// This file implements a linear scan register allocator.
//
//===----------------------------------------------------------------------===//
+
#define DEBUG_TYPE "regalloc"
#include "llvm/Function.h"
-#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/LiveVariables.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/MRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
-#include "llvm/Support/CFG.h"
#include "Support/Debug.h"
-#include "Support/DepthFirstIterator.h"
-#include "Support/Statistic.h"
#include "Support/STLExtras.h"
+#include "LiveIntervals.h"
+#include "PhysRegTracker.h"
+#include "VirtRegMap.h"
+#include <algorithm>
+#include <cmath>
+#include <iostream>
+#include <set>
+
using namespace llvm;
namespace {
- Statistic<> numSpilled ("ra-linearscan", "Number of registers spilled");
- Statistic<> numReloaded("ra-linearscan", "Number of registers reloaded");
- Statistic<> numPeep ("ra-linearscan",
- "Number of identity moves eliminated");
-
class RA : public MachineFunctionPass {
private:
MachineFunction* mf_;
const TargetMachine* tm_;
const MRegisterInfo* mri_;
LiveIntervals* li_;
- MachineFunction::iterator currentMbb_;
- MachineBasicBlock::iterator currentInstr_;
- typedef std::vector<const LiveIntervals::Interval*> IntervalPtrs;
- IntervalPtrs unhandled_, fixed_, active_, inactive_;
-
- typedef std::vector<unsigned> Regs;
- Regs tempUseOperands_;
- Regs tempDefOperands_;
-
- typedef std::vector<bool> RegMask;
- RegMask reserved_;
-
- unsigned regUse_[MRegisterInfo::FirstVirtualRegister];
- unsigned regUseBackup_[MRegisterInfo::FirstVirtualRegister];
+ typedef std::list<LiveInterval*> IntervalPtrs;
+ IntervalPtrs unhandled_, fixed_, active_, inactive_, handled_;
- typedef std::map<unsigned, unsigned> Virt2PhysMap;
- Virt2PhysMap v2pMap_;
+ std::auto_ptr<PhysRegTracker> prt_;
+ std::auto_ptr<VirtRegMap> vrm_;
+ std::auto_ptr<Spiller> spiller_;
- typedef std::map<unsigned, int> Virt2StackSlotMap;
- Virt2StackSlotMap v2ssMap_;
-
- int instrAdded_;
+ typedef std::vector<float> SpillWeights;
+ SpillWeights spillWeights_;
public:
virtual const char* getPassName() const {
MachineFunctionPass::getAnalysisUsage(AU);
}
- private:
/// runOnMachineFunction - register allocate the whole function
bool runOnMachineFunction(MachineFunction&);
+ void releaseMemory();
+
+ private:
+ /// linearScan - the linear scan algorithm
+ void linearScan();
+
/// initIntervalSets - initializa the four interval sets:
/// unhandled, fixed, active and inactive
- void initIntervalSets(const LiveIntervals::Intervals& li);
+ void initIntervalSets(LiveIntervals::Intervals& li);
/// processActiveIntervals - expire old intervals and move
/// non-overlapping ones to the incative list
/// overlapping ones to the active list
void processInactiveIntervals(IntervalPtrs::value_type cur);
- /// assignStackSlotAtInterval - choose and spill
- /// interval. Currently we spill the interval with the last
- /// end point in the active and inactive lists and the current
- /// interval
- void assignStackSlotAtInterval(IntervalPtrs::value_type cur);
+ /// updateSpillWeights - updates the spill weights of the
+ /// specifed physical register and its weight
+ void updateSpillWeights(unsigned reg, SpillWeights::value_type weight);
+
+ /// assignRegOrStackSlotAtInterval - assign a register if one
+ /// is available, or spill.
