DomTree = MDT;
Alloc = VNIA;
- MainLiveOutData.reset(MF->getNumBlockIDs());
- LiveIn.clear();
+ unsigned NumBlocks = MF->getNumBlockIDs();
+ Seen.clear();
+ Seen.resize(NumBlocks);
+ Map.resize(NumBlocks);
}
-static SlotIndex getDefIndex(const SlotIndexes &Indexes, const MachineInstr &MI,
- bool EarlyClobber) {
- // PHI defs begin at the basic block start index.
- if (MI.isPHI())
- return Indexes.getMBBStartIdx(MI.getParent());
-
- // Instructions are either normal 'r', or early clobber 'e'.
- return Indexes.getInstructionIndex(&MI).getRegSlot(EarlyClobber);
+static void createDeadDef(SlotIndexes &Indexes, VNInfo::Allocator &Alloc,
+ LiveRange &LR, const MachineOperand &MO) {
+ const MachineInstr *MI = MO.getParent();
+ SlotIndex DefIdx;
+ if (MI->isPHI()) {
+ DefIdx = Indexes.getMBBStartIdx(MI->getParent());
+ } else {
+ DefIdx = Indexes.getInstructionIndex(MI).getRegSlot(MO.isEarlyClobber());
+ }
+ // Create the def in LR. This may find an existing def.
+ LR.createDeadDef(DefIdx, Alloc);
}
-void LiveRangeCalc::createDeadDefs(LiveInterval &LI) {
+void LiveRangeCalc::calculate(LiveInterval &LI) {
assert(MRI && Indexes && "call reset() first");
+ // Step 1: Create minimal live segments for every definition of Reg.
// Visit all def operands. If the same instruction has multiple defs of Reg,
// LR.createDeadDef() will deduplicate.
const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo();
unsigned Reg = LI.reg;
- for (const MachineOperand &MO : MRI->def_operands(Reg)) {
- const MachineInstr *MI = MO.getParent();
- SlotIndex Idx = getDefIndex(*Indexes, *MI, MO.isEarlyClobber());
+ for (const MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
unsigned SubReg = MO.getSubReg();
if (LI.hasSubRanges() || (SubReg != 0 && MRI->tracksSubRegLiveness())) {
unsigned Mask = SubReg != 0 ? TRI.getSubRegIndexLaneMask(SubReg)
assert(Common == S.LaneMask);
CommonRange = &S;
}
- CommonRange->createDeadDef(Idx, *Alloc);
+ if (MO.isDef())
+ createDeadDef(*Indexes, *Alloc, *CommonRange, MO);
Mask &= ~Common;
}
+ // Create a new SubRange for subregs we did not cover yet.
if (Mask != 0) {
- LiveInterval::SubRange *SubRange = LI.createSubRange(*Alloc, Mask);
- SubRange->createDeadDef(Idx, *Alloc);
+ LiveInterval::SubRange *NewRange = LI.createSubRange(*Alloc, Mask);
+ if (MO.isDef())
+ createDeadDef(*Indexes, *Alloc, *NewRange, MO);
}
}
- // Create the def in LR. This may find an existing def.
- LI.createDeadDef(Idx, *Alloc);
+ // Create the def in the main liverange.
+ if (MO.isDef())
+ createDeadDef(*Indexes, *Alloc, LI, MO);
}
+
+ // Step 2: Extend live segments to all uses, constructing SSA form as
+ // necessary.
+ for (LiveInterval::SubRange &S : LI.subranges()) {
+ extendToUses(S, Reg, S.LaneMask);
+ }
+ extendToUses(LI, Reg, ~0u);
}
-void LiveRangeCalc::createDeadDefs(LiveRange &LR, unsigned Reg) {
+void LiveRangeCalc::calculate(LiveRange &LR, unsigned Reg, bool IgnoreUses) {
assert(MRI && Indexes && "call reset() first");
+ // Step 1: Create minimal live segments for every definition of Reg.
// Visit all def operands. If the same instruction has multiple defs of Reg,
// LR.createDeadDef() will deduplicate.
for (MachineOperand &MO : MRI->def_operands(Reg)) {
- const MachineInstr *MI = MO.getParent();
- SlotIndex Idx = getDefIndex(*Indexes, *MI, MO.isEarlyClobber());
- // Create the def in LR. This may find an existing def.
