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-rw-r--r--llvm/lib/CodeGen/LiveIntervalAnalysis.cpp310
1 files changed, 200 insertions, 110 deletions
diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 238d8aa2c3c..75d5aac4048 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -42,12 +42,15 @@ namespace {
cl::init(false), cl::Hidden);
cl::opt<bool> SplitAtBB("split-intervals-at-bb",
- cl::init(false), cl::Hidden);
+ cl::init(false), cl::Hidden);
+ cl::opt<int> SplitLimit("split-limit",
+ cl::init(-1), cl::Hidden);
}
STATISTIC(numIntervals, "Number of original intervals");
STATISTIC(numIntervalsAfter, "Number of intervals after coalescing");
-STATISTIC(numFolded , "Number of loads/stores folded into instructions");
+STATISTIC(numFolds , "Number of loads/stores folded into instructions");
+STATISTIC(numSplits , "Number of intervals split");
char LiveIntervals::ID = 0;
namespace {
@@ -389,7 +392,7 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
unsigned killIndex = getInstructionIndex(&mbb->back()) + InstrSlots::NUM;
LiveRange LR(defIndex, killIndex, ValNo);
interval.addRange(LR);
- interval.addKill(ValNo, killIndex-1); // odd # means phi node
+ interval.addKill(ValNo, killIndex+1); // odd # means phi node
DOUT << " +" << LR;
}
}
@@ -652,13 +655,17 @@ bool LiveIntervals::tryFoldMemoryOperand(MachineInstr* &MI,
else
LiveVariables::transferKillDeadInfo(MI, fmi, mri_);
MachineBasicBlock &MBB = *MI->getParent();
- vrm.virtFolded(reg, MI, i, fmi);
+ if (isSS) {
+ if (!mf_->getFrameInfo()->isFixedObjectIndex(slot))
+ vrm.virtFolded(reg, MI, i, fmi);
+ }
vrm.transferSpillPts(MI, fmi);
+ vrm.transferRestorePts(MI, fmi);
mi2iMap_.erase(MI);
i2miMap_[index/InstrSlots::NUM] = fmi;
mi2iMap_[fmi] = index;
MI = MBB.insert(MBB.erase(MI), fmi);
- ++numFolded;
+ ++numFolds;
return true;
}
return false;
@@ -681,20 +688,6 @@ bool LiveIntervals::intervalIsInOneMBB(const LiveInterval &li) const {
return true;
}
-static
-bool hasALaterUse(MachineBasicBlock *MBB, MachineInstr *MI, unsigned Reg) {
- MachineBasicBlock::iterator I = MI;
- if (I == MBB->end())
- return false;
- ++I;
- while (I != MBB->end()) {
- if (I->findRegisterUseOperandIdx(Reg) != -1)
- return true;
- ++I;
- }
- return false;
-}
-
/// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper functions
/// for addIntervalsForSpills to rewrite uses / defs for the given live range.
void LiveIntervals::
@@ -738,6 +731,7 @@ rewriteInstructionForSpills(const LiveInterval &li, bool TrySplit,
}
// If def for this use can't be rematerialized, then try folding.
+ // If def is rematerializable and it's a load, also try folding.
TryFold = !ReMatOrigDefMI ||
(ReMatOrigDefMI && (MI == ReMatOrigDefMI || isLoad));
if (isLoad) {
@@ -747,15 +741,10 @@ rewriteInstructionForSpills(const LiveInterval &li, bool TrySplit,
}
}
- // If we are splitting live intervals, only fold if it's 1) the first
- // use and it's a kill or 2) there isn't another use later in this MBB.
- TryFold &= NewVReg == 0;
- if (TryFold && TrySplit)
- // Do not fold store into def here if we are splitting. We'll find an
- // optimal point to insert a store later.
- if (HasDef || mop.isDef() ||
- (!mop.isKill() && hasALaterUse(MI->getParent(), MI, li.reg)))
- TryFold = false;
+ // Do not fold load / store here if we are splitting. We'll find an
+ // optimal point to insert a load / store later.
+ if (TryFold)
+ TryFold = !TrySplit && NewVReg == 0;
// FIXME: fold subreg use
if (!isSubReg && TryFold &&
@@ -859,27 +848,13 @@ rewriteInstructionForSpills(const LiveInterval &li, bool TrySplit,
}
bool LiveIntervals::anyKillInMBBAfterIdx(const LiveInterval &li,
- MachineBasicBlock *MBB, unsigned Idx,
- const VNInfo *VNI) const {
+ const VNInfo *VNI,
+ MachineBasicBlock *MBB, unsigned Idx) const {
unsigned End = getMBBEndIdx(MBB);
- if (VNI) {
- for (unsigned j = 0, ee = VNI->kills.size(); j != ee; ++j) {
- unsigned KillIdx = VNI->kills[j];
- if (KillIdx > Idx && KillIdx < End)
- return true;
- }
- return false;
- }
-
- // Look at all the VNInfo's.
