#include "LiveRangeEdit.h"
#include "VirtRegMap.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
-static cl::opt<bool>
-AllowSplit("spiller-splits-edges",
- cl::desc("Allow critical edge splitting during spilling"));
-
STATISTIC(NumFinished, "Number of splits finished");
STATISTIC(NumSimple, "Number of splits that were simple");
LIS(lis),
Loops(mli),
TII(*MF.getTarget().getInstrInfo()),
- CurLI(0) {}
+ CurLI(0),
+ LastSplitPoint(MF.getNumBlockIDs()) {}
void SplitAnalysis::clear() {
UseSlots.clear();
- UsingInstrs.clear();
- UsingBlocks.clear();
- LiveBlocks.clear();
+ UseBlocks.clear();
+ ThroughBlocks.clear();
CurLI = 0;
}
-bool SplitAnalysis::canAnalyzeBranch(const MachineBasicBlock *MBB) {
- MachineBasicBlock *T, *F;
- SmallVector<MachineOperand, 4> Cond;
- return !TII.AnalyzeBranch(const_cast<MachineBasicBlock&>(*MBB), T, F, Cond);
+SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
+ const MachineBasicBlock *MBB = MF.getBlockNumbered(Num);
+ const MachineBasicBlock *LPad = MBB->getLandingPadSuccessor();
+ std::pair<SlotIndex, SlotIndex> &LSP = LastSplitPoint[Num];
+
+ // Compute split points on the first call. The pair is independent of the
+ // current live interval.
+ if (!LSP.first.isValid()) {
+ MachineBasicBlock::const_iterator FirstTerm = MBB->getFirstTerminator();
+ if (FirstTerm == MBB->end())
+ LSP.first = LIS.getMBBEndIdx(MBB);
+ else
+ LSP.first = LIS.getInstructionIndex(FirstTerm);
+
+ // If there is a landing pad successor, also find the call instruction.
+ if (!LPad)
+ return LSP.first;
+ // There may not be a call instruction (?) in which case we ignore LPad.
+ LSP.second = LSP.first;
+ for (MachineBasicBlock::const_iterator I = FirstTerm, E = MBB->begin();
+ I != E; --I)
+ if (I->getDesc().isCall()) {
+ LSP.second = LIS.getInstructionIndex(I);
+ break;
+ }
+ }
+
+ // If CurLI is live into a landing pad successor, move the last split point
+ // back to the call that may throw.
+ if (LPad && LSP.second.isValid() && LIS.isLiveInToMBB(*CurLI, LPad))
+ return LSP.second;
+ else
+ return LSP.first;
}
/// analyzeUses - Count instructions, basic blocks, and loops using CurLI.
void SplitAnalysis::analyzeUses() {
+ assert(UseSlots.empty() && "Call clear first");
+
+ // First get all the defs from the interval values. This provides the correct
+ // slots for early clobbers.
+ for (LiveInterval::const_vni_iterator I = CurLI->vni_begin(),
+ E = CurLI->vni_end(); I != E; ++I)
+ if (!(*I)->isPHIDef() && !(*I)->isUnused())
+ UseSlots.push_back((*I)->def);
+
+ // Get use slots form the use-def chain.
const MachineRegisterInfo &MRI = MF.getRegInfo();
- for (MachineRegisterInfo::reg_iterator I = MRI.reg_begin(CurLI->reg),
- E = MRI.reg_end(); I != E; ++I) {
- MachineOperand &MO = I.getOperand();
- if (MO.isUse() && MO.isUndef())
- continue;
- MachineInstr *MI = MO.getParent();
- if (MI->isDebugValue() || !UsingInstrs.insert(MI))
- continue;
- UseSlots.push_back(LIS.getInstructionIndex(MI).getDefIndex());
- MachineBasicBlock *MBB = MI->getParent();
- UsingBlocks[MBB]++;
- }
+ for (MachineRegisterInfo::use_nodbg_iterator
+ I = MRI.use_nodbg_begin(CurLI->reg), E = MRI.use_nodbg_end(); I != E;
+ ++I)
+ if (!I.getOperand().isUndef())
+ UseSlots.push_back(LIS.getInstructionIndex(&*I).getDefIndex());
+
array_pod_sort(UseSlots.begin(), UseSlots.end());
+ // Remove duplicates, keeping the smaller slot for each instruction.
+ // That is what we want for early clobbers.
