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Eliminate the use of spill (reserved) registers.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11476 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alkis Evlogimenos 2004-02-15 10:24:21 +00:00
parent 9f3c7f7da9
commit 843b160a20
5 changed files with 354 additions and 364 deletions
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17
include/llvm/CodeGen/LiveIntervalAnalysis.h
View File

@ -100,6 +100,9 @@ namespace llvm {
typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
Mi2IndexMap mi2iMap_;
typedef std::vector<MachineInstr*> Index2MiMap;
Index2MiMap i2miMap_;
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
@ -114,14 +117,13 @@ namespace llvm {
/// runOnMachineFunction - pass entry point
virtual bool runOnMachineFunction(MachineFunction&);
unsigned getInstructionIndex(MachineInstr* instr) const;
MachineInstr* getInstructionFromIndex(unsigned index) const;
Intervals& getIntervals() { return intervals_; }
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void updateSpilledInterval(Interval& i);
private:
/// computeIntervals - compute live intervals
@ -151,7 +153,8 @@ namespace llvm {
bool overlapsAliases(const Interval& lhs, const Interval& rhs) const;
unsigned getInstructionIndex(MachineInstr* instr) const;
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void printRegName(unsigned reg) const;
};

17
include/llvm/CodeGen/LiveIntervals.h
View File

@ -100,6 +100,9 @@ namespace llvm {
typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
Mi2IndexMap mi2iMap_;
typedef std::vector<MachineInstr*> Index2MiMap;
Index2MiMap i2miMap_;
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
@ -114,14 +117,13 @@ namespace llvm {
/// runOnMachineFunction - pass entry point
virtual bool runOnMachineFunction(MachineFunction&);
unsigned getInstructionIndex(MachineInstr* instr) const;
MachineInstr* getInstructionFromIndex(unsigned index) const;
Intervals& getIntervals() { return intervals_; }
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void updateSpilledInterval(Interval& i);
private:
/// computeIntervals - compute live intervals
@ -151,7 +153,8 @@ namespace llvm {
bool overlapsAliases(const Interval& lhs, const Interval& rhs) const;
unsigned getInstructionIndex(MachineInstr* instr) const;
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void printRegName(unsigned reg) const;
};

146
lib/CodeGen/LiveIntervalAnalysis.cpp
View File

@ -30,6 +30,7 @@
#include "Support/CommandLine.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
#include "Support/STLExtras.h"
#include <cmath>
#include <iostream>
#include <limits>
@ -42,6 +43,8 @@ namespace {
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",
@ -64,7 +67,7 @@ void LiveIntervals::releaseMemory()
{
mbbi2mbbMap_.clear();
mi2iMap_.clear();
r2iMap_.clear();
i2miMap_.clear();
r2iMap_.clear();
r2rMap_.clear();
intervals_.clear();
@ -74,7 +77,7 @@ void LiveIntervals::releaseMemory()
/// 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();
@ -94,47 +97,110 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
mi != miEnd; ++mi) {
inserted = mi2iMap_.insert(std::make_pair(mi, miIndex)).second;
assert(inserted && "multiple MachineInstr -> index mappings");
i2miMap_.push_back(mi);
miIndex += 2;
}
}
computeIntervals();
// compute spill weights
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;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
for (MachineBasicBlock::const_iterator mi = mbb->begin(),
mie = mbb->end(); mi != mie; ++mi) {
for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
const MachineOperand& mop = mi->getOperand(i);
if (mop.isRegister() &&
MRegisterInfo::isVirtualRegister(mop.getReg())) {
unsigned reg = mop.getReg();
Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
assert(r2iit != r2iMap_.end());
r2iit->second->weight += pow(10.0F, loopDepth);
}
}
}
}
numIntervals += intervals_.size();
// join intervals if requested
if (join) joinIntervals();
numIntervals += intervals_.size();
// 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::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
MachineBasicBlock* mbb = mbbi;
unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
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);
}
}
}
// 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;
}
}
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) {
li.addRange(index, 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))