+ void assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur);
///
/// register handling helpers
/// 0
unsigned getFreePhysReg(IntervalPtrs::value_type cur);
- /// physRegAvailable - returns true if the specifed physical
- /// register is available
- bool physRegAvailable(unsigned physReg);
-
- /// tempPhysRegAvailable - returns true if the specifed
- /// temporary physical register is available
- bool tempPhysRegAvailable(unsigned physReg);
-
- /// getFreeTempPhysReg - return a free temprorary physical
- /// register for this virtual register if we have one (should
- /// never return 0)
- unsigned getFreeTempPhysReg(unsigned virtReg);
-
- /// assignVirt2PhysReg - assigns the free physical register to
- /// the virtual register passed as arguments
- void assignVirt2PhysReg(unsigned virtReg, unsigned physReg);
-
- /// clearVirtReg - free the physical register associated with this
- /// virtual register and disassociate virtual->physical and
- /// physical->virtual mappings
- void clearVirtReg(unsigned virtReg);
-
/// assignVirt2StackSlot - assigns this virtual register to a
- /// stack slot
- void assignVirt2StackSlot(unsigned virtReg);
-
- /// getStackSlot - returns the offset of the specified
- /// register on the stack
- int getStackSlot(unsigned virtReg);
-
- /// spillVirtReg - spills the virtual register
- void spillVirtReg(unsigned virtReg);
-
- /// loadPhysReg - loads to the physical register the value of
- /// the virtual register specifed. Virtual register must have
- /// an assigned stack slot
- void loadVirt2PhysReg(unsigned virtReg, unsigned physReg);
-
- void markPhysRegFree(unsigned physReg);
- void markPhysRegNotFree(unsigned physReg);
-
- void backupRegUse() {
- memcpy(regUseBackup_, regUse_, sizeof(regUseBackup_));
- }
-
- void restoreRegUse() {
- memcpy(regUse_, regUseBackup_, sizeof(regUseBackup_));
- }
-
- void printVirtRegAssignment() const {
- std::cerr << "register assignment:\n";
- for (Virt2PhysMap::const_iterator
- i = v2pMap_.begin(), e = v2pMap_.end(); i != e; ++i) {
- assert(i->second != 0);
- std::cerr << '[' << i->first << ','
- << mri_->getName(i->second) << "]\n";
- }
- for (Virt2StackSlotMap::const_iterator
- i = v2ssMap_.begin(), e = v2ssMap_.end(); i != e; ++i) {
- std::cerr << '[' << i->first << ",ss#" << i->second << "]\n";
- }
- std::cerr << '\n';
- }
+ /// stack slot. returns the stack slot
+ int assignVirt2StackSlot(unsigned virtReg);
void printIntervals(const char* const str,
RA::IntervalPtrs::const_iterator i,
RA::IntervalPtrs::const_iterator e) const {
if (str) std::cerr << str << " intervals:\n";
for (; i != e; ++i) {
- std::cerr << "\t\t" << **i << " -> ";
+ std::cerr << "\t" << **i << " -> ";
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg)) {
- Virt2PhysMap::const_iterator it = v2pMap_.find(reg);
- reg = (it == v2pMap_.end() ? 0 : it->second);
+ reg = vrm_->getPhys(reg);
}
std::cerr << mri_->getName(reg) << '\n';
}
}
- void printFreeRegs(const char* const str,
- const TargetRegisterClass* rc) const {
- if (str) std::cerr << str << ':';
- for (TargetRegisterClass::iterator i =
- rc->allocation_order_begin(*mf_);
- i != rc->allocation_order_end(*mf_); ++i) {
- unsigned reg = *i;
- if (!regUse_[reg]) {
- std::cerr << ' ' << mri_->getName(reg);
- if (reserved_[reg]) std::cerr << "*";
- }
- }
- std::cerr << '\n';
- }
+// void verifyAssignment() const {
+// for (Virt2PhysMap::const_iterator i = v2pMap_.begin(),
+// e = v2pMap_.end(); i != e; ++i)
+// for (Virt2PhysMap::const_iterator i2 = next(i); i2 != e; ++i2)
+// if (MRegisterInfo::isVirtualRegister(i->second) &&
+// (i->second == i2->second ||
+// mri_->areAliases(i->second, i2->second))) {
+// const Interval
+// &in = li_->getInterval(i->second),
+// &in2 = li_->getInterval(i2->second);
+// if (in.overlaps(in2)) {
+// std::cerr << in << " overlaps " << in2 << '\n';
+// assert(0);
+// }
+// }
+// }
};
}
+void RA::releaseMemory()
+{
+ unhandled_.clear();
+ fixed_.clear();
+ active_.clear();
+ inactive_.clear();
+ handled_.clear();
+}
+
bool RA::runOnMachineFunction(MachineFunction &fn) {
mf_ = &fn;
tm_ = &fn.getTarget();
mri_ = tm_->getRegisterInfo();
li_ = &getAnalysis<LiveIntervals>();
+ if (!prt_.get()) prt_.reset(new PhysRegTracker(*mri_));
+ vrm_.reset(new VirtRegMap(*mf_));
+ if (!spiller_.get()) spiller_.reset(createSpiller());
+
initIntervalSets(li_->getIntervals());
- v2pMap_.clear();
- v2ssMap_.clear();
- memset(regUse_, 0, sizeof(regUse_));
- memset(regUseBackup_, 0, sizeof(regUseBackup_));
-
- // FIXME: this will work only for the X86 backend. I need to
- // device an algorthm to select the minimal (considering register
- // aliasing) number of temp registers to reserve so that we have 2
- // registers for each register class available.
