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Removed the older style (in-allocator) problem construction system from the PBQP allocator. Problem construction is now done exclusively with the new builders.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115502 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames 2010-10-04 12:13:07 +00:00
parent 3af96330a5
commit ab62b7e861
1 changed files with 9 additions and 628 deletions
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637
lib/CodeGen/RegAllocPBQP.cpp
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@ -67,12 +67,6 @@ pbqpCoalescing("pbqp-coalescing",
cl::desc("Attempt coalescing during PBQP register allocation."),
cl::init(false), cl::Hidden);
static cl::opt<bool>
pbqpBuilder("pbqp-builder",
cl::desc("Use new builder system."),
cl::init(true), cl::Hidden);
static cl::opt<bool>
pbqpPreSplitting("pbqp-pre-splitting",
cl::desc("Pre-split before PBQP register allocation."),
@ -129,74 +123,15 @@ private:
LiveStacks *lss;
VirtRegMap *vrm;
LI2NodeMap li2Node;
Node2LIMap node2LI;
AllowedSetMap allowedSets;
RegSet vregsToAlloc, emptyIntervalVRegs;
NodeVector problemNodes;
/// Builds a PBQP cost vector.
template <typename RegContainer>
PBQP::Vector buildCostVector(unsigned vReg,
const RegContainer &allowed,
const CoalesceMap &cealesces,
PBQP::PBQPNum spillCost) const;
/// \brief Builds a PBQP interference matrix.
///
/// @return Either a pointer to a non-zero PBQP matrix representing the
/// allocation option costs, or a null pointer for a zero matrix.
///
/// Expects allowed sets for two interfering LiveIntervals. These allowed
/// sets should contain only allocable registers from the LiveInterval's
/// register class, with any interfering pre-colored registers removed.
template <typename RegContainer>
PBQP::Matrix* buildInterferenceMatrix(const RegContainer &allowed1,
const RegContainer &allowed2) const;
///
/// Expects allowed sets for two potentially coalescable LiveIntervals,
/// and an estimated benefit due to coalescing. The allowed sets should
/// contain only allocable registers from the LiveInterval's register
/// classes, with any interfering pre-colored registers removed.
template <typename RegContainer>
PBQP::Matrix* buildCoalescingMatrix(const RegContainer &allowed1,
const RegContainer &allowed2,
PBQP::PBQPNum cBenefit) const;
/// \brief Finds coalescing opportunities and returns them as a map.
///
/// Any entries in the map are guaranteed coalescable, even if their
/// corresponding live intervals overlap.
CoalesceMap findCoalesces();
/// \brief Finds the initial set of vreg intervals to allocate.
void findVRegIntervalsToAlloc();
/// \brief Constructs a PBQP problem representation of the register
/// allocation problem for this function.
///
/// Old Construction Process - this functionality has been subsumed
/// by PBQPBuilder. This function will only be hanging around for a little
/// while until the new system has been fully tested.
///
/// @return a PBQP solver object for the register allocation problem.
PBQP::Graph constructPBQPProblemOld();
/// \brief Adds a stack interval if the given live interval has been
/// spilled. Used to support stack slot coloring.
void addStackInterval(const LiveInterval *spilled,MachineRegisterInfo* mri);
/// \brief Given a solved PBQP problem maps this solution back to a register
/// assignment.
///
/// Old Construction Process - this functionality has been subsumed
/// by PBQPBuilder. This function will only be hanging around for a little
/// while until the new system has been fully tested.
///
bool mapPBQPToRegAllocOld(const PBQP::Solution &solution);
/// \brief Given a solved PBQP problem maps this solution back to a register
/// assignment.
bool mapPBQPToRegAlloc(const PBQPRAProblem &problem,
@ -510,306 +445,6 @@ void RegAllocPBQP::getAnalysisUsage(AnalysisUsage &au) const {
MachineFunctionPass::getAnalysisUsage(au);
}
template <typename RegContainer>
PBQP::Vector RegAllocPBQP::buildCostVector(unsigned vReg,
const RegContainer &allowed,
const CoalesceMap &coalesces,
PBQP::PBQPNum spillCost) const {
typedef typename RegContainer::const_iterator AllowedItr;
// Allocate vector. Additional element (0th) used for spill option
PBQP::Vector v(allowed.size() + 1, 0);
v[0] = spillCost;
// Iterate over the allowed registers inserting coalesce benefits if there
// are any.
unsigned ai = 0;
for (AllowedItr itr = allowed.begin(), end = allowed.end();
itr != end; ++itr, ++ai) {
unsigned pReg = *itr;
CoalesceMap::const_iterator cmItr =
coalesces.find(RegPair(vReg, pReg));
// No coalesce - on to the next preg.
