// 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 "llvm/Support/Debug.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/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_) {
- }
-
- 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);
- }
+ Statistic<double> efficiency
+ ("regalloc", "Ratio of intervals processed over total intervals");
+ Statistic<> NumBacktracks("regalloc", "Number of times we had to backtrack");
+
+ static unsigned numIterations = 0;
+ static unsigned numIntervals = 0;
+
+ struct RA : public MachineFunctionPass {
+ typedef std::pair<LiveInterval*, LiveInterval::iterator> IntervalPtr;
+ typedef std::vector<IntervalPtr> IntervalPtrs;
+ private:
+ MachineFunction* mf_;
+ const TargetMachine* tm_;
+ const MRegisterInfo* mri_;
+ LiveIntervals* li_;
+ bool *PhysRegsUsed;
+
+ /// handled_ - Intervals are added to the handled_ set in the order of their
+ /// start value. This is uses for backtracking.
+ std::vector<LiveInterval*> handled_;
+
+ /// fixed_ - Intervals that correspond to machine registers.
+ ///
+ IntervalPtrs fixed_;
+
+ /// active_ - Intervals that are currently being processed, and which have a
+ /// live range active for the current point.
+ IntervalPtrs active_;
+
+ /// inactive_ - Intervals that are currently being processed, but which have
+ /// a hold at the current point.
+ IntervalPtrs inactive_;
+
+ typedef std::priority_queue<LiveInterval*,
+ std::vector<LiveInterval*>,
+ greater_ptr<LiveInterval> > IntervalHeap;
+ IntervalHeap unhandled_;
+ std::auto_ptr<PhysRegTracker> prt_;
+ std::auto_ptr<VirtRegMap> vrm_;
+ std::auto_ptr<Spiller> spiller_;
+
+ public:
+ virtual const char* getPassName() const {
+ return "Linear Scan Register Allocator";
+ }
- bool isReservedPhysRegAvail(unsigned physReg) const {
- return regUse_[physReg] == 0 && isPhysRegReserved(physReg);
- }
- };
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LiveIntervals>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+ }
- 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_;
+ /// runOnMachineFunction - register allocate the whole function
+ bool runOnMachineFunction(MachineFunction&);
- PhysRegTracker prt_;
+ private:
+ /// linearScan - the linear scan algorithm
+ void linearScan();
- typedef std::map<unsigned, unsigned> Virt2PhysMap;
- Virt2PhysMap v2pMap_;
+ /// initIntervalSets - initialize the interval sets.
+ ///
+ void initIntervalSets();
- typedef std::map<unsigned, int> Virt2StackSlotMap;
- Virt2StackSlotMap v2ssMap_;
+ /// processActiveIntervals - expire old intervals and move non-overlapping
+ /// ones to the inactive list.
+ void processActiveIntervals(unsigned CurPoint);
- int instrAdded_;
+ /// processInactiveIntervals - expire old intervals and move overlapping
+ /// ones to the active list.
+ void processInactiveIntervals(unsigned CurPoint);
- public:
- RA()
- : prt_(NULL) {
+ /// assignRegOrStackSlotAtInterval - assign a register if one
+ /// is available, or spill.
+ void assignRegOrStackSlotAtInterval(LiveInterval* cur);
- }
+ ///
+ /// register handling helpers
+ ///
- virtual const char* getPassName() const {
- return "Linear Scan Register Allocator";
- }
+ /// getFreePhysReg - return a free physical register for this virtual
+ /// register interval if we have one, otherwise return 0.