-
- // reserve R8: CH, CL
- // R16: CX, DI,
- // R32: ECX, EDI,
- // RFP: FP5, FP6
- reserved_.assign(MRegisterInfo::FirstVirtualRegister, false);
- reserved_[ 8] = true; /* CH */
- reserved_[ 9] = true; /* CL */
- reserved_[10] = true; /* CX */
- reserved_[12] = true; /* DI */
- reserved_[18] = true; /* ECX */
- reserved_[19] = true; /* EDI */
- reserved_[28] = true; /* FP5 */
- reserved_[29] = true; /* FP6 */
+ linearScan();
+
+ spiller_->runOnMachineFunction(*mf_, *vrm_);
+ return true;
+}
+
+void RA::linearScan()
+{
// linear scan algorithm
- DEBUG(std::cerr << "Machine Function\n");
+ DEBUG(std::cerr << "********** LINEAR SCAN **********\n");
+ DEBUG(std::cerr << "********** Function: "
+ << mf_->getFunction()->getName() << '\n');
- DEBUG(printIntervals("\tunhandled", unhandled_.begin(), unhandled_.end()));
- DEBUG(printIntervals("\tfixed", fixed_.begin(), fixed_.end()));
- DEBUG(printIntervals("\tactive", active_.begin(), active_.end()));
- DEBUG(printIntervals("\tinactive", inactive_.begin(), inactive_.end()));
+ DEBUG(printIntervals("unhandled", unhandled_.begin(), unhandled_.end()));
+ DEBUG(printIntervals("fixed", fixed_.begin(), fixed_.end()));
+ DEBUG(printIntervals("active", active_.begin(), active_.end()));
+ DEBUG(printIntervals("inactive", inactive_.begin(), inactive_.end()));
- while (!unhandled_.empty() || !fixed_.empty()) {
+ while (!unhandled_.empty()) {
// pick the interval with the earliest start point
- IntervalPtrs::value_type cur;
- if (fixed_.empty()) {
- cur = unhandled_.front();
- unhandled_.erase(unhandled_.begin());
- }
- else if (unhandled_.empty()) {
- cur = fixed_.front();
- fixed_.erase(fixed_.begin());
- }
- else if (unhandled_.front()->start() < fixed_.front()->start()) {
- cur = unhandled_.front();
- unhandled_.erase(unhandled_.begin());
- }
- else {
- cur = fixed_.front();
- fixed_.erase(fixed_.begin());
- }
+ IntervalPtrs::value_type cur = unhandled_.front();
+ unhandled_.pop_front();
- DEBUG(std::cerr << *cur << '\n');
+ DEBUG(std::cerr << "\n*** CURRENT ***: " << *cur << '\n');
processActiveIntervals(cur);
processInactiveIntervals(cur);
// if this register is fixed we are done
if (MRegisterInfo::isPhysicalRegister(cur->reg)) {
- markPhysRegNotFree(cur->reg);
+ prt_->addRegUse(cur->reg);
active_.push_back(cur);
+ handled_.push_back(cur);
}
// otherwise we are allocating a virtual register. try to find
// a free physical register or spill an interval in order to
// assign it one (we could spill the current though).
else {
- backupRegUse();
-
- // for every interval in inactive we overlap with, mark the
- // register as not free
- for (IntervalPtrs::const_iterator i = inactive_.begin(),
- e = inactive_.end(); i != e; ++i) {
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg))
- reg = v2pMap_[reg];
-
- if (cur->overlaps(**i)) {
- markPhysRegNotFree(reg);
- }
- }
-
- // for every interval in fixed we overlap with,
- // mark the register as not free
- for (IntervalPtrs::const_iterator i = fixed_.begin(),
- e = fixed_.end(); i != e; ++i) {
- assert(MRegisterInfo::isPhysicalRegister((*i)->reg) &&
- "virtual register interval in fixed set?");
- if (cur->overlaps(**i))
- markPhysRegNotFree((*i)->reg);
- }
-
- DEBUG(std::cerr << "\tallocating current interval:\n");
-
- unsigned physReg = getFreePhysReg(cur);
- if (!physReg) {
- assignStackSlotAtInterval(cur);
- }
- else {
- restoreRegUse();
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
- }
+ assignRegOrStackSlotAtInterval(cur);
}
- DEBUG(printIntervals("\tactive", active_.begin(), active_.end()));
- DEBUG(printIntervals("\tinactive", inactive_.begin(), inactive_.end())); }
+ DEBUG(printIntervals("active", active_.begin(), active_.end()));
+ DEBUG(printIntervals("inactive", inactive_.begin(), inactive_.end()));
+ // DEBUG(verifyAssignment());
+ }
// expire any remaining active intervals
for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
unsigned reg = (*i)->reg;
- DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- markPhysRegFree(reg);
- }
- active_.clear();
- inactive_.clear();
-
- typedef LiveIntervals::Reg2RegMap Reg2RegMap;
- const Reg2RegMap& r2rMap = li_->getJoinedRegMap();
-
- DEBUG(printVirtRegAssignment());
- DEBUG(std::cerr << "Performing coalescing on joined intervals\n");
- // perform coalescing if we were passed joined intervals
- for(Reg2RegMap::const_iterator i = r2rMap.begin(), e = r2rMap.end();
- i != e; ++i) {
- unsigned reg = i->first;
- unsigned rep = li_->rep(reg);
-
- assert((MRegisterInfo::isPhysicalRegister(rep) ||
- v2pMap_.find(rep) != v2pMap_.end() ||
- v2ssMap_.find(rep) != v2ssMap_.end()) &&