@ -277,9 +343,16 @@ void LiveIntervals::handleRegisterDef(MachineBasicBlock* mbb,
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
@ -288,20 +361,19 @@ unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
/// 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) {
const TargetInstrDescriptor& tid =
tm_->getInstrInfo().get(mi->getOpcode());
DEBUG(std::cerr << "\t[" << getInstructionIndex(mi) << "] ";
DEBUG(std::cerr << "[" << getInstructionIndex(mi) << "]\t";
mi->print(std::cerr, *tm_););
// handle implicit defs
@ -329,22 +401,20 @@ unsigned LiveIntervals::rep(unsigned reg)
void LiveIntervals::joinIntervals()
{
DEBUG(std::cerr << "joining compatible intervals:\n");
DEBUG(std::cerr << "** JOINING INTERVALS ***\n");
const TargetInstrInfo& tii = tm_->getInstrInfo();
for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
MachineBasicBlock* mbb = mbbi;
DEBUG(std::cerr << "machine basic block: "
<< mbb->getBasicBlock()->getName() << "\n");
DEBUG(std::cerr << mbb->getBasicBlock()->getName() << ":\n");
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

17
lib/CodeGen/LiveIntervalAnalysis.h
View File

@ -100,6 +100,9 @@ namespace llvm {
typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
Mi2IndexMap mi2iMap_;
typedef std::vector<MachineInstr*> Index2MiMap;
Index2MiMap i2miMap_;
typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
@ -114,14 +117,13 @@ namespace llvm {
/// runOnMachineFunction - pass entry point
virtual bool runOnMachineFunction(MachineFunction&);
unsigned getInstructionIndex(MachineInstr* instr) const;
MachineInstr* getInstructionFromIndex(unsigned index) const;
Intervals& getIntervals() { return intervals_; }
const Reg2RegMap& getJoinedRegMap() const {
return r2rMap_;
}
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void updateSpilledInterval(Interval& i);
private:
/// computeIntervals - compute live intervals
@ -151,7 +153,8 @@ namespace llvm {
bool overlapsAliases(const Interval& lhs, const Interval& rhs) const;
unsigned getInstructionIndex(MachineInstr* instr) const;
/// rep - returns the representative of this register
unsigned rep(unsigned reg);
void printRegName(unsigned reg) const;
};

521
lib/CodeGen/RegAllocLinearScan.cpp
View File

@ -27,46 +27,37 @@
#include "Support/DepthFirstIterator.h"
#include "Support/Statistic.h"
#include "Support/STLExtras.h"
#include <algorithm>
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 PhysRegTracker {
private:
const MRegisterInfo* mri_;
std::vector<bool> reserved_;
std::vector<unsigned> regUse_;
public:
PhysRegTracker(MachineFunction* mf)
: mri_(mf ? mf->getTarget().getRegisterInfo() : NULL) {
if (mri_) {
reserved_.assign(mri_->getNumRegs(), false);
regUse_.assign(mri_->getNumRegs(), 0);
}
}
PhysRegTracker(const PhysRegTracker& rhs)
: mri_(rhs.mri_),
reserved_(rhs.reserved_),
regUse_(rhs.regUse_) {
}
const PhysRegTracker& operator=(const PhysRegTracker& rhs) {
mri_ = rhs.mri_;
reserved_ = rhs.reserved_;
regUse_ = rhs.regUse_;
return *this;
}
void reservePhysReg(unsigned physReg) {
reserved_[physReg] = true;
}
void addPhysRegUse(unsigned physReg) {
++regUse_[physReg];
for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
@ -85,16 +76,8 @@ namespace {
}
}
bool isPhysRegReserved(unsigned physReg) const {
return reserved_[physReg];
}
bool isPhysRegAvail(unsigned physReg) const {
return regUse_[physReg] == 0 && !isPhysRegReserved(physReg);
}
bool isReservedPhysRegAvail(unsigned physReg) const {
return regUse_[physReg] == 0 && isPhysRegReserved(physReg);
return regUse_[physReg] == 0;
}
};
@ -104,10 +87,8 @@ namespace {
const TargetMachine* tm_;
const MRegisterInfo* mri_;
LiveIntervals* li_;
MachineFunction::iterator currentMbb_;
MachineBasicBlock::iterator currentInstr_;
typedef std::vector<const LiveIntervals::Interval*> IntervalPtrs;
IntervalPtrs unhandled_, fixed_, active_, inactive_;
typedef std::list<LiveIntervals::Interval*> IntervalPtrs;
IntervalPtrs unhandled_, fixed_, active_, inactive_, handled_;
PhysRegTracker prt_;
@ -146,7 +127,7 @@ namespace {
private:
/// initIntervalSets - initializa the four interval sets:
/// unhandled, fixed, active and inactive
void initIntervalSets(const LiveIntervals::Intervals& li);
void initIntervalSets(LiveIntervals::Intervals& li);
/// processActiveIntervals - expire old intervals and move
/// non-overlapping ones to the incative list
@ -164,6 +145,10 @@ namespace {
/// is available, or spill.
void assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur);
/// addSpillCode - adds spill code for interval. The interval
/// must be modified by LiveIntervals::updateIntervalForSpill.
void addSpillCode(IntervalPtrs::value_type li, int slot);
///
/// register handling helpers
///
@ -173,11 +158,6 @@ namespace {
/// 0
unsigned getFreePhysReg(IntervalPtrs::value_type cur);
/// getFreeTempPhysReg - return a free temprorary physical
/// register for this virtual register if we have one (should
/// never return 0)
unsigned getFreeTempPhysReg(unsigned virtReg);
/// assignVirt2PhysReg - assigns the free physical register to
/// the virtual register passed as arguments
Virt2PhysMap::iterator
@ -189,22 +169,13 @@ namespace {
void clearVirtReg(Virt2PhysMap::iterator it);
/// assignVirt2StackSlot - assigns this virtual register to a
/// stack slot
void assignVirt2StackSlot(unsigned virtReg);
/// stack slot. returns the stack slot
int assignVirt2StackSlot(unsigned virtReg);
/// getStackSlot - returns the offset of the specified
/// register on the stack
int getStackSlot(unsigned virtReg);
/// spillVirtReg - spills the virtual register
void spillVirtReg(Virt2PhysMap::iterator it);
/// loadPhysReg - loads to the physical register the value of
/// the virtual register specifed. Virtual register must have
/// an assigned stack slot
Virt2PhysMap::iterator
loadVirt2PhysReg(unsigned virtReg, unsigned physReg);
void printVirtRegAssignment() const {
std::cerr << "register assignment:\n";
@ -235,21 +206,6 @@ namespace {
std::cerr << mri_->getName(reg) << '\n';
}
}
// void printFreeRegs(const char* const str,
// const TargetRegisterClass* rc) const {
// if (str) std::cerr << str << ':';
// for (TargetRegisterClass::iterator i =
// rc->allocation_order_begin(*mf_);
// i != rc->allocation_order_end(*mf_); ++i) {
// unsigned reg = *i;
// if (!regUse_[reg]) {
// std::cerr << ' ' << mri_->getName(reg);
// if (reserved_[reg]) std::cerr << "*";
// }
// }
// std::cerr << '\n';
// }
};
}
@ -261,7 +217,7 @@ void RA::releaseMemory()
active_.clear();
inactive_.clear();
fixed_.clear();
handled_.clear();
}
bool RA::runOnMachineFunction(MachineFunction &fn) {
@ -273,24 +229,6 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
initIntervalSets(li_->getIntervals());
// FIXME: this will work only for the X86 backend. I need to
// device an algorthm to select the minimal (considering register
// aliasing) number of temp registers to reserve so that we have 2
// registers for each register class available.
