// 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 "LiveIntervalAnalysis.h"
+#include "PhysRegTracker.h"
+#include "VirtRegMap.h"
+#include <algorithm>
+#include <cmath>
+#include <set>
+#include <queue>
+
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 PhysRegTracker {
- private:
- const MRegisterInfo* mri_;
- std::vector<bool> reserved_;
- std::vector<unsigned> regUse_;
-
- public:
- PhysRegTracker(MachineFunction* mf)
- : mri_(mf ? mf->getTarget().getRegisterInfo() : NULL) {
- if (mri_) {
- reserved_.assign(mri_->getNumRegs(), false);
- regUse_.assign(mri_->getNumRegs(), 0);
- }
- }
- PhysRegTracker(const PhysRegTracker& rhs)
- : mri_(rhs.mri_),
- reserved_(rhs.reserved_),
- regUse_(rhs.regUse_) {
- }
+ Statistic<double> efficiency
+ ("regalloc", "Ratio of intervals processed over total intervals");
- const PhysRegTracker& operator=(const PhysRegTracker& rhs) {
- mri_ = rhs.mri_;
- reserved_ = rhs.reserved_;
- regUse_ = rhs.regUse_;
- return *this;
- }
-
- void reservePhysReg(unsigned physReg) {
- reserved_[physReg] = true;
- }
-
- void addPhysRegUse(unsigned physReg) {
- ++regUse_[physReg];
- for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
- physReg = *as;
- ++regUse_[physReg];
- }
- }
-
- void delPhysRegUse(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];
- }
- }
-
- bool isPhysRegReserved(unsigned physReg) const {
- return reserved_[physReg];
- }
-
- bool isPhysRegAvail(unsigned physReg) const {
- return regUse_[physReg] == 0 && !isPhysRegReserved(physReg);
- }
-
- bool isReservedPhysRegAvail(unsigned physReg) const {
- return regUse_[physReg] == 0 && isPhysRegReserved(physReg);
- }
- };
+ static unsigned numIterations = 0;
+ static unsigned numIntervals = 0;
class RA : public MachineFunctionPass {
private:
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_;
-
- PhysRegTracker prt_;
-
- typedef std::map<unsigned, unsigned> Virt2PhysMap;
- Virt2PhysMap v2pMap_;
-
- typedef std::map<unsigned, int> Virt2StackSlotMap;
- Virt2StackSlotMap v2ssMap_;
-
- int instrAdded_;
+ typedef std::vector<LiveInterval*> IntervalPtrs;
+ IntervalPtrs handled_, fixed_, active_, inactive_;
+ typedef std::priority_queue<LiveInterval*,
+ IntervalPtrs,
+ greater_ptr<LiveInterval> > IntervalHeap;
+ IntervalHeap unhandled_;
+ std::auto_ptr<PhysRegTracker> prt_;
+ std::auto_ptr<VirtRegMap> vrm_;
+ std::auto_ptr<Spiller> spiller_;
typedef std::vector<float> SpillWeights;
SpillWeights spillWeights_;
public:
- RA()
- : prt_(NULL) {
-
- }
-
virtual const char* getPassName() const {
return "Linear Scan Register Allocator";
}
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();
/// processActiveIntervals - expire old intervals and move
/// non-overlapping ones to the incative list
- void processActiveIntervals(IntervalPtrs::value_type cur);
+ void processActiveIntervals(LiveInterval* cur);
/// processInactiveIntervals - expire old intervals and move
/// overlapping ones to the active list
- void processInactiveIntervals(IntervalPtrs::value_type cur);
+ void processInactiveIntervals(LiveInterval* cur);
/// updateSpillWeights - updates the spill weights of the
/// specifed physical register and its weight
/// assignRegOrStackSlotAtInterval - assign a register if one
/// is available, or spill.
