//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regalloc"
-#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "PhysRegTracker.h"
#include "VirtRegMap.h"
+#include "VirtRegRewriter.h"
+#include "Spiller.h"
#include "llvm/Function.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
-#include "llvm/CodeGen/SSARegMap.h"
-#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/CodeGen/RegisterCoalescer.h"
+#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/ADT/EquivalenceClasses.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include <cmath>
using namespace llvm;
-namespace {
+STATISTIC(NumIters , "Number of iterations performed");
+STATISTIC(NumBacktracks, "Number of times we had to backtrack");
+STATISTIC(NumCoalesce, "Number of copies coalesced");
+STATISTIC(NumDowngrade, "Number of registers downgraded");
+
+static cl::opt<bool>
+NewHeuristic("new-spilling-heuristic",
+ cl::desc("Use new spilling heuristic"),
+ cl::init(false), cl::Hidden);
- static Statistic NumIters
- ("regalloc", "Number of iterations performed");
- static Statistic NumBacktracks
- ("regalloc", "Number of times we had to backtrack");
+static cl::opt<bool>
+PreSplitIntervals("pre-alloc-split",
+ cl::desc("Pre-register allocation live interval splitting"),
+ cl::init(false), cl::Hidden);
- static RegisterRegAlloc
- linearscanRegAlloc("linearscan", " linear scan register allocator",
- createLinearScanRegisterAllocator);
+static cl::opt<bool>
+NewSpillFramework("new-spill-framework",
+ cl::desc("New spilling framework"),
+ cl::init(false), cl::Hidden);
- static unsigned numIterations = 0;
- static unsigned numIntervals = 0;
+static RegisterRegAlloc
+linearscanRegAlloc("linearscan", "linear scan register allocator",
+ createLinearScanRegisterAllocator);
+
+namespace {
+ struct VISIBILITY_HIDDEN RALinScan : public MachineFunctionPass {
+ static char ID;
+ RALinScan() : MachineFunctionPass(&ID) {}
- struct VISIBILITY_HIDDEN RA : public MachineFunctionPass {
typedef std::pair<LiveInterval*, LiveInterval::iterator> IntervalPtr;
- typedef std::vector<IntervalPtr> IntervalPtrs;
+ typedef SmallVector<IntervalPtr, 32> IntervalPtrs;
private:
/// RelatedRegClasses - This structure is built the first time a function is
/// compiled, and keeps track of which register classes have registers that
/// belong to multiple classes or have aliases that are in other classes.
EquivalenceClasses<const TargetRegisterClass*> RelatedRegClasses;
- std::map<unsigned, const TargetRegisterClass*> OneClassForEachPhysReg;
+ DenseMap<unsigned, const TargetRegisterClass*> OneClassForEachPhysReg;
+
+ // NextReloadMap - For each register in the map, it maps to the another
+ // register which is defined by a reload from the same stack slot and
+ // both reloads are in the same basic block.
+ DenseMap<unsigned, unsigned> NextReloadMap;
+
+ // DowngradedRegs - A set of registers which are being "downgraded", i.e.
+ // un-favored for allocation.
+ SmallSet<unsigned, 8> DowngradedRegs;
+
+ // DowngradeMap - A map from virtual registers to physical registers being
+ // downgraded for the virtual registers.
+ DenseMap<unsigned, unsigned> DowngradeMap;
MachineFunction* mf_;
+ MachineRegisterInfo* mri_;
const TargetMachine* tm_;
- const MRegisterInfo* mri_;
+ const TargetRegisterInfo* tri_;
+ const TargetInstrInfo* tii_;
+ BitVector allocatableRegs_;
LiveIntervals* li_;
- bool *PhysRegsUsed;
+ LiveStacks* ls_;
+ const MachineLoopInfo *loopInfo;
/// handled_ - Intervals are added to the handled_ set in the order of their
/// start value. This is uses for backtracking.
IntervalPtrs inactive_;
typedef std::priority_queue<LiveInterval*,
- std::vector<LiveInterval*>,
+ SmallVector<LiveInterval*, 64>,
greater_ptr<LiveInterval> > IntervalHeap;
IntervalHeap unhandled_;
- std::auto_ptr<PhysRegTracker> prt_;
- std::auto_ptr<VirtRegMap> vrm_;
+
+ /// regUse_ - Tracks register usage.
+ SmallVector<unsigned, 32> regUse_;
+ SmallVector<unsigned, 32> regUseBackUp_;
+
+ /// vrm_ - Tracks register assignments.
+ VirtRegMap* vrm_;
+
+ std::auto_ptr<VirtRegRewriter> rewriter_;
+
std::auto_ptr<Spiller> spiller_;
public:
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<LiveIntervals>();
+ if (StrongPHIElim)
+ AU.addRequiredID(StrongPHIEliminationID);
+ // Make sure PassManager knows which analyses to make available
+ // to coalescing and which analyses coalescing invalidates.
+ AU.addRequiredTransitive<RegisterCoalescer>();
+ if (PreSplitIntervals)
+ AU.addRequiredID(PreAllocSplittingID);
+ AU.addRequired<LiveStacks>();
+ AU.addPreserved<LiveStacks>();
+ AU.addRequired<MachineLoopInfo>();
+ AU.addPreserved<MachineLoopInfo>();
+ AU.addRequired<VirtRegMap>();
+ AU.addPreserved<VirtRegMap>();
+ AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
/// ones to the active list.
void processInactiveIntervals(unsigned CurPoint);
+ /// hasNextReloadInterval - Return the next liveinterval that's being
+ /// defined by a reload from the same SS as the specified one.
+ LiveInterval *hasNextReloadInterval(LiveInterval *cur);
+
+ /// DowngradeRegister - Downgrade a register for allocation.
+ void DowngradeRegister(LiveInterval *li, unsigned Reg);
+
+ /// UpgradeRegister - Upgrade a register for allocation.
+ void UpgradeRegister(unsigned Reg);
+
/// assignRegOrStackSlotAtInterval - assign a register if one
/// is available, or spill.
void assignRegOrStackSlotAtInterval(LiveInterval* cur);
+ void updateSpillWeights(std::vector<float> &Weights,
+ unsigned reg, float weight,
+ const TargetRegisterClass *RC);
+
+ /// findIntervalsToSpill - Determine the intervals to spill for the
+ /// specified interval. It's passed the physical registers whose spill
+ /// weight is the lowest among all the registers whose live intervals
+ /// conflict with the interval.
+ void findIntervalsToSpill(LiveInterval *cur,
+ std::vector<std::pair<unsigned,float> > &Candidates,
+ unsigned NumCands,
+ SmallVector<LiveInterval*, 8> &SpillIntervals);
+
+ /// attemptTrivialCoalescing - If a simple interval is defined by a copy,
+ /// try allocate the definition the same register as the source register
+ /// if the register is not defined during live time of the interval. This
+ /// eliminate a copy. This is used to coalesce copies which were not
+ /// coalesced away before allocation either due to dest and src being in
+ /// different register classes or because the coalescer was overly
+ /// conservative.