// reserve R8: CH, CL
// R16: CX, DI,
// R32: ECX, EDI,
// RFP: FP5, FP6
prt_.reservePhysReg( 8); /* CH */
prt_.reservePhysReg( 9); /* CL */
prt_.reservePhysReg(10); /* CX */
prt_.reservePhysReg(12); /* DI */
prt_.reservePhysReg(18); /* ECX */
prt_.reservePhysReg(19); /* EDI */
prt_.reservePhysReg(28); /* FP5 */
prt_.reservePhysReg(29); /* FP6 */
// linear scan algorithm
DEBUG(std::cerr << "Machine Function\n");
@ -304,19 +242,19 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
IntervalPtrs::value_type cur;
if (fixed_.empty()) {
cur = unhandled_.front();
unhandled_.erase(unhandled_.begin());
unhandled_.pop_front();
}
else if (unhandled_.empty()) {
cur = fixed_.front();
fixed_.erase(fixed_.begin());
fixed_.pop_front();
}
else if (unhandled_.front()->start() < fixed_.front()->start()) {
cur = unhandled_.front();
unhandled_.erase(unhandled_.begin());
unhandled_.pop_front();
}
else {
cur = fixed_.front();
fixed_.erase(fixed_.begin());
fixed_.pop_front();
}
DEBUG(std::cerr << *cur << '\n');
@ -328,6 +266,7 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
if (MRegisterInfo::isPhysicalRegister(cur->reg)) {
prt_.addPhysRegUse(cur->reg);
active_.push_back(cur);
handled_.push_back(cur);
}
// otherwise we are allocating a virtual register. try to find
// a free physical register or spill an interval in order to
@ -349,166 +288,53 @@ bool RA::runOnMachineFunction(MachineFunction &fn) {
prt_.delPhysRegUse(reg);
}
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((MRegisterInfo::isPhysicalRegister(rep) ||
v2pMap_.count(rep) || v2ssMap_.count(rep)) &&
"representative register is not allocated!");
assert(MRegisterInfo::isVirtualRegister(reg) &&
!v2pMap_.count(reg) && !v2ssMap_.count(reg) &&
"coalesced register is already allocated!");
if (MRegisterInfo::isPhysicalRegister(rep)) {
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_) {
for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
instrAdded_ = 0;
for (currentInstr_ = currentMbb_->begin();
currentInstr_ != currentMbb_->end(); ) {
DEBUG(std::cerr << "\tinstruction: ";
currentInstr_->print(std::cerr, *tm_););
for (MachineBasicBlock::iterator mii = mbbi->begin(), mie = mbbi->end();
mii != mie; ++mii) {
DEBUG(std::cerr << '\t'; mii->print(std::cerr, *tm_));
// use our current mapping and actually replace and
// use our current mapping and actually replace every
// virtual register with its allocated physical registers
DEBUG(std::cerr << "\t\treplacing virtual registers with mapped "
"physical registers:\n");
for (unsigned i = 0, e = currentInstr_->getNumOperands();
for (unsigned i = 0, e = mii->getNumOperands();
i != e; ++i) {
MachineOperand& op = currentInstr_->getOperand(i);
MachineOperand& op = mii->getOperand(i);
if (op.isRegister() &&
MRegisterInfo::isVirtualRegister(op.getReg())) {
unsigned virtReg = op.getReg();
Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
if (it != v2pMap_.end()) {
DEBUG(std::cerr << "\t\t\t%reg" << it->first
<< " -> " << mri_->getName(it->second) << '\n');
currentInstr_->SetMachineOperandReg(i, it->second);
}
}
}
unsigned srcReg, dstReg;
if (tii.isMoveInstr(*currentInstr_, srcReg, dstReg) &&
((MRegisterInfo::isPhysicalRegister(srcReg) &&
MRegisterInfo::isPhysicalRegister(dstReg) &&
srcReg == dstReg) ||
(MRegisterInfo::isVirtualRegister(srcReg) &&