+ unsigned getFreePhysReg(LiveInterval* cur);
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<LiveVariables>();
- AU.addRequired<LiveIntervals>();
- MachineFunctionPass::getAnalysisUsage(AU);
- }
-
- /// runOnMachineFunction - register allocate the whole function
- bool runOnMachineFunction(MachineFunction&);
-
- void releaseMemory();
-
- private:
- /// initIntervalSets - initializa the four interval sets:
- /// unhandled, fixed, active and inactive
- void initIntervalSets(const LiveIntervals::Intervals& li);
-
- /// processActiveIntervals - expire old intervals and move
- /// non-overlapping ones to the incative list
- void processActiveIntervals(IntervalPtrs::value_type cur);
-
- /// processInactiveIntervals - expire old intervals and move
- /// 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,
- const PhysRegTracker& backupPtr);
-
- ///
- /// 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
- 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 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';
- }
+ /// assignVirt2StackSlot - assigns this virtual register to a
+ /// 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 << " -> ";
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg)) {
- Virt2PhysMap::const_iterator it = v2pMap_.find(reg);
- reg = (it == v2pMap_.end() ? 0 : it->second);
- }
- std::cerr << mri_->getName(reg) << '\n';
- }
+ 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" << *i->first << " -> ";
+ unsigned reg = i->first->reg;
+ if (MRegisterInfo::isVirtualRegister(reg)) {
+ reg = vrm_->getPhys(reg);
}
-
-// 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();
- active_.clear();
- inactive_.clear();
- fixed_.clear();
-
+ std::cerr << mri_->getName(reg) << '\n';
+ }
+ }
+ };
}
bool RA::runOnMachineFunction(MachineFunction &fn) {
- mf_ = &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 */
-
- // linear scan algorithm
- DEBUG(std::cerr << "Machine Function\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()));
-
- while (!unhandled_.empty() || !fixed_.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());
- }
+ mf_ = &fn;
+ tm_ = &fn.getTarget();
+ mri_ = tm_->getRegisterInfo();
+ li_ = &getAnalysis<LiveIntervals>();
- DEBUG(std::cerr << *cur << '\n');
+ PhysRegsUsed = new bool[mri_->getNumRegs()];
+ std::fill(PhysRegsUsed, PhysRegsUsed+mri_->getNumRegs(), false);
+ fn.setUsedPhysRegs(PhysRegsUsed);
- processActiveIntervals(cur);
- processInactiveIntervals(cur);
+ if (!prt_.get()) prt_.reset(new PhysRegTracker(*mri_));
+ vrm_.reset(new VirtRegMap(*mf_));
+ if (!spiller_.get()) spiller_.reset(createSpiller());
- // if this register is fixed we are done
- if (MRegisterInfo::isPhysicalRegister(cur->reg)) {
- prt_.addPhysRegUse(cur->reg);
- active_.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 {
- PhysRegTracker backupPrt = prt_;
-
- // 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)) {
- prt_.addPhysRegUse(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))
- prt_.addPhysRegUse((*i)->reg);
- }
-
- DEBUG(std::cerr << "\tallocating current interval:\n");
-
- unsigned physReg = getFreePhysReg(cur);
- if (!physReg) {
- assignStackSlotAtInterval(cur, backupPrt);
- }
- else {
- prt_ = backupPrt;
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
- }
- }
+ initIntervalSets();
- DEBUG(printIntervals("\tactive", active_.begin(), active_.end()));
- DEBUG(printIntervals("\tinactive", inactive_.begin(), inactive_.end())); }
+ linearScan();
- // 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];
- }
- prt_.delPhysRegUse(reg);
- }
+ // Rewrite spill code and update the PhysRegsUsed set.
+ spiller_->runOnMachineFunction(*mf_, *vrm_);
- typedef LiveIntervals::Reg2RegMap Reg2RegMap;
- const Reg2RegMap& r2rMap = li_->getJoinedRegMap();
+ vrm_.reset(); // Free the VirtRegMap
- 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!");
+ while (!unhandled_.empty()) unhandled_.pop();
+ fixed_.clear();
+ active_.clear();
+ inactive_.clear();
+ handled_.clear();
- 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(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->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]))) {
- delete *currentInstr_;
- currentInstr_ = currentMbb_->erase(currentInstr_);
- ++numPeep;
- DEBUG(std::cerr << "\t\tdeleting instruction\n");
- continue;
- }
-
- typedef std::vector<unsigned> 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.isVirtualRegister() && op.isUse()) {
- 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);
- // we will clear uses that are not also defs
- // before we allocate registers the defs
- if (op.isDef())
- toSpill.push_back(virtReg);
- else
- toClear.push_back(virtReg);
- }
- (*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.isVirtualRegister()) {
- assert(!op.isUse() && "we should not have uses here!");
- 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);
- assignVirt2PhysReg(virtReg, physReg);
- // need to spill this after we are done with
- // this instruction
- toSpill.push_back(virtReg);
- }
- (*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));
- }
- }
-
- return true;
+ return true;
}
-void RA::initIntervalSets(const LiveIntervals::Intervals& li)
+/// initIntervalSets - initialize the interval sets.
