#define DEBUG_TYPE "regalloc"
#include "RenderMachineFunction.h"
#include "Splitter.h"
#include "VirtRegMap.h"
#include "VirtRegRewriter.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/RegAllocPBQP.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PBQP/HeuristicSolver.h"
#include "llvm/CodeGen/PBQP/Graph.h"
#include "llvm/CodeGen/PBQP/Heuristics/Briggs.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include <limits>
#include <memory>
#include <set>
#include <vector>
using namespace llvm;
static RegisterRegAlloc
registerPBQPRepAlloc("pbqp", "PBQP register allocator",
createDefaultPBQPRegisterAllocator);
static cl::opt<bool>
pbqpCoalescing("pbqp-coalescing",
cl::desc("Attempt coalescing during PBQP register allocation."),
cl::init(false), cl::Hidden);
static cl::opt<bool>
pbqpPreSplitting("pbqp-pre-splitting",
cl::desc("Pre-split before PBQP register allocation."),
cl::init(false), cl::Hidden);
namespace {
class RegAllocPBQP : public MachineFunctionPass {
public:
static char ID;
RegAllocPBQP(std::auto_ptr<PBQPBuilder> b)
: MachineFunctionPass(ID), builder(b) {
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
initializeRegisterCoalescerAnalysisGroup(*PassRegistry::getPassRegistry());
initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
initializeLiveStacksPass(*PassRegistry::getPassRegistry());
initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
initializeLoopSplitterPass(*PassRegistry::getPassRegistry());
initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
initializeRenderMachineFunctionPass(*PassRegistry::getPassRegistry());
}
virtual const char* getPassName() const {
return "PBQP Register Allocator";
}
virtual void getAnalysisUsage(AnalysisUsage &au) const;
virtual bool runOnMachineFunction(MachineFunction &MF);
private:
typedef std::map<const LiveInterval*, unsigned> LI2NodeMap;
typedef std::vector<const LiveInterval*> Node2LIMap;
typedef std::vector<unsigned> AllowedSet;
typedef std::vector<AllowedSet> AllowedSetMap;
typedef std::pair<unsigned, unsigned> RegPair;
typedef std::map<RegPair, PBQP::PBQPNum> CoalesceMap;
typedef std::vector<PBQP::Graph::NodeItr> NodeVector;
typedef std::set<unsigned> RegSet;
std::auto_ptr<PBQPBuilder> builder;
MachineFunction *mf;
const TargetMachine *tm;
const TargetRegisterInfo *tri;
const TargetInstrInfo *tii;
const MachineLoopInfo *loopInfo;
MachineRegisterInfo *mri;
RenderMachineFunction *rmf;
LiveIntervals *lis;
LiveStacks *lss;
VirtRegMap *vrm;
RegSet vregsToAlloc, emptyIntervalVRegs;
void findVRegIntervalsToAlloc();
void addStackInterval(const LiveInterval *spilled,MachineRegisterInfo* mri);
bool mapPBQPToRegAlloc(const PBQPRAProblem &problem,
const PBQP::Solution &solution);
void finalizeAlloc() const;
};
char RegAllocPBQP::ID = 0;
}
unsigned PBQPRAProblem::getVRegForNode(PBQP::Graph::ConstNodeItr node) const {
Node2VReg::const_iterator vregItr = node2VReg.find(node);
assert(vregItr != node2VReg.end() && "No vreg for node.");
return vregItr->second;
}
PBQP::Graph::NodeItr PBQPRAProblem::getNodeForVReg(unsigned vreg) const {
VReg2Node::const_iterator nodeItr = vreg2Node.find(vreg);
assert(nodeItr != vreg2Node.end() && "No node for vreg.");
return nodeItr->second;
}
const PBQPRAProblem::AllowedSet&