MRegisterInfo::isVirtualRegister(dstReg) &&
v2ssMap_[srcReg] == v2ssMap_[dstReg]))) {
currentInstr_ = currentMbb_->erase(currentInstr_);
++numPeep;
DEBUG(std::cerr << "\t\tdeleting instruction\n");
continue;
}
typedef std::vector<Virt2PhysMap::iterator> Regs;
Regs toClear;
Regs toSpill;
const unsigned numOperands = currentInstr_->getNumOperands();
DEBUG(std::cerr << "\t\tloading temporarily used operands to "
"registers:\n");
for (unsigned i = 0; i != numOperands; ++i) {
MachineOperand& op = currentInstr_->getOperand(i);
if (op.isRegister() && op.isUse() &&
MRegisterInfo::isVirtualRegister(op.getReg())) {
unsigned virtReg = op.getReg();
unsigned physReg = 0;
Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
if (it != v2pMap_.end()) {
physReg = it->second;
}
else {
physReg = getFreeTempPhysReg(virtReg);
it = loadVirt2PhysReg(virtReg, physReg);
// we will clear uses that are not also defs
// before we allocate registers the defs
if (op.isDef())
toSpill.push_back(it);
else
toClear.push_back(it);
}
currentInstr_->SetMachineOperandReg(i, physReg);
assert(it != v2pMap_.end() &&
"all virtual registers must be allocated");
unsigned physReg = it->second;
assert(MRegisterInfo::isPhysicalRegister(physReg));
DEBUG(std::cerr << "\t\t\t%reg" << virtReg
<< " -> " << mri_->getName(physReg) << '\n');
mii->SetMachineOperandReg(i, physReg);
}
}
DEBUG(std::cerr << "\t\tclearing temporarily used but not defined "
"operands:\n");
std::for_each(toClear.begin(), toClear.end(),
std::bind1st(std::mem_fun(&RA::clearVirtReg), this));
DEBUG(std::cerr << "\t\tassigning temporarily defined operands to "
"registers:\n");
for (unsigned i = 0; i != numOperands; ++i) {
MachineOperand& op = currentInstr_->getOperand(i);
if (op.isRegister() &&
MRegisterInfo::isVirtualRegister(op.getReg())) {
assert(!op.isUse() && "we should not have uses here!");
unsigned virtReg = op.getReg();
unsigned physReg = 0;
Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
if (it != v2pMap_.end()) {
physReg = it->second;
}
else {
physReg = getFreeTempPhysReg(virtReg);
it = assignVirt2PhysReg(virtReg, physReg);
// need to spill this after we are done with
// this instruction
toSpill.push_back(it);
}
currentInstr_->SetMachineOperandReg(i, physReg);
}
}
++currentInstr_; // spills will go after this instruction
DEBUG(std::cerr << "\t\tspilling temporarily defined operands:\n");
std::for_each(toSpill.begin(), toSpill.end(),
std::bind1st(std::mem_fun(&RA::spillVirtReg), this));
}
}
return true;
}
void RA::initIntervalSets(const LiveIntervals::Intervals& li)
void RA::initIntervalSets(LiveIntervals::Intervals& li)
{
assert(unhandled_.empty() && fixed_.empty() &&
active_.empty() && inactive_.empty() &&
"interval sets should be empty on initialization");
for (LiveIntervals::Intervals::const_iterator i = li.begin(), e = li.end();
for (LiveIntervals::Intervals::iterator i = li.begin(), e = li.end();
i != e; ++i) {
if (MRegisterInfo::isPhysicalRegister(i->reg))
fixed_.push_back(&*i);
@ -629,17 +455,22 @@ void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
}
unsigned physReg = getFreePhysReg(cur);
// if we find a free register, we are done: restore original
// register tracker, assign this virtual to the free physical
// register and add this interval to the active list.
