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Add option to join live intervals. Two intervals are joined if there

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is a move between two registers, at least one of the registers is
virtual and the two live intervals do not overlap.

This results in about 40% reduction in intervals, 30% decrease in the
register allocators running time and a 20% increase in peephole
optimizations (mainly move eliminations).

The option can be enabled by passing -join-liveintervals where
appropriate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10965 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alkis Evlogimenos 2004-01-22 23:08:45 +00:00
parent 8abff7945a
commit e88280a422
5 changed files with 300 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
include/llvm/CodeGen/LiveIntervalAnalysis.h
View File

@ -26,6 +26,7 @@
#include <iostream>
#include <list>
#include <map>
#include <vector>
namespace llvm {
@ -39,10 +40,9 @@ namespace llvm {
typedef std::pair<unsigned, unsigned> Range;
typedef std::vector<Range> Ranges;
unsigned reg; // the register of this interval
unsigned hint;
float weight; // weight of this interval (number of uses
// * 10^loopDepth)
Ranges ranges; // the ranges this register is valid
Ranges ranges; // the ranges in which this register is live
Interval(unsigned r);
@ -66,10 +66,12 @@ namespace llvm {
void addRange(unsigned start, unsigned end);
private:
void mergeRangesForward(Ranges::iterator it);
void join(const Interval& other);
void mergeRangesBackward(Ranges::iterator it);
private:
Ranges::iterator mergeRangesForward(Ranges::iterator it);
Ranges::iterator mergeRangesBackward(Ranges::iterator it);
};
struct StartPointComp {
@ -85,6 +87,7 @@ namespace llvm {
};
typedef std::list<Interval> Intervals;
typedef std::map<unsigned, unsigned> Reg2RegMap;
typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
private:
@ -104,11 +107,15 @@ namespace llvm {
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
Reg2RegMap r2rMap_;
Intervals intervals_;
public:
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
Intervals& getIntervals() { return intervals_; }
MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
MachineBasicBlockPtrs result;
for (MbbIndex2MbbMap::const_iterator
@ -119,6 +126,13 @@ namespace llvm {
return result;
}
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
private:
/// runOnMachineFunction - pass entry point
bool runOnMachineFunction(MachineFunction&);
@ -126,6 +140,8 @@ namespace llvm {
/// computeIntervals - compute live intervals
void computeIntervals();
/// joinIntervals - join compatible live intervals
void joinIntervals();
/// handleRegisterDef - update intervals for a register def
/// (calls handlePhysicalRegisterDef and

26
include/llvm/CodeGen/LiveIntervals.h
View File

@ -26,6 +26,7 @@
#include <iostream>
#include <list>
#include <map>
#include <vector>
namespace llvm {
@ -39,10 +40,9 @@ namespace llvm {
typedef std::pair<unsigned, unsigned> Range;
typedef std::vector<Range> Ranges;
unsigned reg; // the register of this interval
unsigned hint;
float weight; // weight of this interval (number of uses
// * 10^loopDepth)
Ranges ranges; // the ranges this register is valid
Ranges ranges; // the ranges in which this register is live
Interval(unsigned r);
@ -66,10 +66,12 @@ namespace llvm {
void addRange(unsigned start, unsigned end);
private:
void mergeRangesForward(Ranges::iterator it);
void join(const Interval& other);
void mergeRangesBackward(Ranges::iterator it);
private:
Ranges::iterator mergeRangesForward(Ranges::iterator it);
Ranges::iterator mergeRangesBackward(Ranges::iterator it);
};
struct StartPointComp {
@ -85,6 +87,7 @@ namespace llvm {
};
typedef std::list<Interval> Intervals;
typedef std::map<unsigned, unsigned> Reg2RegMap;
typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
private:
@ -104,11 +107,15 @@ namespace llvm {
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
Reg2RegMap r2rMap_;
Intervals intervals_;
public:
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
Intervals& getIntervals() { return intervals_; }
MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
MachineBasicBlockPtrs result;
for (MbbIndex2MbbMap::const_iterator
@ -119,6 +126,13 @@ namespace llvm {
return result;
}
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
private:
/// runOnMachineFunction - pass entry point
bool runOnMachineFunction(MachineFunction&);
@ -126,6 +140,8 @@ namespace llvm {
/// computeIntervals - compute live intervals
void computeIntervals();
/// joinIntervals - join compatible live intervals
void joinIntervals();
/// handleRegisterDef - update intervals for a register def
/// (calls handlePhysicalRegisterDef and

