[llvm-commits] CVS: llvm/lib/CodeGen/LiveIntervals.cpp RegAllocLinearScan.cpp
Alkis Evlogimenos
alkis at cs.uiuc.edu
Sun Feb 15 04:25:01 PST 2004
Changes in directory llvm/lib/CodeGen:
LiveIntervals.cpp updated: 1.50 -> 1.51
RegAllocLinearScan.cpp updated: 1.47 -> 1.48
---
Log message:
Eliminate the use of spill (reserved) registers.
---
Diffs of the changes: (+317 -336)
Index: llvm/lib/CodeGen/LiveIntervals.cpp
diff -u llvm/lib/CodeGen/LiveIntervals.cpp:1.50 llvm/lib/CodeGen/LiveIntervals.cpp:1.51
--- llvm/lib/CodeGen/LiveIntervals.cpp:1.50 Fri Feb 13 18:44:07 2004
+++ llvm/lib/CodeGen/LiveIntervals.cpp Sun Feb 15 04:24:21 2004
@@ -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 @@
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 @@
{
mbbi2mbbMap_.clear();
mi2iMap_.clear();
- r2iMap_.clear();
+ i2miMap_.clear();
r2iMap_.clear();
r2rMap_.clear();
intervals_.clear();
@@ -74,7 +77,7 @@
/// 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 @@
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
+ 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 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);
+ 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;
}
}
- // 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) {
+ 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 @@
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 @@
/// 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 @@
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
Index: llvm/lib/CodeGen/RegAllocLinearScan.cpp
diff -u llvm/lib/CodeGen/RegAllocLinearScan.cpp:1.47 llvm/lib/CodeGen/RegAllocLinearScan.cpp:1.48
--- llvm/lib/CodeGen/RegAllocLinearScan.cpp:1.47 Fri Feb 13 18:44:07 2004
+++ llvm/lib/CodeGen/RegAllocLinearScan.cpp Sun Feb 15 04:24:21 2004
@@ -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 @@
}
}
- 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 @@
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 @@
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 @@
/// 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 @@
/// 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 @@
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 @@
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 @@
active_.clear();
inactive_.clear();
fixed_.clear();
-
+ handled_.clear();
}
bool RA::runOnMachineFunction(MachineFunction &fn) {
@@ -273,24 +229,6 @@
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 @@
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 @@
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 @@
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);
- 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);
- }
- }
-
- 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);
+ MachineOperand& op = mii->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);
+ 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);
}
}
- ++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 @@
}
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 @@
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 @@
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);
+ 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());
+ }
+ }
+
+ 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 {
- ++i;
+ if (MRegisterInfo::isPhysicalRegister(i->reg))
+ fixed_.push_front(i);
+ else {
+ Virt2PhysMap::iterator v2pIt = v2pMap_.find(i->reg);
+ clearVirtReg(v2pIt);
+ unhandled_.push_front(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);
+ }
}
}
+}
- physReg = getFreePhysReg(cur);
- assert(physReg && "no free physical register after spill?");
+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;
+ }
- prt_ = backupPrt;
- for (unsigned i = 0; i < spilled.size(); ++i)
- prt_.delPhysRegUse(spilled[i]);
+ // 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);
+ }
+ }
- assignVirt2PhysReg(cur->reg, physReg);
- active_.push_back(cur);
+ // 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 @@
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 @@
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() {
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