if (cmItr == coalesces.end())
continue;
// We have a coalesce - insert the benefit.
v[ai + 1] = -cmItr->second;
}
return v;
}
template <typename RegContainer>
PBQP::Matrix* RegAllocPBQP::buildInterferenceMatrix(
const RegContainer &allowed1, const RegContainer &allowed2) const {
typedef typename RegContainer::const_iterator RegContainerIterator;
// Construct a PBQP matrix representing the cost of allocation options. The
// rows and columns correspond to the allocation options for the two live
// intervals. Elements will be infinite where corresponding registers alias,
// since we cannot allocate aliasing registers to interfering live intervals.
// All other elements (non-aliasing combinations) will have zero cost. Note
// that the spill option (element 0,0) has zero cost, since we can allocate
// both intervals to memory safely (the cost for each individual allocation
// to memory is accounted for by the cost vectors for each live interval).
PBQP::Matrix *m =
new PBQP::Matrix(allowed1.size() + 1, allowed2.size() + 1, 0);
// Assume this is a zero matrix until proven otherwise. Zero matrices occur
// between interfering live ranges with non-overlapping register sets (e.g.
// non-overlapping reg classes, or disjoint sets of allowed regs within the
// same class). The term "overlapping" is used advisedly: sets which do not
// intersect, but contain registers which alias, will have non-zero matrices.
// We optimize zero matrices away to improve solver speed.
bool isZeroMatrix = true;
// Row index. Starts at 1, since the 0th row is for the spill option, which
// is always zero.
unsigned ri = 1;
// Iterate over allowed sets, insert infinities where required.
for (RegContainerIterator a1Itr = allowed1.begin(), a1End = allowed1.end();
a1Itr != a1End; ++a1Itr) {
// Column index, starts at 1 as for row index.
unsigned ci = 1;
unsigned reg1 = *a1Itr;
for (RegContainerIterator a2Itr = allowed2.begin(), a2End = allowed2.end();
a2Itr != a2End; ++a2Itr) {
unsigned reg2 = *a2Itr;
// If the row/column regs are identical or alias insert an infinity.
if (tri->regsOverlap(reg1, reg2)) {
(*m)[ri][ci] = std::numeric_limits<PBQP::PBQPNum>::infinity();
isZeroMatrix = false;
}
++ci;
}
++ri;
}
// If this turns out to be a zero matrix...
if (isZeroMatrix) {
// free it and return null.
delete m;
return 0;
}
// ...otherwise return the cost matrix.
return m;
}
template <typename RegContainer>
PBQP::Matrix* RegAllocPBQP::buildCoalescingMatrix(
const RegContainer &allowed1, const RegContainer &allowed2,
PBQP::PBQPNum cBenefit) const {
typedef typename RegContainer::const_iterator RegContainerIterator;
// Construct a PBQP Matrix representing the benefits of coalescing. As with
// interference matrices the rows and columns represent allowed registers
// for the LiveIntervals which are (potentially) to be coalesced. The amount
// -cBenefit will be placed in any element representing the same register
// for both intervals.
PBQP::Matrix *m =
new PBQP::Matrix(allowed1.size() + 1, allowed2.size() + 1, 0);
// Reset costs to zero.
m->reset(0);
// Assume the matrix is zero till proven otherwise. Zero matrices will be
// optimized away as in the interference case.
bool isZeroMatrix = true;
// Row index. Starts at 1, since the 0th row is for the spill option, which
// is always zero.
unsigned ri = 1;
// Iterate over the allowed sets, insert coalescing benefits where
// appropriate.
for (RegContainerIterator a1Itr = allowed1.begin(), a1End = allowed1.end();
a1Itr != a1End; ++a1Itr) {
// Column index, starts at 1 as for row index.
unsigned ci = 1;
unsigned reg1 = *a1Itr;
for (RegContainerIterator a2Itr = allowed2.begin(), a2End = allowed2.end();
a2Itr != a2End; ++a2Itr) {
// If the row and column represent the same register insert a beneficial
// cost to preference this allocation - it would allow us to eliminate a
// move instruction.
if (reg1 == *a2Itr) {
(*m)[ri][ci] = -cBenefit;
isZeroMatrix = false;
}
++ci;
}
++ri;
}
// If this turns out to be a zero matrix...
if (isZeroMatrix) {
// ...free it and return null.