219
lib/CodeGen/LiveIntervalAnalysis.cpp
View File

@ -30,6 +30,7 @@
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegInfo.h"
#include "llvm/Support/CFG.h"
#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/DepthFirstIterator.h"
#include "Support/Statistic.h"
@ -44,6 +45,11 @@ namespace {
"Live Interval Analysis");
Statistic<> numIntervals("liveintervals", "Number of intervals");
cl::opt<bool>
join("join-liveintervals",
cl::desc("Join compatible live intervals"),
cl::init(false));
};
void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
@ -69,6 +75,7 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
mi2iMap_.clear();
r2iMap_.clear();
r2iMap_.clear();
r2rMap_.clear();
intervals_.clear();
// number MachineInstrs
@ -95,18 +102,17 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
const LoopInfo& loopInfo = getAnalysis<LoopInfo>();
const TargetInstrInfo& tii = tm_->getInstrInfo();
for (MbbIndex2MbbMap::iterator
it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
it != itEnd; ++it) {
MachineBasicBlock* mbb = it->second;
for (MachineFunction::const_iterator mbbi = mf_->begin(),
mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
const MachineBasicBlock* mbb = mbbi;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
mi != miEnd; ++mi) {
MachineInstr* instr = *mi;
for (int i = instr->getNumOperands() - 1; i >= 0; --i) {
MachineOperand& mop = instr->getOperand(i);
for (MachineBasicBlock::const_iterator mii = mbb->begin(),
mie = mbb->end(); mii != mie; ++mii) {
MachineInstr* mi = *mii;
for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
MachineOperand& mop = mi->getOperand(i);
if (!mop.isVirtualRegister())
continue;
@ -119,6 +125,9 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
}
}
// join intervals if requested
if (join) joinIntervals();
numIntervals += intervals_.size();
return true;
@ -326,48 +335,111 @@ void LiveIntervals::computeIntervals()
std::ostream_iterator<Interval>(std::cerr, "\n")));
}
unsigned LiveIntervals::rep(unsigned reg)
{
Reg2RegMap::iterator it = r2rMap_.find(reg);
if (it != r2rMap_.end())
return it->second = rep(it->second);
return reg;
}
void LiveIntervals::joinIntervals()
{
DEBUG(std::cerr << "joining compatible intervals:\n");
const TargetInstrInfo& tii = tm_->getInstrInfo();
for (MachineFunction::const_iterator mbbi = mf_->begin(),
mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
const MachineBasicBlock* mbb = mbbi;
DEBUG(std::cerr << "machine basic block: "
<< mbb->getBasicBlock()->getName() << "\n");
for (MachineBasicBlock::const_iterator mii = mbb->begin(),
mie = mbb->end(); mii != mie; ++mii) {
MachineInstr* mi = *mii;
const TargetInstrDescriptor& tid =
tm_->getInstrInfo().get(mi->getOpcode());
DEBUG(std::cerr << "\t\tinstruction["
<< getInstructionIndex(mi) << "]: ";
mi->print(std::cerr, *tm_););
unsigned srcReg, dstReg;
if (tii.isMoveInstr(*mi, srcReg, dstReg) &&
(srcReg >= MRegisterInfo::FirstVirtualRegister ||
lv_->getAllocatablePhysicalRegisters()[srcReg]) &&
(dstReg >= MRegisterInfo::FirstVirtualRegister ||
lv_->getAllocatablePhysicalRegisters()[dstReg])) {
// get representative registers
srcReg = rep(srcReg);
dstReg = rep(dstReg);
// if they are already joined we continue
if (srcReg == dstReg)
continue;
Reg2IntervalMap::iterator r2iSrc = r2iMap_.find(srcReg);
assert(r2iSrc != r2iMap_.end());
Reg2IntervalMap::iterator r2iDst = r2iMap_.find(dstReg);
assert(r2iDst != r2iMap_.end());
Intervals::iterator srcInt = r2iSrc->second;
Intervals::iterator dstInt = r2iDst->second;
if (srcInt->reg < MRegisterInfo::FirstVirtualRegister) {
if (dstInt->reg == srcInt->reg ||
(dstInt->reg >= MRegisterInfo::FirstVirtualRegister &&
!dstInt->overlaps(*srcInt))) {
srcInt->join(*dstInt);
r2iDst->second = r2iSrc->second;
r2rMap_.insert(std::make_pair(dstInt->reg, srcInt->reg));
intervals_.erase(dstInt);
}
}
else if (dstInt->reg < MRegisterInfo::FirstVirtualRegister) {
if (srcInt->reg == dstInt->reg ||