+ unsigned attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg);
+
+ ///
+ /// Register usage / availability tracking helpers.
+ ///
+
+ void initRegUses() {
+ regUse_.resize(tri_->getNumRegs(), 0);
+ regUseBackUp_.resize(tri_->getNumRegs(), 0);
+ }
+
+ void finalizeRegUses() {
+#ifndef NDEBUG
+ // Verify all the registers are "freed".
+ bool Error = false;
+ for (unsigned i = 0, e = tri_->getNumRegs(); i != e; ++i) {
+ if (regUse_[i] != 0) {
+ cerr << tri_->getName(i) << " is still in use!\n";
+ Error = true;
+ }
+ }
+ if (Error)
+ abort();
+#endif
+ regUse_.clear();
+ regUseBackUp_.clear();
+ }
+
+ void addRegUse(unsigned physReg) {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ ++regUse_[physReg];
+ for (const unsigned* as = tri_->getAliasSet(physReg); *as; ++as)
+ ++regUse_[*as];
+ }
+
+ void delRegUse(unsigned physReg) {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ assert(regUse_[physReg] != 0);
+ --regUse_[physReg];
+ for (const unsigned* as = tri_->getAliasSet(physReg); *as; ++as) {
+ assert(regUse_[*as] != 0);
+ --regUse_[*as];
+ }
+ }
+
+ bool isRegAvail(unsigned physReg) const {
+ assert(TargetRegisterInfo::isPhysicalRegister(physReg) &&
+ "should be physical register!");
+ return regUse_[physReg] == 0;
+ }
+
+ void backUpRegUses() {
+ regUseBackUp_ = regUse_;
+ }
+
+ void restoreRegUses() {
+ regUse_ = regUseBackUp_;
+ }
+
///
- /// register handling helpers
+ /// Register handling helpers.
///
/// getFreePhysReg - return a free physical register for this virtual
/// register interval if we have one, otherwise return 0.
unsigned getFreePhysReg(LiveInterval* cur);
+ unsigned getFreePhysReg(const TargetRegisterClass *RC,
+ unsigned MaxInactiveCount,
+ SmallVector<unsigned, 256> &inactiveCounts,
+ bool SkipDGRegs);
/// assignVirt2StackSlot - assigns this virtual register to a
/// stack slot. returns the stack slot
for (; i != e; ++i) {
DOUT << "\t" << *i->first << " -> ";
unsigned reg = i->first->reg;
- if (MRegisterInfo::isVirtualRegister(reg)) {
+ if (TargetRegisterInfo::isVirtualRegister(reg)) {
reg = vrm_->getPhys(reg);
}
- DOUT << mri_->getName(reg) << '\n';
+ DOUT << tri_->getName(reg) << '\n';
}
}
};
+ char RALinScan::ID = 0;
}
-void RA::ComputeRelatedRegClasses() {
- const MRegisterInfo &MRI = *mri_;
-
+static RegisterPass<RALinScan>
+X("linearscan-regalloc", "Linear Scan Register Allocator");
+
+void RALinScan::ComputeRelatedRegClasses() {
// First pass, add all reg classes to the union, and determine at least one
// reg class that each register is in.
bool HasAliases = false;
- for (MRegisterInfo::regclass_iterator RCI = MRI.regclass_begin(),
- E = MRI.regclass_end(); RCI != E; ++RCI) {
+ for (TargetRegisterInfo::regclass_iterator RCI = tri_->regclass_begin(),
+ E = tri_->regclass_end(); RCI != E; ++RCI) {
RelatedRegClasses.insert(*RCI);
for (TargetRegisterClass::iterator I = (*RCI)->begin(), E = (*RCI)->end();
I != E; ++I) {
- HasAliases = HasAliases || *MRI.getAliasSet(*I) != 0;
+ HasAliases = HasAliases || *tri_->getAliasSet(*I) != 0;
const TargetRegisterClass *&PRC = OneClassForEachPhysReg[*I];
if (PRC) {
// belongs to, add info about aliases. We don't need to do this for targets
// without register aliases.
if (HasAliases)
- for (std::map<unsigned, const TargetRegisterClass*>::iterator
+ for (DenseMap<unsigned, const TargetRegisterClass*>::iterator
I = OneClassForEachPhysReg.begin(), E = OneClassForEachPhysReg.end();
I != E; ++I)
- for (const unsigned *AS = MRI.getAliasSet(I->first); *AS; ++AS)
+ for (const unsigned *AS = tri_->getAliasSet(I->first); *AS; ++AS)
RelatedRegClasses.unionSets(I->second, OneClassForEachPhysReg[*AS]);
}
-bool RA::runOnMachineFunction(MachineFunction &fn) {
+/// attemptTrivialCoalescing - If a simple interval is defined by a copy,
+/// try allocate the definition the same register as the source register
+/// if the register is not defined during live time of the interval. This
+/// eliminate a copy. This is used to coalesce copies which were not
+/// coalesced away before allocation either due to dest and src being in
+/// different register classes or because the coalescer was overly
+/// conservative.
+unsigned RALinScan::attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg) {
+ if ((cur.preference && cur.preference == Reg) || !cur.containsOneValue())
+ return Reg;
+
+ VNInfo *vni = cur.begin()->valno;
+ if (!vni->def || vni->def == ~1U || vni->def == ~0U)
+ return Reg;
+ MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg, PhysReg;
+ if (!CopyMI ||
+ !tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubReg, DstSubReg))
+ return Reg;
+ PhysReg = SrcReg;
+ if (TargetRegisterInfo::isVirtualRegister(SrcReg)) {
+ if (!vrm_->isAssignedReg(SrcReg))
+ return Reg;
+ PhysReg = vrm_->getPhys(SrcReg);
+ }
+ if (Reg == PhysReg)
+ return Reg;
+
+ const TargetRegisterClass *RC = mri_->getRegClass(cur.reg);
+ if (!RC->contains(PhysReg))
+ return Reg;
+
+ // Try to coalesce.
+ if (!li_->conflictsWithPhysRegDef(cur, *vrm_, PhysReg)) {
+ DOUT << "Coalescing: " << cur << " -> " << tri_->getName(PhysReg)
+ << '\n';
+ vrm_->clearVirt(cur.reg);
+ vrm_->assignVirt2Phys(cur.reg, PhysReg);
+
+ // Remove unnecessary kills since a copy does not clobber the register.
