//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regcoalescing"
-#include "llvm/CodeGen/SimpleRegisterCoalescing.h"
-#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "SimpleRegisterCoalescing.h"
#include "VirtRegMap.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/Value.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/LiveVariables.h"
cl::desc("Coalesce copies (default=true)"),
cl::init(true));
+ static cl::opt<bool>
+ NewHeuristic("new-coalescer-heuristic",
+ cl::desc("Use new coalescer heuristic"),
+ cl::init(false));
+
RegisterPass<SimpleRegisterCoalescing>
X("simple-register-coalescing", "Simple Register Coalescing");
const PassInfo *llvm::SimpleRegisterCoalescingID = X.getPassInfo();
void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
- //AU.addPreserved<LiveVariables>();
AU.addPreserved<LiveIntervals>();
AU.addPreservedID(PHIEliminationID);
AU.addPreservedID(TwoAddressInstructionPassID);
if (UIdx != -1)
ValLREndInst->getOperand(UIdx).unsetIsKill();
- // Finally, delete the copy instruction.
- li_->RemoveMachineInstrFromMaps(CopyMI);
- CopyMI->eraseFromParent();
++numPeep;
return true;
}
+/// AddSubRegIdxPairs - Recursively mark all the registers represented by the
+/// specified register as sub-registers. The recursion level is expected to be
+/// shallow.
+void SimpleRegisterCoalescing::AddSubRegIdxPairs(unsigned Reg, unsigned SubIdx) {
+ std::vector<unsigned> &JoinedRegs = r2rRevMap_[Reg];
+ for (unsigned i = 0, e = JoinedRegs.size(); i != e; ++i) {
+ SubRegIdxes.push_back(std::make_pair(JoinedRegs[i], SubIdx));
+ AddSubRegIdxPairs(JoinedRegs[i], SubIdx);
+ }
+}
+
+/// isBackEdgeCopy - Returns true if CopyMI is a back edge copy.
+///
+bool SimpleRegisterCoalescing::isBackEdgeCopy(MachineInstr *CopyMI,
+ unsigned DstReg) {
+ MachineBasicBlock *MBB = CopyMI->getParent();
+ const BasicBlock *BB = MBB->getBasicBlock();
+ const Loop *L = loopInfo->getLoopFor(BB);
+ if (!L)
+ return false;
+ if (BB != L->getLoopLatch())
+ return false;
+
+ DstReg = rep(DstReg);
+ LiveInterval &LI = li_->getInterval(DstReg);
+ unsigned DefIdx = li_->getInstructionIndex(CopyMI);
+ LiveInterval::const_iterator DstLR =
+ LI.FindLiveRangeContaining(li_->getDefIndex(DefIdx));
+ if (DstLR == LI.end())
+ return false;
+ unsigned KillIdx = li_->getInstructionIndex(&MBB->back()) + InstrSlots::NUM-1;
+ if (DstLR->valno->kills.size() == 1 && DstLR->valno->kills[0] == KillIdx)
+ return true;
+ return false;
+}
+
/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns true
-/// if the copy was successfully coalesced away, or if it is never possible
-/// to coalesce this copy, due to register constraints. It returns
-/// false if it is not currently possible to coalesce this interval, but
-/// it may be possible if other things get coalesced.
-bool SimpleRegisterCoalescing::JoinCopy(MachineInstr *CopyMI,
- unsigned SrcReg, unsigned DstReg) {
+/// if the copy was successfully coalesced away. If it is not currently
+/// possible to coalesce this interval, but it may be possible if other
+/// things get coalesced, then it returns true by reference in 'Again'.
+bool SimpleRegisterCoalescing::JoinCopy(CopyRec TheCopy, bool &Again) {
+ MachineInstr *CopyMI = TheCopy.MI;
+
+ Again = false;
+ if (JoinedCopies.count(CopyMI))
+ return false; // Already done.
+
DOUT << li_->getInstructionIndex(CopyMI) << '\t' << *CopyMI;
// Get representative registers.
+ unsigned SrcReg = TheCopy.SrcReg;
+ unsigned DstReg = TheCopy.DstReg;
unsigned repSrcReg = rep(SrcReg);
unsigned repDstReg = rep(DstReg);
// If they are already joined we continue.
if (repSrcReg == repDstReg) {
DOUT << "\tCopy already coalesced.\n";
- return true; // Not coalescable.
