// Replace Br with a branch which has the opposite condition code and a
// MachineBasicBlock operand MBBOpnd.
void MipsLongBranch::replaceBranch(MachineBasicBlock &MBB, Iter Br,
const DebugLoc &DL,
MachineBasicBlock *MBBOpnd) {
const MipsInstrInfo *TII = static_cast<const MipsInstrInfo *>(
MBB.getParent()->getSubtarget().getInstrInfo());
unsigned NewOpc = TII->getOppositeBranchOpc(Br->getOpcode());
const MCInstrDesc &NewDesc = TII->get(NewOpc);
MachineInstrBuilder MIB = BuildMI(MBB, Br, DL, NewDesc);
for (unsigned I = 0, E = Br->getDesc().getNumOperands(); I < E; ++I) {
MachineOperand &MO = Br->getOperand(I);
if (!MO.isReg()) {
assert(MO.isMBB() && "MBB operand expected.");
break;
}
MIB.addReg(MO.getReg());
}
MIB.addMBB(MBBOpnd);
if (Br->hasDelaySlot()) {
// Bundle the instruction in the delay slot to the newly created branch
// and erase the original branch.
assert(Br->isBundledWithSucc());
MachineBasicBlock::instr_iterator II(Br);
MIBundleBuilder(&*MIB).append((++II)->removeFromBundle());
}
Br->eraseFromParent();
}
/// runOnMachineBasicBlock - Fill in delay slots for the given basic block.
/// We assume there is only one delay slot per delayed instruction.
bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
bool Changed = false;
for (Iter I = MBB.begin(); I != MBB.end(); ++I) {
if (!I->hasDelaySlot())
continue;
++FilledSlots;
Changed = true;
Iter D;
// Delay slot filling is disabled at -O0.
if (!DisableDelaySlotFiller && (TM.getOptLevel() != CodeGenOpt::None) &&
findDelayInstr(MBB, I, D)) {
MBB.splice(llvm::next(I), &MBB, D);
++UsefulSlots;
} else
BuildMI(MBB, llvm::next(I), I->getDebugLoc(), TII->get(Mips::NOP));
// Bundle the delay slot filler to the instruction with the delay slot.
MIBundleBuilder(MBB, I, llvm::next(llvm::next(I)));
}
return Changed;
}
