// pressure, it can caused fewer GPRs to be held in the queue.
static cl::opt<unsigned>
NumRecentlyUsedRegs("linearscan-skip-count",
- cl::desc("Number of registers for linearscan to remember to skip."),
+ cl::desc("Number of registers for linearscan to remember"
+ "to skip."),
cl::init(0),
cl::Hidden);
-
+
struct RALinScan : public MachineFunctionPass {
static char ID;
- RALinScan() : MachineFunctionPass(&ID) {
+ RALinScan() : MachineFunctionPass(ID) {
// Initialize the queue to record recently-used registers.
if (NumRecentlyUsedRegs > 0)
RecentRegs.resize(NumRecentlyUsedRegs, 0);
const TargetRegisterInfo* tri_;
const TargetInstrInfo* tii_;
BitVector allocatableRegs_;
+ BitVector reservedRegs_;
LiveIntervals* li_;
LiveStacks* ls_;
- const MachineLoopInfo *loopInfo;
+ MachineLoopInfo *loopInfo;
/// handled_ - Intervals are added to the handled_ set in the order of their
/// start value. This is uses for backtracking.
SmallVector<LiveInterval*, 8> &SpillIntervals);
/// attemptTrivialCoalescing - If a simple interval is defined by a copy,
- /// try allocate the definition the same register as the source register
- /// if the register is not defined during live time of the interval. This
- /// eliminate a copy. This is used to coalesce copies which were not
+ /// try to allocate the definition to the same register as the source,
+ /// if the register is not defined during the life time of the interval.
+ /// This eliminates a copy, and is used to coalesce copies which were not
/// coalesced away before allocation either due to dest and src being in
/// different register classes or because the coalescer was overly
/// conservative.
SmallVector<unsigned, 256> &inactiveCounts,
bool SkipDGRegs);
+ /// getFirstNonReservedPhysReg - return the first non-reserved physical
+ /// register in the register class.
+ unsigned getFirstNonReservedPhysReg(const TargetRegisterClass *RC) {
+ TargetRegisterClass::iterator aoe = RC->allocation_order_end(*mf_);
+ TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_);
+ while (i != aoe && reservedRegs_.test(*i))
+ ++i;
+ assert(i != aoe && "All registers reserved?!");
+ return *i;
+ }
+
void ComputeRelatedRegClasses();
template <typename ItTy>
char RALinScan::ID = 0;
}
-static RegisterPass<RALinScan>
-X("linearscan-regalloc", "Linear Scan Register Allocator");
+INITIALIZE_PASS(RALinScan, "linearscan-regalloc",
+ "Linear Scan Register Allocator", false, false);
void RALinScan::ComputeRelatedRegClasses() {
// First pass, add all reg classes to the union, and determine at least one
for (TargetRegisterClass::iterator I = (*RCI)->begin(), E = (*RCI)->end();
I != E; ++I) {
HasAliases = HasAliases || *tri_->getAliasSet(*I) != 0;
-
+
const TargetRegisterClass *&PRC = OneClassForEachPhysReg[*I];
if (PRC) {
// Already processed this register. Just make sure we know that
}
}
}
-
+
// Second pass, now that we know conservatively what register classes each reg
// belongs to, add info about aliases. We don't need to do this for targets
// without register aliases.
unsigned CandReg;
{
MachineInstr *CopyMI;
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
if (vni->def != SlotIndex() && vni->isDefAccurate() &&
- (CopyMI = li_->getInstructionFromIndex(vni->def)) &&
- tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubReg, DstSubReg))
+ (CopyMI = li_->getInstructionFromIndex(vni->def)) && CopyMI->isCopy())
// Defined by a copy, try to extend SrcReg forward
- CandReg = SrcReg;
+ CandReg = CopyMI->getOperand(1).getReg();
else if (TrivCoalesceEnds &&
- (CopyMI =
- li_->getInstructionFromIndex(range.end.getBaseIndex())) &&
- tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- cur.reg == SrcReg)
+ (CopyMI = li_->getInstructionFromIndex(range.end.getBaseIndex())) &&
+ CopyMI->isCopy() && cur.reg == CopyMI->getOperand(1).getReg())
// Only used by a copy, try to extend DstReg backwards
- CandReg = DstReg;
+ CandReg = CopyMI->getOperand(0).getReg();
else
return Reg;
}
tri_ = tm_->getRegisterInfo();
tii_ = tm_->getInstrInfo();
allocatableRegs_ = tri_->getAllocatableSet(fn);
+ reservedRegs_ = tri_->getReservedRegs(fn);
li_ = &getAnalysis<LiveIntervals>();
ls_ = &getAnalysis<LiveStacks>();
loopInfo = &getAnalysis<MachineLoopInfo>();
vrm_ = &getAnalysis<VirtRegMap>();
if (!rewriter_.get()) rewriter_.reset(createVirtRegRewriter());
-
- spiller_.reset(createSpiller(mf_, li_, loopInfo, vrm_));
-
+
+ spiller_.reset(createSpiller(*this, *mf_, *vrm_));
+
initIntervalSets();
linearScan();
// linear scan algorithm
DEBUG({
dbgs() << "********** LINEAR SCAN **********\n"
- << "********** Function: "
+ << "********** Function: "
<< mf_->getFunction()->getName() << '\n';
printIntervals("fixed", fixed_.begin(), fixed_.end());
});
return IP.end();
}
-static void RevertVectorIteratorsTo(RALinScan::IntervalPtrs &V, SlotIndex Point){
+static void RevertVectorIteratorsTo(RALinScan::IntervalPtrs &V,
+ SlotIndex Point){
for (unsigned i = 0, e = V.size(); i != e; ++i) {
RALinScan::IntervalPtr &IP = V[i];
LiveInterval::iterator I = std::upper_bound(IP.first->begin(),
static
float getConflictWeight(LiveInterval *cur, unsigned Reg, LiveIntervals *li_,
MachineRegisterInfo *mri_,
- const MachineLoopInfo *loopInfo) {
+ MachineLoopInfo *loopInfo) {
float Conflicts = 0;
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(Reg),
E = mri_->reg_end(); I != E; ++I) {
dbgs() << tri_->getName(Candidates[i].first) << " ";
dbgs() << "\n";
});
-
+
// Calculate the number of conflicts of each candidate.