- void assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur);
+ void assignRegOrStackSlotAtInterval(LiveInterval* cur);
///
/// register handling helpers
/// getFreePhysReg - return a free physical register for this
/// virtual register interval if we have one, otherwise return
/// 0
- unsigned getFreePhysReg(IntervalPtrs::value_type cur);
-
- /// 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
- Virt2PhysMap::iterator
- 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(Virt2PhysMap::iterator it);
+ unsigned getFreePhysReg(LiveInterval* cur);
/// 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(Virt2PhysMap::iterator it);
-
- /// loadPhysReg - loads to the physical register the value of
- /// the virtual register specifed. Virtual register must have
- /// an assigned stack slot
- Virt2PhysMap::iterator
- loadVirt2PhysReg(unsigned virtReg, unsigned physReg);
-
- 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 {
+ template <typename ItTy>
+ void printIntervals(const char* const str, ItTy i, ItTy 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 RA::releaseMemory()
{
- v2pMap_.clear();
- v2ssMap_.clear();
- unhandled_.clear();
+ while (!unhandled_.empty()) unhandled_.pop();
+ fixed_.clear();
active_.clear();
inactive_.clear();
- fixed_.clear();
-
+ handled_.clear();
}
bool RA::runOnMachineFunction(MachineFunction &fn) {
tm_ = &fn.getTarget();
mri_ = tm_->getRegisterInfo();
li_ = &getAnalysis<LiveIntervals>();
- prt_ = PhysRegTracker(mf_);
-
- initIntervalSets(li_->getIntervals());
-
- // 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
- prt_.reservePhysReg( 8); /* CH */
- prt_.reservePhysReg( 9); /* CL */
- prt_.reservePhysReg(10); /* CX */
- prt_.reservePhysReg(12); /* DI */
- prt_.reservePhysReg(18); /* ECX */
- prt_.reservePhysReg(19); /* EDI */
- prt_.reservePhysReg(28); /* FP5 */
- prt_.reservePhysReg(29); /* FP6 */
+ if (!prt_.get()) prt_.reset(new PhysRegTracker(*mri_));
+ vrm_.reset(new VirtRegMap(*mf_));
+ if (!spiller_.get()) spiller_.reset(createSpiller());
+ initIntervalSets();
+
+ 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());
- }
-
- DEBUG(std::cerr << *cur << '\n');
+ LiveInterval* cur = unhandled_.top();
+ unhandled_.pop();
+ ++numIterations;
+ DEBUG(std::cerr << "\n*** CURRENT ***: " << *cur << '\n');
processActiveIntervals(cur);
processInactiveIntervals(cur);
// if this register is fixed we are done
if (MRegisterInfo::isPhysicalRegister(cur->reg)) {
- prt_.addPhysRegUse(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
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()));
+ }
+ numIntervals += li_->getNumIntervals();
+ efficiency = double(numIterations) / double(numIntervals);
// expire any remaining active intervals
- for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
+ for (IntervalPtrs::reverse_iterator
+ i = active_.rbegin(); i != active_.rend(); ) {
unsigned reg = (*i)->reg;
- DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- prt_.delPhysRegUse(reg);
- }
-
- 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_.count(rep) || v2ssMap_.count(rep)) &&
- "representative register is not allocated!");
-
- assert(MRegisterInfo::isVirtualRegister(reg) &&
- !v2pMap_.count(reg) && !v2ssMap_.count(reg) &&
- "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(std::cerr << "\tinterval " << **i << " expired\n");
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
- 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.isRegister() &&
- MRegisterInfo::isVirtualRegister(op.getReg())) {
- unsigned virtReg = op.getReg();
- Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- DEBUG(std::cerr << "\t\t\t%reg" << it->first
- << " -> " << 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]))) {
- currentInstr_ = currentMbb_->erase(currentInstr_);
- ++numPeep;
- DEBUG(std::cerr << "\t\tdeleting instruction\n");
- continue;
- }
-
- typedef std::vector<Virt2PhysMap::iterator> Regs;
