lib/CodeGen/EarlyIfConversion.cpp

74 //             Tail                       Tail
77 // Head block, and phis in the Tail block are converted to select instructions.
90   MachineBasicBlock *Tail;
99   /// equal to Tail.
100   bool isTriangle() const { return TBB == Tail || FBB == Tail; }
102   /// Returns the Tail predecessor for the True side.
103   MachineBasicBlock *getTPred() const { return TBB == Tail ? Head : TBB; }
105   /// Returns the Tail predecessor for the  False side.
106   MachineBasicBlock *getFPred() const { return FBB == Tail ? Head : FBB; }
108   /// Information about each phi in the Tail block.
146   /// Replace PHI instructions in Tail with selects.
341   TBB = FBB = Tail = 0;
355   Tail = Succ0->succ_begin()[0];
358   if (Tail != Succ1) {
361         Succ1->succ_begin()[0] != Tail)
366                  << " -> BB#" << Tail->getNumber() << '\n');
369     if (!Tail->livein_empty()) {
370       DEBUG(dbgs() << "Tail has live-ins.\n");
376                  << " -> BB#" << Tail->getNumber() << '\n');
380   // If Tail doesn't have any phis, there must be side effects.
381   if (Tail->empty() || !Tail->front().isPHI()) {
407   for (MachineBasicBlock::iterator I = Tail->begin(), E = Tail->end();
432   if (TBB != Tail && !canSpeculateInstrs(TBB))
434   if (FBB != Tail && !canSpeculateInstrs(FBB))
450 /// This is possible when the only Tail predecessors are the if-converted
453   assert(Tail->pred_size() == 2 && "Cannot replace PHIs");
470 /// rewritePHIOperands - When there are additional Tail predecessors, insert
472 /// Keep the PHI instructions in Tail to handle the other predecessors.
508   assert(Head && Tail && TBB && FBB && "Call canConvertIf first.");
517   if (TBB != Tail)
519   if (FBB != Tail)
522   // Are there extra Tail predecessors?
523   bool ExtraPreds = Tail->pred_size() != 2;
532   if (TBB != Tail)
533     TBB->removeSuccessor(Tail);
534   if (FBB != Tail)
535     FBB->removeSuccessor(Tail);
543   // through to Tail, and we can join the two blocks.
544   if (TBB != Tail) {
548   if (FBB != Tail) {
554   if (!ExtraPreds && Head->isLayoutSuccessor(Tail)) {
555     // Splice Tail onto the end of Head.
556     DEBUG(dbgs() << "Joining tail BB#" << Tail->getNumber()
558     Head->splice(Head->end(), Tail,
559                      Tail->begin(), Tail->end());
560     Head->transferSuccessorsAndUpdatePHIs(Tail);
561     RemovedBlocks.push_back(Tail);
562     Tail->eraseFromParent();
564     // We need a branch to Tail, let code placement work it out later.
567     TII->InsertBranch(*Head, Tail, 0, EmptyCond, HeadDL);
568     Head->addSuccessor(Tail);
630   // convertIf can remove TBB, FBB, and Tail can be merged into Head.
632   // Tail children should be transferred to Head.
638       assert(Node->getBlock() == IfConv.Tail && "Unexpected children");
659   Traces->invalidate(IfConv.Tail);
696   if (IfConv.TBB != IfConv.Tail)
716   MachineTraceMetrics::Trace TailTrace = MinInstr->getTrace(IfConv.Tail);