+ if (li_->hasInterval(SrcReg)) {
+ LiveInterval &SrcLI = li_->getInterval(SrcReg);
+ for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(cur.reg),
+ E = mri_->reg_end(); I != E; ++I) {
+ MachineOperand &O = I.getOperand();
+ if (!O.isUse() || !O.isKill())
+ continue;
+ MachineInstr *MI = &*I;
+ if (SrcLI.liveAt(li_->getDefIndex(li_->getInstructionIndex(MI))))
+ O.setIsKill(false);
+ }
+ }
+
+ ++NumCoalesce;
+ return SrcReg;
+ }
+
+ return Reg;
+}
+
+bool RALinScan::runOnMachineFunction(MachineFunction &fn) {
mf_ = &fn;
+ mri_ = &fn.getRegInfo();
tm_ = &fn.getTarget();
- mri_ = tm_->getRegisterInfo();
+ tri_ = tm_->getRegisterInfo();
+ tii_ = tm_->getInstrInfo();
+ allocatableRegs_ = tri_->getAllocatableSet(fn);
li_ = &getAnalysis<LiveIntervals>();
+ ls_ = &getAnalysis<LiveStacks>();
+ loopInfo = &getAnalysis<MachineLoopInfo>();
+
+ // We don't run the coalescer here because we have no reason to
+ // interact with it. If the coalescer requires interaction, it
+ // won't do anything. If it doesn't require interaction, we assume
+ // it was run as a separate pass.
// If this is the first function compiled, compute the related reg classes.
if (RelatedRegClasses.empty())
ComputeRelatedRegClasses();
-
- PhysRegsUsed = new bool[mri_->getNumRegs()];
- std::fill(PhysRegsUsed, PhysRegsUsed+mri_->getNumRegs(), false);
- fn.setUsedPhysRegs(PhysRegsUsed);
- if (!prt_.get()) prt_.reset(new PhysRegTracker(*mri_));
- vrm_.reset(new VirtRegMap(*mf_));
- if (!spiller_.get()) spiller_.reset(createSpiller());
+ // Also resize register usage trackers.
+ initRegUses();
+
+ vrm_ = &getAnalysis<VirtRegMap>();
+ if (!rewriter_.get()) rewriter_.reset(createVirtRegRewriter());
+
+ if (NewSpillFramework) {
+ spiller_.reset(createSpiller(mf_, li_, vrm_));
+ }
+ else {
+ spiller_.reset(0);
+ }
initIntervalSets();
linearScan();
// Rewrite spill code and update the PhysRegsUsed set.
- spiller_->runOnMachineFunction(*mf_, *vrm_);
+ rewriter_->runOnMachineFunction(*mf_, *vrm_, li_);
- vrm_.reset(); // Free the VirtRegMap
+ assert(unhandled_.empty() && "Unhandled live intervals remain!");
+ finalizeRegUses();
- while (!unhandled_.empty()) unhandled_.pop();
fixed_.clear();
active_.clear();
inactive_.clear();
handled_.clear();
+ NextReloadMap.clear();
+ DowngradedRegs.clear();
+ DowngradeMap.clear();
return true;
}
/// initIntervalSets - initialize the interval sets.
///
-void RA::initIntervalSets()
+void RALinScan::initIntervalSets()
{
assert(unhandled_.empty() && fixed_.empty() &&
active_.empty() && inactive_.empty() &&
"interval sets should be empty on initialization");
+ handled_.reserve(li_->getNumIntervals());
+
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()));
+ if (TargetRegisterInfo::isPhysicalRegister(i->second->reg)) {
+ mri_->setPhysRegUsed(i->second->reg);
+ fixed_.push_back(std::make_pair(i->second, i->second->begin()));
} else
- unhandled_.push(&i->second);
+ unhandled_.push(i->second);
}
}
-void RA::linearScan()
+void RALinScan::linearScan()
{
// linear scan algorithm
DOUT << "********** LINEAR SCAN **********\n";
DOUT << "********** 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;
+ ++NumIters;
DOUT << "\n*** CURRENT ***: " << *cur << '\n';
- processActiveIntervals(cur->beginNumber());
- processInactiveIntervals(cur->beginNumber());
+ if (!cur->empty()) {
+ processActiveIntervals(cur->beginNumber());
+ processInactiveIntervals(cur->beginNumber());
- assert(MRegisterInfo::isVirtualRegister(cur->reg) &&
- "Can only allocate virtual registers!");
+ assert(TargetRegisterInfo::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
DEBUG(printIntervals("active", active_.begin(), active_.end()));
DEBUG(printIntervals("inactive", inactive_.begin(), inactive_.end()));
}
- numIntervals += li_->getNumIntervals();
- NumIters += numIterations;
- // expire any remaining active intervals
- for (IntervalPtrs::reverse_iterator
- i = active_.rbegin(); i != active_.rend(); ) {
- unsigned reg = i->first->reg;
- DOUT << "\tinterval " << *i->first << " expired\n";
- assert(MRegisterInfo::isVirtualRegister(reg) &&
+ // Expire any remaining active intervals
+ while (!active_.empty()) {
+ IntervalPtr &IP = active_.back();
+ unsigned reg = IP.first->reg;
+ DOUT << "\tinterval " << *IP.first << " expired\n";
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
- i = IntervalPtrs::reverse_iterator(active_.erase(i.base()-1));
+ delRegUse(reg);
+ active_.pop_back();
}
- // expire any remaining inactive intervals
- for (IntervalPtrs::reverse_iterator
- i = inactive_.rbegin(); i != inactive_.rend(); ) {
- DOUT << "\tinterval " << *i->first << " expired\n";
- i = IntervalPtrs::reverse_iterator(inactive_.erase(i.base()-1));
+ // Expire any remaining inactive intervals
+ DEBUG(for (IntervalPtrs::reverse_iterator
+ i = inactive_.rbegin(); i != inactive_.rend(); ++i)
+ DOUT << "\tinterval " << *i->first << " expired\n");
+ inactive_.clear();
+
+ // Add live-ins to every BB except for entry. Also perform trivial coalescing.
+ MachineFunction::iterator EntryMBB = mf_->begin();
+ SmallVector<MachineBasicBlock*, 8> LiveInMBBs;
+ for (LiveIntervals::iterator i = li_->begin(), e = li_->end(); i != e; ++i) {
+ LiveInterval &cur = *i->second;
+ unsigned Reg = 0;
+ bool isPhys = TargetRegisterInfo::isPhysicalRegister(cur.reg);
+ if (isPhys)
+ Reg = cur.reg;
+ else if (vrm_->isAssignedReg(cur.reg))
+ Reg = attemptTrivialCoalescing(cur, vrm_->getPhys(cur.reg));
+ if (!Reg)
+ continue;
+ // Ignore splited live intervals.
+ if (!isPhys && vrm_->getPreSplitReg(cur.reg))
+ continue;
+ for (LiveInterval::Ranges::const_iterator I = cur.begin(), E = cur.end();
+ I != E; ++I) {
+ const LiveRange &LR = *I;
+ if (li_->findLiveInMBBs(LR.start, LR.end, LiveInMBBs)) {
+ for (unsigned i = 0, e = LiveInMBBs.size(); i != e; ++i)
+ if (LiveInMBBs[i] != EntryMBB)
+ LiveInMBBs[i]->addLiveIn(Reg);
+ LiveInMBBs.clear();
+ }
+ }
}
DOUT << *vrm_;
+
+ // Look for physical registers that end up not being allocated even though
+ // register allocator had to spill other registers in its register class.
+ if (ls_->getNumIntervals() == 0)
+ return;
+ if (!vrm_->FindUnusedRegisters(tri_, li_))
+ return;
}
/// processActiveIntervals - expire old intervals and move non-overlapping ones
/// to the inactive list.