for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
unsigned Reg = i->first->reg;
if (cur->empty()) {
unsigned physReg = vrm_->getRegAllocPref(cur->reg);
if (!physReg)
- physReg = *RC->allocation_order_begin(*mf_);
+ physReg = getFirstNonReservedPhysReg(RC);
DEBUG(dbgs() << tri_->getName(physReg) << '\n');
// Note the register is not really in use.
vrm_->assignVirt2Phys(cur->reg, physReg);
if ((vni->def != SlotIndex()) && !vni->isUnused() &&
vni->isDefAccurate()) {
MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
- if (CopyMI &&
- tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubReg, DstSubReg)) {
+ if (CopyMI && CopyMI->isCopy()) {
+ unsigned DstSubReg = CopyMI->getOperand(0).getSubReg();
+ unsigned SrcReg = CopyMI->getOperand(1).getReg();
+ unsigned SrcSubReg = CopyMI->getOperand(1).getSubReg();
unsigned Reg = 0;
if (TargetRegisterInfo::isPhysicalRegister(SrcReg))
Reg = SrcReg;
assert(TargetRegisterInfo::isVirtualRegister(Reg) &&
"Can only allocate virtual registers!");
const TargetRegisterClass *RegRC = mri_->getRegClass(Reg);
- // If this is not in a related reg class to the register we're allocating,
+ // If this is not in a related reg class to the register we're allocating,
// don't check it.
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
cur->overlapsFrom(*i->first, i->second-1)) {
SpillWeightsToAdd.push_back(std::make_pair(Reg, i->first->weight));
}
}
-
+
// Speculatively check to see if we can get a register right now. If not,
// we know we won't be able to by adding more constraints. If so, we can
// check to see if it is valid. Doing an exhaustive search of the fixed_ list
SmallSet<unsigned, 8> RegAliases;
for (const unsigned *AS = tri_->getAliasSet(physReg); *AS; ++AS)
RegAliases.insert(*AS);
-
+
bool ConflictsWithFixed = false;
for (unsigned i = 0, e = fixed_.size(); i != e; ++i) {
IntervalPtr &IP = fixed_[i];
}
}
}
-
+
// Okay, the register picked by our speculative getFreePhysReg call turned
// out to be in use. Actually add all of the conflicting fixed registers to
// regUse_ so we can do an accurate query.
LiveInterval *I = IP.first;
const TargetRegisterClass *RegRC = OneClassForEachPhysReg[I->reg];
- if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
+ if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
I->endIndex() > StartPosition) {
LiveInterval::iterator II = I->advanceTo(IP.second, StartPosition);
IP.second = II;
physReg = getFreePhysReg(cur);
}
}
-
+
// Restore the physical register tracker, removing information about the
// future.
restoreRegUses();
-
+
// If we find a free register, we are done: assign this virtual to
// the free physical register and add this interval to the active
// list.
UpgradeRegister(physReg);
if (LiveInterval *NextReloadLI = hasNextReloadInterval(cur)) {
// "Downgrade" physReg to try to keep physReg from being allocated until
- // the next reload from the same SS is allocated.
+ // the next reload from the same SS is allocated.
mri_->setRegAllocationHint(NextReloadLI->reg, 0, physReg);
DowngradeRegister(cur, physReg);
}
for (std::vector<std::pair<unsigned, float> >::iterator
I = SpillWeightsToAdd.begin(), E = SpillWeightsToAdd.end(); I != E; ++I)
updateSpillWeights(SpillWeights, I->first, I->second, RC);
-
+
// for each interval in active, update spill weights.
for (IntervalPtrs::const_iterator i = active_.begin(), e = active_.end();
i != e; ++i) {
reg = vrm_->getPhys(reg);
updateSpillWeights(SpillWeights, reg, i->first->weight, RC);
}
-
+
DEBUG(dbgs() << "\tassigning stack slot at interval "<< *cur << ":\n");
// Find a register to spill.
e = RC->allocation_order_end(*mf_); i != e; ++i) {
unsigned reg = *i;
float regWeight = SpillWeights[reg];
- // Skip recently allocated registers.