- LR.createDeadDef(Idx, *Alloc);
- }
-}
-
-
-static SlotIndex getUseIndex(const SlotIndexes &Indexes,
- const MachineOperand &MO) {
- const MachineInstr *MI = MO.getParent();
- unsigned OpNo = (&MO - &MI->getOperand(0));
- if (MI->isPHI()) {
- assert(!MO.isDef() && "Cannot handle PHI def of partial register.");
- // The actual place where a phi operand is used is the end of the pred MBB.
- // PHI operands are paired: (Reg, PredMBB).
- return Indexes.getMBBEndIdx(MI->getOperand(OpNo+1).getMBB());
+ createDeadDef(*Indexes, *Alloc, LR, MO);
}
- // Check for early-clobber redefs.
- bool isEarlyClobber = false;
- unsigned DefIdx;
- if (MO.isDef()) {
- isEarlyClobber = MO.isEarlyClobber();
- } else if (MI->isRegTiedToDefOperand(OpNo, &DefIdx)) {
- // FIXME: This would be a lot easier if tied early-clobber uses also
- // had an early-clobber flag.
- isEarlyClobber = MI->getOperand(DefIdx).isEarlyClobber();
- }
- return Indexes.getInstructionIndex(MI).getRegSlot(isEarlyClobber);
+ // Step 2: Extend live segments to all uses, constructing SSA form as
+ // necessary.
+ if (!IgnoreUses)
+ extendToUses(LR, Reg, ~0u);
}
-void LiveRangeCalc::extendToUses(LiveRange &LR, unsigned Reg) {
- assert(MRI && Indexes && "call reset() first");
+void LiveRangeCalc::extendToUses(LiveRange &LR, unsigned Reg, unsigned Mask) {
+ unsigned NumBlocks = MF->getNumBlockIDs();
+ Seen.clear();
+ Seen.resize(NumBlocks);
+ Map.resize(NumBlocks);
// Visit all operands that read Reg. This may include partial defs.
- for (MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
- // Clear all kill flags. They will be reinserted after register allocation
- // by LiveIntervalAnalysis::addKillFlags().
- if (MO.isUse())
- MO.setIsKill(false);
- if (!MO.readsReg())
- continue;
- // MI is reading Reg. We may have visited MI before if it happens to be
- // reading Reg multiple times. That is OK, extend() is idempotent.
- SlotIndex Idx = getUseIndex(*Indexes, MO);
- extend(LR, Idx, Reg, MainLiveOutData);
- }
-}
-
-
-void LiveRangeCalc::extendToUses(LiveInterval &LI) {
- assert(MRI && Indexes && "call reset() first");
-
const TargetRegisterInfo &TRI = *MRI->getTargetRegisterInfo();
- SmallVector<LiveOutData,2> LiveOuts;
- unsigned NumSubRanges = 0;
- for (const auto &S : LI.subranges()) {
- (void)S;
- ++NumSubRanges;
- LiveOuts.push_back(LiveOutData());
- LiveOuts.back().reset(MF->getNumBlockIDs());
- }
-
- // Visit all operands that read Reg. This may include partial defs.
- unsigned Reg = LI.reg;
for (MachineOperand &MO : MRI->reg_nodbg_operands(Reg)) {
// Clear all kill flags. They will be reinserted after register allocation
// by LiveIntervalAnalysis::addKillFlags().
if (MO.isUse())
MO.setIsKill(false);
- if (!MO.readsReg())
+ // We are only interested in uses. For the main range this also includes
+ // the reads happening on partial register defs.
+ if (!MO.isUse() && (!MO.readsReg() || Mask != ~0u))
continue;
- SlotIndex Idx = getUseIndex(*Indexes, MO);
unsigned SubReg = MO.getSubReg();
- if (MO.isUse() && (LI.hasSubRanges() ||
- (MRI->tracksSubRegLiveness() && SubReg != 0))) {
- unsigned Mask = SubReg != 0
- ? TRI.getSubRegIndexLaneMask(SubReg)
- : MRI->getMaxLaneMaskForVReg(Reg);
+ if (SubReg != 0) {
+ unsigned SubRegMask = TRI.getSubRegIndexLaneMask(SubReg);
+ // Ignore uses not covering the current subrange.
+ if ((SubRegMask & Mask) == 0)
+ continue;
+ // The create dead-defs logic in calculate() splits subranges as fine as
+ // necessary for all uses, so SubRegMask shouldn't be smaller than Mask.