-void RA::processActiveIntervals(unsigned CurPoint)
+void RALinScan::processActiveIntervals(unsigned CurPoint)
{
DOUT << "\tprocessing active intervals:\n";
if (IntervalPos == Interval->end()) { // Remove expired intervals.
DOUT << "\t\tinterval " << *Interval << " expired\n";
- assert(MRegisterInfo::isVirtualRegister(reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
+ delRegUse(reg);
// Pop off the end of the list.
active_[i] = active_.back();
} else if (IntervalPos->start > CurPoint) {
// Move inactive intervals to inactive list.
DOUT << "\t\tinterval " << *Interval << " inactive\n";
- assert(MRegisterInfo::isVirtualRegister(reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->delRegUse(reg);
+ delRegUse(reg);
// add to inactive.
inactive_.push_back(std::make_pair(Interval, IntervalPos));
/// processInactiveIntervals - expire old intervals and move overlapping
/// ones to the active list.
-void RA::processInactiveIntervals(unsigned CurPoint)
+void RALinScan::processInactiveIntervals(unsigned CurPoint)
{
DOUT << "\tprocessing inactive intervals:\n";
} else if (IntervalPos->start <= CurPoint) {
// move re-activated intervals in active list
DOUT << "\t\tinterval " << *Interval << " active\n";
- assert(MRegisterInfo::isVirtualRegister(reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- prt_->addRegUse(reg);
+ addRegUse(reg);
// add to active
active_.push_back(std::make_pair(Interval, IntervalPos));
/// 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) {
+void RALinScan::updateSpillWeights(std::vector<float> &Weights,
+ unsigned reg, float weight,
+ const TargetRegisterClass *RC) {
+ SmallSet<unsigned, 4> Processed;
+ SmallSet<unsigned, 4> SuperAdded;
+ SmallVector<unsigned, 4> Supers;
Weights[reg] += weight;
- for (const unsigned* as = MRI->getAliasSet(reg); *as; ++as)
+ Processed.insert(reg);
+ for (const unsigned* as = tri_->getAliasSet(reg); *as; ++as) {
Weights[*as] += weight;
+ Processed.insert(*as);
+ if (tri_->isSubRegister(*as, reg) &&
+ SuperAdded.insert(*as) &&
+ RC->contains(*as)) {
+ Supers.push_back(*as);
+ }
+ }
+
+ // If the alias is a super-register, and the super-register is in the
+ // register class we are trying to allocate. Then add the weight to all
+ // sub-registers of the super-register even if they are not aliases.
+ // e.g. allocating for GR32, bh is not used, updating bl spill weight.
+ // bl should get the same spill weight otherwise it will be choosen
+ // as a spill candidate since spilling bh doesn't make ebx available.
+ for (unsigned i = 0, e = Supers.size(); i != e; ++i) {
+ for (const unsigned *sr = tri_->getSubRegisters(Supers[i]); *sr; ++sr)
+ if (!Processed.count(*sr))
+ Weights[*sr] += weight;
+ }
}
-static RA::IntervalPtrs::iterator FindIntervalInVector(RA::IntervalPtrs &IP,
- LiveInterval *LI) {
- for (RA::IntervalPtrs::iterator I = IP.begin(), E = IP.end(); I != E; ++I)
+static
+RALinScan::IntervalPtrs::iterator
+FindIntervalInVector(RALinScan::IntervalPtrs &IP, LiveInterval *LI) {
+ for (RALinScan::IntervalPtrs::iterator I = IP.begin(), E = IP.end();
+ I != E; ++I)
if (I->first == LI) return I;
return IP.end();
}
-static void RevertVectorIteratorsTo(RA::IntervalPtrs &V, unsigned Point) {
+static void RevertVectorIteratorsTo(RALinScan::IntervalPtrs &V, unsigned Point){
for (unsigned i = 0, e = V.size(); i != e; ++i) {
- RA::IntervalPtr &IP = V[i];
+ RALinScan::IntervalPtr &IP = V[i];
LiveInterval::iterator I = std::upper_bound(IP.first->begin(),
IP.second, Point);
if (I != IP.first->begin()) --I;
}
}
+/// addStackInterval - Create a LiveInterval for stack if the specified live
+/// interval has been spilled.
+static void addStackInterval(LiveInterval *cur, LiveStacks *ls_,
+ LiveIntervals *li_,
+ MachineRegisterInfo* mri_, VirtRegMap &vrm_) {
+ int SS = vrm_.getStackSlot(cur->reg);
+ if (SS == VirtRegMap::NO_STACK_SLOT)
+ return;
+
+ const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
+ LiveInterval &SI = ls_->getOrCreateInterval(SS, RC);
+
+ VNInfo *VNI;
+ if (SI.hasAtLeastOneValue())
+ VNI = SI.getValNumInfo(0);
+ else
+ VNI = SI.getNextValue(~0U, 0, ls_->getVNInfoAllocator());
+
+ LiveInterval &RI = li_->getInterval(cur->reg);
+ // FIXME: This may be overly conservative.
+ SI.MergeRangesInAsValue(RI, VNI);
+}
+
+/// getConflictWeight - Return the number of conflicts between cur
+/// live interval and defs and uses of Reg weighted by loop depthes.
+static
+float getConflictWeight(LiveInterval *cur, unsigned Reg, LiveIntervals *li_,
+ MachineRegisterInfo *mri_,
+ const MachineLoopInfo *loopInfo) {
+ float Conflicts = 0;
+ for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(Reg),
+ E = mri_->reg_end(); I != E; ++I) {
+ MachineInstr *MI = &*I;
+ if (cur->liveAt(li_->getInstructionIndex(MI))) {
+ unsigned loopDepth = loopInfo->getLoopDepth(MI->getParent());
+ Conflicts += powf(10.0f, (float)loopDepth);
+ }
+ }
+ return Conflicts;
+}
+
+/// findIntervalsToSpill - Determine the intervals to spill for the
+/// specified interval. It's passed the physical registers whose spill
+/// weight is the lowest among all the registers whose live intervals
+/// conflict with the interval.
+void RALinScan::findIntervalsToSpill(LiveInterval *cur,
+ std::vector<std::pair<unsigned,float> > &Candidates,
+ unsigned NumCands,
+ SmallVector<LiveInterval*, 8> &SpillIntervals) {
+ // We have figured out the *best* register to spill. But there are other
+ // registers that are pretty good as well (spill weight within 3%). Spill
+ // the one that has fewest defs and uses that conflict with cur.
+ float Conflicts[3] = { 0.0f, 0.0f, 0.0f };
+ SmallVector<LiveInterval*, 8> SLIs[3];
+
+ DOUT << "\tConsidering " << NumCands << " candidates: ";
+ DEBUG(for (unsigned i = 0; i != NumCands; ++i)
+ DOUT << tri_->getName(Candidates[i].first) << " ";
+ DOUT << "\n";);
+
+ // Calculate the number of conflicts of each candidate.