PBQPRAProblem::getAllowedSet(unsigned vreg) const {
AllowedSetMap::const_iterator allowedSetItr = allowedSets.find(vreg);
assert(allowedSetItr != allowedSets.end() && "No pregs for vreg.");
const AllowedSet &allowedSet = allowedSetItr->second;
return allowedSet;
}
unsigned PBQPRAProblem::getPRegForOption(unsigned vreg, unsigned option) const {
assert(isPRegOption(vreg, option) && "Not a preg option.");
const AllowedSet& allowedSet = getAllowedSet(vreg);
assert(option <= allowedSet.size() && "Option outside allowed set.");
return allowedSet[option - 1];
}
std::auto_ptr<PBQPRAProblem> PBQPBuilder::build(MachineFunction *mf,
const LiveIntervals *lis,
const MachineLoopInfo *loopInfo,
const RegSet &vregs) {
typedef std::vector<const LiveInterval*> LIVector;
MachineRegisterInfo *mri = &mf->getRegInfo();
const TargetRegisterInfo *tri = mf->getTarget().getRegisterInfo();
std::auto_ptr<PBQPRAProblem> p(new PBQPRAProblem());
PBQP::Graph &g = p->getGraph();
RegSet pregs;
for (LiveIntervals::const_iterator itr = lis->begin(), end = lis->end();
itr != end; ++itr) {
if (TargetRegisterInfo::isPhysicalRegister(itr->first)) {
pregs.insert(itr->first);
mri->setPhysRegUsed(itr->first);
}
}
BitVector reservedRegs = tri->getReservedRegs(*mf);
for (RegSet::const_iterator vregItr = vregs.begin(), vregEnd = vregs.end();
vregItr != vregEnd; ++vregItr) {
unsigned vreg = *vregItr;
const TargetRegisterClass *trc = mri->getRegClass(vreg);
const LiveInterval *vregLI = &lis->getInterval(vreg);
typedef std::vector<unsigned> VRAllowed;
VRAllowed vrAllowed;
for (TargetRegisterClass::iterator aoItr = trc->allocation_order_begin(*mf),
aoEnd = trc->allocation_order_end(*mf);
aoItr != aoEnd; ++aoItr) {
unsigned preg = *aoItr;
if (!reservedRegs.test(preg)) {
vrAllowed.push_back(preg);
}
}
for (RegSet::const_iterator pregItr = pregs.begin(),
pregEnd = pregs.end();
pregItr != pregEnd; ++pregItr) {
unsigned preg = *pregItr;
const LiveInterval *pregLI = &lis->getInterval(preg);
if (pregLI->empty()) {
continue;
}
if (!vregLI->overlaps(*pregLI)) {
continue;
}
VRAllowed::iterator eraseItr =
std::find(vrAllowed.begin(), vrAllowed.end(), preg);
if (eraseItr != vrAllowed.end()) {
vrAllowed.erase(eraseItr);
}
const unsigned *aliasItr = tri->getAliasSet(preg);
if (aliasItr != 0) {
for (; *aliasItr != 0; ++aliasItr) {
VRAllowed::iterator eraseItr =
std::find(vrAllowed.begin(), vrAllowed.end(), *aliasItr);
if (eraseItr != vrAllowed.end()) {
vrAllowed.erase(eraseItr);
}
}
}
}
PBQP::Graph::NodeItr node =
g.addNode(PBQP::Vector(vrAllowed.size() + 1, 0));
p->recordVReg(vreg, node, vrAllowed.begin(), vrAllowed.end());
PBQP::PBQPNum spillCost = (vregLI->weight != 0.0) ?
vregLI->weight : std::numeric_limits<PBQP::PBQPNum>::min();
addSpillCosts(g.getNodeCosts(node), spillCost);
}
for (RegSet::const_iterator vr1Itr = vregs.begin(), vrEnd = vregs.end();
vr1Itr != vrEnd; ++vr1Itr) {
unsigned vr1 = *vr1Itr;
const LiveInterval &l1 = lis->getInterval(vr1);
const PBQPRAProblem::AllowedSet &vr1Allowed = p->getAllowedSet(vr1);
for (RegSet::const_iterator vr2Itr = llvm::next(vr1Itr);
vr2Itr != vrEnd; ++vr2Itr) {
unsigned vr2 = *vr2Itr;
const LiveInterval &l2 = lis->getInterval(vr2);
const PBQPRAProblem::AllowedSet &vr2Allowed = p->getAllowedSet(vr2);