// restore the physical register tracker
prt_ = backupPrt;
// 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) {
prt_ = backupPrt;
assignVirt2PhysReg(cur->reg, physReg);
active_.push_back(cur);
handled_.push_back(cur);
return;
}
DEBUG(std::cerr << "\t\tassigning stack slot at interval "<< *cur << ":\n");
// push the current interval back to unhandled since we are going
// to re-run at least this iteration
unhandled_.push_front(cur);
float minWeight = std::numeric_limits<float>::infinity();
unsigned minReg = 0;
@ -647,7 +478,7 @@ void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
for (TargetRegisterClass::iterator i = rc->allocation_order_begin(*mf_);
i != rc->allocation_order_end(*mf_); ++i) {
unsigned reg = *i;
if (!prt_.isPhysRegReserved(reg) && minWeight > spillWeights_[reg]) {
if (minWeight > spillWeights_[reg]) {
minWeight = spillWeights_[reg];
minReg = reg;
}
@ -655,61 +486,197 @@ void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
DEBUG(std::cerr << "\t\t\tregister with min weight: "
<< mri_->getName(minReg) << " (" << minWeight << ")\n");
// if the current has the minimum weight, we are done: restore
// original register tracker and assign a stack slot to this
// virtual register
// if the current has the minimum weight, we need to modify it,
// push it back in unhandled and let the linear scan algorithm run
// again
if (cur->weight < minWeight) {
prt_ = backupPrt;
DEBUG(std::cerr << "\t\t\t\tspilling: " << *cur << '\n');
assignVirt2StackSlot(cur->reg);
DEBUG(std::cerr << "\t\t\t\tspilling(c): " << *cur;);
int slot = assignVirt2StackSlot(cur->reg);
li_->updateSpilledInterval(*cur);
addSpillCode(cur, slot);
DEBUG(std::cerr << "[ " << *cur << " ]\n");
return;
}
// otherwise 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<bool> toSpill(mri_->getNumRegs(), false);
toSpill[minReg] = true;
for (const unsigned* as = mri_->getAliasSet(minReg); *as; ++as)
toSpill[*as] = true;
unsigned earliestStart = cur->start();
std::vector<unsigned> spilled;
for (IntervalPtrs::iterator i = active_.begin();
i != active_.end(); ) {
i != active_.end(); ++i) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg) &&
toSpill[v2pMap_[reg]] &&
cur->overlaps(**i)) {
spilled.push_back(v2pMap_[reg]);
DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
assignVirt2StackSlot(reg);
i = active_.erase(i);
}
else {
++i;
DEBUG(std::cerr << "\t\t\t\tspilling(a): " << **i);
int slot = assignVirt2StackSlot((*i)->reg);
li_->updateSpilledInterval(**i);
addSpillCode(*i, slot);
DEBUG(std::cerr << "[ " << **i << " ]\n");
earliestStart = std::min(earliestStart, (*i)->start());
}
}
for (IntervalPtrs::iterator i = inactive_.begin();
i != inactive_.end(); ) {
i != inactive_.end(); ++i) {
unsigned reg = (*i)->reg;
if (MRegisterInfo::isVirtualRegister(reg) &&
toSpill[v2pMap_[reg]] &&
cur->overlaps(**i)) {
DEBUG(std::cerr << "\t\t\t\tspilling : " << **i << '\n');
assignVirt2StackSlot(reg);
i = inactive_.erase(i);
}
else {
++i;
DEBUG(std::cerr << "\t\t\t\tspilling(i): " << **i << '\n');
int slot = assignVirt2StackSlot((*i)->reg);
li_->updateSpilledInterval(**i);
addSpillCode(*i, slot);
DEBUG(std::cerr << "[ " << **i << " ]\n");
earliestStart = std::min(earliestStart, (*i)->start());
}
}
physReg = getFreePhysReg(cur);
assert(physReg && "no free physical register after spill?");
DEBUG(std::cerr << "\t\t\t\trolling back to: " << earliestStart << '\n');
// scan handled in reverse order and undo each one, restoring the
// state of unhandled and fixed
while (!handled_.empty()) {
IntervalPtrs::value_type i = handled_.back();
// if this interval starts before t we are done
if (i->start() < earliestStart)