+ for (IntervalPtrs::iterator i = active_.begin(); i != active_.end(); ++i) {
+ unsigned Reg = i->first->reg;
+ unsigned PhysReg = vrm_->getPhys(Reg);
+ if (!cur->overlapsFrom(*i->first, i->second))
+ continue;
+ for (unsigned j = 0; j < NumCands; ++j) {
+ unsigned Candidate = Candidates[j].first;
+ if (tri_->regsOverlap(PhysReg, Candidate)) {
+ if (NumCands > 1)
+ Conflicts[j] += getConflictWeight(cur, Reg, li_, mri_, loopInfo);
+ SLIs[j].push_back(i->first);
+ }
+ }
+ }
+
+ for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end(); ++i){
+ unsigned Reg = i->first->reg;
+ unsigned PhysReg = vrm_->getPhys(Reg);
+ if (!cur->overlapsFrom(*i->first, i->second-1))
+ continue;
+ for (unsigned j = 0; j < NumCands; ++j) {
+ unsigned Candidate = Candidates[j].first;
+ if (tri_->regsOverlap(PhysReg, Candidate)) {
+ if (NumCands > 1)
+ Conflicts[j] += getConflictWeight(cur, Reg, li_, mri_, loopInfo);
+ SLIs[j].push_back(i->first);
+ }
+ }
+ }
+
+ // Which is the best candidate?
+ unsigned BestCandidate = 0;
+ float MinConflicts = Conflicts[0];
+ for (unsigned i = 1; i != NumCands; ++i) {
+ if (Conflicts[i] < MinConflicts) {
+ BestCandidate = i;
+ MinConflicts = Conflicts[i];
+ }
+ }
+
+ std::copy(SLIs[BestCandidate].begin(), SLIs[BestCandidate].end(),
+ std::back_inserter(SpillIntervals));
+}
+
+namespace {
+ struct WeightCompare {
+ typedef std::pair<unsigned, float> RegWeightPair;
+ bool operator()(const RegWeightPair &LHS, const RegWeightPair &RHS) const {
+ return LHS.second < RHS.second;
+ }
+ };
+}
+
+static bool weightsAreClose(float w1, float w2) {
+ if (!NewHeuristic)
+ return false;
+
+ float diff = w1 - w2;
+ if (diff <= 0.02f) // Within 0.02f
+ return true;
+ return (diff / w2) <= 0.05f; // Within 5%.
+}
+
+LiveInterval *RALinScan::hasNextReloadInterval(LiveInterval *cur) {
+ DenseMap<unsigned, unsigned>::iterator I = NextReloadMap.find(cur->reg);
+ if (I == NextReloadMap.end())
+ return 0;
+ return &li_->getInterval(I->second);
+}
+
+void RALinScan::DowngradeRegister(LiveInterval *li, unsigned Reg) {
+ bool isNew = DowngradedRegs.insert(Reg);
+ isNew = isNew; // Silence compiler warning.
+ assert(isNew && "Multiple reloads holding the same register?");
+ DowngradeMap.insert(std::make_pair(li->reg, Reg));
+ for (const unsigned *AS = tri_->getAliasSet(Reg); *AS; ++AS) {
+ isNew = DowngradedRegs.insert(*AS);
+ isNew = isNew; // Silence compiler warning.
+ assert(isNew && "Multiple reloads holding the same register?");
+ DowngradeMap.insert(std::make_pair(li->reg, *AS));
+ }
+ ++NumDowngrade;
+}
+
+void RALinScan::UpgradeRegister(unsigned Reg) {
+ if (Reg) {
+ DowngradedRegs.erase(Reg);
+ for (const unsigned *AS = tri_->getAliasSet(Reg); *AS; ++AS)
+ DowngradedRegs.erase(*AS);
+ }
+}
+
+namespace {
+ struct LISorter {
+ bool operator()(LiveInterval* A, LiveInterval* B) {
+ return A->beginNumber() < B->beginNumber();
+ }
+ };
+}
+
/// assignRegOrStackSlotAtInterval - assign a register if one is available, or
/// spill.
-void RA::assignRegOrStackSlotAtInterval(LiveInterval* cur)
+void RALinScan::assignRegOrStackSlotAtInterval(LiveInterval* cur)
{
DOUT << "\tallocating current interval: ";
- PhysRegTracker backupPrt = *prt_;
+ // This is an implicitly defined live interval, just assign any register.
+ const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
+ if (cur->empty()) {
+ unsigned physReg = cur->preference;
+ if (!physReg)
+ physReg = *RC->allocation_order_begin(*mf_);
+ DOUT << tri_->getName(physReg) << '\n';
+ // Note the register is not really in use.
+ vrm_->assignVirt2Phys(cur->reg, physReg);
+ return;
+ }
+
+ backUpRegUses();
std::vector<std::pair<unsigned, float> > SpillWeightsToAdd;
unsigned StartPosition = cur->beginNumber();
- const TargetRegisterClass *RC = mf_->getSSARegMap()->getRegClass(cur->reg);
const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
-
- // for every interval in inactive we overlap with, mark the
+
+ // If start of this live interval is defined by a move instruction and its
+ // source is assigned a physical register that is compatible with the target
+ // register class, then we should try to assign it the same register.
+ // This can happen when the move is from a larger register class to a smaller
+ // one, e.g. X86::mov32to32_. These move instructions are not coalescable.
+ if (!cur->preference && cur->hasAtLeastOneValue()) {
+ VNInfo *vni = cur->begin()->valno;
+ if (vni->def && vni->def != ~1U && vni->def != ~0U) {
+ MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
+ if (CopyMI &&
+ tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubReg, DstSubReg)) {
+ unsigned Reg = 0;
+ if (TargetRegisterInfo::isPhysicalRegister(SrcReg))
+ Reg = SrcReg;
+ else if (vrm_->isAssignedReg(SrcReg))
+ Reg = vrm_->getPhys(SrcReg);
+ if (Reg) {
+ if (SrcSubReg)
+ Reg = tri_->getSubReg(Reg, SrcSubReg);
+ if (DstSubReg)
+ Reg = tri_->getMatchingSuperReg(Reg, DstSubReg, RC);
+ if (Reg && allocatableRegs_[Reg] && RC->contains(Reg))
+ cur->preference = Reg;
+ }
+ }
+ }
+ }
+
+ // 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) {
unsigned Reg = i->first->reg;
- assert(MRegisterInfo::isVirtualRegister(Reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(Reg) &&
"Can only allocate virtual registers!");
- const TargetRegisterClass *RegRC = mf_->getSSARegMap()->getRegClass(Reg);
+ const TargetRegisterClass *RegRC = mri_->getRegClass(Reg);
// If this is not in a related reg class to the register we're allocating,
// don't check it.
if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader &&
cur->overlapsFrom(*i->first, i->second-1)) {
Reg = vrm_->getPhys(Reg);
- prt_->addRegUse(Reg);
+ addRegUse(Reg);
SpillWeightsToAdd.push_back(std::make_pair(Reg, i->first->weight));
}
}
// is very bad (it contains all callee clobbered registers for any functions
// with a call), so we want to avoid doing that if possible.
unsigned physReg = getFreePhysReg(cur);
+ unsigned BestPhysReg = physReg;
if (physReg) {
// We got a register. However, if it's in the fixed_ list, we might
// conflict with it. Check to see if we conflict with it or any of its
// aliases.