- for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
- i != e; ++i) {
- const VNInfo *VNI = *i;
- for (unsigned j = 0, ee = VNI->kills.size(); j != ee; ++j) {
- unsigned KillIdx = VNI->kills[j];
- if (KillIdx > Idx && KillIdx < End)
- return true;
- }
+ for (unsigned j = 0, ee = VNI->kills.size(); j != ee; ++j) {
+ unsigned KillIdx = VNI->kills[j];
+ if (KillIdx > Idx && KillIdx < End)
+ return true;
}
return false;
}
@@ -895,7 +870,9 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
SmallVector<int, 4> &ReMatIds,
const LoopInfo *loopInfo,
BitVector &SpillMBBs,
- std::map<unsigned, std::pair<int, unsigned> > &SpillIdxes,
+ std::map<unsigned, std::pair<int, bool> > &SpillIdxes,
+ BitVector &RestoreMBBs,
+ std::map<unsigned, std::pair<int, bool> > &RestoreIdxes,
std::map<unsigned,unsigned> &NewVRegs,
std::vector<LiveInterval*> &NewLIs) {
unsigned NewVReg = 0;
@@ -930,53 +907,79 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
// Update weight of spill interval.
LiveInterval &nI = getOrCreateInterval(NewVReg);
- if (!TrySplitMI)
+ if (!TrySplitMI) {
// The spill weight is now infinity as it cannot be spilled again.
nI.weight = HUGE_VALF;
- else {
- // Keep track of the last def in each MBB.
- if (HasDef) {
- if (MI != ReMatOrigDefMI || !CanDelete) {
- // If this is a two-address code, then this index probably starts a
- // VNInfo so we should examine all the VNInfo's.
- bool HasKill = HasUse
- ? anyKillInMBBAfterIdx(li, MBB, getDefIndex(index))
- : anyKillInMBBAfterIdx(li, MBB, getDefIndex(index), I->valno);
- if (!HasKill) {
- unsigned MBBId = MBB->getNumber();
- // High bit specify whether this spill ought to be folded if
- // possible.
- std::map<unsigned, std::pair<int,unsigned> >::iterator SII =
- SpillIdxes.find(MBBId);
- if (SII == SpillIdxes.end() || (int)index > SII->second.first)
- SpillIdxes[MBBId] = std::make_pair(index, NewVReg | (1 << 31));
- SpillMBBs.set(MBBId);
- }
+ continue;
+ }
+
+ // Keep track of the last def and first use in each MBB.
+ unsigned MBBId = MBB->getNumber();
+ if (HasDef) {
+ if (MI != ReMatOrigDefMI || !CanDelete) {
+ // If this is a two-address code, then this index probably starts a
+ // VNInfo so we should examine all the VNInfo's.
+ bool HasKill = false;
+ if (!HasUse)
+ HasKill = anyKillInMBBAfterIdx(li, I->valno, MBB, getDefIndex(index));
+ else {
+ const VNInfo *VNI = NULL;
+ for (LiveInterval::const_vni_iterator i = li.vni_begin(),
+ e = li.vni_end(); i != e; ++i)
+ if ((*i)->def == getDefIndex(index)) {
+ VNI = *i;
+ break;
+ }
+ if (VNI)
+ HasKill = anyKillInMBBAfterIdx(li, VNI, MBB, getDefIndex(index));
}
- if (!IsNew) {
- // It this interval hasn't been assigned a stack slot
- // (because earlier def is remat), do it now.
- int SS = vrm.getStackSlot(NewVReg);
- if (SS != (int)Slot) {
- assert(SS == VirtRegMap::NO_STACK_SLOT);
- vrm.assignVirt2StackSlot(NewVReg, Slot);
+ if (!HasKill) {
+ std::map<unsigned, std::pair<int, bool> >::iterator SII =
+ SpillIdxes.find(MBBId);
+ if (SII == SpillIdxes.end())
+ SpillIdxes[MBBId] = std::make_pair(index, true);
+ else if ((int)index > SII->second.first) {
+ // If there is an earlier def and this is a two-address
+ // instruction, then it's not possible to fold the store (which
+ // would also fold the load).
+ SpillIdxes[MBBId] = std::make_pair(index, !HasUse);
}
+ SpillMBBs.set(MBBId);
}
- } else if (HasUse) {
- // Use(s) following the last def, it's not safe to fold the spill.