- "representative register is not allocated!");
-
- assert(MRegisterInfo::isVirtualRegister(reg) &&
- v2pMap_.find(reg) == v2pMap_.end() &&
- v2ssMap_.find(reg) == v2ssMap_.end() &&
- "coalesced register is already allocated!");
-
- if (MRegisterInfo::isPhysicalRegister(rep)) {
- v2pMap_.insert(std::make_pair(reg, rep));
- }
- else {
- Virt2PhysMap::const_iterator pr = v2pMap_.find(rep);
- if (pr != v2pMap_.end()) {
- v2pMap_.insert(std::make_pair(reg, pr->second));
- }
- else {
- Virt2StackSlotMap::const_iterator ss = v2ssMap_.find(rep);
- assert(ss != v2ssMap_.end());
- v2ssMap_.insert(std::make_pair(reg, ss->second));
- }
- }
- }
-
- DEBUG(printVirtRegAssignment());
- DEBUG(std::cerr << "finished register allocation\n");
-
- const TargetInstrInfo& tii = tm_->getInstrInfo();
-
- DEBUG(std::cerr << "Rewrite machine code:\n");
- for (currentMbb_ = mf_->begin(); currentMbb_ != mf_->end(); ++currentMbb_) {
- instrAdded_ = 0;
-
- for (currentInstr_ = currentMbb_->begin();
- currentInstr_ != currentMbb_->end(); ) {
-
- DEBUG(std::cerr << "\tinstruction: ";
- (*currentInstr_)->print(std::cerr, *tm_););
-
- // use our current mapping and actually replace and
- // virtual register with its allocated physical registers
- DEBUG(std::cerr << "\t\treplacing virtual registers with mapped "
- "physical registers:\n");
- for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
- i != e; ++i) {
- MachineOperand& op = (*currentInstr_)->getOperand(i);
- if (op.isVirtualRegister()) {
- unsigned virtReg = op.getAllocatedRegNum();
- Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- DEBUG(std::cerr << "\t\t\t%reg" << it->second
- << " -> " << mri_->getName(it->second) << '\n');
- (*currentInstr_)->SetMachineOperandReg(i, it->second);
- }
- }
- }
-
- unsigned srcReg, dstReg;
- if (tii.isMoveInstr(**currentInstr_, srcReg, dstReg) &&
- ((MRegisterInfo::isPhysicalRegister(srcReg) &&
- MRegisterInfo::isPhysicalRegister(dstReg) &&
- srcReg == dstReg) ||
- (MRegisterInfo::isVirtualRegister(srcReg) &&
- MRegisterInfo::isVirtualRegister(dstReg) &&
- v2ssMap_[srcReg] == v2ssMap_[dstReg]))) {
- delete *currentInstr_;
- currentInstr_ = currentMbb_->erase(currentInstr_);
- ++numPeep;
- DEBUG(std::cerr << "\t\tdeleting instruction\n");
- continue;
- }
-
- DEBUG(std::cerr << "\t\tloading temporarily used operands to "
- "registers:\n");
- for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
- i != e; ++i) {
- MachineOperand& op = (*currentInstr_)->getOperand(i);
- if (op.isVirtualRegister() && op.isUse() && !op.isDef()) {
- unsigned virtReg = op.getAllocatedRegNum();
- unsigned physReg = 0;
- Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- physReg = it->second;
- }
- else {
- physReg = getFreeTempPhysReg(virtReg);
- loadVirt2PhysReg(virtReg, physReg);
- tempUseOperands_.push_back(virtReg);
- }
- (*currentInstr_)->SetMachineOperandReg(i, physReg);
- }
- }
-
- DEBUG(std::cerr << "\t\tclearing temporarily used operands:\n");
- for (unsigned i = 0, e = tempUseOperands_.size(); i != e; ++i) {
- clearVirtReg(tempUseOperands_[i]);
- }
- tempUseOperands_.clear();
-
- DEBUG(std::cerr << "\t\tassigning temporarily defined operands to "
- "registers:\n");
- for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
- i != e; ++i) {
- MachineOperand& op = (*currentInstr_)->getOperand(i);
- if (op.isVirtualRegister() && op.isDef()) {
- unsigned virtReg = op.getAllocatedRegNum();
- unsigned physReg = 0;
- Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- physReg = it->second;
- }
- else {
- physReg = getFreeTempPhysReg(virtReg);
- }
- if (op.isUse()) { // def and use
- loadVirt2PhysReg(virtReg, physReg);
- }
- else {
- assignVirt2PhysReg(virtReg, physReg);
- }
- tempDefOperands_.push_back(virtReg);
- (*currentInstr_)->SetMachineOperandReg(i, physReg);
- }
- }
-
- DEBUG(std::cerr << "\t\tspilling temporarily defined operands "
- "of this instruction:\n");
- ++currentInstr_; // we want to insert after this instruction
- for (unsigned i = 0, e = tempDefOperands_.size(); i != e; ++i) {
- spillVirtReg(tempDefOperands_[i]);
- }
- --currentInstr_; // restore currentInstr_ iterator
- tempDefOperands_.clear();
- ++currentInstr_;
- }
+ DEBUG(std::cerr << "\tinterval " << **i << " expired\n");
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
}
- return true;
+ DEBUG(std::cerr << *vrm_);
}
-void RA::initIntervalSets(const LiveIntervals::Intervals& li)
+void RA::initIntervalSets(LiveIntervals::Intervals& li)
{
assert(unhandled_.empty() && fixed_.empty() &&
active_.empty() && inactive_.empty() &&
"interval sets should be empty on initialization");
- for (LiveIntervals::Intervals::const_iterator i = li.begin(), e = li.end();