(srcInt->reg >= MRegisterInfo::FirstVirtualRegister &&
!srcInt->overlaps(*dstInt))) {
dstInt->join(*srcInt);
r2iSrc->second = r2iDst->second;
r2rMap_.insert(std::make_pair(srcInt->reg, dstInt->reg));
intervals_.erase(srcInt);
}
}
else {
const TargetRegisterClass *srcRc, *dstRc;
srcRc = mf_->getSSARegMap()->getRegClass(srcInt->reg);
dstRc = mf_->getSSARegMap()->getRegClass(dstInt->reg);
if (srcRc == dstRc && !dstInt->overlaps(*srcInt)) {
srcInt->join(*dstInt);
r2iDst->second = r2iSrc->second;
r2rMap_.insert(std::make_pair(dstInt->reg, srcInt->reg));
intervals_.erase(dstInt);
}
}
}
}
}
intervals_.sort(StartPointComp());
DEBUG(std::copy(intervals_.begin(), intervals_.end(),
std::ostream_iterator<Interval>(std::cerr, "\n")));
DEBUG(for (Reg2RegMap::const_iterator i = r2rMap_.begin(),
e = r2rMap_.end(); i != e; ++i)
std::cerr << i->first << " -> " << i->second << '\n';);
}
LiveIntervals::Interval::Interval(unsigned r)
: reg(r), hint(0),
: reg(r),
weight((r < MRegisterInfo::FirstVirtualRegister ?
std::numeric_limits<float>::max() : 0.0F))
{
}
void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
{
DEBUG(std::cerr << "\t\t\tadding range: [" << start <<','<< end << ") -> ");
//assert(start < end && "invalid range?");
Range range = std::make_pair(start, end);
Ranges::iterator it =
ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
range);
mergeRangesForward(it);
mergeRangesBackward(it);
DEBUG(std::cerr << *this << '\n');
}
void LiveIntervals::Interval::mergeRangesForward(Ranges::iterator it)
{
for (Ranges::iterator next = it + 1;
next != ranges.end() && it->second >= next->first; ) {
it->second = std::max(it->second, next->second);
next = ranges.erase(next);
}
}
void LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
{
for (Ranges::iterator prev = it - 1;
it != ranges.begin() && it->first <= prev->second; ) {
it->first = std::min(it->first, prev->first);
it->second = std::max(it->second, prev->second);
it = ranges.erase(prev);
prev = it - 1;
}
}
bool LiveIntervals::Interval::liveAt(unsigned index) const
{
Ranges::const_iterator r = ranges.begin();
@ -409,6 +481,63 @@ bool LiveIntervals::Interval::overlaps(const Interval& other) const
return false;
}
void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
{
DEBUG(std::cerr << "\t\t\tadding range: [" << start <<','<< end << ") -> ");
//assert(start < end && "invalid range?");
Range range = std::make_pair(start, end);
Ranges::iterator it =
ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
range);
it = mergeRangesForward(it);
it = mergeRangesBackward(it);
DEBUG(std::cerr << "\t\t\t\tafter merging: " << *this << '\n');
}
void LiveIntervals::Interval::join(const LiveIntervals::Interval& other)
{
DEBUG(std::cerr << "\t\t\t\tjoining intervals: "
<< other << " and " << *this << '\n');
Ranges::iterator cur = ranges.begin();
for (Ranges::const_iterator i = other.ranges.begin(),
e = other.ranges.end(); i != e; ++i) {
cur = ranges.insert(std::upper_bound(cur, ranges.end(), *i), *i);
cur = mergeRangesForward(cur);
cur = mergeRangesBackward(cur);
}
if (reg >= MRegisterInfo::FirstVirtualRegister)
weight += other.weight;
DEBUG(std::cerr << "\t\t\t\tafter merging: " << *this << '\n');
}
LiveIntervals::Interval::Ranges::iterator
LiveIntervals::Interval::mergeRangesForward(Ranges::iterator it)
{
for (Ranges::iterator next = it + 1;
next != ranges.end() && it->second >= next->first; ) {
it->second = std::max(it->second, next->second);
next = ranges.erase(next);
}
return it;
}
LiveIntervals::Interval::Ranges::iterator
LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
{
for (Ranges::iterator prev = it - 1;
it != ranges.begin() && it->first <= prev->second; ) {
it->first = std::min(it->first, prev->first);
it->second = std::max(it->second, prev->second);
it = ranges.erase(prev);
prev = it - 1;
}
return it;
}
std::ostream& llvm::operator<<(std::ostream& os,
const LiveIntervals::Interval& li)
{