- Regs toClear;
- Regs toSpill;
-
- const unsigned numOperands = currentInstr_->getNumOperands();
-
- DEBUG(std::cerr << "\t\tloading temporarily used operands to "
- "registers:\n");
- for (unsigned i = 0; i != numOperands; ++i) {
- MachineOperand& op = currentInstr_->getOperand(i);
- if (op.isRegister() && op.isUse() &&
- MRegisterInfo::isVirtualRegister(op.getReg())) {
- unsigned virtReg = op.getAllocatedRegNum();
- unsigned physReg = 0;
- Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- physReg = it->second;
- }
- else {
- physReg = getFreeTempPhysReg(virtReg);
- it = loadVirt2PhysReg(virtReg, physReg);
- // we will clear uses that are not also defs
- // before we allocate registers the defs
- if (op.isDef())
- toSpill.push_back(it);
- else
- toClear.push_back(it);
- }
- currentInstr_->SetMachineOperandReg(i, physReg);
- }
- }
-
- DEBUG(std::cerr << "\t\tclearing temporarily used but not defined "
- "operands:\n");
- std::for_each(toClear.begin(), toClear.end(),
- std::bind1st(std::mem_fun(&RA::clearVirtReg), this));
-
- DEBUG(std::cerr << "\t\tassigning temporarily defined operands to "
- "registers:\n");
- for (unsigned i = 0; i != numOperands; ++i) {
- MachineOperand& op = currentInstr_->getOperand(i);
- if (op.isRegister() &&
- MRegisterInfo::isVirtualRegister(op.getReg())) {
- assert(!op.isUse() && "we should not have uses here!");
- unsigned virtReg = op.getReg();
- unsigned physReg = 0;
- Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- physReg = it->second;
- }
- else {
- physReg = getFreeTempPhysReg(virtReg);
- it = assignVirt2PhysReg(virtReg, physReg);
- // need to spill this after we are done with
- // this instruction
- toSpill.push_back(it);
- }
- currentInstr_->SetMachineOperandReg(i, physReg);
- }
- }
- ++currentInstr_; // spills will go after this instruction
-
- DEBUG(std::cerr << "\t\tspilling temporarily defined operands:\n");
- std::for_each(toSpill.begin(), toSpill.end(),
- std::bind1st(std::mem_fun(&RA::spillVirtReg), this));
- }
+ // expire any remaining inactive intervals
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend(); ) {
+ DEBUG(std::cerr << "\tinterval " << **i << " expired\n");
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
- return true;
+ DEBUG(std::cerr << *vrm_);
}
-void RA::initIntervalSets(const LiveIntervals::Intervals& li)
+void RA::initIntervalSets()
{
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();
- i != e; ++i) {
- if (MRegisterInfo::isPhysicalRegister(i->reg))
- fixed_.push_back(&*i);
- else
- unhandled_.push_back(&*i);
+ for (LiveIntervals::iterator i = li_->begin(), e = li_->end(); i != e; ++i){
+ unhandled_.push(&i->second);
+ if (MRegisterInfo::isPhysicalRegister(i->second.reg))
+ fixed_.push_back(&i->second);
}
}
void RA::processActiveIntervals(IntervalPtrs::value_type cur)
{
DEBUG(std::cerr << "\tprocessing active intervals:\n");
- for (IntervalPtrs::iterator i = active_.begin(); i != active_.end();) {
+ for (IntervalPtrs::reverse_iterator
+ i = active_.rbegin(); i != active_.rend();) {
unsigned reg = (*i)->reg;
// remove expired intervals
if ((*i)->expiredAt(cur->start())) {
DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
- if (MRegisterInfo::isVirtualRegister(reg)) {
- reg = v2pMap_[reg];
- }
- prt_.delPhysRegUse(reg);
+ if (MRegisterInfo::isVirtualRegister(reg))
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
// remove from active
- i = active_.erase(i);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
// 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];
- }
- prt_.delPhysRegUse(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
- i = active_.erase(i);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
}
else {
++i;
void RA::processInactiveIntervals(IntervalPtrs::value_type cur)
{
DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
- for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end();) {