- std::set<unsigned> RegAliases;
- for (const unsigned *AS = mri_->getAliasSet(physReg); *AS; ++AS)
+ SmallSet<unsigned, 8> RegAliases;
+ for (const unsigned *AS = tri_->getAliasSet(physReg); *AS; ++AS)
RegAliases.insert(*AS);
bool ConflictsWithFixed = false;
// Okay, the register picked by our speculative getFreePhysReg call turned
// out to be in use. Actually add all of the conflicting fixed registers to
- // prt so we can do an accurate query.
+ // regUse_ so we can do an accurate query.
if (ConflictsWithFixed) {
// For every interval in fixed we overlap with, mark the register as not
// free and update spill weights.
--II;
if (cur->overlapsFrom(*I, II)) {
unsigned reg = I->reg;
- prt_->addRegUse(reg);
+ addRegUse(reg);
SpillWeightsToAdd.push_back(std::make_pair(reg, I->weight));
}
}
}
- // Using the newly updated prt_ object, which includes conflicts in the
+ // Using the newly updated regUse_ object, which includes conflicts in the
// future, see if there are any registers available.
physReg = getFreePhysReg(cur);
}
// Restore the physical register tracker, removing information about the
// future.
- *prt_ = backupPrt;
+ restoreRegUses();
- // if we find a free register, we are done: assign this virtual to
+ // 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) {
- DOUT << mri_->getName(physReg) << '\n';
+ DOUT << tri_->getName(physReg) << '\n';
vrm_->assignVirt2Phys(cur->reg, physReg);
- prt_->addRegUse(physReg);
+ addRegUse(physReg);
active_.push_back(std::make_pair(cur, cur->begin()));
handled_.push_back(cur);
+
+ // "Upgrade" the physical register since it has been allocated.
+ UpgradeRegister(physReg);
+ if (LiveInterval *NextReloadLI = hasNextReloadInterval(cur)) {
+ // "Downgrade" physReg to try to keep physReg from being allocated until
+ // the next reload from the same SS is allocated.
+ NextReloadLI->preference = physReg;
+ DowngradeRegister(cur, physReg);
+ }
return;
}
DOUT << "no free registers\n";
// Compile the spill weights into an array that is better for scanning.
- std::vector<float> SpillWeights(mri_->getNumRegs(), 0.0);
+ std::vector<float> SpillWeights(tri_->getNumRegs(), 0.0f);
for (std::vector<std::pair<unsigned, float> >::iterator
I = SpillWeightsToAdd.begin(), E = SpillWeightsToAdd.end(); I != E; ++I)
- updateSpillWeights(SpillWeights, I->first, I->second, mri_);
+ updateSpillWeights(SpillWeights, I->first, I->second, RC);
// for each interval in active, update spill weights.
for (IntervalPtrs::const_iterator i = active_.begin(), e = active_.end();
i != e; ++i) {
unsigned reg = i->first->reg;
- assert(MRegisterInfo::isVirtualRegister(reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
"Can only allocate virtual registers!");
reg = vrm_->getPhys(reg);
- updateSpillWeights(SpillWeights, reg, i->first->weight, mri_);
+ updateSpillWeights(SpillWeights, reg, i->first->weight, RC);
}
DOUT << "\tassigning stack slot at interval "<< *cur << ":\n";
// Find a register to spill.
float minWeight = HUGE_VALF;
- unsigned minReg = 0;
- 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;
+ unsigned minReg = 0; /*cur->preference*/; // Try the pref register first.
+
+ bool Found = false;
+ std::vector<std::pair<unsigned,float> > RegsWeights;
+ if (!minReg || SpillWeights[minReg] == HUGE_VALF)
+ for (TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_),
+ e = RC->allocation_order_end(*mf_); i != e; ++i) {
+ unsigned reg = *i;
+ float regWeight = SpillWeights[reg];
+ if (minWeight > regWeight)
+ Found = true;
+ RegsWeights.push_back(std::make_pair(reg, regWeight));
}
- }
// If we didn't find a register that is spillable, try aliases?
- if (!minReg) {
+ if (!Found) {
for (TargetRegisterClass::iterator i = RC->allocation_order_begin(*mf_),
e = RC->allocation_order_end(*mf_); i != e; ++i) {
unsigned reg = *i;
// No need to worry about if the alias register size < regsize of RC.
// We are going to spill all registers that alias it anyway.
- for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as) {
- if (minWeight > SpillWeights[*as]) {
- minWeight = SpillWeights[*as];
- minReg = *as;
+ for (const unsigned* as = tri_->getAliasSet(reg); *as; ++as)
+ RegsWeights.push_back(std::make_pair(*as, SpillWeights[*as]));
+ }
+ }
+
+ // Sort all potential spill candidates by weight.
+ std::sort(RegsWeights.begin(), RegsWeights.end(), WeightCompare());
+ minReg = RegsWeights[0].first;
+ minWeight = RegsWeights[0].second;
+ if (minWeight == HUGE_VALF) {
+ // All registers must have inf weight. Just grab one!
+ minReg = BestPhysReg ? BestPhysReg : *RC->allocation_order_begin(*mf_);
+ if (cur->weight == HUGE_VALF ||
+ li_->getApproximateInstructionCount(*cur) == 0) {
+ // Spill a physical register around defs and uses.
+ if (li_->spillPhysRegAroundRegDefsUses(*cur, minReg, *vrm_)) {
+ // spillPhysRegAroundRegDefsUses may have invalidated iterator stored
+ // in fixed_. Reset them.
+ for (unsigned i = 0, e = fixed_.size(); i != e; ++i) {
+ IntervalPtr &IP = fixed_[i];
+ LiveInterval *I = IP.first;
+ if (I->reg == minReg || tri_->isSubRegister(minReg, I->reg))
+ IP.second = I->advanceTo(I->begin(), StartPosition);
}
+
+ DowngradedRegs.clear();
+ assignRegOrStackSlotAtInterval(cur);
+ } else {
+ cerr << "Ran out of registers during register allocation!\n";
+ exit(1);
}
+ return;
}
+ }
- // All registers must have inf weight. Just grab one!
- if (!minReg)
- minReg = *RC->allocation_order_begin(*mf_);
+ // Find up to 3 registers to consider as spill candidates.
