#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
+#include "Support/STLExtras.h"
#include <cmath>
#include <iostream>
#include <limits>
Statistic<> numIntervals("liveintervals", "Number of intervals");
Statistic<> numJoined ("liveintervals", "Number of joined intervals");
+ Statistic<> numPeep ("liveintervals", "Number of identity moves "
+ "eliminated after coalescing");
cl::opt<bool>
join("join-liveintervals",
{
mbbi2mbbMap_.clear();
mi2iMap_.clear();
- r2iMap_.clear();
+ i2miMap_.clear();
r2iMap_.clear();
r2rMap_.clear();
intervals_.clear();
/// runOnMachineFunction - Register allocate the whole function
///
bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
- DEBUG(std::cerr << "Machine Function\n");
+ DEBUG(std::cerr << "MACHINE FUNCTION: "; fn.print(std::cerr));
mf_ = &fn;
tm_ = &fn.getTarget();
mri_ = tm_->getRegisterInfo();
for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
mi != miEnd; ++mi) {
- inserted = mi2iMap_.insert(std::make_pair(*mi, miIndex)).second;
+ inserted = mi2iMap_.insert(std::make_pair(mi, miIndex)).second;
assert(inserted && "multiple MachineInstr -> index mappings");
- ++miIndex;
+ i2miMap_.push_back(mi);
+ miIndex += 2;
}
}
computeIntervals();
- // compute spill weights
+ numIntervals += intervals_.size();
+
+ // join intervals if requested
+ if (join) joinIntervals();
+
+ // perform a final pass over the instructions and compute spill
+ // weights, coalesce virtual registers and remove identity moves
const LoopInfo& loopInfo = getAnalysis<LoopInfo>();
const TargetInstrInfo& tii = tm_->getInstrInfo();
- for (MachineFunction::const_iterator mbbi = mf_->begin(),
- mbbe = mf_->end(); mbbi != mbbe; ++mbbi) {
- const MachineBasicBlock* mbb = mbbi;
+ for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
+ mbbi != mbbe; ++mbbi) {
+ MachineBasicBlock* mbb = mbbi;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
- for (MachineBasicBlock::const_iterator mii = mbb->begin(),
- mie = mbb->end(); mii != mie; ++mii) {
- MachineInstr* mi = *mii;
+ for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
+ mii != mie; ) {
+ for (unsigned i = 0; i < mii->getNumOperands(); ++i) {
+ const MachineOperand& mop = mii->getOperand(i);
+ if (mop.isRegister()) {
+ // replace register with representative register
+ unsigned reg = rep(mop.getReg());
+ mii->SetMachineOperandReg(i, reg);
+
+ if (MRegisterInfo::isVirtualRegister(reg)) {
+ Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
+ assert(r2iit != r2iMap_.end());
+ r2iit->second->weight += pow(10.0F, loopDepth);
+ }
+ }
+ }
- for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
- MachineOperand& mop = mi->getOperand(i);
- if (mop.isVirtualRegister()) {
- unsigned reg = mop.getAllocatedRegNum();
- Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
- assert(r2iit != r2iMap_.end());
- r2iit->second->weight += pow(10.0F, loopDepth);
+ // if the move is now an identity move delete it
+ unsigned srcReg, dstReg;
+ if (tii.isMoveInstr(*mii, srcReg, dstReg) && srcReg == dstReg) {
+ // remove index -> MachineInstr and
+ // MachineInstr -> index mappings
+ Mi2IndexMap::iterator mi2i = mi2iMap_.find(mii);
+ if (mi2i != mi2iMap_.end()) {
+ i2miMap_[mi2i->second/2] = 0;
+ mi2iMap_.erase(mi2i);
}
+ mii = mbbi->erase(mii);
+ ++numPeep;
}
+ else
+ ++mii;
}
}
- // join intervals if requested
- if (join) joinIntervals();
-
- numIntervals += intervals_.size();
-
intervals_.sort(StartPointComp());
+ DEBUG(std::cerr << "*** INTERVALS ***\n");
DEBUG(std::copy(intervals_.begin(), intervals_.end(),
std::ostream_iterator<Interval>(std::cerr, "\n")));
+ DEBUG(std::cerr << "*** MACHINEINSTRS ***\n");
+ DEBUG(
+ for (unsigned i = 0; i != i2miMap_.size(); ++i) {
+ if (const MachineInstr* mi = i2miMap_[i]) {
+ std:: cerr << i*2 << '\t';
+ mi->print(std::cerr, *tm_);
+ }
+ });
+
return true;
}
+void LiveIntervals::updateSpilledInterval(Interval& li)
+{
+ assert(li.weight != std::numeric_limits<float>::infinity() &&
+ "attempt to spill already spilled interval!");
+ Interval::Ranges oldRanges;
+ swap(oldRanges, li.ranges);
+
+ for (Interval::Ranges::iterator i = oldRanges.begin(), e = oldRanges.end();
+ i != e; ++i) {
+ unsigned index = i->first & ~1;
+ unsigned end = i->second;
+
+ for (; index < end; index += 2) {
+ // skip deleted instructions
+ while (!getInstructionFromIndex(index)) index += 2;
+ MachineInstr* mi = getInstructionFromIndex(index);
+ for (unsigned i = 0; i < mi->getNumOperands(); ++i) {
+ MachineOperand& mop = mi->getOperand(i);
+ if (mop.isRegister()) {
+ unsigned reg = mop.getReg();
+ if (rep(reg) == li.reg) {
+ if (mop.isUse())
+ li.addRange(index, index+2);
+ else
+ li.addRange(index+1, index+2);
+ }
+ }
+ }
+ }
+ }
+ // the new spill weight is now infinity as it cannot be spilled again
+ li.weight = std::numeric_limits<float>::infinity();
+}
+
void LiveIntervals::printRegName(unsigned reg) const
{
if (MRegisterInfo::isPhysicalRegister(reg))
{
DEBUG(std::cerr << "\t\tregister: ";printRegName(reg); std::cerr << '\n');
- unsigned instrIndex = getInstructionIndex(*mi);
-
LiveVariables::VarInfo& vi = lv_->getVarInfo(reg);
Interval* interval = 0;
// update interval index for this register
r2iMap_.insert(r2iit, std::make_pair(reg, --intervals_.end()));
interval = &intervals_.back();
+
+ // iterate over all of the blocks that the variable is
+ // completely live in, adding them to the live
+ // interval. obviously we only need to do this once.