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend();) {
unsigned reg = (*i)->reg;
// 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);
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
// 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];
- }
- prt_.addPhysRegUse(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
- i = inactive_.erase(i);
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
}
else {
++i;
spillWeights_[*as] += weight;
}
-void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
+void RA::assignRegOrStackSlotAtInterval(LiveInterval* cur)
{
- DEBUG(std::cerr << "\tallocating current interval:\n");
+ DEBUG(std::cerr << "\tallocating current interval: ");
- PhysRegTracker backupPrt = prt_;
+ PhysRegTracker backupPrt = *prt_;
spillWeights_.assign(mri_->getNumRegs(), 0.0);
i != e; ++i) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg))
- reg = v2pMap_[reg];
+ reg = vrm_->getPhys(reg);
updateSpillWeights(reg, (*i)->weight);
}
if (cur->overlaps(**i)) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg))
- reg = v2pMap_[reg];
- prt_.addPhysRegUse(reg);
+ reg = vrm_->getPhys(reg);
+ prt_->addRegUse(reg);
updateSpillWeights(reg, (*i)->weight);
}
}
e = fixed_.end(); i != e; ++i) {
if (cur->overlaps(**i)) {
unsigned reg = (*i)->reg;
- prt_.addPhysRegUse(reg);
+ prt_->addRegUse(reg);
updateSpillWeights(reg, (*i)->weight);
}
}
unsigned physReg = getFreePhysReg(cur);
- // if we find a free register, we are done: restore original
- // register tracker, assign this virtual to the free physical
- // register and add this interval to the active list.
+ // 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) {
- prt_ = backupPrt;
- assignVirt2PhysReg(cur->reg, 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");
- DEBUG(std::cerr << "\t\tassigning stack slot at interval "<< *cur << ":\n");
+ DEBUG(std::cerr << "\tassigning stack slot at interval "<< *cur << ":\n");
- float minWeight = std::numeric_limits<float>::max();
+ 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 (!prt_.isPhysRegReserved(reg) && minWeight > spillWeights_[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 the current has the minimum weight, we are done: restore
- // original register tracker and assign a stack slot to this
- // virtual register
- if (cur->weight < minWeight) {
- prt_ = backupPrt;
- 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);
+ if (added.empty())
+ return; // Early exit if all spills were folded.
+
+ // Merge added with unhandled. Note that we know that
+ // addIntervalsForSpills returns intervals sorted by their starting
+ // point.
+ for (unsigned i = 0, e = added.size(); i != e; ++i)
+ unhandled_.push(added[i]);
return;
}
+ // 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(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);
+ // we are going to spill minReg and all its aliases
toSpill[minReg] = true;
for (const unsigned* as = mri_->getAliasSet(minReg); *as; ++as)
toSpill[*as] = true;
- std::vector<unsigned> spilled;
- for (IntervalPtrs::iterator i = active_.begin();
- i != active_.end(); ) {
+ // the earliest start of a spilled interval indicates up to where
+ // in handled we need to roll back
+ unsigned earliestStart = cur->start();
+
+ // set of spilled vregs (used later to rollback properly)
+ std::set<unsigned> spilled;
+
+ // 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
+ for (IntervalPtrs::iterator
+ i = active_.begin(); i != active_.end(); ++i) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill[v2pMap_[reg]] &&
+ toSpill[vrm_->getPhys(reg)] &&
cur->overlaps(**i)) {
- spilled.push_back(v2pMap_[reg]);
- DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
- assignVirt2StackSlot(reg);
- i = active_.erase(i);
- }
- else {
- ++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(); ) {
+ for (IntervalPtrs::iterator