+ unsigned LastCandidate = RegsWeights.size() >= 3 ? 3 : 1;
+ while (LastCandidate > 1) {
+ if (weightsAreClose(RegsWeights[LastCandidate-1].second, minWeight))
+ break;
+ --LastCandidate;
}
-
- DOUT << "\t\tregister with min weight: "
- << mri_->getName(minReg) << " (" << minWeight << ")\n";
- // if the current has the minimum weight, we need to spill it and
+ DOUT << "\t\tregister(s) with min weight(s): ";
+ DEBUG(for (unsigned i = 0; i != LastCandidate; ++i)
+ DOUT << tri_->getName(RegsWeights[i].first)
+ << " (" << RegsWeights[i].second << ")\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 != HUGE_VALF && cur->weight <= minWeight) {
DOUT << "\t\t\tspilling(c): " << *cur << '\n';
- int slot = vrm_->assignVirt2StackSlot(cur->reg);
- std::vector<LiveInterval*> added =
- li_->addIntervalsForSpills(*cur, *vrm_, slot);
+ SmallVector<LiveInterval*, 8> spillIs;
+ std::vector<LiveInterval*> added;
+
+ if (!NewSpillFramework) {
+ added = li_->addIntervalsForSpills(*cur, spillIs, loopInfo, *vrm_);
+ }
+ else {
+ added = spiller_->spill(cur);
+ }
+
+ std::sort(added.begin(), added.end(), LISorter());
+ addStackInterval(cur, ls_, li_, mri_, *vrm_);
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
+ // Merge added with unhandled. Note that we have already sorted
+ // intervals returned by addIntervalsForSpills by their starting
// point.
- for (unsigned i = 0, e = added.size(); i != e; ++i)
- unhandled_.push(added[i]);
+ // This also update the NextReloadMap. That is, it adds mapping from a
+ // register defined by a reload from SS to the next reload from SS in the
+ // same basic block.
+ MachineBasicBlock *LastReloadMBB = 0;
+ LiveInterval *LastReload = 0;
+ int LastReloadSS = VirtRegMap::NO_STACK_SLOT;
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ LiveInterval *ReloadLi = added[i];
+ if (ReloadLi->weight == HUGE_VALF &&
+ li_->getApproximateInstructionCount(*ReloadLi) == 0) {
+ unsigned ReloadIdx = ReloadLi->beginNumber();
+ MachineBasicBlock *ReloadMBB = li_->getMBBFromIndex(ReloadIdx);
+ int ReloadSS = vrm_->getStackSlot(ReloadLi->reg);
+ if (LastReloadMBB == ReloadMBB && LastReloadSS == ReloadSS) {
+ // Last reload of same SS is in the same MBB. We want to try to
+ // allocate both reloads the same register and make sure the reg
+ // isn't clobbered in between if at all possible.
+ assert(LastReload->beginNumber() < ReloadIdx);
+ NextReloadMap.insert(std::make_pair(LastReload->reg, ReloadLi->reg));
+ }
+ LastReloadMBB = ReloadMBB;
+ LastReload = ReloadLi;
+ LastReloadSS = ReloadSS;
+ }
+ unhandled_.push(ReloadLi);
+ }
return;
}
++NumBacktracks;
- // push the current interval back to unhandled since we are going
+ // 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
+ assert(TargetRegisterInfo::isPhysicalRegister(minReg) &&
+ "did not choose a register to spill?");
+
+ // 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);
+ SmallVector<LiveInterval*, 8> spillIs;
- // 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;
+ // Determine which intervals have to be spilled.
+ findIntervalsToSpill(cur, RegsWeights, LastCandidate, spillIs);
- // the earliest start of a spilled interval indicates up to where
+ // Set of spilled vregs (used later to rollback properly)
+ SmallSet<unsigned, 8> spilled;
+
+ // 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
+ // 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)) {
- DOUT << "\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);
- }
- }
- 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)) {
- DOUT << "\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);
- }
+ std::vector<LiveInterval*> added;
+ while (!spillIs.empty()) {
+ LiveInterval *sli = spillIs.back();
+ spillIs.pop_back();
+ DOUT << "\t\t\tspilling(a): " << *sli << '\n';
+ earliestStart = std::min(earliestStart, sli->beginNumber());
+ std::vector<LiveInterval*> newIs =
+ li_->addIntervalsForSpills(*sli, spillIs, loopInfo, *vrm_);
+ addStackInterval(sli, ls_, li_, mri_, *vrm_);
+ std::copy(newIs.begin(), newIs.end(), std::back_inserter(added));
+ spilled.insert(sli->reg);
}
DOUT << "\t\trolling back to: " << earliestStart << '\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.
+ // inactive to properly update regUse_ and the VirtRegMap.
IntervalPtrs::iterator it;
if ((it = FindIntervalInVector(active_, i)) != active_.end()) {
active_.erase(it);
- assert(!MRegisterInfo::isPhysicalRegister(i->reg));
+ assert(!TargetRegisterInfo::isPhysicalRegister(i->reg));
if (!spilled.count(i->reg))
unhandled_.push(i);
- prt_->delRegUse(vrm_->getPhys(i->reg));
+ delRegUse(vrm_->getPhys(i->reg));
vrm_->clearVirt(i->reg);
} else if ((it = FindIntervalInVector(inactive_, i)) != inactive_.end()) {
inactive_.erase(it);
- assert(!MRegisterInfo::isPhysicalRegister(i->reg));
+ assert(!TargetRegisterInfo::isPhysicalRegister(i->reg));
if (!spilled.count(i->reg))
unhandled_.push(i);
vrm_->clearVirt(i->reg);
} else {
- assert(MRegisterInfo::isVirtualRegister(i->reg) &&
+ assert(TargetRegisterInfo::isVirtualRegister(i->reg) &&
"Can only allocate virtual registers!");
vrm_->clearVirt(i->reg);
unhandled_.push(i);
}
+
+ DenseMap<unsigned, unsigned>::iterator ii = DowngradeMap.find(i->reg);
+ if (ii == DowngradeMap.end())
+ // It interval has a preference, it must be defined by a copy. Clear the
+ // preference now since the source interval allocation may have been
+ // undone as well.
+ i->preference = 0;
+ else {
+ UpgradeRegister(ii->second);
+ }
}
// Rewind the iterators in the active, inactive, and fixed lists back to the
RevertVectorIteratorsTo(inactive_, earliestStart);
RevertVectorIteratorsTo(fixed_, earliestStart);
- // scan the rest and undo each interval that expired after t and
+ // 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) {
HI->expiredAt(cur->beginNumber())) {
DOUT << "\t\t\tundo changes for: " << *HI << '\n';
active_.push_back(std::make_pair(HI, HI->begin()));
- assert(!MRegisterInfo::isPhysicalRegister(HI->reg));
- prt_->addRegUse(vrm_->getPhys(HI->reg));
+ assert(!TargetRegisterInfo::isPhysicalRegister(HI->reg));
+ addRegUse(vrm_->getPhys(HI->reg));
}
}
- // merge added with unhandled
- for (unsigned i = 0, e = added.size(); i != e; ++i)
- unhandled_.push(added[i]);
-}
-
-/// getFreePhysReg - return a free physical register for this virtual register
-/// interval if we have one, otherwise return 0.
