// Top-level driver to manage the queue of unassigned VirtRegs and call the
// selectOrSplit implementation.
void RegAllocBase::allocatePhysRegs() {
seedLiveRegs();
// Continue assigning vregs one at a time to available physical registers.
while (LiveInterval *VirtReg = dequeue()) {
assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
// Unused registers can appear when the spiller coalesces snippets.
if (MRI->reg_nodbg_empty(VirtReg->reg)) {
DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
LIS->removeInterval(VirtReg->reg);
continue;
}
// Invalidate all interference queries, live ranges could have changed.
invalidateVirtRegs();
// selectOrSplit requests the allocator to return an available physical
// register if possible and populate a list of new live intervals that
// result from splitting.
DEBUG(dbgs() << "\nselectOrSplit "
<< MRI->getRegClass(VirtReg->reg)->getName()
<< ':' << *VirtReg << '\n');
typedef SmallVector<LiveInterval*, 4> VirtRegVec;
VirtRegVec SplitVRegs;
unsigned AvailablePhysReg = selectOrSplit(*VirtReg, SplitVRegs);
if (AvailablePhysReg == ~0u) {
// selectOrSplit failed to find a register!
std::string msg;
raw_string_ostream Msg(msg);
Msg << "Ran out of registers during register allocation!"
"\nCannot allocate: " << *VirtReg;
for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(VirtReg->reg);
MachineInstr *MI = I.skipInstruction();) {
if (!MI->isInlineAsm())
continue;
Msg << "\nPlease check your inline asm statement for "
"invalid constraints:\n";
MI->print(Msg, &VRM->getMachineFunction().getTarget());
}
report_fatal_error(Msg.str());
}
if (AvailablePhysReg)
assign(*VirtReg, AvailablePhysReg);
for (VirtRegVec::iterator I = SplitVRegs.begin(), E = SplitVRegs.end();
I != E; ++I) {
LiveInterval *SplitVirtReg = *I;
assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
DEBUG(dbgs() << "not queueing unused " << *SplitVirtReg << '\n');
LIS->removeInterval(SplitVirtReg->reg);
continue;
}
DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
assert(TargetRegisterInfo::isVirtualRegister(SplitVirtReg->reg) &&
"expect split value in virtual register");
enqueue(SplitVirtReg);
++NumNewQueued;
}
}
}
// Top-level driver to manage the queue of unassigned VirtRegs and call the
// selectOrSplit implementation.
void RegAllocBase::allocatePhysRegs() {
seedLiveRegs();
// Continue assigning vregs one at a time to available physical registers.
while (LiveInterval *VirtReg = dequeue()) {
assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
// Unused registers can appear when the spiller coalesces snippets.
if (MRI->reg_nodbg_empty(VirtReg->reg)) {
DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
LIS->removeInterval(VirtReg->reg);
continue;
}
// Invalidate all interference queries, live ranges could have changed.
invalidateVirtRegs();
// selectOrSplit requests the allocator to return an available physical
// register if possible and populate a list of new live intervals that
// result from splitting.
DEBUG(dbgs() << "\nselectOrSplit "
<< MRI->getRegClass(VirtReg->reg)->getName()
<< ':' << *VirtReg << '\n');
typedef SmallVector<LiveInterval*, 4> VirtRegVec;
VirtRegVec SplitVRegs;
unsigned AvailablePhysReg = selectOrSplit(*VirtReg, SplitVRegs);
if (AvailablePhysReg == ~0u) {
// selectOrSplit failed to find a register!
const char *Msg = "ran out of registers during register allocation";
// Probably caused by an inline asm.
MachineInstr *MI;
for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(VirtReg->reg);
(MI = I.skipInstruction());)
if (MI->isInlineAsm())
break;
if (MI)
MI->emitError(Msg);
else
report_fatal_error(Msg);
// Keep going after reporting the error.
VRM->assignVirt2Phys(VirtReg->reg,
RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg)).front());
continue;
}
if (AvailablePhysReg)
assign(*VirtReg, AvailablePhysReg);
for (VirtRegVec::iterator I = SplitVRegs.begin(), E = SplitVRegs.end();
I != E; ++I) {
LiveInterval *SplitVirtReg = *I;
assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
DEBUG(dbgs() << "not queueing unused " << *SplitVirtReg << '\n');
LIS->removeInterval(SplitVirtReg->reg);
continue;
}
DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
assert(TargetRegisterInfo::isVirtualRegister(SplitVirtReg->reg) &&
"expect split value in virtual register");
enqueue(SplitVirtReg);
++NumNewQueued;
}
}
}