+///
+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);
- }
+ assert(unhandled_.empty() && fixed_.empty() &&
+ active_.empty() && inactive_.empty() &&
+ "interval sets should be empty on initialization");
+
+ for (LiveIntervals::iterator i = li_->begin(), e = li_->end(); i != e; ++i) {
+ if (MRegisterInfo::isPhysicalRegister(i->second.reg)) {
+ PhysRegsUsed[i->second.reg] = true;
+ fixed_.push_back(std::make_pair(&i->second, i->second.begin()));
+ } else
+ unhandled_.push(&i->second);
+ }
}
-void RA::processActiveIntervals(IntervalPtrs::value_type cur)
+void RA::linearScan()
{
- DEBUG(std::cerr << "\tprocessing active intervals:\n");
- for (IntervalPtrs::iterator i = active_.begin(); i != active_.end();) {
- 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);
- // 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];
- }
- prt_.delPhysRegUse(reg);
- // add to inactive
- inactive_.push_back(*i);
- // remove from active
- i = active_.erase(i);
- }
- else {
- ++i;
- }
- }
+ // linear scan algorithm
+ DEBUG(std::cerr << "********** LINEAR SCAN **********\n");
+ DEBUG(std::cerr << "********** Function: "
+ << mf_->getFunction()->getName() << '\n');
+
+ // 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()) {
+ // pick the interval with the earliest start point
+ LiveInterval* cur = unhandled_.top();
+ unhandled_.pop();
+ ++numIterations;
+ DEBUG(std::cerr << "\n*** CURRENT ***: " << *cur << '\n');
+
+ processActiveIntervals(cur->beginNumber());
+ processInactiveIntervals(cur->beginNumber());
+
+ assert(MRegisterInfo::isVirtualRegister(cur->reg) &&
+ "Can only allocate virtual registers!");
+
+ // Allocating a virtual register. try to find a free
+ // physical register or spill an interval (possibly this one) in order to
+ // assign it one.
+ assignRegOrStackSlotAtInterval(cur);
+
+ 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::reverse_iterator
+ i = active_.rbegin(); i != active_.rend(); ) {
+ unsigned reg = i->first->reg;
+ DEBUG(std::cerr << "\tinterval " << *i->first << " expired\n");
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
+ i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+ }
+
+ // expire any remaining inactive intervals
+ for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend(); ) {
+ DEBUG(std::cerr << "\tinterval " << *i->first << " expired\n");
+ i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+ }
+
+ DEBUG(std::cerr << *vrm_);
}
-void RA::processInactiveIntervals(IntervalPtrs::value_type cur)
+/// processActiveIntervals - expire old intervals and move non-overlapping ones
+/// to the inactive list.
+void RA::processActiveIntervals(unsigned CurPoint)
{
- DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
- for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end();) {
- unsigned reg = (*i)->reg;
-
- // remove expired intervals
- if ((*i)->expiredAt(cur->start())) {
- DEBUG(std::cerr << "\t\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];
- }
- prt_.addPhysRegUse(reg);
- // add to active
- active_.push_back(*i);
- // remove from inactive
- i = inactive_.erase(i);
- }
- else {
- ++i;
- }
+ DEBUG(std::cerr << "\tprocessing active intervals:\n");
+
+ for (unsigned i = 0, e = active_.size(); i != e; ++i) {
+ LiveInterval *Interval = active_[i].first;
+ LiveInterval::iterator IntervalPos = active_[i].second;
+ unsigned reg = Interval->reg;
+
+ IntervalPos = Interval->advanceTo(IntervalPos, CurPoint);
+
+ if (IntervalPos == Interval->end()) { // Remove expired intervals.
+ DEBUG(std::cerr << "\t\tinterval " << *Interval << " expired\n");
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
+
+ // Pop off the end of the list.
+ active_[i] = active_.back();
+ active_.pop_back();
+ --i; --e;
+
+ } else if (IntervalPos->start > CurPoint) {
+ // Move inactive intervals to inactive list.
+ DEBUG(std::cerr << "\t\tinterval " << *Interval << " inactive\n");
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ prt_->delRegUse(reg);
+ // add to inactive.