+ return false; // Not coalescable.
}
bool SrcIsPhys = MRegisterInfo::isPhysicalRegister(repSrcReg);
// If they are both physical registers, we cannot join them.
if (SrcIsPhys && DstIsPhys) {
DOUT << "\tCan not coalesce physregs.\n";
- return true; // Not coalescable.
+ return false; // Not coalescable.
}
// We only join virtual registers with allocatable physical registers.
if (SrcIsPhys && !allocatableRegs_[repSrcReg]) {
DOUT << "\tSrc reg is unallocatable physreg.\n";
- return true; // Not coalescable.
+ return false; // Not coalescable.
}
if (DstIsPhys && !allocatableRegs_[repDstReg]) {
DOUT << "\tDst reg is unallocatable physreg.\n";
- return true; // Not coalescable.
+ return false; // Not coalescable.
}
bool isExtSubReg = CopyMI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG;
RHS.overlaps(li_->getInterval(RealDstReg))) {
DOUT << "Interfere with register ";
DEBUG(li_->getInterval(RealDstReg).print(DOUT, mri_));
- return true; // Not coalescable
+ return false; // Not coalescable
}
for (const unsigned* SR = mri_->getSubRegisters(RealDstReg); *SR; ++SR)
if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
DOUT << "Interfere with sub-register ";
DEBUG(li_->getInterval(*SR).print(DOUT, mri_));
- return true; // Not coalescable
+ return false; // Not coalescable
}
- } else if (li_->getInterval(repDstReg).getSize() >
- li_->getInterval(repSrcReg).getSize()) {
+ } else {
+ unsigned SrcSize= li_->getInterval(repSrcReg).getSize() / InstrSlots::NUM;
+ unsigned DstSize= li_->getInterval(repDstReg).getSize() / InstrSlots::NUM;
+ const TargetRegisterClass *RC=mf_->getSSARegMap()->getRegClass(repDstReg);
+ unsigned Threshold = allocatableRCRegs_[RC].count();
// Be conservative. If both sides are virtual registers, do not coalesce
- // if the sub-register live interval is longer.
- return false;
+ // if this will cause a high use density interval to target a smaller set
+ // of registers.
+ if (DstSize > Threshold || SrcSize > Threshold) {
+ LiveVariables::VarInfo &svi = lv_->getVarInfo(repSrcReg);
+ LiveVariables::VarInfo &dvi = lv_->getVarInfo(repDstReg);
+ if ((float)dvi.NumUses / DstSize < (float)svi.NumUses / SrcSize) {
+ Again = true; // May be possible to coalesce later.
+ return false;
+ }
+ }
}
} else if (differingRegisterClasses(repSrcReg, repDstReg)) {
// If they are not of the same register class, we cannot join them.
// a physical register that's compatible with the other side. e.g.
// r1024 = MOV32to32_ r1025
// but later r1024 is assigned EAX then r1025 may be coalesced with EAX.
+ Again = true; // May be possible to coalesce later.
return false;
}
unsigned JoinPReg = SrcIsPhys ? repSrcReg : repDstReg;
const TargetRegisterClass *RC = mf_->getSSARegMap()->getRegClass(JoinVReg);
unsigned Threshold = allocatableRCRegs_[RC].count();
+ if (TheCopy.isBackEdge)
+ Threshold *= 2; // Favors back edge copies.
// If the virtual register live interval is long but it has low use desity,
// do not join them, instead mark the physical register as its allocation
JoinVInt.preference = JoinPReg;
++numAborts;
DOUT << "\tMay tie down a physical register, abort!\n";
+ Again = true; // May be possible to coalesce later.
return false;
}
}
// Coalescing failed.
// If we can eliminate the copy without merging the live ranges, do so now.
- if (!isExtSubReg && AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI))
+ if (!isExtSubReg && AdjustCopiesBackFrom(SrcInt, DstInt, CopyMI)) {
+ JoinedCopies.insert(CopyMI);
return true;
+ }
// Otherwise, we are unable to join the intervals.