delete m;
return 0;
}
return m;
}
RegAllocPBQP::CoalesceMap RegAllocPBQP::findCoalesces() {
typedef MachineFunction::const_iterator MFIterator;
typedef MachineBasicBlock::const_iterator MBBIterator;
typedef LiveInterval::const_vni_iterator VNIIterator;
CoalesceMap coalescesFound;
// To find coalesces we need to iterate over the function looking for
// copy instructions.
for (MFIterator bbItr = mf->begin(), bbEnd = mf->end();
bbItr != bbEnd; ++bbItr) {
const MachineBasicBlock *mbb = &*bbItr;
for (MBBIterator iItr = mbb->begin(), iEnd = mbb->end();
iItr != iEnd; ++iItr) {
const MachineInstr *instr = &*iItr;
// If this isn't a copy then continue to the next instruction.
if (!instr->isCopy())
continue;
unsigned srcReg = instr->getOperand(1).getReg();
unsigned dstReg = instr->getOperand(0).getReg();
// If the registers are already the same our job is nice and easy.
if (dstReg == srcReg)
continue;
bool srcRegIsPhysical = TargetRegisterInfo::isPhysicalRegister(srcReg),
dstRegIsPhysical = TargetRegisterInfo::isPhysicalRegister(dstReg);
// If both registers are physical then we can't coalesce.
if (srcRegIsPhysical && dstRegIsPhysical)
continue;
// If it's a copy that includes two virtual register but the source and
// destination classes differ then we can't coalesce.
if (!srcRegIsPhysical && !dstRegIsPhysical &&
mri->getRegClass(srcReg) != mri->getRegClass(dstReg))
continue;
// If one is physical and one is virtual, check that the physical is
// allocatable in the class of the virtual.
if (srcRegIsPhysical && !dstRegIsPhysical) {
const TargetRegisterClass *dstRegClass = mri->getRegClass(dstReg);
if (std::find(dstRegClass->allocation_order_begin(*mf),
dstRegClass->allocation_order_end(*mf), srcReg) ==
dstRegClass->allocation_order_end(*mf))
continue;
}
if (!srcRegIsPhysical && dstRegIsPhysical) {
const TargetRegisterClass *srcRegClass = mri->getRegClass(srcReg);
if (std::find(srcRegClass->allocation_order_begin(*mf),
srcRegClass->allocation_order_end(*mf), dstReg) ==
srcRegClass->allocation_order_end(*mf))
continue;
}
// If we've made it here we have a copy with compatible register classes.
// We can probably coalesce, but we need to consider overlap.
const LiveInterval *srcLI = &lis->getInterval(srcReg),
*dstLI = &lis->getInterval(dstReg);
if (srcLI->overlaps(*dstLI)) {
// Even in the case of an overlap we might still be able to coalesce,
// but we need to make sure that no definition of either range occurs
// while the other range is live.
// Otherwise start by assuming we're ok.
bool badDef = false;
// Test all defs of the source range.
for (VNIIterator
vniItr = srcLI->vni_begin(), vniEnd = srcLI->vni_end();
vniItr != vniEnd; ++vniItr) {
// If we find a poorly defined def we err on the side of caution.
if (!(*vniItr)->def.isValid()) {
badDef = true;
break;
}
// If we find a def that kills the coalescing opportunity then
// record it and break from the loop.
if (dstLI->liveAt((*vniItr)->def)) {
badDef = true;
break;
}
}
// If we have a bad def give up, continue to the next instruction.
if (badDef)
continue;
// Otherwise test definitions of the destination range.
for (VNIIterator
vniItr = dstLI->vni_begin(), vniEnd = dstLI->vni_end();
vniItr != vniEnd; ++vniItr) {
// We want to make sure we skip the copy instruction itself.
if ((*vniItr)->getCopy() == instr)
continue;
if (!(*vniItr)->def.isValid()) {
badDef = true;
break;
}
if (srcLI->liveAt((*vniItr)->def)) {
badDef = true;
break;
}
}
// As before a bad def we give up and continue to the next instr.
if (badDef)
continue;
}
// If we make it to here then either the ranges didn't overlap, or they
// did, but none of their definitions would prevent us from coalescing.
// We're good to go with the coalesce.
float cBenefit = std::pow(10.0f, (float)loopInfo->getLoopDepth(mbb)) / 5.0;
coalescesFound[RegPair(srcReg, dstReg)] = cBenefit;
coalescesFound[RegPair(dstReg, srcReg)] = cBenefit;
}
}
return coalescesFound;
}
void RegAllocPBQP::findVRegIntervalsToAlloc() {
// Iterate over all live ranges.