- unsigned MBBId = MBB->getNumber();
- std::map<unsigned, std::pair<int,unsigned> >::iterator SII =
- SpillIdxes.find(MBBId);
- if (SII != SpillIdxes.end() &&
- (SII->second.second & ((1<<31)-1)) == NewVReg &&
- (int)getUseIndex(index) > SII->second.first)
- SpillIdxes[MBBId].second &= (1<<31)-1;
}
+ if (!IsNew) {
+ // It this interval hasn't been assigned a stack slot
+ // (because earlier def is remat), do it now.
+ int SS = vrm.getStackSlot(NewVReg);
+ if (SS != (int)Slot) {
+ assert(SS == VirtRegMap::NO_STACK_SLOT);
+ vrm.assignVirt2StackSlot(NewVReg, Slot);
+ }
+ }
+ }
- // Update spill weight.
- unsigned loopDepth = loopInfo->getLoopDepth(MBB->getBasicBlock());
- nI.weight += getSpillWeight(HasDef, HasUse, loopDepth);
+ if (HasUse) {
+ std::map<unsigned, std::pair<int, bool> >::iterator SII =
+ SpillIdxes.find(MBBId);
+ if (SII != SpillIdxes.end() && (int)index > SII->second.first)
+ // Use(s) following the last def, it's not safe to fold the spill.
+ SII->second.second = false;
+ std::map<unsigned, std::pair<int, bool> >::iterator RII =
+ RestoreIdxes.find(MBBId);
+ if (RII != RestoreIdxes.end())
+ // If we are splitting live intervals, only fold if it's the first
+ // use and there isn't another use later in the MBB.
+ RII->second.second = false;
+ else if (IsNew) {
+ // Only need a reload if there isn't an earlier def / use.
+ RestoreIdxes[MBBId] = std::make_pair(index, true);
+ RestoreMBBs.set(MBBId);
+ }
}
+
+ // Update spill weight.
+ unsigned loopDepth = loopInfo->getLoopDepth(MBB->getBasicBlock());
+ nI.weight += getSpillWeight(HasDef, HasUse, loopDepth);
}
}
@@ -998,7 +1001,9 @@ addIntervalsForSpills(const LiveInterval &li,
// Each bit specify whether it a spill is required in the MBB.
BitVector SpillMBBs(mf_->getNumBlockIDs());
- std::map<unsigned, std::pair<int, unsigned> > SpillIdxes;
+ std::map<unsigned, std::pair<int, bool> > SpillIdxes;
+ BitVector RestoreMBBs(mf_->getNumBlockIDs());
+ std::map<unsigned, std::pair<int, bool> > RestoreIdxes;
std::map<unsigned,unsigned> NewVRegs;
std::vector<LiveInterval*> NewLIs;
SSARegMap *RegMap = mf_->getSSARegMap();
@@ -1036,13 +1041,15 @@ addIntervalsForSpills(const LiveInterval &li,
if (IsFirstRange) {
rewriteInstructionsForSpills(li, false, I, NULL, ReMatDefMI,
Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
- false, vrm, RegMap, rc, ReMatIds,
- loopInfo, SpillMBBs, SpillIdxes, NewVRegs, NewLIs);
+ false, vrm, RegMap, rc, ReMatIds, loopInfo,
+ SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
+ NewVRegs, NewLIs);
} else {
rewriteInstructionsForSpills(li, false, I, NULL, 0,
Slot, 0, false, false, false,
- false, vrm, RegMap, rc, ReMatIds,
- loopInfo, SpillMBBs, SpillIdxes, NewVRegs, NewLIs);
+ false, vrm, RegMap, rc, ReMatIds, loopInfo,
+ SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
+ NewVRegs, NewLIs);
}
IsFirstRange = false;
}
@@ -1050,6 +1057,10 @@ addIntervalsForSpills(const LiveInterval &li,
}
bool TrySplit = SplitAtBB && !intervalIsInOneMBB(li);
+ if (SplitLimit != -1 && (int)numSplits >= SplitLimit)
+ TrySplit = false;
+ if (TrySplit)
+ ++numSplits;
bool NeedStackSlot = false;
for (LiveInterval::const_vni_iterator i = li.vni_begin(), e = li.vni_end();
i != e; ++i) {
@@ -1110,39 +1121,118 @@ addIntervalsForSpills(const LiveInterval &li,
bool isLoad = isLoadSS ||
(DefIsReMat && (ReMatDefMI->getInstrDescriptor()->Flags & M_LOAD_FLAG));
rewriteInstructionsForSpills(li, TrySplit, I, ReMatOrigDefMI, ReMatDefMI,
- Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
- CanDelete, vrm, RegMap, rc, ReMatIds,
- loopInfo, SpillMBBs, SpillIdxes, NewVRegs, NewLIs);
+ Slot, LdSlot, isLoad, isLoadSS, DefIsReMat,
+ CanDelete, vrm, RegMap, rc, ReMatIds, loopInfo,
+ SpillMBBs, SpillIdxes, RestoreMBBs, RestoreIdxes,
+ NewVRegs, NewLIs);
}
- // Insert spills if we are splitting.