DOUT << "Interference!\n";
+ Again = true; // May be possible to coalesce later.
return false;
}
std::swap(repSrcReg, repDstReg);
std::swap(ResSrcInt, ResDstInt);
}
- SubRegIdxes.push_back(std::make_pair(DstReg,
- CopyMI->getOperand(2).getImm()));
+ unsigned SubIdx = CopyMI->getOperand(2).getImm();
+ SubRegIdxes.push_back(std::make_pair(repSrcReg, SubIdx));
+ AddSubRegIdxPairs(repSrcReg, SubIdx);
+ }
+
+ if (NewHeuristic) {
+ for (LiveInterval::const_vni_iterator i = ResSrcInt->vni_begin(),
+ e = ResSrcInt->vni_end(); i != e; ++i) {
+ const VNInfo *vni = *i;
+ if (vni->def && vni->def != ~1U && vni->def != ~0U) {
+ MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
+ unsigned SrcReg, DstReg;
+ if (CopyMI && tii_->isMoveInstr(*CopyMI, SrcReg, DstReg) &&
+ JoinedCopies.count(CopyMI) == 0) {
+ unsigned LoopDepth =
+ loopInfo->getLoopDepth(CopyMI->getParent()->getBasicBlock());
+ JoinQueue->push(CopyRec(CopyMI, SrcReg, DstReg, LoopDepth,
+ isBackEdgeCopy(CopyMI, DstReg)));
+ }
+ }
+ }
}
DOUT << "\n\t\tJoined. Result = "; ResDstInt->print(DOUT, mri_);
// being merged.
li_->removeInterval(repSrcReg);
r2rMap_[repSrcReg] = repDstReg;
+ r2rRevMap_[repDstReg].push_back(repSrcReg);
// Finally, delete the copy instruction.
- li_->RemoveMachineInstrFromMaps(CopyMI);
- CopyMI->eraseFromParent();
+ JoinedCopies.insert(CopyMI);
++numPeep;
++numJoins;
return true;
i != e; ++i) {
VNInfo *VNI = *i;
unsigned ValSrcReg = VNI->reg;
- if (ValSrcReg == 0) // Src not defined by a copy?
+ if (VNI->def == ~1U ||ValSrcReg == 0) // Src not defined by a copy?
continue;
// DstReg is known to be a register in the LHS interval. If the src is
i != e; ++i) {
VNInfo *VNI = *i;
unsigned ValSrcReg = VNI->reg;
- if (ValSrcReg == 0) // Src not defined by a copy?
+ if (VNI->def == ~1U || ValSrcReg == 0) // Src not defined by a copy?
continue;
// DstReg is known to be a register in the RHS interval. If the src is
};
}
+/// getRepIntervalSize - Returns the size of the interval that represents the
+/// specified register.
+template<class SF>
+unsigned JoinPriorityQueue<SF>::getRepIntervalSize(unsigned Reg) {
+ return Rc->getRepIntervalSize(Reg);
+}
+
+/// CopyRecSort::operator - Join priority queue sorting function.
+///
+bool CopyRecSort::operator()(CopyRec left, CopyRec right) const {
+ // Inner loops first.
+ if (left.LoopDepth > right.LoopDepth)
+ return false;
+ else if (left.LoopDepth == right.LoopDepth) {
+ if (left.isBackEdge && !right.isBackEdge)
+ return false;
+ else if (left.isBackEdge == right.isBackEdge) {
+ // Join virtuals to physical registers first.
+ bool LDstIsPhys = MRegisterInfo::isPhysicalRegister(left.DstReg);
+ bool LSrcIsPhys = MRegisterInfo::isPhysicalRegister(left.SrcReg);
+ bool LIsPhys = LDstIsPhys || LSrcIsPhys;
+ bool RDstIsPhys = MRegisterInfo::isPhysicalRegister(right.DstReg);
+ bool RSrcIsPhys = MRegisterInfo::isPhysicalRegister(right.SrcReg);
+ bool RIsPhys = RDstIsPhys || RSrcIsPhys;
+ if (LIsPhys && !RIsPhys)
+ return false;
+ else if (LIsPhys == RIsPhys) {
+ // Join shorter intervals first.