+ assert((SubRegMask & ~Mask) == 0);
+ }
- // If this is the first time we see a subregister def/use. Initialize
- // subranges by creating a copy of the main range.
- if (!LI.hasSubRanges()) {
- unsigned ClassMask = MRI->getMaxLaneMaskForVReg(Reg);
- LI.createSubRangeFrom(*Alloc, ClassMask, LI);
- LiveOuts.insert(LiveOuts.begin(), LiveOutData());
- LiveOuts.front().reset(MF->getNumBlockIDs());
- ++NumSubRanges;
- }
- unsigned SubRangeIdx = 0;
- for (LiveInterval::subrange_iterator S = LI.subrange_begin(),
- SE = LI.subrange_end(); S != SE; ++S, ++SubRangeIdx) {
- // A Mask for subregs common to the existing subrange and current def.
- unsigned Common = S->LaneMask & Mask;
- if (Common == 0)
- continue;
- // A Mask for subregs covered by the subrange but not the current def.
- unsigned LRest = S->LaneMask & ~Mask;
- LiveInterval::SubRange *CommonRange;
- unsigned CommonRangeIdx;
- if (LRest != 0) {
- // Split current subrange into Common and LRest ranges.
- S->LaneMask = LRest;
- CommonRange = LI.createSubRangeFrom(*Alloc, Common, *S);
- CommonRangeIdx = 0;
- LiveOuts.insert(LiveOuts.begin(), LiveOutData());
- LiveOuts.front().reset(MF->getNumBlockIDs());
- ++NumSubRanges;
- ++SubRangeIdx;
- } else {
- // The subrange and current def lanemasks match completely.
- assert(Common == S->LaneMask);
- CommonRange = &*S;
- CommonRangeIdx = SubRangeIdx;
- }
- extend(*CommonRange, Idx, Reg, LiveOuts[CommonRangeIdx]);
- Mask &= ~Common;
+ // Determine the actual place of the use.
+ const MachineInstr *MI = MO.getParent();
+ unsigned OpNo = (&MO - &MI->getOperand(0));
+ SlotIndex UseIdx;
+ if (MI->isPHI()) {
+ assert(!MO.isDef() && "Cannot handle PHI def of partial register.");
+ // The actual place where a phi operand is used is the end of the pred
+ // MBB. PHI operands are paired: (Reg, PredMBB).
+ UseIdx = Indexes->getMBBEndIdx(MI->getOperand(OpNo+1).getMBB());
+ } else {
+ // Check for early-clobber redefs.
+ bool isEarlyClobber = false;
+ unsigned DefIdx;
+ if (MO.isDef()) {
+ isEarlyClobber = MO.isEarlyClobber();
+ } else if (MI->isRegTiedToDefOperand(OpNo, &DefIdx)) {
+ // FIXME: This would be a lot easier if tied early-clobber uses also
+ // had an early-clobber flag.
+ isEarlyClobber = MI->getOperand(DefIdx).isEarlyClobber();
}
- assert(SubRangeIdx == NumSubRanges);
+ UseIdx = Indexes->getInstructionIndex(MI).getRegSlot(isEarlyClobber);
}
- extend(LI, Idx, Reg, MainLiveOutData);
+
+ // MI is reading Reg. We may have visited MI before if it happens to be
+ // reading Reg multiple times. That is OK, extend() is idempotent.
+ extend(LR, UseIdx, Reg);
}
}
-void LiveRangeCalc::updateFromLiveIns(LiveOutData &LiveOuts) {
+void LiveRangeCalc::updateFromLiveIns() {
LiveRangeUpdater Updater;
for (const LiveInBlock &I : LiveIn) {
if (!I.DomNode)
else {
// The value is live-through, update LiveOut as well.
// Defer the Domtree lookup until it is needed.
- assert(LiveOuts.Seen.test(MBB->getNumber()));
- LiveOuts.Map[MBB] = LiveOutPair(I.Value, nullptr);
+ assert(Seen.test(MBB->getNumber()));
+ Map[MBB] = LiveOutPair(I.Value, nullptr);
}
Updater.setDest(&I.LR);
Updater.add(Start, End, I.Value);
}
-void LiveRangeCalc::extend(LiveRange &LR, SlotIndex Kill, unsigned PhysReg,
- LiveOutData &LiveOuts) {
+void LiveRangeCalc::extend(LiveRange &LR, SlotIndex Kill, unsigned PhysReg) {
assert(Kill.isValid() && "Invalid SlotIndex");
assert(Indexes && "Missing SlotIndexes");
assert(DomTree && "Missing dominator tree");
// multiple values, and we may need to create even more phi-defs to preserve
// VNInfo SSA form. Perform a search for all predecessor blocks where we
// know the dominating VNInfo.