@ -834,171 +469,6 @@ void RegAllocPBQP::findVRegIntervalsToAlloc() {
}
}
PBQP::Graph RegAllocPBQP::constructPBQPProblemOld() {
typedef std::vector<const LiveInterval*> LIVector;
typedef std::vector<unsigned> RegVector;
// This will store the physical intervals for easy reference.
LIVector physIntervals;
// Start by clearing the old node <-> live interval mappings & allowed sets
li2Node.clear();
node2LI.clear();
allowedSets.clear();
// Populate physIntervals, update preg use:
for (LiveIntervals::iterator itr = lis->begin(), end = lis->end();
itr != end; ++itr) {
if (TargetRegisterInfo::isPhysicalRegister(itr->first)) {
physIntervals.push_back(itr->second);
mri->setPhysRegUsed(itr->second->reg);
}
}
// Iterate over vreg intervals, construct live interval <-> node number
// mappings.
for (RegSet::const_iterator itr = vregsToAlloc.begin(),
end = vregsToAlloc.end();
itr != end; ++itr) {
const LiveInterval *li = &lis->getInterval(*itr);
li2Node[li] = node2LI.size();
node2LI.push_back(li);
}
// Get the set of potential coalesces.
CoalesceMap coalesces;
if (pbqpCoalescing) {
coalesces = findCoalesces();
}
// Construct a PBQP solver for this problem
PBQP::Graph problem;
problemNodes.resize(vregsToAlloc.size());
// Resize allowedSets container appropriately.
allowedSets.resize(vregsToAlloc.size());
BitVector ReservedRegs = tri->getReservedRegs(*mf);
// Iterate over virtual register intervals to compute allowed sets...
for (unsigned node = 0; node < node2LI.size(); ++node) {
// Grab pointers to the interval and its register class.
const LiveInterval *li = node2LI[node];
const TargetRegisterClass *liRC = mri->getRegClass(li->reg);
// Start by assuming all allocable registers in the class are allowed...
RegVector liAllowed;
TargetRegisterClass::iterator aob = liRC->allocation_order_begin(*mf);
TargetRegisterClass::iterator aoe = liRC->allocation_order_end(*mf);
for (TargetRegisterClass::iterator it = aob; it != aoe; ++it)
if (!ReservedRegs.test(*it))
liAllowed.push_back(*it);
// Eliminate the physical registers which overlap with this range, along
// with all their aliases.
for (LIVector::iterator pItr = physIntervals.begin(),
pEnd = physIntervals.end(); pItr != pEnd; ++pItr) {
if (!li->overlaps(**pItr))
continue;
unsigned pReg = (*pItr)->reg;
// If we get here then the live intervals overlap, but we're still ok
// if they're coalescable.
if (coalesces.find(RegPair(li->reg, pReg)) != coalesces.end()) {
DEBUG(dbgs() << "CoalescingOverride: (" << li->reg << ", " << pReg << ")\n");
continue;
}
// If we get here then we have a genuine exclusion.
// Remove the overlapping reg...
RegVector::iterator eraseItr =
std::find(liAllowed.begin(), liAllowed.end(), pReg);
if (eraseItr != liAllowed.end())
liAllowed.erase(eraseItr);
const unsigned *aliasItr = tri->getAliasSet(pReg);
if (aliasItr != 0) {
// ...and its aliases.
for (; *aliasItr != 0; ++aliasItr) {
RegVector::iterator eraseItr =
std::find(liAllowed.begin(), liAllowed.end(), *aliasItr);
if (eraseItr != liAllowed.end()) {
liAllowed.erase(eraseItr);
}
}
}
}
// Copy the allowed set into a member vector for use when constructing cost
// vectors & matrices, and mapping PBQP solutions back to assignments.
allowedSets[node] = AllowedSet(liAllowed.begin(), liAllowed.end());
// Set the spill cost to the interval weight, or epsilon if the
// interval weight is zero
PBQP::PBQPNum spillCost = (li->weight != 0.0) ?
li->weight : std::numeric_limits<PBQP::PBQPNum>::min();
// Build a cost vector for this interval.
problemNodes[node] =
problem.addNode(
buildCostVector(li->reg, allowedSets[node], coalesces, spillCost));
}
// Now add the cost matrices...
for (unsigned node1 = 0; node1 < node2LI.size(); ++node1) {
const LiveInterval *li = node2LI[node1];
// Test for live range overlaps and insert interference matrices.