assert(!l2.empty() && "Empty interval in vreg set?");
if (l1.overlaps(l2)) {
PBQP::Graph::EdgeItr edge =
g.addEdge(p->getNodeForVReg(vr1), p->getNodeForVReg(vr2),
PBQP::Matrix(vr1Allowed.size()+1, vr2Allowed.size()+1, 0));
addInterferenceCosts(g.getEdgeCosts(edge), vr1Allowed, vr2Allowed, tri);
}
}
}
return p;
}
void PBQPBuilder::addSpillCosts(PBQP::Vector &costVec,
PBQP::PBQPNum spillCost) {
costVec[0] = spillCost;
}
void PBQPBuilder::addInterferenceCosts(
PBQP::Matrix &costMat,
const PBQPRAProblem::AllowedSet &vr1Allowed,
const PBQPRAProblem::AllowedSet &vr2Allowed,
const TargetRegisterInfo *tri) {
assert(costMat.getRows() == vr1Allowed.size() + 1 && "Matrix height mismatch.");
assert(costMat.getCols() == vr2Allowed.size() + 1 && "Matrix width mismatch.");
for (unsigned i = 0; i != vr1Allowed.size(); ++i) {
unsigned preg1 = vr1Allowed[i];
for (unsigned j = 0; j != vr2Allowed.size(); ++j) {
unsigned preg2 = vr2Allowed[j];
if (tri->regsOverlap(preg1, preg2)) {
costMat[i + 1][j + 1] = std::numeric_limits<PBQP::PBQPNum>::infinity();
}
}
}
}
std::auto_ptr<PBQPRAProblem> PBQPBuilderWithCoalescing::build(
MachineFunction *mf,
const LiveIntervals *lis,
const MachineLoopInfo *loopInfo,
const RegSet &vregs) {
std::auto_ptr<PBQPRAProblem> p = PBQPBuilder::build(mf, lis, loopInfo, vregs);
PBQP::Graph &g = p->getGraph();
const TargetMachine &tm = mf->getTarget();
CoalescerPair cp(*tm.getInstrInfo(), *tm.getRegisterInfo());
for (MachineFunction::const_iterator mbbItr = mf->begin(),
mbbEnd = mf->end();
mbbItr != mbbEnd; ++mbbItr) {
const MachineBasicBlock *mbb = &*mbbItr;
for (MachineBasicBlock::const_iterator miItr = mbb->begin(),
miEnd = mbb->end();
miItr != miEnd; ++miItr) {
const MachineInstr *mi = &*miItr;
if (!cp.setRegisters(mi)) {
continue; }
if (cp.getSrcReg() == cp.getDstReg()) {
continue; }
unsigned dst = cp.getDstReg(),
src = cp.getSrcReg();
const float copyFactor = 0.5;
PBQP::PBQPNum cBenefit =
copyFactor * LiveIntervals::getSpillWeight(false, true,
loopInfo->getLoopDepth(mbb));
if (cp.isPhys()) {
if (!lis->isAllocatable(dst)) {
continue;
}
const PBQPRAProblem::AllowedSet &allowed = p->getAllowedSet(src);
unsigned pregOpt = 0;
while (pregOpt < allowed.size() && allowed[pregOpt] != dst) {
++pregOpt;
}
if (pregOpt < allowed.size()) {
++pregOpt; PBQP::Graph::NodeItr node = p->getNodeForVReg(src);
addPhysRegCoalesce(g.getNodeCosts(node), pregOpt, cBenefit);
}
} else {
const PBQPRAProblem::AllowedSet *allowed1 = &p->getAllowedSet(dst);
const PBQPRAProblem::AllowedSet *allowed2 = &p->getAllowedSet(src);
PBQP::Graph::NodeItr node1 = p->getNodeForVReg(dst);
PBQP::Graph::NodeItr node2 = p->getNodeForVReg(src);
PBQP::Graph::EdgeItr edge = g.findEdge(node1, node2);
if (edge == g.edgesEnd()) {
edge = g.addEdge(node1, node2, PBQP::Matrix(allowed1->size() + 1,
allowed2->size() + 1,
0));
} else {
if (g.getEdgeNode1(edge) == node2) {
std::swap(node1, node2);
std::swap(allowed1, allowed2);
}
}
addVirtRegCoalesce(g.getEdgeCosts(edge), *allowed1, *allowed2,
cBenefit);
}
}
}
return p;
}
void PBQPBuilderWithCoalescing::addPhysRegCoalesce(PBQP::Vector &costVec,
unsigned pregOption,
PBQP::PBQPNum benefit) {
costVec[pregOption] += -benefit;
}
void PBQPBuilderWithCoalescing::addVirtRegCoalesce(
PBQP::Matrix &costMat,