+ for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
+ if (vi.AliveBlocks[i]) {
+ MachineBasicBlock* mbb = lv_->getIndexMachineBasicBlock(i);
+ if (!mbb->empty()) {
+ interval->addRange(getInstructionIndex(&mbb->front()),
+ getInstructionIndex(&mbb->back()) + 1);
+ }
+ }
+ }
}
else {
interval = &*r2iit->second;
}
- // iterate over all of the blocks that the variable is completely
- // live in, adding them to the live interval
- for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
- if (vi.AliveBlocks[i]) {
- MachineBasicBlock* mbb = lv_->getIndexMachineBasicBlock(i);
- if (!mbb->empty()) {
- interval->addRange(getInstructionIndex(mbb->front()),
- getInstructionIndex(mbb->back()) + 1);
- }
- }
- }
+ // we consider defs to happen at the second time slot of the
+ // instruction
+ unsigned instrIndex = getInstructionIndex(mi) + 1;
bool killedInDefiningBasicBlock = false;
for (int i = 0, e = vi.Kills.size(); i != e; ++i) {
MachineInstr* killerInstr = vi.Kills[i].second;
unsigned start = (mbb == killerBlock ?
instrIndex :
- getInstructionIndex(killerBlock->front()));
- unsigned end = getInstructionIndex(killerInstr) + 1;
+ getInstructionIndex(&killerBlock->front()));
+ unsigned end = (killerInstr == mi ?
+ instrIndex + 1 : // dead
+ getInstructionIndex(killerInstr) + 1); // killed
// we do not want to add invalid ranges. these can happen when
// a variable has its latest use and is redefined later on in
// the same basic block (common with variables introduced by
}
if (!killedInDefiningBasicBlock) {
- unsigned end = getInstructionIndex(mbb->back()) + 1;
+ unsigned end = getInstructionIndex(&mbb->back()) + 1;
interval->addRange(instrIndex, end);
}
}
DEBUG(std::cerr << "\t\tregister: "; printRegName(reg));
MachineBasicBlock::iterator e = mbb->end();
- unsigned start = getInstructionIndex(*mi);
- unsigned end = start + 1;
+ // we consider defs to happen at the second time slot of the
+ // instruction
+ unsigned start, end;
+ start = end = getInstructionIndex(mi) + 1;
// a variable can be dead by the instruction defining it
- for (KillIter ki = lv_->dead_begin(*mi), ke = lv_->dead_end(*mi);
+ for (KillIter ki = lv_->dead_begin(mi), ke = lv_->dead_end(mi);
ki != ke; ++ki) {
if (reg == ki->second) {
DEBUG(std::cerr << " dead\n");
+ ++end;
goto exit;
}
}
// a variable can only be killed by subsequent instructions
do {
++mi;
- ++end;
- for (KillIter ki = lv_->killed_begin(*mi), ke = lv_->killed_end(*mi);
+ end += 2;
+ for (KillIter ki = lv_->killed_begin(mi), ke = lv_->killed_end(mi);
ki != ke; ++ki) {
if (reg == ki->second) {
DEBUG(std::cerr << " killed\n");
unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
{
- assert(mi2iMap_.find(instr) != mi2iMap_.end() &&
- "instruction not assigned a number");
- return mi2iMap_.find(instr)->second;
+ Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
+ return it == mi2iMap_.end() ? std::numeric_limits<unsigned>::max() : it->second;
+}
+
+MachineInstr* LiveIntervals::getInstructionFromIndex(unsigned index) const
+{
+ index /= 2; // convert index to vector index
+ assert(index < i2miMap_.size() &&
+ "index does not correspond to an instruction");
+ return i2miMap_[index];
}
/// computeIntervals - computes the live intervals for virtual
/// which a variable is live
void LiveIntervals::computeIntervals()
{
- DEBUG(std::cerr << "computing live intervals:\n");
+ DEBUG(std::cerr << "*** COMPUTING LIVE INTERVALS ***\n");
for (MbbIndex2MbbMap::iterator
it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
it != itEnd; ++it) {
MachineBasicBlock* mbb = it->second;
- DEBUG(std::cerr << "machine basic block: "
- << mbb->getBasicBlock()->getName() << "\n");
+ DEBUG(std::cerr << mbb->getBasicBlock()->getName() << ":\n");
for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