-unsigned RA::getFreePhysReg(LiveInterval *cur) {
- std::vector<unsigned> inactiveCounts(mri_->getNumRegs(), 0);
- unsigned MaxInactiveCount = 0;
-
- const TargetRegisterClass *RC = mf_->getSSARegMap()->getRegClass(cur->reg);
- const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
-
- for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
- i != e; ++i) {
- unsigned reg = i->first->reg;
- assert(MRegisterInfo::isVirtualRegister(reg) &&
- "Can only allocate virtual registers!");
-
- // If this is not in a related reg class to the register we're allocating,
- // don't check it.
- const TargetRegisterClass *RegRC = mf_->getSSARegMap()->getRegClass(reg);
- if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader) {
- reg = vrm_->getPhys(reg);
- ++inactiveCounts[reg];
- MaxInactiveCount = std::max(MaxInactiveCount, inactiveCounts[reg]);
+ // Merge added with unhandled.
+ // This also update the NextReloadMap. That is, it adds mapping from a
+ // register defined by a reload from SS to the next reload from SS in the
+ // same basic block.
+ MachineBasicBlock *LastReloadMBB = 0;
+ LiveInterval *LastReload = 0;
+ int LastReloadSS = VirtRegMap::NO_STACK_SLOT;
+ std::sort(added.begin(), added.end(), LISorter());
+ for (unsigned i = 0, e = added.size(); i != e; ++i) {
+ LiveInterval *ReloadLi = added[i];
+ if (ReloadLi->weight == HUGE_VALF &&
+ li_->getApproximateInstructionCount(*ReloadLi) == 0) {
+ unsigned ReloadIdx = ReloadLi->beginNumber();
+ MachineBasicBlock *ReloadMBB = li_->getMBBFromIndex(ReloadIdx);
+ int ReloadSS = vrm_->getStackSlot(ReloadLi->reg);
+ if (LastReloadMBB == ReloadMBB && LastReloadSS == ReloadSS) {
+ // Last reload of same SS is in the same MBB. We want to try to
+ // allocate both reloads the same register and make sure the reg
+ // isn't clobbered in between if at all possible.
+ assert(LastReload->beginNumber() < ReloadIdx);
+ NextReloadMap.insert(std::make_pair(LastReload->reg, ReloadLi->reg));
+ }
+ LastReloadMBB = ReloadMBB;
+ LastReload = ReloadLi;
+ LastReloadSS = ReloadSS;
}
+ unhandled_.push(ReloadLi);
}
+}
- const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(cur->reg);
-
+unsigned RALinScan::getFreePhysReg(const TargetRegisterClass *RC,
+ unsigned MaxInactiveCount,
+ SmallVector<unsigned, 256> &inactiveCounts,
+ bool SkipDGRegs) {
unsigned FreeReg = 0;
unsigned FreeRegInactiveCount = 0;
-
+
+ TargetRegisterClass::iterator I = RC->allocation_order_begin(*mf_);
+ TargetRegisterClass::iterator E = RC->allocation_order_end(*mf_);
+ assert(I != E && "No allocatable register in this register class!");
+
// Scan for the first available register.
- TargetRegisterClass::iterator I = rc->allocation_order_begin(*mf_);
- TargetRegisterClass::iterator E = rc->allocation_order_end(*mf_);
- for (; I != E; ++I)
- if (prt_->isRegAvail(*I)) {
- FreeReg = *I;
- FreeRegInactiveCount = inactiveCounts[FreeReg];
+ for (; I != E; ++I) {
+ unsigned Reg = *I;
+ // Ignore "downgraded" registers.
+ if (SkipDGRegs && DowngradedRegs.count(Reg))
+ continue;
+ if (isRegAvail(Reg)) {
+ FreeReg = Reg;
+ if (FreeReg < inactiveCounts.size())
+ FreeRegInactiveCount = inactiveCounts[FreeReg];
+ else
+ FreeRegInactiveCount = 0;
break;
}
-
+ }
+
// If there are no free regs, or if this reg has the max inactive count,
// return this register.
- if (FreeReg == 0 || FreeRegInactiveCount == MaxInactiveCount) return FreeReg;
+ if (FreeReg == 0 || FreeRegInactiveCount == MaxInactiveCount)
+ return FreeReg;
// Continue scanning the registers, looking for the one with the highest
// inactive count. Alkis found that this reduced register pressure very
// reevaluated now.
for (; I != E; ++I) {
unsigned Reg = *I;
- if (prt_->isRegAvail(Reg) && FreeRegInactiveCount < inactiveCounts[Reg]) {
+ // Ignore "downgraded" registers.
+ if (SkipDGRegs && DowngradedRegs.count(Reg))
+ continue;
+ if (isRegAvail(Reg) && Reg < inactiveCounts.size() &&
+ FreeRegInactiveCount < inactiveCounts[Reg]) {
FreeReg = Reg;
FreeRegInactiveCount = inactiveCounts[Reg];
if (FreeRegInactiveCount == MaxInactiveCount)
break; // We found the one with the max inactive count.
}
}
-
+
return FreeReg;
}
+/// getFreePhysReg - return a free physical register for this virtual register
+/// interval if we have one, otherwise return 0.
+unsigned RALinScan::getFreePhysReg(LiveInterval *cur) {
+ SmallVector<unsigned, 256> inactiveCounts;
+ unsigned MaxInactiveCount = 0;
+
+ const TargetRegisterClass *RC = mri_->getRegClass(cur->reg);
+ const TargetRegisterClass *RCLeader = RelatedRegClasses.getLeaderValue(RC);
+
+ for (IntervalPtrs::iterator i = inactive_.begin(), e = inactive_.end();
+ i != e; ++i) {
+ unsigned reg = i->first->reg;
+ assert(TargetRegisterInfo::isVirtualRegister(reg) &&
+ "Can only allocate virtual registers!");
+
+ // If this is not in a related reg class to the register we're allocating,
+ // don't check it.
+ const TargetRegisterClass *RegRC = mri_->getRegClass(reg);
+ if (RelatedRegClasses.getLeaderValue(RegRC) == RCLeader) {
+ reg = vrm_->getPhys(reg);
+ if (inactiveCounts.size() <= reg)
+ inactiveCounts.resize(reg+1);
+ ++inactiveCounts[reg];
+ MaxInactiveCount = std::max(MaxInactiveCount, inactiveCounts[reg]);
+ }
+ }
+
+ // If copy coalescer has assigned a "preferred" register, check if it's
+ // available first.
+ if (cur->preference) {
+ DOUT << "(preferred: " << tri_->getName(cur->preference) << ") ";
+ if (isRegAvail(cur->preference) &&
+ RC->contains(cur->preference))
+ return cur->preference;
+ }
+
+ if (!DowngradedRegs.empty()) {
+ unsigned FreeReg = getFreePhysReg(RC, MaxInactiveCount, inactiveCounts,
+ true);
+ if (FreeReg)
+ return FreeReg;
+ }
+ return getFreePhysReg(RC, MaxInactiveCount, inactiveCounts, false);
+}
+
FunctionPass* llvm::createLinearScanRegisterAllocator() {
- return new RA();
+ return new RALinScan();
}
projects / oota-llvm.git / blobdiff