const PBQPRAProblem::AllowedSet &vr1Allowed,
const PBQPRAProblem::AllowedSet &vr2Allowed,
PBQP::PBQPNum benefit) {
assert(costMat.getRows() == vr1Allowed.size() + 1 && "Size mismatch.");
assert(costMat.getCols() == vr2Allowed.size() + 1 && "Size mismatch.");
for (unsigned i = 0; i != vr1Allowed.size(); ++i) {
unsigned preg1 = vr1Allowed[i];
for (unsigned j = 0; j != vr2Allowed.size(); ++j) {
unsigned preg2 = vr2Allowed[j];
if (preg1 == preg2) {
costMat[i + 1][j + 1] += -benefit;
}
}
}
}
void RegAllocPBQP::getAnalysisUsage(AnalysisUsage &au) const {
au.addRequired<SlotIndexes>();
au.addPreserved<SlotIndexes>();
au.addRequired<LiveIntervals>();
au.addRequired<RegisterCoalescer>();
au.addRequired<CalculateSpillWeights>();
au.addRequired<LiveStacks>();
au.addPreserved<LiveStacks>();
au.addRequired<MachineLoopInfo>();
au.addPreserved<MachineLoopInfo>();
if (pbqpPreSplitting)
au.addRequired<LoopSplitter>();
au.addRequired<VirtRegMap>();
au.addRequired<RenderMachineFunction>();
MachineFunctionPass::getAnalysisUsage(au);
}
void RegAllocPBQP::findVRegIntervalsToAlloc() {
for (LiveIntervals::iterator itr = lis->begin(), end = lis->end();
itr != end; ++itr) {
if (TargetRegisterInfo::isPhysicalRegister(itr->first))
continue;
LiveInterval *li = itr->second;
if (!li->empty()) {
vregsToAlloc.insert(li->reg);
} else {
emptyIntervalVRegs.insert(li->reg);
}
}
}
void RegAllocPBQP::addStackInterval(const LiveInterval *spilled,
MachineRegisterInfo* mri) {
int stackSlot = vrm->getStackSlot(spilled->reg);
if (stackSlot == VirtRegMap::NO_STACK_SLOT) {
return;
}
const TargetRegisterClass *RC = mri->getRegClass(spilled->reg);
LiveInterval &stackInterval = lss->getOrCreateInterval(stackSlot, RC);
VNInfo *vni;
if (stackInterval.getNumValNums() != 0) {
vni = stackInterval.getValNumInfo(0);
} else {
vni = stackInterval.getNextValue(
SlotIndex(), 0, lss->getVNInfoAllocator());
}
LiveInterval &rhsInterval = lis->getInterval(spilled->reg);
stackInterval.MergeRangesInAsValue(rhsInterval, vni);
}
bool RegAllocPBQP::mapPBQPToRegAlloc(const PBQPRAProblem &problem,
const PBQP::Solution &solution) {
bool anotherRoundNeeded = false;
vrm->clearAllVirt();
const PBQP::Graph &g = problem.getGraph();
for (PBQP::Graph::ConstNodeItr node = g.nodesBegin(),
nodeEnd = g.nodesEnd();
node != nodeEnd; ++node) {
unsigned vreg = problem.getVRegForNode(node);
unsigned alloc = solution.getSelection(node);
if (problem.isPRegOption(vreg, alloc)) {
unsigned preg = problem.getPRegForOption(vreg, alloc);
DEBUG(dbgs() << "VREG " << vreg << " -> " << tri->getName(preg) << "\n");
assert(preg != 0 && "Invalid preg selected.");
vrm->assignVirt2Phys(vreg, preg);
} else if (problem.isSpillOption(vreg, alloc)) {
vregsToAlloc.erase(vreg);
const LiveInterval* spillInterval = &lis->getInterval(vreg);
double oldWeight = spillInterval->weight;
rmf->rememberUseDefs(spillInterval);
std::vector<LiveInterval*> newSpills =
lis->addIntervalsForSpills(*spillInterval, 0, loopInfo, *vrm);
addStackInterval(spillInterval, mri);
rmf->rememberSpills(spillInterval, newSpills);
(void) oldWeight;
DEBUG(dbgs() << "VREG " << vreg << " -> SPILLED (Cost: "
<< oldWeight << ", New vregs: ");
for (std::vector<LiveInterval*>::const_iterator
itr = newSpills.begin(), end = newSpills.end();