+ UseSlots.erase(std::unique(UseSlots.begin(), UseSlots.end(),
+ SlotIndex::isSameInstr),
+ UseSlots.end());
+
// Compute per-live block info.
if (!calcLiveBlockInfo()) {
// FIXME: calcLiveBlockInfo found inconsistencies in the live range.
DEBUG(dbgs() << "*** Fixing inconsistent live interval! ***\n");
const_cast<LiveIntervals&>(LIS)
.shrinkToUses(const_cast<LiveInterval*>(CurLI));
- LiveBlocks.clear();
+ UseBlocks.clear();
+ ThroughBlocks.clear();
bool fixed = calcLiveBlockInfo();
(void)fixed;
assert(fixed && "Couldn't fix broken live interval");
}
- DEBUG(dbgs() << " counted "
- << UsingInstrs.size() << " instrs, "
- << UsingBlocks.size() << " blocks.\n");
+ DEBUG(dbgs() << "Analyze counted "
+ << UseSlots.size() << " instrs in "
+ << UseBlocks.size() << " blocks, through "
+ << ThroughBlocks.size() << " blocks.\n");
}
/// calcLiveBlockInfo - Fill the LiveBlocks array with information about blocks
for (;;) {
BlockInfo BI;
BI.MBB = MFI;
- tie(BI.Start, BI.Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB);
-
- // The last split point is the latest possible insertion point that dominates
- // all successor blocks. If interference reaches LastSplitPoint, it is not
- // possible to insert a split or reload that makes CurLI live in the
- // outgoing bundle.
- MachineBasicBlock::iterator LSP = LIS.getLastSplitPoint(*CurLI, BI.MBB);
- if (LSP == BI.MBB->end())
- BI.LastSplitPoint = BI.Stop;
- else
- BI.LastSplitPoint = LIS.getInstructionIndex(LSP);
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB);
// LVI is the first live segment overlapping MBB.
- BI.LiveIn = LVI->start <= BI.Start;
+ BI.LiveIn = LVI->start <= Start;
if (!BI.LiveIn)
BI.Def = LVI->start;
// Find the first and last uses in the block.
- BI.Uses = hasUses(MFI);
- if (BI.Uses && UseI != UseE) {
+ bool Uses = UseI != UseE && *UseI < Stop;
+ if (Uses) {
BI.FirstUse = *UseI;
- assert(BI.FirstUse >= BI.Start);
+ assert(BI.FirstUse >= Start);
do ++UseI;
- while (UseI != UseE && *UseI < BI.Stop);
+ while (UseI != UseE && *UseI < Stop);
BI.LastUse = UseI[-1];
- assert(BI.LastUse < BI.Stop);
+ assert(BI.LastUse < Stop);
}
// Look for gaps in the live range.
bool hasGap = false;
BI.LiveOut = true;
- while (LVI->end < BI.Stop) {
+ while (LVI->end < Stop) {
SlotIndex LastStop = LVI->end;
- if (++LVI == LVE || LVI->start >= BI.Stop) {
+ if (++LVI == LVE || LVI->start >= Stop) {
BI.Kill = LastStop;
BI.LiveOut = false;
break;
// Don't set LiveThrough when the block has a gap.
BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut;
- LiveBlocks.push_back(BI);
+ if (Uses)
+ UseBlocks.push_back(BI);
+ else
+ ThroughBlocks.push_back(BI.MBB->getNumber());
// FIXME: This should never happen. The live range stops or starts without a
// corresponding use. An earlier pass did something wrong.
- if (!BI.LiveThrough && !BI.Uses)
+ if (!BI.LiveThrough && !Uses)
return false;
// LVI is now at LVE or LVI->end >= Stop.
break;
// Live segment ends exactly at Stop. Move to the next segment.
- if (LVI->end == BI.Stop && ++LVI == LVE)
+ if (LVI->end == Stop && ++LVI == LVE)
break;
// Pick the next basic block.
- if (LVI->start < BI.Stop)
+ if (LVI->start < Stop)
++MFI;
else
MFI = LIS.getMBBFromIndex(LVI->start);
return I != Orig.begin() && (--I)->end == Idx;
}
-void SplitAnalysis::print(const BlockPtrSet &B, raw_ostream &OS) const {
- for (BlockPtrSet::const_iterator I = B.begin(), E = B.end(); I != E; ++I) {
- unsigned count = UsingBlocks.lookup(*I);
- OS << " BB#" << (*I)->getNumber();
- if (count)
- OS << '(' << count << ')';
- }
-}
-
void SplitAnalysis::analyze(const LiveInterval *li) {
clear();
CurLI = li;
// Create a new value.