+ for (LiveIntervals::Intervals::iterator i = li.begin(), e = li.end();
i != e; ++i) {
+ unhandled_.push_back(&*i);
if (MRegisterInfo::isPhysicalRegister(i->reg))
fixed_.push_back(&*i);
- else
- unhandled_.push_back(&*i);
}
}
// remove expired intervals
if ((*i)->expiredAt(cur->start())) {
DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- markPhysRegFree(reg);
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
// remove from active
i = active_.erase(i);
}
// move inactive intervals to inactive list
else if (!(*i)->liveAt(cur->start())) {
- DEBUG(std::cerr << "\t\t\tinterval " << **i << " inactive\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- markPhysRegFree(reg);
+ DEBUG(std::cerr << "\t\tinterval " << **i << " inactive\n");
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
// add to inactive
inactive_.push_back(*i);
// remove from active
// remove expired intervals
if ((*i)->expiredAt(cur->start())) {
- DEBUG(std::cerr << "\t\t\tinterval " << **i << " expired\n");
+ DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
// remove from inactive
i = inactive_.erase(i);
}
// move re-activated intervals in active list
else if ((*i)->liveAt(cur->start())) {
- DEBUG(std::cerr << "\t\t\tinterval " << **i << " active\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- markPhysRegNotFree(reg);
+ DEBUG(std::cerr << "\t\tinterval " << **i << " active\n");
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->addRegUse(reg);
// add to active
active_.push_back(*i);
// remove from inactive
}
}
-namespace {
- template <typename T>
- void updateWeight(T rw[], int reg, T w)
- {
- if (rw[reg] == std::numeric_limits<T>::max() ||
- w == std::numeric_limits<T>::max())
- rw[reg] = std::numeric_limits<T>::max();
- else
- rw[reg] += w;
- }
+void RA::updateSpillWeights(unsigned reg, SpillWeights::value_type weight)
+{
+ spillWeights_[reg] += weight;
+ for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as)
+ spillWeights_[*as] += weight;
}
-void RA::assignStackSlotAtInterval(IntervalPtrs::value_type cur)
+void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
{
- DEBUG(std::cerr << "\t\tassigning stack slot at interval "
- << *cur << ":\n");
+ DEBUG(std::cerr << "\tallocating current interval: ");
+
+ PhysRegTracker backupPrt = *prt_;
- // set all weights to zero
- float regWeight[MRegisterInfo::FirstVirtualRegister];
- for (unsigned i = 0; i < MRegisterInfo::FirstVirtualRegister; ++i)
- regWeight[i] = 0.0F;
+ spillWeights_.assign(mri_->getNumRegs(), 0.0);
- // for each interval in active
+ // for each interval in active update spill weights
for (IntervalPtrs::const_iterator i = active_.begin(), e = active_.end();
i != e; ++i) {
unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- updateWeight(regWeight, reg, (*i)->weight);
- for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as)
- updateWeight(regWeight, *as, (*i)->weight);
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ updateSpillWeights(reg, (*i)->weight);
}
- // for each interval in inactive that overlaps
+ // for every interval in inactive we overlap with, mark the
+ // register as not free and update spill weights
for (IntervalPtrs::const_iterator i = inactive_.begin(),
e = inactive_.end(); i != e; ++i) {
- if (!cur->overlaps(**i))
- continue;
+ if (cur->overlaps(**i)) {
+ unsigned reg = (*i)->reg;
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->addRegUse(reg);
+ updateSpillWeights(reg, (*i)->weight);
+ }
+ }
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
+ // for every interval in fixed we overlap with,
+ // mark the register as not free and update spill weights
+ for (IntervalPtrs::const_iterator i = fixed_.begin(),
+ e = fixed_.end(); i != e; ++i) {
+ if (cur->overlaps(**i)) {
+ unsigned reg = (*i)->reg;
+ prt_->addRegUse(reg);
+ updateSpillWeights(reg, (*i)->weight);
}
- updateWeight(regWeight, reg, (*i)->weight);
- for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as)
- updateWeight(regWeight, *as, (*i)->weight);
}
- // for each fixed interval that overlaps
- for (IntervalPtrs::const_iterator i = fixed_.begin(), e = fixed_.end();
- i != e; ++i) {
- if (!cur->overlaps(**i))
- continue;
-
- assert(MRegisterInfo::isPhysicalRegister((*i)->reg) &&
- "virtual register interval in fixed set?");
- updateWeight(regWeight, (*i)->reg, (*i)->weight);
- for (const unsigned* as = mri_->getAliasSet((*i)->reg); *as; ++as)
- updateWeight(regWeight, *as, (*i)->weight);
+ unsigned physReg = getFreePhysReg(cur);
+ // restore the physical register tracker
+ *prt_ = backupPrt;
+ // 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.