+ i = inactive_.begin(); i != inactive_.end(); ++i) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill[v2pMap_[reg]] &&
+ toSpill[vrm_->getPhys(reg)] &&
cur->overlaps(**i)) {
- DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
- assignVirt2StackSlot(reg);
- i = inactive_.erase(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 up to the earliaset start of a
+ // spilled live interval and undo each one, restoring the state of
+ // unhandled
+ while (!handled_.empty()) {
+ LiveInterval* 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();
+ // when undoing a live interval allocation we must know if it
+ // is active or inactive to properly update the PhysRegTracker
+ // and the VirtRegMap
+ 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(i);
+ }
+ else {
+ if (!spilled.count(i->reg))
+ unhandled_.push(i);
+ prt_->delRegUse(vrm_->getPhys(i->reg));
+ vrm_->clearVirt(i->reg);
+ }
+ }
+ else if ((it = find(inactive_.begin(), inactive_.end(), i)) != inactive_.end()) {
+ inactive_.erase(it);
+ if (MRegisterInfo::isPhysicalRegister(i->reg))
+ unhandled_.push(i);
+ else {
+ if (!spilled.count(i->reg))
+ unhandled_.push(i);
+ vrm_->clearVirt(i->reg);
+ }
}
else {
- ++i;
+ if (MRegisterInfo::isVirtualRegister(i->reg))
+ vrm_->clearVirt(i->reg);
+ unhandled_.push(i);
}
}
- physReg = getFreePhysReg(cur);
- assert(physReg && "no free physical register after spill?");
-
- prt_ = backupPrt;
- for (unsigned i = 0; i < spilled.size(); ++i)
- prt_.delPhysRegUse(spilled[i]);
+ // 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));
+ }
+ }
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
+ std::sort(added.begin(), added.end(), less_ptr<LiveInterval>());
+ // merge added with unhandled
+ for (unsigned i = 0, e = added.size(); i != e; ++i)
+ unhandled_.push(added[i]);
}
-unsigned RA::getFreePhysReg(IntervalPtrs::value_type cur)
+unsigned RA::getFreePhysReg(LiveInterval* 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 (prt_.isPhysRegAvail(reg)) {
- DEBUG(std::cerr << mri_->getName(reg) << '\n');
- return reg;
- }
- }
-
- DEBUG(std::cerr << "no free register\n");
- return 0;
-}
-
-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
- typedef std::reverse_iterator<TargetRegisterClass::iterator> TRCRevIter;
- for (TRCRevIter
- i(rc->allocation_order_end(*mf_)),
- e(rc->allocation_order_begin(*mf_)); i != e; ++i) {
- unsigned reg = *i;
- if (prt_.isReservedPhysRegAvail(reg)) {
- DEBUG(std::cerr << mri_->getName(reg) << '\n');
+ if (prt_->isRegAvail(reg))
return reg;
- }
}
-
- assert(0 && "no free temporary physical register?");
return 0;
}
-RA::Virt2PhysMap::iterator
-RA::assignVirt2PhysReg(unsigned virtReg, unsigned physReg)
-{
- bool inserted;
- Virt2PhysMap::iterator it;
- tie(it, inserted) = v2pMap_.insert(std::make_pair(virtReg, physReg));
- assert(inserted && "attempting to assign a virt->phys mapping to an "
- "already mapped register");
- prt_.addPhysRegUse(physReg);
- return it;
-}
-
-void RA::clearVirtReg(Virt2PhysMap::iterator it)
-{
- assert(it != v2pMap_.end() &&
- "attempting to clear a not allocated virtual register");
- unsigned physReg = it->second;
- prt_.delPhysRegUse(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
- Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
- if (it != v2pMap_.end()) {
- clearVirtReg(it);
- }
-}
-
-int RA::getStackSlot(unsigned virtReg)
-{
- 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(Virt2PhysMap::iterator it)
-{
- assert(it != v2pMap_.end() &&
- "attempt to spill a not allocated virtual register");
- unsigned virtReg = it->first;
- 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_,
- it->second, frameIndex, rc);
- clearVirtReg(it);
-}
-
-RA::Virt2PhysMap::iterator
-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);
- return assignVirt2PhysReg(virtReg, physReg);
-}
-
FunctionPass* llvm::createLinearScanRegisterAllocator() {
return new RA();
}
projects / oota-llvm.git / blobdiff