VNInfo *VNI = LI->getNextValue(Idx, 0, LIS.getVNInfoAllocator());
- // Preserve the PHIDef bit.
- if (ParentVNI->isPHIDef() && Idx == ParentVNI->def)
- VNI->setIsPHIDef(true);
-
// Use insert for lookup, so we can add missing values with a second lookup.
std::pair<ValueMap::iterator, bool> InsP =
Values.insert(std::make_pair(std::make_pair(RegIdx, ParentVNI->id), VNI));
// Using LiveOutCache as a visited set, perform a BFS for all reaching defs.
for (unsigned i = 0; i != LiveIn.size(); ++i) {
MachineBasicBlock *MBB = LiveIn[i]->getBlock();
+ assert(!MBB->pred_empty() && "Value live-in to entry block?");
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
MachineBasicBlock *Pred = *PI;
// Create the complement as index 0.
if (Edit->empty())
- Edit->create(MRI, LIS, VRM);
+ Edit->create(LIS, VRM);
// Create the open interval.
OpenIdx = Edit->size();
- Edit->create(MRI, LIS, VRM);
+ Edit->create(LIS, VRM);
}
SlotIndex SplitEditor::enterIntvBefore(SlotIndex Idx) {
"Range cannot span basic blocks");
// The complement interval will be extended as needed by extendRange().
- markComplexMapped(0, ParentVNI);
+ if (ParentVNI)
+ markComplexMapped(0, ParentVNI);
DEBUG(dbgs() << " overlapIntv [" << Start << ';' << End << "):");
RegAssign.insert(Start, End, OpenIdx);
DEBUG(dump());
}
SlotIndex Idx = LIS.getInstructionIndex(MI);
- Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
+ if (MO.isDef())
+ Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
// Rewrite to the mapped register at Idx.
unsigned RegIdx = RegAssign.lookup(Idx);
DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
<< Idx << ':' << RegIdx << '\t' << *MI);
- // Extend liveness to Idx.
- if (ExtendRanges)
- extendRange(RegIdx, Idx);
+ // Extend liveness to Idx if the instruction reads reg.
+ if (!ExtendRanges)
+ continue;
+
+ // Skip instructions that don't read Reg.
+ if (MO.isDef()) {
+ if (!MO.getSubReg() && !MO.isEarlyClobber())
+ continue;
+ // We may wan't to extend a live range for a partial redef, or for a use
+ // tied to an early clobber.
+ Idx = Idx.getPrevSlot();
+ if (!Edit->getParent().liveAt(Idx))
+ continue;
+ } else
+ Idx = Idx.getUseIndex();
+
+ extendRange(RegIdx, Idx);
}
}
-/// rewriteSplit - Rewrite uses of Intvs[0] according to the ConEQ mapping.
-void SplitEditor::rewriteComponents(const SmallVectorImpl<LiveInterval*> &Intvs,
- const ConnectedVNInfoEqClasses &ConEq) {
- for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Intvs[0]->reg),
- RE = MRI.reg_end(); RI != RE;) {
- MachineOperand &MO = RI.getOperand();
- MachineInstr *MI = MO.getParent();
- ++RI;
- if (MO.isUse() && MO.isUndef())
- continue;
- // DBG_VALUE instructions should have been eliminated earlier.
- SlotIndex Idx = LIS.getInstructionIndex(MI);
- Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
- DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
- << Idx << ':');
- const VNInfo *VNI = Intvs[0]->getVNInfoAt(Idx);
- assert(VNI && "Interval not live at use.");
- MO.setReg(Intvs[ConEq.getEqClass(VNI)]->reg);
- DEBUG(dbgs() << VNI->id << '\t' << *MI);
+void SplitEditor::deleteRematVictims() {
+ SmallVector<MachineInstr*, 8> Dead;
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
+ LiveInterval *LI = *I;
+ for (LiveInterval::const_iterator LII = LI->begin(), LIE = LI->end();
+ LII != LIE; ++LII) {
+ // Dead defs end at the store slot.