for (unsigned node2 = node1 + 1; node2 < node2LI.size(); ++node2) {
const LiveInterval *li2 = node2LI[node2];
CoalesceMap::const_iterator cmItr =
coalesces.find(RegPair(li->reg, li2->reg));
PBQP::Matrix *m = 0;
if (cmItr != coalesces.end()) {
m = buildCoalescingMatrix(allowedSets[node1], allowedSets[node2],
cmItr->second);
}
else if (li->overlaps(*li2)) {
m = buildInterferenceMatrix(allowedSets[node1], allowedSets[node2]);
}
if (m != 0) {
problem.addEdge(problemNodes[node1],
problemNodes[node2],
*m);
delete m;
}
}
}
assert(problem.getNumNodes() == allowedSets.size());
/*
std::cerr << "Allocating for " << problem.getNumNodes() << " nodes, "
<< problem.getNumEdges() << " edges.\n";
problem.printDot(std::cerr);
*/
// We're done, PBQP problem constructed - return it.
return problem;
}
void RegAllocPBQP::addStackInterval(const LiveInterval *spilled,
MachineRegisterInfo* mri) {
int stackSlot = vrm->getStackSlot(spilled->reg);
@ -1020,77 +490,6 @@ void RegAllocPBQP::addStackInterval(const LiveInterval *spilled,
stackInterval.MergeRangesInAsValue(rhsInterval, vni);
}
bool RegAllocPBQP::mapPBQPToRegAllocOld(const PBQP::Solution &solution) {
// Set to true if we have any spills
bool anotherRoundNeeded = false;
// Clear the existing allocation.
vrm->clearAllVirt();
// Iterate over the nodes mapping the PBQP solution to a register assignment.
for (unsigned node = 0; node < node2LI.size(); ++node) {
unsigned virtReg = node2LI[node]->reg,
allocSelection = solution.getSelection(problemNodes[node]);
// If the PBQP solution is non-zero it's a physical register...
if (allocSelection != 0) {
// Get the physical reg, subtracting 1 to account for the spill option.
unsigned physReg = allowedSets[node][allocSelection - 1];
DEBUG(dbgs() << "VREG " << virtReg << " -> "
<< tri->getName(physReg) << " (Option: " << allocSelection << ")\n");
assert(physReg != 0);
// Add to the virt reg map and update the used phys regs.
vrm->assignVirt2Phys(virtReg, physReg);
}
// ...Otherwise it's a spill.
else {
// Make sure we ignore this virtual reg on the next round
// of allocation
vregsToAlloc.erase(virtReg);
// Insert spill ranges for this live range
const LiveInterval *spillInterval = node2LI[node];
double oldSpillWeight = spillInterval->weight;
SmallVector<LiveInterval*, 8> spillIs;
rmf->rememberUseDefs(spillInterval);
std::vector<LiveInterval*> newSpills =
lis->addIntervalsForSpills(*spillInterval, spillIs, loopInfo, *vrm);
addStackInterval(spillInterval, mri);
rmf->rememberSpills(spillInterval, newSpills);
(void) oldSpillWeight;
DEBUG(dbgs() << "VREG " << virtReg << " -> SPILLED (Option: 0, Cost: "
<< oldSpillWeight << ", New vregs: ");
// Copy any newly inserted live intervals into the list of regs to
// allocate.
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");
// We need another round if spill intervals were added.
anotherRoundNeeded |= !newSpills.empty();
}
}
return !anotherRoundNeeded;
}
bool RegAllocPBQP::mapPBQPToRegAlloc(const PBQPRAProblem &problem,
const PBQP::Solution &solution) {
// Set to true if we have any spills
@ -1255,32 +654,18 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
bool pbqpAllocComplete = false;
unsigned round = 0;
if (!pbqpBuilder) {
while (!pbqpAllocComplete) {
DEBUG(dbgs() << " PBQP Regalloc round " << round << ":\n");
while (!pbqpAllocComplete) {
DEBUG(dbgs() << " PBQP Regalloc round " << round << ":\n");
PBQP::Graph problem = constructPBQPProblemOld();
PBQP::Solution solution =
PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(problem);
std::auto_ptr<PBQPRAProblem> problem =
builder->build(mf, lis, loopInfo, vregsToAlloc);
PBQP::Solution solution =
PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
problem->getGraph());
pbqpAllocComplete = mapPBQPToRegAllocOld(solution);
pbqpAllocComplete = mapPBQPToRegAlloc(*problem, solution);
++round;
}
} else {
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;
}
++round;
}
}
@ -1291,10 +676,6 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
vregsToAlloc.clear();
emptyIntervalVRegs.clear();
li2Node.clear();
node2LI.clear();
allowedSets.clear();
problemNodes.clear();
DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *vrm << "\n");