- if (findReachingDefs(LR, *KillMBB, Kill, PhysReg, LiveOuts))
+ if (findReachingDefs(LR, *KillMBB, Kill, PhysReg))
return;
// When there were multiple different values, we may need new PHIs.
- calculateValues(LiveOuts);
+ calculateValues();
}
// This function is called by a client after using the low-level API to add
// live-out and live-in blocks. The unique value optimization is not
// available, SplitEditor::transferValues handles that case directly anyway.
-void LiveRangeCalc::calculateValues(LiveOutData &LiveOuts) {
+void LiveRangeCalc::calculateValues() {
assert(Indexes && "Missing SlotIndexes");
assert(DomTree && "Missing dominator tree");
- updateSSA(LiveOuts);
- updateFromLiveIns(LiveOuts);
+ updateSSA();
+ updateFromLiveIns();
}
bool LiveRangeCalc::findReachingDefs(LiveRange &LR, MachineBasicBlock &KillMBB,
- SlotIndex Kill, unsigned PhysReg,
- LiveOutData &LiveOuts) {
+ SlotIndex Kill, unsigned PhysReg) {
unsigned KillMBBNum = KillMBB.getNumber();
// Block numbers where LR should be live-in.
MachineBasicBlock *Pred = *PI;
// Is this a known live-out block?
- if (LiveOuts.Seen.test(Pred->getNumber())) {
- if (VNInfo *VNI = LiveOuts.Map[Pred].first) {
+ if (Seen.test(Pred->getNumber())) {
+ if (VNInfo *VNI = Map[Pred].first) {
if (TheVNI && TheVNI != VNI)
UniqueVNI = false;
TheVNI = VNI;
// First time we see Pred. Try to determine the live-out value, but set
// it as null if Pred is live-through with an unknown value.
VNInfo *VNI = LR.extendInBlock(Start, End);
- LiveOuts.setLiveOutValue(Pred, VNI);
+ setLiveOutValue(Pred, VNI);
if (VNI) {
if (TheVNI && TheVNI != VNI)
UniqueVNI = false;
if (*I == KillMBBNum && Kill.isValid())
End = Kill;
else
- LiveOuts.Map[MF->getBlockNumbered(*I)] =
- LiveOutPair(TheVNI, nullptr);
+ Map[MF->getBlockNumbered(*I)] = LiveOutPair(TheVNI, nullptr);
Updater.add(Start, End, TheVNI);
}
return true;
// This is essentially the same iterative algorithm that SSAUpdater uses,
// except we already have a dominator tree, so we don't have to recompute it.
-void LiveRangeCalc::updateSSA(LiveOutData &LiveOuts) {
+void LiveRangeCalc::updateSSA() {
assert(Indexes && "Missing SlotIndexes");
assert(DomTree && "Missing dominator tree");
// We need a live-in value to a block with no immediate dominator?
// This is probably an unreachable block that has survived somehow.
- bool needPHI = !IDom
- || !LiveOuts.Seen.test(IDom->getBlock()->getNumber());
+ bool needPHI = !IDom || !Seen.test(IDom->getBlock()->getNumber());
// IDom dominates all of our predecessors, but it may not be their
// immediate dominator. Check if any of them have live-out values that are
// properly dominated by IDom. If so, we need a phi-def here.
if (!needPHI) {
- IDomValue = LiveOuts.Map[IDom->getBlock()];
+ IDomValue = Map[IDom->getBlock()];
// Cache the DomTree node that defined the value.
if (IDomValue.first && !IDomValue.second)
- LiveOuts.Map[IDom->getBlock()].second = IDomValue.second =
+ Map[IDom->getBlock()].second = IDomValue.second =
DomTree->getNode(Indexes->getMBBFromIndex(IDomValue.first->def));
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
- LiveOutPair &Value = LiveOuts.Map[*PI];
+ LiveOutPair &Value = Map[*PI];
if (!Value.first || Value.first == IDomValue.first)
continue;
// The value may be live-through even if Kill is set, as can happen when
// we are called from extendRange. In that case LiveOutSeen is true, and
// LiveOut indicates a foreign or missing value.