break;
DEBUG(std::cerr << "\t\t\t\t\tundo changes for: " << *i << '\n');
handled_.pop_back();
IntervalPtrs::iterator it;
if ((it = find(active_.begin(), active_.end(), i)) != active_.end()) {
active_.erase(it);
if (MRegisterInfo::isPhysicalRegister(i->reg)) {
fixed_.push_front(i);
prt_.delPhysRegUse(i->reg);
}
else {
Virt2PhysMap::iterator v2pIt = v2pMap_.find(i->reg);
clearVirtReg(v2pIt);
unhandled_.push_front(i);
prt_.delPhysRegUse(v2pIt->second);
}
}
else if ((it = find(inactive_.begin(), inactive_.end(), i)) != inactive_.end()) {
inactive_.erase(it);
if (MRegisterInfo::isPhysicalRegister(i->reg))
fixed_.push_front(i);
else {
Virt2PhysMap::iterator v2pIt = v2pMap_.find(i->reg);
clearVirtReg(v2pIt);
unhandled_.push_front(i);
}
}
else {
if (MRegisterInfo::isPhysicalRegister(i->reg))
fixed_.push_front(i);
else {
Virt2PhysMap::iterator v2pIt = v2pMap_.find(i->reg);
clearVirtReg(v2pIt);
unhandled_.push_front(i);
}
}
}
prt_ = backupPrt;
for (unsigned i = 0; i < spilled.size(); ++i)
prt_.delPhysRegUse(spilled[i]);
// 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)
IntervalPtrs::iterator i = handled_.begin(), e = handled_.end();
for (; i != e; ++i) {
if (!(*i)->expiredAt(earliestStart) && (*i)->expiredAt(cur->start())) {
DEBUG(std::cerr << "\t\t\t\t\tundo changes for: " << **i << '\n');
active_.push_back(*i);
if (MRegisterInfo::isPhysicalRegister((*i)->reg))
prt_.addPhysRegUse((*i)->reg);
else {
assert(v2pMap_.count((*i)->reg));
prt_.addPhysRegUse(v2pMap_.find((*i)->reg)->second);
}
}
}
}
assignVirt2PhysReg(cur->reg, physReg);
active_.push_back(cur);
void RA::addSpillCode(IntervalPtrs::value_type li, int slot)
{
// We scan the instructions corresponding to each range. We load
// when we have a use and spill at end of basic blocks or end of
// ranges only if the register was modified.
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(li->reg);
for (LiveIntervals::Interval::Ranges::iterator i = li->ranges.begin(),
e = li->ranges.end(); i != e; ++i) {
unsigned index = i->first & ~1;
unsigned end = i->second;
entry:
bool dirty = false, loaded = false;
// skip deleted instructions. getInstructionFromIndex returns
// null if the instruction was deleted (because of coalescing
// for example)
while (!li_->getInstructionFromIndex(index)) index += 2;
MachineBasicBlock::iterator mi = li_->getInstructionFromIndex(index);
MachineBasicBlock* mbb = mi->getParent();
for (; index < end; index += 2) {
// ignore deleted instructions
while (!li_->getInstructionFromIndex(index)) index += 2;
// if we changed basic block we need to start over
mi = li_->getInstructionFromIndex(index);
if (mbb != mi->getParent()) {
if (dirty) {
mi = li_->getInstructionFromIndex(index-2);
assert(mbb == mi->getParent() &&
"rewound to wrong instruction?");
DEBUG(std::cerr << "add store for reg" << li->reg << " to "
"stack slot " << slot << " after: ";
mi->print(std::cerr, *tm_));
++numSpilled;
mri_->storeRegToStackSlot(*mi->getParent(),
next(mi), li->reg, slot, rc);
}
goto entry;
}
// if it is used in this instruction load it
for (unsigned i = 0; i < mi->getNumOperands(); ++i) {
MachineOperand& mop = mi->getOperand(i);
if (mop.isRegister() && mop.getReg() == li->reg &&
mop.isUse() && !loaded) {
loaded = true;
DEBUG(std::cerr << "add load for reg" << li->reg
<< " from stack slot " << slot << " before: ";
mi->print(std::cerr, *tm_));
++numReloaded;
mri_->loadRegFromStackSlot(*mi->getParent(),
mi, li->reg, slot, rc);
}
}
// if it is defined in this instruction mark as dirty
for (unsigned i = 0; i < mi->getNumOperands(); ++i) {
MachineOperand& mop = mi->getOperand(i);