+ if (LII->end != LII->valno->def.getNextSlot())
+ continue;
+ MachineInstr *MI = LIS.getInstructionFromIndex(LII->valno->def);
+ assert(MI && "Missing instruction for dead def");
+ MI->addRegisterDead(LI->reg, &TRI);
+
+ if (!MI->allDefsAreDead())
+ continue;
+
+ DEBUG(dbgs() << "All defs dead: " << *MI);
+ Dead.push_back(MI);
+ }
}
+
+ if (Dead.empty())
+ return;
+
+ Edit->eliminateDeadDefs(Dead, LIS, VRM, TII);
}
void SplitEditor::finish() {
if (ParentVNI->isUnused())
continue;
unsigned RegIdx = RegAssign.lookup(ParentVNI->def);
- defValue(RegIdx, ParentVNI, ParentVNI->def);
+ VNInfo *VNI = defValue(RegIdx, ParentVNI, ParentVNI->def);
+ VNI->setIsPHIDef(ParentVNI->isPHIDef());
+ VNI->setCopy(ParentVNI->getCopy());
+
// Mark rematted values as complex everywhere to force liveness computation.
// The new live ranges may be truncated.
if (Edit->didRematerialize(ParentVNI))
// Rewrite virtual registers, possibly extending ranges.
rewriteAssigned(Complex);
- // FIXME: Delete defs that were rematted everywhere.
+ // Delete defs that were rematted everywhere.
+ if (Complex)
+ deleteRematVictims();
// Get rid of unused values and set phi-kill flags.
for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I)
SmallVector<LiveInterval*, 8> dups;
dups.push_back(li);
for (unsigned i = 1; i != NumComp; ++i)
- dups.push_back(&Edit->create(MRI, LIS, VRM));
- rewriteComponents(dups, ConEQ);
- ConEQ.Distribute(&dups[0]);
+ dups.push_back(&Edit->create(LIS, VRM));
+ ConEQ.Distribute(&dups[0], MRI);
}
// Calculate spill weight and allocation hints for new intervals.
- VirtRegAuxInfo vrai(VRM.getMachineFunction(), LIS, SA.Loops);
- for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
- LiveInterval &li = **I;
- vrai.CalculateRegClass(li.reg);
- vrai.CalculateWeightAndHint(li);
- DEBUG(dbgs() << " new interval " << MRI.getRegClass(li.reg)->getName()
- << ":" << li << '\n');
- }
+ Edit->calculateRegClassAndHint(VRM.getMachineFunction(), LIS, SA.Loops);
}
/// may be an advantage to split CurLI for the duration of the block.
bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) {
// If CurLI is local to one block, there is no point to splitting it.
- if (LiveBlocks.size() <= 1)
+ if (UseBlocks.size() <= 1)
return false;
// Add blocks with multiple uses.
- for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
- const BlockInfo &BI = LiveBlocks[i];
- if (!BI.Uses)
- continue;
- unsigned Instrs = UsingBlocks.lookup(BI.MBB);
- if (Instrs <= 1)
- continue;
- if (Instrs == 2 && BI.LiveIn && BI.LiveOut && !BI.LiveThrough)
+ for (unsigned i = 0, e = UseBlocks.size(); i != e; ++i) {
+ const BlockInfo &BI = UseBlocks[i];
+ if (BI.FirstUse == BI.LastUse)
continue;
Blocks.insert(BI.MBB);
}
/// basic block in Blocks.
void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) {
DEBUG(dbgs() << " splitSingleBlocks for " << Blocks.size() << " blocks.\n");
-
- for (unsigned i = 0, e = SA.LiveBlocks.size(); i != e; ++i) {
- const SplitAnalysis::BlockInfo &BI = SA.LiveBlocks[i];
- if (!BI.Uses || !Blocks.count(BI.MBB))
+ ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA.getUseBlocks();
+ for (unsigned i = 0; i != UseBlocks.size(); ++i) {
+ const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
+ if (!Blocks.count(BI.MBB))
continue;
openIntv();
- SlotIndex SegStart = enterIntvBefore(BI.FirstUse);
- if (!BI.LiveOut || BI.LastUse < BI.LastSplitPoint) {
+ SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB->getNumber());
+ SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstUse,
+ LastSplitPoint));
+ if (!BI.LiveOut || BI.LastUse < LastSplitPoint) {
useIntv(SegStart, leaveIntvAfter(BI.LastUse));
} else {
// The last use is after the last valid split point.
- SlotIndex SegStop = leaveIntvBefore(BI.LastSplitPoint);
+ SlotIndex SegStop = leaveIntvBefore(LastSplitPoint);
useIntv(SegStart, SegStop);
overlapIntv(SegStop, BI.LastUse);
}
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