFG. DestA and DestB can be
/// null.
-///
+///
/// Besides DestA and DestB, retain other edges leading to LandingPads
/// (currently there can be only one; we don't check or require that here).
/// Note it is possible that DestA and/or DestB are LandingPads.
/// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
/// any DBG_VALUE instructions. Return UnknownLoc if there is none.
DebugLoc
-MachineBasicBlock::findDebugLoc(MachineBasicBlock::iterator &MBBI) {
+MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
DebugLoc DL;
- MachineBasicBlock::iterator E = end();
- if (MBBI != E) {
- // Skip debug declarations, we don't want a DebugLoc from them.
- MachineBasicBlock::iterator MBBI2 = MBBI;
- while (MBBI2 != E && MBBI2->isDebugValue())
- MBBI2++;
- if (MBBI2 != E)
- DL = MBBI2->getDebugLoc();
- }
+ instr_iterator E = instr_end();
+ if (MBBI == E)
+ return DL;
+
+ // Skip debug declarations, we don't want a DebugLoc from them.
+ while (MBBI != E && MBBI->isDebugValue())
+ MBBI++;
+ if (MBBI != E)
+ DL = MBBI->getDebugLoc();
return DL;
}
+/// getSuccWeight - Return weight of the edge from this block to MBB.
+///
+uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const {
+ if (Weights.empty())
+ return 0;
+
+ const_succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
+ return *getWeightIterator(I);
+}
+
+/// getWeightIterator - Return wight iterator corresonding to the I successor
+/// iterator
+MachineBasicBlock::weight_iterator MachineBasicBlock::
+getWeightIterator(MachineBasicBlock::succ_iterator I) {
+ assert(Weights.size() == Successors.size() && "Async weight list!");
+ size_t index = std::distance(Successors.begin(), I);
+ assert(index < Weights.size() && "Not a current successor!");
+ return Weights.begin() + index;
+}
+
+/// getWeightIterator - Return wight iterator corresonding to the I successor
+/// iterator
+MachineBasicBlock::const_weight_iterator MachineBasicBlock::
+getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
+ assert(Weights.size() == Successors.size() && "Async weight list!");
+ const size_t index = std::distance(Successors.begin(), I);
+ assert(index < Weights.size() && "Not a current successor!");
+ return Weights.begin() + index;
+}
+
void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
bool t) {
OS << "BB#" << MBB->getNumber();