if (mop.isRegister() && mop.getReg() == li->reg &&
mop.isDef())
dirty = loaded = true;
}
}
if (dirty) {
mi = li_->getInstructionFromIndex(index-2);
assert(mbb == mi->getParent() &&
"rewound to wrong instruction?");
DEBUG(std::cerr << "add store for reg" << li->reg << " to "
"stack slot " << slot << " after: ";
mi->print(std::cerr, *tm_));
++numSpilled;
mri_->storeRegToStackSlot(*mi->getParent(),
next(mi), li->reg, slot, rc);
}
}
}
unsigned RA::getFreePhysReg(IntervalPtrs::value_type cur)
@ -730,27 +697,6 @@ unsigned RA::getFreePhysReg(IntervalPtrs::value_type cur)
return 0;
}
unsigned RA::getFreeTempPhysReg(unsigned virtReg)
{
DEBUG(std::cerr << "\t\tgetting free temporary physical register: ");
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
// go in reverse allocation order for the temp registers
typedef std::reverse_iterator<TargetRegisterClass::iterator> TRCRevIter;
for (TRCRevIter
i(rc->allocation_order_end(*mf_)),
e(rc->allocation_order_begin(*mf_)); i != e; ++i) {
unsigned reg = *i;
if (prt_.isReservedPhysRegAvail(reg)) {
DEBUG(std::cerr << mri_->getName(reg) << '\n');
return reg;
}
}
assert(0 && "no free temporary physical register?");
return 0;
}
RA::Virt2PhysMap::iterator
RA::assignVirt2PhysReg(unsigned virtReg, unsigned physReg)
{
@ -768,62 +714,27 @@ void RA::clearVirtReg(Virt2PhysMap::iterator it)
assert(it != v2pMap_.end() &&
"attempting to clear a not allocated virtual register");
unsigned physReg = it->second;
prt_.delPhysRegUse(physReg);
v2pMap_.erase(it);
DEBUG(std::cerr << "\t\t\tcleared register " << mri_->getName(physReg)
<< "\n");
}
void RA::assignVirt2StackSlot(unsigned virtReg)
int RA::assignVirt2StackSlot(unsigned virtReg)
{
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
int frameIndex = mf_->getFrameInfo()->CreateStackObject(rc);
bool inserted = v2ssMap_.insert(std::make_pair(virtReg, frameIndex)).second;
assert(inserted &&
"attempt to assign stack slot to already assigned register?");
// if the virtual register was previously assigned clear the mapping
// and free the virtual register
Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
if (it != v2pMap_.end()) {
clearVirtReg(it);
}
assert(inserted && "attempt to assign stack slot to spilled register!");
return frameIndex;
}
int RA::getStackSlot(unsigned virtReg)
{
Virt2StackSlotMap::iterator it = v2ssMap_.find(virtReg);
assert(it != v2ssMap_.end() &&
"attempt to get stack slot on register that does not live on the stack");
return it->second;
}
void RA::spillVirtReg(Virt2PhysMap::iterator it)
{
assert(it != v2pMap_.end() &&
"attempt to spill a not allocated virtual register");
unsigned virtReg = it->first;
DEBUG(std::cerr << "\t\t\tspilling register: " << virtReg);
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
int frameIndex = getStackSlot(virtReg);
DEBUG(std::cerr << " to stack slot #" << frameIndex << '\n');
++numSpilled;
instrAdded_ += mri_->storeRegToStackSlot(*currentMbb_, currentInstr_,
it->second, frameIndex, rc);
clearVirtReg(it);
}
RA::Virt2PhysMap::iterator
RA::loadVirt2PhysReg(unsigned virtReg, unsigned physReg)
{
DEBUG(std::cerr << "\t\t\tloading register: " << virtReg);
const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
int frameIndex = getStackSlot(virtReg);
DEBUG(std::cerr << " from stack slot #" << frameIndex << '\n');
++numReloaded;
instrAdded_ += mri_->loadRegFromStackSlot(*currentMbb_, currentInstr_,
physReg, frameIndex, rc);
return assignVirt2PhysReg(virtReg, physReg);
assert(v2ssMap_.count(virtReg) &&
"attempt to get stack slot for a non spilled register");
return v2ssMap_.find(virtReg)->second;
}
FunctionPass* llvm::createLinearScanRegisterAllocator() {