mi != miEnd; ++mi) {
- MachineInstr* instr = *mi;
const TargetInstrDescriptor& tid =
- tm_->getInstrInfo().get(instr->getOpcode());
- DEBUG(std::cerr << "\t[" << getInstructionIndex(instr) << "] ";
- instr->print(std::cerr, *tm_););
+ tm_->getInstrInfo().get(mi->getOpcode());
+ DEBUG(std::cerr << "[" << getInstructionIndex(mi) << "]\t";
+ mi->print(std::cerr, *tm_););
// handle implicit defs
for (const unsigned* id = tid.ImplicitDefs; *id; ++id)
handleRegisterDef(mbb, mi, *id);
// handle explicit defs
- for (int i = instr->getNumOperands() - 1; i >= 0; --i) {
- MachineOperand& mop = instr->getOperand(i);
+ for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
+ MachineOperand& mop = mi->getOperand(i);
// handle register defs - build intervals
if (mop.isRegister() && mop.isDef())
- handleRegisterDef(mbb, mi, mop.getAllocatedRegNum());
+ handleRegisterDef(mbb, mi, mop.getReg());
}
}
}
void LiveIntervals::joinIntervals()
{
- DEBUG(std::cerr << "joining compatible intervals:\n");
+ DEBUG(std::cerr << "** JOINING 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 (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
+ mbbi != mbbe; ++mbbi) {
+ MachineBasicBlock* mbb = mbbi;
+ DEBUG(std::cerr << mbb->getBasicBlock()->getName() << ":\n");
- for (MachineBasicBlock::const_iterator mii = mbb->begin(),
- mie = mbb->end(); mii != mie; ++mii) {
- MachineInstr* mi = *mii;
+ for (MachineBasicBlock::iterator mi = mbb->begin(), mie = mbb->end();
+ mi != mie; ++mi) {
const TargetInstrDescriptor& tid =
tm_->getInstrInfo().get(mi->getOpcode());
- DEBUG(std::cerr << "\t\tinstruction["
- << getInstructionIndex(mi) << "]: ";
+ DEBUG(std::cerr << "[" << getInstructionIndex(mi) << "]\t";
mi->print(std::cerr, *tm_););
// we only join virtual registers with allocatable
LiveIntervals::Interval::Interval(unsigned r)
: reg(r),
weight((MRegisterInfo::isPhysicalRegister(r) ?
- std::numeric_limits<float>::max() : 0.0F))
+ std::numeric_limits<float>::infinity() : 0.0F))
{
}
-// This example is provided becaues liveAt() is non-obvious:
+// An example for liveAt():
//
-// this = [1,2), liveAt(1) will return false. The idea is that the
-// variable is defined in 1 and not live after definition. So it was
-// dead to begin with (defined but never used).
+// this = [1,2), liveAt(0) will return false. The instruction defining
+// this spans slots [0,1]. Since it is a definition we say that it is
+// live in the second slot onwards. By ending the lifetime of this
+// interval at 2 it means that it is not used at all. liveAt(1)
+// returns true which means that this clobbers a register at
+// instruction at 0.
//
-// this = [1,3), liveAt(2) will return false. The variable is used at
-// 2 but 2 is the last use so the variable's allocated register is
-// available for reuse.
+// this = [1,4), liveAt(0) will return false and liveAt(2) will return
+// true. The variable is defined at instruction 0 and last used at 2.
bool LiveIntervals::Interval::liveAt(unsigned index) const
{
Range dummy(index, index+1);
return false;
--r;
- return index >= r->first && index < (r->second - 1);
+ return index >= r->first && index < r->second;
}
-// This example is provided because overlaps() is non-obvious:
+// An example for overlaps():
//
// 0: A = ...
-// 1: B = ...
-// 2: C = A + B ;; last use of A
+// 2: B = ...
+// 4: C = A + B ;; last use of A
//
// The live intervals should look like:
//
-// A = [0, 3)
-// B = [1, x)
-// C = [2, y)
+// A = [1, 5)
+// B = [3, x)
+// C = [5, y)
//
// A->overlaps(C) should return false since we want to be able to join
// A and C.
}
assert(i->first < j->first);
- if ((i->second - 1) > j->first) {
+ if (i->second > j->first) {
return true;
}
else {
projects / oota-llvm.git / blobdiff