+ unsigned LSize = 0;
+ unsigned RSize = 0;
+ if (LIsPhys) {
+ LSize = LDstIsPhys ? 0 : JPQ->getRepIntervalSize(left.DstReg);
+ LSize += LSrcIsPhys ? 0 : JPQ->getRepIntervalSize(left.SrcReg);
+ RSize = RDstIsPhys ? 0 : JPQ->getRepIntervalSize(right.DstReg);
+ RSize += RSrcIsPhys ? 0 : JPQ->getRepIntervalSize(right.SrcReg);
+ } else {
+ LSize = std::min(JPQ->getRepIntervalSize(left.DstReg),
+ JPQ->getRepIntervalSize(left.SrcReg));
+ RSize = std::min(JPQ->getRepIntervalSize(right.DstReg),
+ JPQ->getRepIntervalSize(right.SrcReg));
+ }
+ if (LSize < RSize)
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
std::vector<CopyRec> &TryAgain) {
DOUT << ((Value*)MBB->getBasicBlock())->getName() << ":\n";
-
+
std::vector<CopyRec> VirtCopies;
std::vector<CopyRec> PhysCopies;
+ unsigned LoopDepth = loopInfo->getLoopDepth(MBB->getBasicBlock());
for (MachineBasicBlock::iterator MII = MBB->begin(), E = MBB->end();
MII != E;) {
MachineInstr *Inst = MII++;
unsigned repDstReg = rep(DstReg);
bool SrcIsPhys = MRegisterInfo::isPhysicalRegister(repSrcReg);
bool DstIsPhys = MRegisterInfo::isPhysicalRegister(repDstReg);
- if (SrcIsPhys || DstIsPhys)
- PhysCopies.push_back(getCopyRec(Inst, SrcReg, DstReg));
- else
- VirtCopies.push_back(getCopyRec(Inst, SrcReg, DstReg));
+ if (NewHeuristic) {
+ JoinQueue->push(CopyRec(Inst, SrcReg, DstReg, LoopDepth,
+ isBackEdgeCopy(Inst, DstReg)));
+ } else {
+ if (SrcIsPhys || DstIsPhys)
+ PhysCopies.push_back(CopyRec(Inst, SrcReg, DstReg, 0, false));
+ else
+ VirtCopies.push_back(CopyRec(Inst, SrcReg, DstReg, 0, false));
+ }
}
+ if (NewHeuristic)
+ return;
+
// Try coalescing physical register + virtual register first.
for (unsigned i = 0, e = PhysCopies.size(); i != e; ++i) {
CopyRec &TheCopy = PhysCopies[i];
- if (!JoinCopy(TheCopy.MI, TheCopy.SrcReg, TheCopy.DstReg))
- TryAgain.push_back(TheCopy);
+ bool Again = false;
+ if (!JoinCopy(TheCopy, Again))
+ if (Again)
+ TryAgain.push_back(TheCopy);
}
for (unsigned i = 0, e = VirtCopies.size(); i != e; ++i) {
CopyRec &TheCopy = VirtCopies[i];
- if (!JoinCopy(TheCopy.MI, TheCopy.SrcReg, TheCopy.DstReg))
- TryAgain.push_back(TheCopy);
+ bool Again = false;
+ if (!JoinCopy(TheCopy, Again))
+ if (Again)
+ TryAgain.push_back(TheCopy);
}
}
void SimpleRegisterCoalescing::joinIntervals() {
DOUT << "********** JOINING INTERVALS ***********\n";
+ if (NewHeuristic)
+ JoinQueue = new JoinPriorityQueue<CopyRecSort>(this);
+
JoinedLIs.resize(li_->getNumIntervals());
JoinedLIs.reset();
std::vector<CopyRec> TryAgainList;
- const LoopInfo &LI = getAnalysis<LoopInfo>();
- if (LI.begin() == LI.end()) {
+ if (loopInfo->begin() == loopInfo->end()) {
// If there are no loops in the function, join intervals in function order.
for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
I != E; ++I)
// registers with virtual registers before the intervals got too long.
std::vector<std::pair<unsigned, MachineBasicBlock*> > MBBs;
for (MachineFunction::iterator I = mf_->begin(), E = mf_->end(); I != E;++I)
- MBBs.push_back(std::make_pair(LI.getLoopDepth(I->getBasicBlock()), I));
+ MBBs.push_back(std::make_pair(loopInfo->
+ getLoopDepth(I->getBasicBlock()), I));
// Sort by loop depth.
std::sort(MBBs.begin(), MBBs.end(), DepthMBBCompare());
// Joining intervals can allow other intervals to be joined. Iteratively join
// until we make no progress.
