bool Filler::tryCombineRestoreWithPrevInst(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI)
{
// No previous instruction.
if (MBBI == MBB.begin())
return false;
// assert that MBBI is a "restore %g0, %g0, %g0".
assert(MBBI->getOpcode() == SP::RESTORErr
&& MBBI->getOperand(0).getReg() == SP::G0
&& MBBI->getOperand(1).getReg() == SP::G0
&& MBBI->getOperand(2).getReg() == SP::G0);
MachineBasicBlock::iterator PrevInst = std::prev(MBBI);
// It cannot be combined with a bundled instruction.
if (PrevInst->isBundledWithSucc())
return false;
const TargetInstrInfo *TII = TM.getInstrInfo();
switch (PrevInst->getOpcode()) {
default: break;
case SP::ADDrr:
case SP::ADDri: return combineRestoreADD(MBBI, PrevInst, TII); break;
case SP::ORrr:
case SP::ORri: return combineRestoreOR(MBBI, PrevInst, TII); break;
case SP::SETHIi: return combineRestoreSETHIi(MBBI, PrevInst, TII); break;
}
// It cannot combine with the previous instruction.
return false;
}
MachineBasicBlock::iterator
Filler::findDelayInstr(MachineBasicBlock &MBB,
MachineBasicBlock::iterator slot)
{
SmallSet<unsigned, 32> RegDefs;
SmallSet<unsigned, 32> RegUses;
bool sawLoad = false;
bool sawStore = false;
if (slot == MBB.begin())
return MBB.end();
if (slot->getOpcode() == SP::RET || slot->getOpcode() == SP::TLS_CALL)
return MBB.end();
if (slot->getOpcode() == SP::RETL) {
MachineBasicBlock::iterator J = slot;
--J;
if (J->getOpcode() == SP::RESTORErr
|| J->getOpcode() == SP::RESTOREri) {
// change retl to ret.
slot->setDesc(TM.getInstrInfo()->get(SP::RET));
return J;
}
}
// Call's delay filler can def some of call's uses.
if (slot->isCall())
insertCallDefsUses(slot, RegDefs, RegUses);
else
insertDefsUses(slot, RegDefs, RegUses);
bool done = false;
MachineBasicBlock::iterator I = slot;
while (!done) {
done = (I == MBB.begin());
if (!done)
--I;
// skip debug value
if (I->isDebugValue())
continue;
if (I->hasUnmodeledSideEffects() || I->isInlineAsm() || I->isPosition() ||
I->hasDelaySlot() || I->isBundledWithSucc())
break;
if (delayHasHazard(I, sawLoad, sawStore, RegDefs, RegUses)) {
insertDefsUses(I, RegDefs, RegUses);
continue;
}
return I;
}
return MBB.end();
}