+ if (physReg) {
+ DEBUG(std::cerr << mri_->getName(physReg) << '\n');
+ vrm_->assignVirt2Phys(cur->reg, physReg);
+ prt_->addRegUse(physReg);
+ active_.push_back(cur);
+ handled_.push_back(cur);
+ return;
}
+ DEBUG(std::cerr << "no free registers\n");
- float minWeight = std::numeric_limits<float>::max();
+ DEBUG(std::cerr << "\tassigning stack slot at interval "<< *cur << ":\n");
+
+ float minWeight = HUGE_VAL;
unsigned minReg = 0;
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_);
i != rc->allocation_order_end(*mf_); ++i) {
unsigned reg = *i;
- if (!reserved_[reg] && minWeight > regWeight[reg]) {
- minWeight = regWeight[reg];
+ if (minWeight > spillWeights_[reg]) {
+ minWeight = spillWeights_[reg];
minReg = reg;
}
}
- DEBUG(std::cerr << "\t\t\tregister with min weight: "
+ DEBUG(std::cerr << "\t\tregister with min weight: "
<< mri_->getName(minReg) << " (" << minWeight << ")\n");
- if (cur->weight < minWeight) {
- restoreRegUse();
- DEBUG(std::cerr << "\t\t\t\tspilling: " << *cur << '\n');
- assignVirt2StackSlot(cur->reg);
+ // if the current has the minimum weight, we need to spill it and
+ // add any added intervals back to unhandled, and restart
+ // linearscan.
+ if (cur->weight <= minWeight) {
+ DEBUG(std::cerr << "\t\t\tspilling(c): " << *cur << '\n';);
+ int slot = vrm_->assignVirt2StackSlot(cur->reg);
+ std::vector<LiveInterval*> added =
+ li_->addIntervalsForSpills(*cur, *vrm_, slot);
+
+ // merge added with unhandled
+ std::vector<LiveInterval*>::iterator addedIt = added.begin();
+ std::vector<LiveInterval*>::iterator addedItEnd = added.end();
+ for (IntervalPtrs::iterator i = unhandled_.begin(), e = unhandled_.end();
+ i != e && addedIt != addedItEnd; ++i) {
+ if ((*i)->start() > (*addedIt)->start())
+ i = unhandled_.insert(i, *(addedIt++));
+ }
+ while (addedIt != addedItEnd)
+ unhandled_.push_back(*(addedIt++));
+
+ return;
}
- else {
- std::set<unsigned> toSpill;
- toSpill.insert(minReg);
- for (const unsigned* as = mri_->getAliasSet(minReg); *as; ++as)
- toSpill.insert(*as);
-
- std::vector<unsigned> spilled;
- for (IntervalPtrs::iterator i = active_.begin();
- i != active_.end(); ) {
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill.find(v2pMap_[reg]) != toSpill.end() &&
- cur->overlaps(**i)) {
- spilled.push_back(v2pMap_[reg]);
- DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
- assignVirt2StackSlot(reg);
- i = active_.erase(i);
+
+ // push the current interval back to unhandled since we are going
+ // to re-run at least this iteration. Since we didn't modify it it
+ // should go back right in the front of the list
+ unhandled_.push_front(cur);
+
+ // otherwise we spill all intervals aliasing the register with
+ // minimum weight, rollback to the interval with the earliest
+ // start point and let the linear scan algorithm run again
+ std::vector<LiveInterval*> added;
+ assert(MRegisterInfo::isPhysicalRegister(minReg) &&
+ "did not choose a register to spill?");
+ std::vector<bool> toSpill(mri_->getNumRegs(), false);
+ toSpill[minReg] = true;
+ for (const unsigned* as = mri_->getAliasSet(minReg); *as; ++as)
+ toSpill[*as] = true;
+ unsigned earliestStart = cur->start();
+
+ std::set<unsigned> spilled;
+
+ for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
+ unsigned reg = (*i)->reg;
+ if (MRegisterInfo::isVirtualRegister(reg) &&
+ toSpill[vrm_->getPhys(reg)] &&
+ cur->overlaps(**i)) {
+ DEBUG(std::cerr << "\t\t\tspilling(a): " << **i << '\n');
+ earliestStart = std::min(earliestStart, (*i)->start());
+ int slot = vrm_->assignVirt2StackSlot((*i)->reg);
+ std::vector<LiveInterval*> newIs =
+ li_->addIntervalsForSpills(**i, *vrm_, slot);
+ std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ spilled.insert(reg);
+ }
+ }
+ for (IntervalPtrs::iterator i = inactive_.begin();
+ i != inactive_.end(); ++i) {