itr != end; ++itr) {
assert(!(*itr)->empty() && "Empty spill range.");
DEBUG(dbgs() << (*itr)->reg << " ");
vregsToAlloc.insert((*itr)->reg);
}
DEBUG(dbgs() << ")\n");
anotherRoundNeeded |= !newSpills.empty();
} else {
assert(false && "Unknown allocation option.");
}
}
return !anotherRoundNeeded;
}
void RegAllocPBQP::finalizeAlloc() const {
typedef LiveIntervals::iterator LIIterator;
typedef LiveInterval::Ranges::const_iterator LRIterator;
for (RegSet::const_iterator
itr = emptyIntervalVRegs.begin(), end = emptyIntervalVRegs.end();
itr != end; ++itr) {
LiveInterval *li = &lis->getInterval(*itr);
unsigned physReg = vrm->getRegAllocPref(li->reg);
if (physReg == 0) {
const TargetRegisterClass *liRC = mri->getRegClass(li->reg);
physReg = *liRC->allocation_order_begin(*mf);
}
vrm->assignVirt2Phys(li->reg, physReg);
}
SmallVector<MachineBasicBlock*, 8> liveInMBBs;
MachineBasicBlock *entryMBB = &*mf->begin();
for (LIIterator liItr = lis->begin(), liEnd = lis->end();
liItr != liEnd; ++liItr) {
const LiveInterval *li = liItr->second;
unsigned reg = 0;
if (TargetRegisterInfo::isPhysicalRegister(li->reg)) {
reg = li->reg;
} else if (vrm->isAssignedReg(li->reg)) {
reg = vrm->getPhys(li->reg);
} else {
continue;
}
if (reg == 0) {
continue;
}
for (LRIterator lrItr = li->begin(), lrEnd = li->end();
lrItr != lrEnd; ++lrItr) {
if (lis->findLiveInMBBs(lrItr->start, lrItr->end, liveInMBBs)) {
for (unsigned i = 0; i != liveInMBBs.size(); ++i) {
if (liveInMBBs[i] != entryMBB) {
if (!liveInMBBs[i]->isLiveIn(reg)) {
liveInMBBs[i]->addLiveIn(reg);
}
}
}
liveInMBBs.clear();
}
}
}
}
bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
mf = &MF;
tm = &mf->getTarget();
tri = tm->getRegisterInfo();
tii = tm->getInstrInfo();
mri = &mf->getRegInfo();
lis = &getAnalysis<LiveIntervals>();
lss = &getAnalysis<LiveStacks>();
loopInfo = &getAnalysis<MachineLoopInfo>();
rmf = &getAnalysis<RenderMachineFunction>();
vrm = &getAnalysis<VirtRegMap>();
DEBUG(dbgs() << "PBQP Register Allocating for " << mf->getFunction()->getName() << "\n");
findVRegIntervalsToAlloc();
if (!vregsToAlloc.empty()) {
bool pbqpAllocComplete = false;
unsigned round = 0;
while (!pbqpAllocComplete) {
DEBUG(dbgs() << " PBQP Regalloc round " << round << ":\n");
std::auto_ptr<PBQPRAProblem> problem =
builder->build(mf, lis, loopInfo, vregsToAlloc);
PBQP::Solution solution =
PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
problem->getGraph());
pbqpAllocComplete = mapPBQPToRegAlloc(*problem, solution);
++round;
}
}
finalizeAlloc();
rmf->renderMachineFunction("After PBQP register allocation.", vrm);
vregsToAlloc.clear();
emptyIntervalVRegs.clear();
DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *vrm << "\n");
std::auto_ptr<VirtRegRewriter> rewriter(createVirtRegRewriter());
rewriter->runOnMachineFunction(*mf, *vrm, lis);
return true;
}
FunctionPass* llvm::createPBQPRegisterAllocator(
std::auto_ptr<PBQPBuilder> builder) {
return new RegAllocPBQP(builder);
}
FunctionPass* llvm::createDefaultPBQPRegisterAllocator() {
if (pbqpCoalescing) {
return createPBQPRegisterAllocator(
std::auto_ptr<PBQPBuilder>(new PBQPBuilderWithCoalescing()));
} return createPBQPRegisterAllocator(
std::auto_ptr<PBQPBuilder>(new PBQPBuilder()));
}
#undef DEBUG_TYPE