+ inactive_.push_back(std::make_pair(Interval, IntervalPos));
+
+ // Pop off the end of the list.
+ active_[i] = active_.back();
+ active_.pop_back();
+ --i; --e;
+ } else {
+ // Otherwise, just update the iterator position.
+ active_[i].second = IntervalPos;
}
+ }
}
-namespace {
- template <typename T>
- void updateWeight(std::vector<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;
+/// processInactiveIntervals - expire old intervals and move overlapping
+/// ones to the active list.
+void RA::processInactiveIntervals(unsigned CurPoint)
+{
+ DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
+
+ for (unsigned i = 0, e = inactive_.size(); i != e; ++i) {
+ LiveInterval *Interval = inactive_[i].first;
+ LiveInterval::iterator IntervalPos = inactive_[i].second;
+ unsigned reg = Interval->reg;
+
+ IntervalPos = Interval->advanceTo(IntervalPos, CurPoint);
+
+ if (IntervalPos == Interval->end()) { // remove expired intervals.
+ DEBUG(std::cerr << "\t\tinterval " << *Interval << " expired\n");
+
+ // Pop off the end of the list.
+ inactive_[i] = inactive_.back();
+ inactive_.pop_back();
+ --i; --e;
+ } else if (IntervalPos->start <= CurPoint) {
+ // move re-activated intervals in active list
+ DEBUG(std::cerr << "\t\tinterval " << *Interval << " active\n");
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ prt_->addRegUse(reg);
+ // add to active
+ active_.push_back(std::make_pair(Interval, IntervalPos));
+
+ // Pop off the end of the list.
+ inactive_[i] = inactive_.back();
+ inactive_.pop_back();
+ --i; --e;
+ } else {
+ // Otherwise, just update the iterator position.
+ inactive_[i].second = IntervalPos;
}
+ }
}
-void RA::assignStackSlotAtInterval(IntervalPtrs::value_type cur,
- const PhysRegTracker& backupPrt)
-{
- DEBUG(std::cerr << "\t\tassigning stack slot at interval "
- << *cur << ":\n");
-
- std::vector<float> regWeight(mri_->getNumRegs(), 0.0);
+/// updateSpillWeights - updates the spill weights of the specifed physical
+/// register and its weight.
+static void updateSpillWeights(std::vector<float> &Weights,
+ unsigned reg, float weight,
+ const MRegisterInfo *MRI) {
+ Weights[reg] += weight;
+ for (const unsigned* as = MRI->getAliasSet(reg); *as; ++as)
+ Weights[*as] += weight;
+}
- // for each interval in active
- 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);
- }
+static RA::IntervalPtrs::iterator FindIntervalInVector(RA::IntervalPtrs &IP,
+ LiveInterval *LI) {
+ for (RA::IntervalPtrs::iterator I = IP.begin(), E = IP.end(); I != E; ++I)
+ if (I->first == LI) return I;
+ return IP.end();
+}
- // for each interval in inactive that overlaps
- for (IntervalPtrs::const_iterator i = inactive_.begin(),
- e = inactive_.end(); i != e; ++i) {
- if (!cur->overlaps(**i))
- continue;
+static void RevertVectorIteratorsTo(RA::IntervalPtrs &V, unsigned Point) {
+ for (unsigned i = 0, e = V.size(); i != e; ++i) {
+ RA::IntervalPtr &IP = V[i];
+ LiveInterval::iterator I = std::upper_bound(IP.first->begin(),
+ IP.second, Point);
+ if (I != IP.first->begin()) --I;
+ IP.second = 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);
- }
- // 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);
+/// assignRegOrStackSlotAtInterval - assign a register if one is available, or
+/// spill.
+void RA::assignRegOrStackSlotAtInterval(LiveInterval* cur)
+{
+ DEBUG(std::cerr << "\tallocating current interval: ");
+
+ PhysRegTracker backupPrt = *prt_;
+
+ std::vector<float> SpillWeights;
+ SpillWeights.assign(mri_->getNumRegs(), 0.0);
+
+ unsigned StartPosition = cur->beginNumber();
+
+ // for each interval in active, update spill weights.