+ unsigned reg = (*i)->reg;
+ if (MRegisterInfo::isVirtualRegister(reg) &&
+ toSpill[vrm_->getPhys(reg)] &&
+ cur->overlaps(**i)) {
+ DEBUG(std::cerr << "\t\t\tspilling(i): " << **i << '\n');
+ earliestStart = std::min(earliestStart, (*i)->start());
+ int slot = vrm_->assignVirt2StackSlot((*i)->reg);
+ std::vector<LiveInterval*> newIs =
+ li_->addIntervalsForSpills(**i, *vrm_, slot);
+ std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ spilled.insert(reg);
+ }
+ }
+
+ DEBUG(std::cerr << "\t\trolling back to: " << earliestStart << '\n');
+ // scan handled in reverse order and undo each one, restoring the
+ // state of unhandled
+ while (!handled_.empty()) {
+ IntervalPtrs::value_type i = handled_.back();
+ // if this interval starts before t we are done
+ if (i->start() < earliestStart)
+ break;
+ DEBUG(std::cerr << "\t\t\tundo changes for: " << *i << '\n');
+ handled_.pop_back();
+ IntervalPtrs::iterator it;
+ if ((it = find(active_.begin(), active_.end(), i)) != active_.end()) {
+ active_.erase(it);
+ if (MRegisterInfo::isPhysicalRegister(i->reg)) {
+ prt_->delRegUse(i->reg);
+ unhandled_.push_front(i);
}
else {
- ++i;
+ if (!spilled.count(i->reg))
+ unhandled_.push_front(i);
+ prt_->delRegUse(vrm_->getPhys(i->reg));
+ vrm_->clearVirt(i->reg);
}
}
- for (IntervalPtrs::iterator i = inactive_.begin();
- i != inactive_.end(); ) {
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill.find(v2pMap_[reg]) != toSpill.end() &&
- cur->overlaps(**i)) {
- DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
- assignVirt2StackSlot(reg);
- i = inactive_.erase(i);
- }
+ else if ((it = find(inactive_.begin(), inactive_.end(), i)) != inactive_.end()) {
+ inactive_.erase(it);
+ if (MRegisterInfo::isPhysicalRegister(i->reg))
+ unhandled_.push_front(i);
else {
- ++i;
+ if (!spilled.count(i->reg))
+ unhandled_.push_front(i);
+ vrm_->clearVirt(i->reg);
}
}
+ else {
+ if (MRegisterInfo::isVirtualRegister(i->reg))
+ vrm_->clearVirt(i->reg);
+ unhandled_.push_front(i);
+ }
+ }
- unsigned physReg = getFreePhysReg(cur);
- assert(physReg && "no free physical register after spill?");
-
- restoreRegUse();
- for (unsigned i = 0; i < spilled.size(); ++i)
- markPhysRegFree(spilled[i]);
-
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
+ // scan the rest and undo each interval that expired after t and
+ // insert it in active (the next iteration of the algorithm will
+ // put it in inactive if required)
+ IntervalPtrs::iterator i = handled_.begin(), e = handled_.end();
+ for (; i != e; ++i) {
+ if (!(*i)->expiredAt(earliestStart) && (*i)->expiredAt(cur->start())) {
+ DEBUG(std::cerr << "\t\t\tundo changes for: " << **i << '\n');
+ active_.push_back(*i);
+ if (MRegisterInfo::isPhysicalRegister((*i)->reg))
+ prt_->addRegUse((*i)->reg);
+ else
+ prt_->addRegUse(vrm_->getPhys((*i)->reg));
+ }
}
-}
-bool RA::physRegAvailable(unsigned physReg)
-{
- assert(!reserved_[physReg] &&
- "cannot call this method with a reserved register");
+ std::sort(added.begin(), added.end(), less_ptr<LiveInterval>());
+ // merge added with unhandled
+ std::vector<LiveInterval*>::iterator addedIt = added.begin();
+ std::vector<LiveInterval*>::iterator addedItEnd = added.end();
+ for (IntervalPtrs::iterator i = unhandled_.begin(), e = unhandled_.end();
+ i != e && addedIt != addedItEnd; ++i) {
+ if ((*i)->start() > (*addedIt)->start())
+ i = unhandled_.insert(i, *(addedIt++));
+ }
+ while (addedIt != addedItEnd)
+ unhandled_.push_back(*(addedIt++));
- return !regUse_[physReg];
}
unsigned RA::getFreePhysReg(IntervalPtrs::value_type cur)
{
- DEBUG(std::cerr << "\t\tgetting free physical register: ");
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_);
i != rc->allocation_order_end(*mf_); ++i) {
unsigned reg = *i;
- if (!reserved_[reg] && !regUse_[reg]) {
