return;
// Live-in registers are in use.
- for (MachineBasicBlock::const_livein_iterator I = MBB->livein_begin(),
+ for (MachineBasicBlock::livein_iterator I = MBB->livein_begin(),
E = MBB->livein_end(); I != E; ++I)
setUsed(*I);
CalleeSavedRegs.set(CSRegs[i]);
}
- // RS used within emit{Pro,Epi}logue()
- if (mbb != MBB) {
- MBB = mbb;
- initRegState();
- }
+ MBB = mbb;
+ initRegState();
Tracking = false;
}
Tracking = true;
} else {
assert(MBBI != MBB->end() && "Already at the end of the basic block!");
- MBBI = next(MBBI);
+ MBBI = llvm::next(MBBI);
}
MachineInstr *MI = MBBI;
ScavengeRestore = NULL;
}
+ if (MI->isDebugValue())
+ return;
+
// Find out which registers are early clobbered, killed, defined, and marked
// def-dead in this instruction.
BitVector EarlyClobberRegs(NumPhysRegs);
if (!Reg || isReserved(Reg))
continue;
if (MO.isUse()) {
- assert(isUsed(Reg) && "Using an undefined register!");
+ if (!isUsed(Reg)) {
+ // Check if it's partial live: e.g.
+ // D0 = insert_subreg D0<undef>, S0
+ // ... D0
+ // The problem is the insert_subreg could be eliminated. The use of
+ // D0 is using a partially undef value. This is not *incorrect* since
+ // S1 is can be freely clobbered.
+ // Ideally we would like a way to model this, but leaving the
+ // insert_subreg around causes both correctness and performance issues.
+ bool SubUsed = false;
+ for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
+ unsigned SubReg = *SubRegs; ++SubRegs)
+ if (isUsed(SubReg)) {
+ SubUsed = true;
+ break;
+ }
+ assert(SubUsed && "Using an undefined register!");
+ }
assert((!EarlyClobberRegs.test(Reg) || MI->isRegTiedToDefOperand(i)) &&
"Using an early clobbered register!");
} else {
///
/// No more than InstrLimit instructions are inspected.
///
-unsigned RegScavenger::findSurvivorReg(MachineBasicBlock::iterator MI,
+unsigned RegScavenger::findSurvivorReg(MachineBasicBlock::iterator StartMI,
BitVector &Candidates,
unsigned InstrLimit,
MachineBasicBlock::iterator &UseMI) {
assert(Survivor > 0 && "No candidates for scavenging");
MachineBasicBlock::iterator ME = MBB->getFirstTerminator();
- assert(MI != ME && "MI already at terminator");
+ assert(StartMI != ME && "MI already at terminator");
+ MachineBasicBlock::iterator RestorePointMI = StartMI;
+ MachineBasicBlock::iterator MI = StartMI;
+ bool inVirtLiveRange = false;
for (++MI; InstrLimit > 0 && MI != ME; ++MI, --InstrLimit) {
+ bool isVirtKillInsn = false;
+ bool isVirtDefInsn = false;
// Remove any candidates touched by instruction.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg() || MO.isUndef() || !MO.getReg() ||
- TargetRegisterInfo::isVirtualRegister(MO.getReg()))
+ if (!MO.isReg() || MO.isUndef() || !MO.getReg())
+ continue;
+ if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
+ if (MO.isDef())
+ isVirtDefInsn = true;
+ else if (MO.isKill())
+ isVirtKillInsn = true;
continue;
+ }
Candidates.reset(MO.getReg());
for (const unsigned *R = TRI->getAliasSet(MO.getReg()); *R; R++)
Candidates.reset(*R);
}
+ // If we're not in a virtual reg's live range, this is a valid
+ // restore point.
+ if (!inVirtLiveRange) RestorePointMI = MI;
+
+ // Update whether we're in the live range of a virtual register
+ if (isVirtKillInsn) inVirtLiveRange = false;
+ if (isVirtDefInsn) inVirtLiveRange = true;
// Was our survivor untouched by this instruction?
if (Candidates.test(Survivor))
Survivor = Candidates.find_first();
}
+ // If we ran off the end, that's where we want to restore.
+ if (MI == ME) RestorePointMI = ME;
+ assert (RestorePointMI != StartMI &&
+ "No available scavenger restore location!");
// We ran out of candidates, so stop the search.
- UseMI = MI;
+ UseMI = RestorePointMI;
return Survivor;
}
unsigned RegScavenger::scavengeRegister(const TargetRegisterClass *RC,
MachineBasicBlock::iterator I,
int SPAdj) {
- assert(ScavengingFrameIndex >= 0 &&
- "Cannot scavenge a register without an emergency spill slot!");
-
// Mask off the registers which are not in the TargetRegisterClass.
BitVector Candidates(NumPhysRegs, false);
CreateRegClassMask(RC, Candidates);
// Avoid infinite regress
ScavengedReg = SReg;
- // Spill the scavenged register before I.
- TII->storeRegToStackSlot(*MBB, I, SReg, true, ScavengingFrameIndex, RC);
- MachineBasicBlock::iterator II = prior(I);
- TRI->eliminateFrameIndex(II, SPAdj, this);
+ // If the target knows how to save/restore the register, let it do so;
+ // otherwise, use the emergency stack spill slot.
+ if (!TRI->saveScavengerRegister(*MBB, I, UseMI, RC, SReg)) {
+ // Spill the scavenged register before I.
+ assert(ScavengingFrameIndex >= 0 &&
+ "Cannot scavenge register without an emergency spill slot!");
+ TII->storeRegToStackSlot(*MBB, I, SReg, true, ScavengingFrameIndex, RC);
+ MachineBasicBlock::iterator II = prior(I);
+ TRI->eliminateFrameIndex(II, SPAdj, NULL, this);
+
+ // Restore the scavenged register before its use (or first terminator).
+ TII->loadRegFromStackSlot(*MBB, UseMI, SReg, ScavengingFrameIndex, RC);
+ II = prior(UseMI);
+ TRI->eliminateFrameIndex(II, SPAdj, NULL, this);
+ }
- // Restore the scavenged register before its use (or first terminator).
- TII->loadRegFromStackSlot(*MBB, UseMI, SReg, ScavengingFrameIndex, RC);
ScavengeRestore = prior(UseMI);
+
// Doing this here leads to infinite regress.
// ScavengedReg = SReg;
ScavengedRC = RC;
projects / oota-llvm.git / blobdiff