- if (TrySplit && NeedStackSlot) {
- int Id = SpillMBBs.find_first();
+ // Insert spills / restores if we are splitting.
+ if (TrySplit) {
+ if (NeedStackSlot) {
+ int Id = SpillMBBs.find_first();
+ while (Id != -1) {
+ unsigned VReg = NewVRegs[Id];
+ int index = SpillIdxes[Id].first;
+ bool DoFold = SpillIdxes[Id].second;
+ bool isReMat = vrm.isReMaterialized(VReg);
+ MachineInstr *MI = getInstructionFromIndex(index);
+ int OpIdx = -1;
+ bool FoldedLoad = false;
+ if (DoFold) {
+ for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
+ MachineOperand &MO = MI->getOperand(j);
+ if (!MO.isRegister() || MO.getReg() != VReg)
+ continue;
+ if (MO.isUse()) {
+ // Can't fold if it's two-address code and the use isn't the
+ // first and only use.
+ // If there are more than one uses, a load is still needed.
+ if (!isReMat && !FoldedLoad &&
+ RestoreMBBs[Id] && RestoreIdxes[Id].first == index &&
+ RestoreIdxes[Id].second) {
+ FoldedLoad = true;
+ continue;
+ } else {
+ OpIdx = -1;
+ break;
+ }
+ }
+ OpIdx = (int)j;
+ }
+ }
+ // Fold the store into the def if possible.
+ if (OpIdx == -1)
+ DoFold = false;
+ if (DoFold) {
+ if (tryFoldMemoryOperand(MI, vrm, NULL, index, OpIdx, true, Slot,
+ VReg)) {
+ if (FoldedLoad) {
+ // Folded a two-address instruction, do not issue a load.
+ RestoreMBBs.reset(Id);
+ RestoreIdxes.erase(Id);
+ }
+ } else
+ DoFold = false;
+ }
+
+ // Else tell the spiller to issue a store for us.
+ if (!DoFold)
+ vrm.addSpillPoint(VReg, MI);
+ Id = SpillMBBs.find_next(Id);
+ }
+ }
+
+ int Id = RestoreMBBs.find_first();
while (Id != -1) {
- unsigned index = SpillIdxes[Id].first;
- unsigned VReg = SpillIdxes[Id].second & ((1 << 31)-1);
- bool TryFold = SpillIdxes[Id].second & (1 << 31);
+ unsigned VReg = NewVRegs[Id];
+ int index = RestoreIdxes[Id].first;
+ bool DoFold = RestoreIdxes[Id].second;
MachineInstr *MI = getInstructionFromIndex(index);
int OpIdx = -1;
- if (TryFold) {
+ if (DoFold) {
for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
MachineOperand &MO = MI->getOperand(j);
if (!MO.isRegister() || MO.getReg() != VReg)
continue;
- if (MO.isUse()) {
+ if (MO.isDef()) {
// Can't fold if it's two-address code.
OpIdx = -1;
break;
}
+ if (OpIdx != -1) {
+ // Multiple uses, do not fold!
+ OpIdx = -1;
+ break;
+ }
OpIdx = (int)j;
}
}
- // Fold the store into the def if possible.
- if (OpIdx == -1 ||
- !tryFoldMemoryOperand(MI, vrm, NULL, index, OpIdx, true, Slot, VReg))
- // Else tell the spiller to issue a store for us.
- vrm.addSpillPoint(VReg, MI);
- Id = SpillMBBs.find_next(Id);
+
+ // Fold the load into the use if possible.
+ if (OpIdx == -1)
+ DoFold = false;
+ if (DoFold) {
+ if (vrm.isReMaterialized(VReg)) {
+ MachineInstr *ReMatDefMI = vrm.getReMaterializedMI(VReg);
+ int LdSlot = 0;
+ bool isLoadSS = tii_->isLoadFromStackSlot(ReMatDefMI, LdSlot);
+ // If the rematerializable def is a load, also try to fold it.
+ if (isLoadSS ||
+ (ReMatDefMI->getInstrDescriptor()->Flags & M_LOAD_FLAG))
+ DoFold = tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index, OpIdx,
+ isLoadSS, LdSlot, VReg);
+ else
+ DoFold = false;
+ } else
+ DoFold = tryFoldMemoryOperand(MI, vrm, NULL, index, OpIdx,
+ true, Slot, VReg);
+ }
+ // If folding is not possible / failed, then tell the spiller to issue a
+ // load / rematerialization for us.
+ if (!DoFold)
+ vrm.addRestorePoint(VReg, MI);
+ Id = RestoreMBBs.find_next(Id);
}
}
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