- DEBUG(std::cerr << mri_->getName(reg) << '\n');
+ if (prt_->isRegAvail(reg))
return reg;
- }
- }
-
- DEBUG(std::cerr << "no free register\n");
- return 0;
-}
-
-bool RA::tempPhysRegAvailable(unsigned physReg)
-{
- assert(reserved_[physReg] &&
- "cannot call this method with a not reserved temp register");
-
- return !regUse_[physReg];
-}
-
-unsigned RA::getFreeTempPhysReg(unsigned virtReg)
-{
- DEBUG(std::cerr << "\t\tgetting free temporary physical register: ");
-
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
- // go in reverse allocation order for the temp registers
- for (TargetRegisterClass::iterator i = rc->allocation_order_end(*mf_) - 1;
- i != rc->allocation_order_begin(*mf_) - 1; --i) {
- unsigned reg = *i;
- if (reserved_[reg] && !regUse_[reg]) {
- DEBUG(std::cerr << mri_->getName(reg) << '\n');
- return reg;
- }
}
-
- assert(0 && "no free temporary physical register?");
return 0;
}
-void RA::assignVirt2PhysReg(unsigned virtReg, unsigned physReg)
-{
- bool inserted = v2pMap_.insert(std::make_pair(virtReg, physReg)).second;
- assert(inserted && "attempting to assign a virt->phys mapping to an "
- "already mapped register");
- markPhysRegNotFree(physReg);
-}
-
-void RA::clearVirtReg(unsigned virtReg)
-{
- Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
- assert(it != v2pMap_.end() &&
- "attempting to clear a not allocated virtual register");
- unsigned physReg = it->second;
- markPhysRegFree(physReg);
- v2pMap_.erase(it);
- DEBUG(std::cerr << "\t\t\tcleared register " << mri_->getName(physReg)
- << "\n");
-}
-
-void RA::assignVirt2StackSlot(unsigned virtReg)
-{
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
- int frameIndex = mf_->getFrameInfo()->CreateStackObject(rc);
-
- bool inserted = v2ssMap_.insert(std::make_pair(virtReg, frameIndex)).second;
- assert(inserted &&
- "attempt to assign stack slot to already assigned register?");
- // if the virtual register was previously assigned clear the mapping
- // and free the virtual register
- if (v2pMap_.find(virtReg) != v2pMap_.end()) {
- clearVirtReg(virtReg);
- }
-}
-
-int RA::getStackSlot(unsigned virtReg)
-{
- // use lower_bound so that we can do a possibly O(1) insert later
- // if necessary
- Virt2StackSlotMap::iterator it = v2ssMap_.find(virtReg);
- assert(it != v2ssMap_.end() &&
- "attempt to get stack slot on register that does not live on the stack");
- return it->second;
-}
-
-void RA::spillVirtReg(unsigned virtReg)
-{
- DEBUG(std::cerr << "\t\t\tspilling register: " << virtReg);
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
- int frameIndex = getStackSlot(virtReg);
- DEBUG(std::cerr << " to stack slot #" << frameIndex << '\n');
- ++numSpilled;
- instrAdded_ += mri_->storeRegToStackSlot(*currentMbb_, currentInstr_,
- v2pMap_[virtReg], frameIndex, rc);
- clearVirtReg(virtReg);
-}
-
-void RA::loadVirt2PhysReg(unsigned virtReg, unsigned physReg)
-{
- DEBUG(std::cerr << "\t\t\tloading register: " << virtReg);
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
- int frameIndex = getStackSlot(virtReg);
- DEBUG(std::cerr << " from stack slot #" << frameIndex << '\n');
- ++numReloaded;
- instrAdded_ += mri_->loadRegFromStackSlot(*currentMbb_, currentInstr_,
- physReg, frameIndex, rc);
- assignVirt2PhysReg(virtReg, physReg);
-}
-
-void RA::markPhysRegFree(unsigned physReg)
-{
- assert(regUse_[physReg] != 0);
- --regUse_[physReg];
- for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
- physReg = *as;
- assert(regUse_[physReg] != 0);
- --regUse_[physReg];
- }
-}
-
-void RA::markPhysRegNotFree(unsigned physReg)
-{
- ++regUse_[physReg];
- for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
- physReg = *as;
- ++regUse_[physReg];
- }
-}
-
FunctionPass* llvm::createLinearScanRegisterAllocator() {
return new RA();
}
projects / oota-llvm.git / blobdiff