+ for (IntervalPtrs::const_iterator i = active_.begin(), e = active_.end();
+ i != e; ++i) {
+ unsigned reg = i->first->reg;
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ updateSpillWeights(SpillWeights, reg, i->first->weight, mri_);
+ }
+
+ // 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->overlapsFrom(*i->first, i->second-1)) {
+ unsigned reg = i->first->reg;
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ prt_->addRegUse(reg);
+ updateSpillWeights(SpillWeights, reg, i->first->weight, mri_);
}
-
- float minWeight = std::numeric_limits<float>::max();
- 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 > regWeight[reg]) {
- minWeight = regWeight[reg];
- minReg = reg;
- }
+ }
+
+ // For every interval in fixed we overlap with, mark the register as not free
+ // and update spill weights.
+ for (unsigned i = 0, e = fixed_.size(); i != e; ++i) {
+ IntervalPtr &IP = fixed_[i];
+ LiveInterval *I = IP.first;
+ if (I->endNumber() > StartPosition) {
+ LiveInterval::iterator II = I->advanceTo(IP.second, StartPosition);
+ IP.second = II;
+ if (II != I->begin() && II->start > StartPosition)
+ --II;
+ if (cur->overlapsFrom(*I, II)) {
+ unsigned reg = I->reg;
+ prt_->addRegUse(reg);
+ updateSpillWeights(SpillWeights, reg, I->weight, mri_);
+ }
}
- DEBUG(std::cerr << "\t\t\tregister with min weight: "
- << mri_->getName(minReg) << " (" << minWeight << ")\n");
-
- if (cur->weight < minWeight) {
- prt_ = backupPrt;
- DEBUG(std::cerr << "\t\t\t\tspilling: " << *cur << '\n');
- assignVirt2StackSlot(cur->reg);
+ }
+
+ 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(std::make_pair(cur, cur->begin()));
+ handled_.push_back(cur);
+ return;
+ }
+ DEBUG(std::cerr << "no free registers\n");
+
+ DEBUG(std::cerr << "\tassigning stack slot at interval "<< *cur << ":\n");
+
+ float minWeight = float(HUGE_VAL);
+ unsigned minReg = 0;
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
+ for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_),
+ e = rc->allocation_order_end(*mf_); i != e; ++i) {
+ unsigned reg = *i;
+ if (minWeight > SpillWeights[reg]) {
+ minWeight = SpillWeights[reg];
+ minReg = reg;
}
- else {
- std::vector<bool> toSpill(mri_->getNumRegs(), false);
- 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(); ) {
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill[v2pMap_[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;
- }
- }
- for (IntervalPtrs::iterator i = inactive_.begin();
- i != inactive_.end(); ) {
- unsigned reg = (*i)->reg;
- if (MRegisterInfo::isVirtualRegister(reg) &&
- toSpill[v2pMap_[reg]] &&
- cur->overlaps(**i)) {
- DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
- assignVirt2StackSlot(reg);
- i = inactive_.erase(i);
- }
- else {
- ++i;
- }
- }
-
- unsigned 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]);
-
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
+ }
+ DEBUG(std::cerr << "\t\tregister with min weight: "
+ << mri_->getName(minReg) << " (" << minWeight << ")\n");
+
+ // 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;
+ }
+
+ ++NumBacktracks;
+
+ // 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;
+
+ // the earliest start of a spilled interval indicates up to where
+ // in handled we need to roll back
+ unsigned earliestStart = cur->beginNumber();
+
+ // 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->first->reg;
+ if (//MRegisterInfo::isVirtualRegister(reg) &&
+ toSpill[vrm_->getPhys(reg)] &&
+ cur->overlapsFrom(*i->first, i->second)) {
+ DEBUG(std::cerr << "\t\t\tspilling(a): " << *i->first << '\n');
+ earliestStart = std::min(earliestStart, i->first->beginNumber());
+ int slot = vrm_->assignVirt2StackSlot(i->first->reg);
+ std::vector<LiveInterval*> newIs =
+ li_->addIntervalsForSpills(*i->first, *vrm_, slot);
+ std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ spilled.insert(reg);
}
-}
-
-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 (prt_.isPhysRegAvail(reg)) {