+ // Don't even consider reserved regs.
+ if (reservedRegs_.test(reg))
+ continue;
+ // Skip recently allocated registers and reserved registers.
if (minWeight > regWeight && !isRecentlyUsed(reg))
Found = true;
RegsWeights.push_back(std::make_pair(reg, regWeight));
}
-
+
// If we didn't find a register that is spillable, try aliases?
if (!Found) {
for (TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_),
e = RC->allocation_order_end(*mf_); i != e; ++i) {
unsigned reg = *i;
+ if (reservedRegs_.test(reg))
+ continue;
// No need to worry about if the alias register size < regsize of RC.
// We are going to spill all registers that alias it anyway.
for (const unsigned* as = tri_->getAliasSet(reg); *as; ++as)
minWeight = RegsWeights[0].second;
if (minWeight == HUGE_VALF) {
// All registers must have inf weight. Just grab one!
- minReg = BestPhysReg ? BestPhysReg : *RC->allocation_order_begin(*mf_);
+ minReg = BestPhysReg ? BestPhysReg : getFirstNonReservedPhysReg(RC);
if (cur->weight == HUGE_VALF ||
li_->getApproximateInstructionCount(*cur) == 0) {
// Spill a physical register around defs and uses.
// linearscan.
if (cur->weight != HUGE_VALF && cur->weight <= minWeight) {
DEBUG(dbgs() << "\t\t\tspilling(c): " << *cur << '\n');
- SmallVector<LiveInterval*, 8> spillIs;
- std::vector<LiveInterval*> added;
+ SmallVector<LiveInterval*, 8> spillIs, added;
spiller_->spill(cur, added, spillIs);
std::sort(added.begin(), added.end(), LISorter());
// The earliest start of a Spilled interval indicates up to where
// in handled we need to roll back
- assert(!spillIs.empty() && "No spill intervals?");
+ assert(!spillIs.empty() && "No spill intervals?");
SlotIndex earliestStart = spillIs[0]->beginIndex();
-
+
// Spill live intervals of virtual regs mapped to the physical register we
// want to clear (and its aliases). We only spill those that overlap with the
// current interval as the rest do not affect its allocation. we also keep
// track of the earliest start of all spilled live intervals since this will
// mark our rollback point.
- std::vector<LiveInterval*> added;
+ SmallVector<LiveInterval*, 8> added;
while (!spillIs.empty()) {
LiveInterval *sli = spillIs.back();
spillIs.pop_back();
DEBUG(dbgs() << "\t\t\tspilling(a): " << *sli << '\n');
if (sli->beginIndex() < earliestStart)
earliestStart = sli->beginIndex();
-
- spiller_->spill(sli, added, spillIs, &earliestStart);
+ spiller_->spill(sli, added, spillIs);
addStackInterval(sli, ls_, li_, mri_, *vrm_);
spilled.insert(sli->reg);
}
+ // Include any added intervals in earliestStart.
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ SlotIndex SI = added[i]->beginIndex();
+ if (SI < earliestStart)
+ earliestStart = SI;
+ }
+
DEBUG(dbgs() << "\t\trolling back to: " << earliestStart << '\n');
// Scan handled in reverse order up to the earliest start of a
// Ignore "downgraded" registers.
if (SkipDGRegs && DowngradedRegs.count(Reg))
continue;
+ // Skip reserved registers.
+ if (reservedRegs_.test(Reg))
+ continue;
// Skip recently allocated registers.
if (isRegAvail(Reg) && !isRecentlyUsed(Reg)) {
FreeReg = Reg;
// Ignore "downgraded" registers.
if (SkipDGRegs && DowngradedRegs.count(Reg))
continue;
+ // Skip reserved registers.
+ if (reservedRegs_.test(Reg))
+ continue;
if (isRegAvail(Reg) && Reg < inactiveCounts.size() &&
FreeRegInactiveCount < inactiveCounts[Reg] && !isRecentlyUsed(Reg)) {
FreeReg = Reg;
unsigned RALinScan::getFreePhysReg(LiveInterval *cur) {
SmallVector<unsigned, 256> inactiveCounts;
unsigned MaxInactiveCount = 0;
-
+
const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
-
+
for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
i != e; ++i) {
unsigned reg = i->first->reg;
assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
- // If this is not in a related reg class to the register we're allocating,
+ // If this is not in a related reg class to the register we're allocating,
// don't check it.
const TargetRegisterClass *RegRC = mri_->getRegClass(reg);
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader) {
unsigned Preference = vrm_->getRegAllocPref(cur->reg);
if (Preference) {
DEBUG(dbgs() << "(preferred: " << tri_->getName(Preference) << ") ");
- if (isRegAvail(Preference) &&
+ if (isRegAvail(Preference) &&
RC->contains(Preference))
return Preference;
}