+ MachineBasicBlock *PredTBB = nullptr, *PredFBB = nullptr;
+ SmallVector<MachineOperand, 4> PredCond;
+ if (TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true))
+ return false;
+
+ if (!PredCond.empty())
+ return false;
+ }
+ return true;
+}
+
+bool
+TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
+ SmallVectorImpl<MachineBasicBlock *> &TDBBs,
+ const DenseSet<unsigned> &UsedByPhi,
+ SmallVectorImpl<MachineInstr *> &Copies) {
+ SmallPtrSet<MachineBasicBlock*, 8> Succs(TailBB->succ_begin(),
+ TailBB->succ_end());
+ SmallVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(),
+ TailBB->pred_end());
+ bool Changed = false;
+ for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
+ PE = Preds.end(); PI != PE; ++PI) {
+ MachineBasicBlock *PredBB = *PI;
+
+ if (PredBB->hasEHPadSuccessor())
+ continue;
+
+ if (bothUsedInPHI(*PredBB, Succs))
+ continue;
+
+ MachineBasicBlock *PredTBB = nullptr, *PredFBB = nullptr;
+ SmallVector<MachineOperand, 4> PredCond;
+ if (TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true))
+ continue;
+
+ Changed = true;
+ DEBUG(dbgs() << "\nTail-duplicating into PredBB: " << *PredBB
+ << "From simple Succ: " << *TailBB);
+
+ MachineBasicBlock *NewTarget = *TailBB->succ_begin();
+ MachineBasicBlock *NextBB = &*std::next(PredBB->getIterator());
+
+ // Make PredFBB explicit.
+ if (PredCond.empty())
+ PredFBB = PredTBB;
+
+ // Make fall through explicit.
+ if (!PredTBB)
+ PredTBB = NextBB;
+ if (!PredFBB)
+ PredFBB = NextBB;
+
+ // Redirect
+ if (PredFBB == TailBB)
+ PredFBB = NewTarget;
+ if (PredTBB == TailBB)
+ PredTBB = NewTarget;
+
+ // Make the branch unconditional if possible
+ if (PredTBB == PredFBB) {
+ PredCond.clear();
+ PredFBB = nullptr;
+ }
+
+ // Avoid adding fall through branches.
+ if (PredFBB == NextBB)
+ PredFBB = nullptr;
+ if (PredTBB == NextBB && PredFBB == nullptr)
+ PredTBB = nullptr;
+
+ TII->RemoveBranch(*PredBB);
+
+ if (PredTBB)
+ TII->InsertBranch(*PredBB, PredTBB, PredFBB, PredCond, DebugLoc());
+
+ auto Prob = MBPI->getEdgeProbability(PredBB, TailBB);
+ PredBB->removeSuccessor(TailBB);
+ unsigned NumSuccessors = PredBB->succ_size();
+ assert(NumSuccessors <= 1);
+ if (NumSuccessors == 0 || *PredBB->succ_begin() != NewTarget)
+ PredBB->addSuccessor(NewTarget, Prob);
+
+ TDBBs.push_back(PredBB);
+ }
+ return Changed;
+}
+
+/// If it is profitable, duplicate TailBB's contents in each
+/// of its predecessors.
+bool
+TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
+ bool IsSimple,
+ MachineFunction &MF,
+ SmallVectorImpl<MachineBasicBlock *> &TDBBs,
+ SmallVectorImpl<MachineInstr *> &Copies) {