/// processImplicitDefs - Process IMPLICIT_DEF instructions and turn them into
/// <undef> operands.
bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &MF) {
DEBUG(dbgs() << "********** PROCESS IMPLICIT DEFS **********\n"
<< "********** Function: " << MF.getName() << '\n');
bool Changed = false;
TII = MF.getSubtarget().getInstrInfo();
TRI = MF.getSubtarget().getRegisterInfo();
MRI = &MF.getRegInfo();
assert(MRI->isSSA() && "ProcessImplicitDefs only works on SSA form.");
assert(WorkList.empty() && "Inconsistent worklist state");
for (MachineFunction::iterator MFI = MF.begin(), MFE = MF.end();
MFI != MFE; ++MFI) {
// Scan the basic block for implicit defs.
for (MachineBasicBlock::instr_iterator MBBI = MFI->instr_begin(),
MBBE = MFI->instr_end(); MBBI != MBBE; ++MBBI)
if (MBBI->isImplicitDef())
WorkList.insert(MBBI);
if (WorkList.empty())
continue;
DEBUG(dbgs() << "BB#" << MFI->getNumber() << " has " << WorkList.size()
<< " implicit defs.\n");
Changed = true;
// Drain the WorkList to recursively process any new implicit defs.
do processImplicitDef(WorkList.pop_back_val());
while (!WorkList.empty());
}
return Changed;
}
bool Filler::delayHasHazard(MachineBasicBlock::instr_iterator MI, bool &SawLoad,
bool &SawStore, SmallSet<unsigned, 32> &RegDefs,
SmallSet<unsigned, 32> &RegUses) {
if (MI->isImplicitDef() || MI->isKill())
return true;
// Loads or stores cannot be moved past a store to the delay slot
// and stores cannot be moved past a load.
if (MI->mayLoad()) {
if (SawStore)
return true;
SawLoad = true;
}
if (MI->mayStore()) {
if (SawStore)
return true;
SawStore = true;
if (SawLoad)
return true;
}
assert((!MI->isCall() && !MI->isReturn()) &&
"Cannot put calls or returns in delay slot.");
for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) {
const MachineOperand &MO = MI->getOperand(I);
unsigned Reg;
if (!MO.isReg() || !(Reg = MO.getReg()))
continue; // skip
if (MO.isDef()) {
// check whether Reg is defined or used before delay slot.
if (isRegInSet(RegDefs, Reg) || isRegInSet(RegUses, Reg))
return true;
}
if (MO.isUse()) {
// check whether Reg is defined before delay slot.
if (isRegInSet(RegDefs, Reg))
return true;
}
}
return false;
}