26
lib/CodeGen/LiveIntervalAnalysis.h
View File

@ -26,6 +26,7 @@
#include <iostream>
#include <list>
#include <map>
#include <vector>
namespace llvm {
@ -39,10 +40,9 @@ namespace llvm {
typedef std::pair<unsigned, unsigned> Range;
typedef std::vector<Range> Ranges;
unsigned reg; // the register of this interval
unsigned hint;
float weight; // weight of this interval (number of uses
// * 10^loopDepth)
Ranges ranges; // the ranges this register is valid
Ranges ranges; // the ranges in which this register is live
Interval(unsigned r);
@ -66,10 +66,12 @@ namespace llvm {
void addRange(unsigned start, unsigned end);
private:
void mergeRangesForward(Ranges::iterator it);
void join(const Interval& other);
void mergeRangesBackward(Ranges::iterator it);
private:
Ranges::iterator mergeRangesForward(Ranges::iterator it);
Ranges::iterator mergeRangesBackward(Ranges::iterator it);
};
struct StartPointComp {
@ -85,6 +87,7 @@ namespace llvm {
};
typedef std::list<Interval> Intervals;
typedef std::map<unsigned, unsigned> Reg2RegMap;
typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
private:
@ -104,11 +107,15 @@ namespace llvm {
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
Reg2RegMap r2rMap_;
Intervals intervals_;
public:
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
Intervals& getIntervals() { return intervals_; }
MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
MachineBasicBlockPtrs result;
for (MbbIndex2MbbMap::const_iterator
@ -119,6 +126,13 @@ namespace llvm {
return result;
}
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
private:
/// runOnMachineFunction - pass entry point
bool runOnMachineFunction(MachineFunction&);
@ -126,6 +140,8 @@ namespace llvm {
/// computeIntervals - compute live intervals
void computeIntervals();
/// joinIntervals - join compatible live intervals
void joinIntervals();
/// handleRegisterDef - update intervals for a register def
/// (calls handlePhysicalRegisterDef and

67
lib/CodeGen/RegAllocLinearScan.cpp
View File

@ -32,12 +32,15 @@ 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 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;
@ -203,8 +206,8 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
mf_ = &fn;
tm_ = &fn.getTarget();
mri_ = tm_->getRegisterInfo();
initIntervalSets(getAnalysis<LiveIntervals>().getIntervals());
li_ = &getAnalysis<LiveIntervals>();
initIntervalSets(li_->getIntervals());
v2pMap_.clear();
v2ssMap_.clear();
@ -231,6 +234,7 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
reserved_[29] = true; /* FP6 */
// linear scan algorithm
DEBUG(std::cerr << "Machine Function\n");
DEBUG(printIntervals("\tunhandled", unhandled_.begin(), unhandled_.end()));
DEBUG(printIntervals("\tfixed", fixed_.begin(), fixed_.end()));
@ -324,15 +328,54 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
active_.clear();
inactive_.clear();
DEBUG(std::cerr << "finished register allocation\n");
typedef LiveIntervals::Reg2RegMap Reg2RegMap;
const Reg2RegMap& r2rMap = li_->getJoinedRegMap();
DEBUG(printVirtRegAssignment());
DEBUG(std::cerr << "Performing coalescing on joined intervals\n");
// perform coalescing if we were passed joined intervals
for(Reg2RegMap::const_iterator i = r2rMap.begin(), e = r2rMap.end();
i != e; ++i) {
unsigned reg = i->first;
unsigned rep = li_->rep(reg);
assert((rep < MRegisterInfo::FirstVirtualRegister ||
v2pMap_.find(rep) != v2pMap_.end() ||
v2ssMap_.find(rep) != v2ssMap_.end()) &&
"representative register is not allocated!");
assert(reg >= MRegisterInfo::FirstVirtualRegister &&
v2pMap_.find(reg) == v2pMap_.end() &&
v2ssMap_.find(reg) == v2ssMap_.end() &&
"coalesced register is already allocated!");
if (rep < MRegisterInfo::FirstVirtualRegister) {
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(); ++currentInstr_) {
currentInstr_ != currentMbb_->end(); ) {
DEBUG(std::cerr << "\tinstruction: ";
(*currentInstr_)->print(std::cerr, *tm_););
@ -355,6 +398,21 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
}
}
unsigned srcReg, dstReg;
if (tii.isMoveInstr(**currentInstr_, srcReg, dstReg) &&
((srcReg < MRegisterInfo::FirstVirtualRegister &&
dstReg < MRegisterInfo::FirstVirtualRegister &&
srcReg == dstReg) ||
(srcReg >= MRegisterInfo::FirstVirtualRegister &&
dstReg >= MRegisterInfo::FirstVirtualRegister &&
v2ssMap_[srcReg] == v2ssMap_[dstReg]))) {
delete *currentInstr_;
currentInstr_ = currentMbb_->erase(currentInstr_);
++numPeep;
DEBUG(std::cerr << "\t\tdeleting instruction\n");
continue;
}
DEBUG(std::cerr << "\t\tloading temporarily used operands to "
"registers:\n");
for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
@ -416,6 +474,7 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
}
--currentInstr_; // restore currentInstr_ iterator
tempDefOperands_.clear();
++currentInstr_;
}
}