- DEBUG(std::cerr << mri_->getName(reg) << '\n');
- return reg;
- }
+ }
+ for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end(); ++i){
+ unsigned reg = i->first->reg;
+ if (//MRegisterInfo::isVirtualRegister(reg) &&
+ toSpill[vrm_->getPhys(reg)] &&
+ cur->overlapsFrom(*i->first, i->second-1)) {
+ DEBUG(std::cerr << "\t\t\tspilling(i): " << *i->first << '\n');
+ earliestStart = std::min(earliestStart, i->first->beginNumber());
+ int slot = vrm_->assignVirt2StackSlot(reg);
+ std::vector<LiveInterval*> newIs =
+ li_->addIntervalsForSpills(*i->first, *vrm_, slot);
+ std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ spilled.insert(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');
- return reg;
- }
+ }
+
+ DEBUG(std::cerr << "\t\trolling back to: " << earliestStart << '\n');
+
+ // Scan handled in reverse order up to the earliest 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->beginNumber() < 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 = FindIntervalInVector(active_, i)) != active_.end()) {
+ active_.erase(it);
+ if (MRegisterInfo::isPhysicalRegister(i->reg)) {
+ assert(0 && "daksjlfd");
+ 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 = FindIntervalInVector(inactive_, i)) != inactive_.end()) {
+ inactive_.erase(it);
+ if (MRegisterInfo::isPhysicalRegister(i->reg)) {
+ assert(0 && "daksjlfd");
+ unhandled_.push(i);
+ } else {
+ if (!spilled.count(i->reg))
+ unhandled_.push(i);
+ vrm_->clearVirt(i->reg);
+ }
+ } else {
+ assert(MRegisterInfo::isVirtualRegister(i->reg) &&
+ "Can only allocate virtual registers!");
+ vrm_->clearVirt(i->reg);
+ unhandled_.push(i);
}
-
- 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");
- prt_.addPhysRegUse(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;
- 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
- if (v2pMap_.count(virtReg)) {
- clearVirtReg(virtReg);
+ }
+
+ // Rewind the iterators in the active, inactive, and fixed lists back to the
+ // point we reverted to.
+ RevertVectorIteratorsTo(active_, earliestStart);
+ RevertVectorIteratorsTo(inactive_, earliestStart);
+ RevertVectorIteratorsTo(fixed_, earliestStart);
+
+ // 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)
+ for (unsigned i = 0, e = handled_.size(); i != e; ++i) {
+ LiveInterval *HI = handled_[i];
+ if (!HI->expiredAt(earliestStart) &&
+ HI->expiredAt(cur->beginNumber())) {
+ DEBUG(std::cerr << "\t\t\tundo changes for: " << *HI << '\n');
+ active_.push_back(std::make_pair(HI, HI->begin()));
+ if (MRegisterInfo::isPhysicalRegister(HI->reg)) {
+ assert(0 &&"sdflkajsdf");
+ prt_->addRegUse(HI->reg);
+ } else
+ prt_->addRegUse(vrm_->getPhys(HI->reg));
}
-}
-
-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(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);
+ // merge added with unhandled
+ for (unsigned i = 0, e = added.size(); i != e; ++i)
+ unhandled_.push(added[i]);
}
-void RA::loadVirt2PhysReg(unsigned virtReg, unsigned physReg)
+/// getFreePhysReg - return a free physical register for this virtual register
+/// interval if we have one, otherwise return 0.
+unsigned RA::getFreePhysReg(LiveInterval* cur)
{
- 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);
+ std::vector<unsigned> inactiveCounts(mri_->getNumRegs(), 0);
+ for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
+ i != e; ++i) {
+ unsigned reg = i->first->reg;
+ assert(MRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+ reg = vrm_->getPhys(reg);
+ ++inactiveCounts[reg];
+ }
+
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
+
+ unsigned freeReg = 0;
+ for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_),
+ e = rc->allocation_order_end(*mf_); i != e; ++i) {
+ unsigned reg = *i;
+ if (prt_->isRegAvail(reg) &&
+ (!freeReg || inactiveCounts[freeReg] < inactiveCounts[reg]))
+ freeReg = reg;
+ }
+ return freeReg;
}
FunctionPass* llvm::createLinearScanRegisterAllocator() {
- return new RA();
+ return new RA();
}
projects / oota-llvm.git / blobdiff