- bool ProgressMade = true;
- while (ProgressMade) {
- ProgressMade = false;
-
- for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
- CopyRec &TheCopy = TryAgainList[i];
- if (TheCopy.MI &&
- JoinCopy(TheCopy.MI, TheCopy.SrcReg, TheCopy.DstReg)) {
- TheCopy.MI = 0; // Mark this one as done.
- ProgressMade = true;
+ if (NewHeuristic) {
+ SmallVector<CopyRec, 16> TryAgain;
+ bool ProgressMade = true;
+ while (ProgressMade) {
+ ProgressMade = false;
+ while (!JoinQueue->empty()) {
+ CopyRec R = JoinQueue->pop();
+ bool Again = false;
+ bool Success = JoinCopy(R, Again);
+ if (Success)
+ ProgressMade = true;
+ else if (Again)
+ TryAgain.push_back(R);
+ }
+
+ if (ProgressMade) {
+ while (!TryAgain.empty()) {
+ JoinQueue->push(TryAgain.back());
+ TryAgain.pop_back();
+ }
+ }
+ }
+ } else {
+ bool ProgressMade = true;
+ while (ProgressMade) {
+ ProgressMade = false;
+
+ for (unsigned i = 0, e = TryAgainList.size(); i != e; ++i) {
+ CopyRec &TheCopy = TryAgainList[i];
+ if (TheCopy.MI) {
+ bool Again = false;
+ bool Success = JoinCopy(TheCopy, Again);
+ if (Success || !Again) {
+ TheCopy.MI = 0; // Mark this one as done.
+ ProgressMade = true;
+ }
+ }
}
}
}
}
RegNum = JoinedLIs.find_next(RegNum);
}
+
+ if (NewHeuristic)
+ delete JoinQueue;
DOUT << "*** Register mapping ***\n";
- for (int i = 0, e = r2rMap_.size(); i != e; ++i)
+ for (unsigned i = 0, e = r2rMap_.size(); i != e; ++i)
if (r2rMap_[i]) {
DOUT << " reg " << i << " -> ";
DEBUG(printRegName(r2rMap_[i]));
}
void SimpleRegisterCoalescing::releaseMemory() {
- r2rMap_.clear();
- JoinedLIs.clear();
- SubRegIdxes.clear();
+ for (unsigned i = 0, e = r2rMap_.size(); i != e; ++i)
+ r2rRevMap_[i].clear();
+ r2rRevMap_.clear();
+ r2rMap_.clear();
+ JoinedLIs.clear();
+ SubRegIdxes.clear();
+ JoinedCopies.clear();
}
static bool isZeroLengthInterval(LiveInterval *li) {
tii_ = tm_->getInstrInfo();
li_ = &getAnalysis<LiveIntervals>();
lv_ = &getAnalysis<LiveVariables>();
+ loopInfo = &getAnalysis<LoopInfo>();
DOUT << "********** SIMPLE REGISTER COALESCING **********\n"
<< "********** Function: "
SSARegMap *RegMap = mf_->getSSARegMap();
r2rMap_.grow(RegMap->getLastVirtReg());
+ r2rRevMap_.grow(RegMap->getLastVirtReg());
// Join (coalesce) intervals if requested.
if (EnableJoining) {
DOUT << "\n";
}
- // Track coalesced sub-registers.
+ // Delete all coalesced copies.
+ for (SmallPtrSet<MachineInstr*,32>::iterator I = JoinedCopies.begin(),
+ E = JoinedCopies.end(); I != E; ++I) {
+ li_->RemoveMachineInstrFromMaps(*I);
+ (*I)->eraseFromParent();
+ }
+
+ // Transfer sub-registers info to SSARegMap now that coalescing information
+ // is complete.
while (!SubRegIdxes.empty()) {
std::pair<unsigned, unsigned> RI = SubRegIdxes.back();
SubRegIdxes.pop_back();
// perform a final pass over the instructions and compute spill
// weights, coalesce virtual registers and remove identity moves.
- const LoopInfo &loopInfo = getAnalysis<LoopInfo>();
-
for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
MachineBasicBlock* mbb = mbbi;
- unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
+ unsigned loopDepth = loopInfo->getLoopDepth(mbb->getBasicBlock());
for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
mii != mie; ) {
projects / oota-llvm.git / blobdiff