- LiveOutPair &LOP = LiveOuts.Map[MBB];
+ LiveOutPair &LOP = Map[MBB];
// Create a phi-def if required.
if (needPHI) {
/// LiveOutMap - Map basic blocks to the value leaving the block.
typedef IndexedMap<LiveOutPair, MBB2NumberFunctor> LiveOutMap;
- struct LiveOutData {
- /// Seen - Bit vector of active entries in LiveOut, also used as a visited
- /// set by findReachingDefs. One entry per basic block, indexed by block
- /// number. This is kept as a separate bit vector because it can be cleared
- /// quickly when switching live ranges.
- BitVector Seen;
-
- /// LiveOut - Map each basic block where a live range is live out to the
- /// live-out value and its defining block.
- ///
- /// For every basic block, MBB, one of these conditions shall be true:
- ///
- /// 1. !Seen.count(MBB->getNumber())
- /// Blocks without a Seen bit are ignored.
- /// 2. LiveOut[MBB].second.getNode() == MBB
- /// The live-out value is defined in MBB.
- /// 3. forall P in preds(MBB): LiveOut[P] == LiveOut[MBB]
- /// The live-out value passses through MBB. All predecessors must carry
- /// the same value.
- ///
- /// The domtree node may be null, it can be computed.
- ///
- /// The map can be shared by multiple live ranges as long as no two are
- /// live-out of the same block.
- LiveOutMap Map;
-
- void reset(unsigned NumBlocks) {
- Seen.clear();
- Seen.resize(NumBlocks);
- Map.resize(NumBlocks);
- }
-
- void setLiveOutValue(MachineBasicBlock *MBB, VNInfo *VNI) {
- Seen.set(MBB->getNumber());
- Map[MBB] = LiveOutPair(VNI, nullptr);
- }
- };
- LiveOutData MainLiveOutData;
+ /// Seen - Bit vector of active entries in LiveOut, also used as a visited
+ /// set by findReachingDefs. One entry per basic block, indexed by block
+ /// number. This is kept as a separate bit vector because it can be cleared
+ /// quickly when switching live ranges.
+ BitVector Seen;
+
+ /// LiveOut - Map each basic block where a live range is live out to the
+ /// live-out value and its defining block.
+ ///
+ /// For every basic block, MBB, one of these conditions shall be true:
+ ///
+ /// 1. !Seen.count(MBB->getNumber())
+ /// Blocks without a Seen bit are ignored.
+ /// 2. LiveOut[MBB].second.getNode() == MBB
+ /// The live-out value is defined in MBB.
+ /// 3. forall P in preds(MBB): LiveOut[P] == LiveOut[MBB]
+ /// The live-out value passses through MBB. All predecessors must carry
+ /// the same value.
+ ///
+ /// The domtree node may be null, it can be computed.
+ ///
+ /// The map can be shared by multiple live ranges as long as no two are
+ /// live-out of the same block.
+ LiveOutMap Map;
/// LiveInBlock - Information about a basic block where a live range is known
/// to be live-in, but the value has not yet been determined.
///
/// PhysReg, when set, is used to verify live-in lists on basic blocks.
bool findReachingDefs(LiveRange &LR, MachineBasicBlock &KillMBB,
- SlotIndex Kill, unsigned PhysReg,
- LiveOutData &LiveOuts);
+ SlotIndex Kill, unsigned PhysReg);
/// updateSSA - Compute the values that will be live in to all requested
/// blocks in LiveIn. Create PHI-def values as required to preserve SSA form.
///
/// Every live-in block must be jointly dominated by the added live-out
/// blocks. No values are read from the live ranges.
- void updateSSA(LiveOutData &LiveOuts);
+ void updateSSA();
/// Transfer information from the LiveIn vector to the live ranges and update
/// the given @p LiveOuts.
- void updateFromLiveIns(LiveOutData &LiveOuts);
+ void updateFromLiveIns();
+
+ /// Extend the live range of @p LR to reach all uses of Reg.
+ ///
+ /// All uses must be jointly dominated by existing liveness. PHI-defs are
+ /// inserted as needed to preserve SSA form.
+ void extendToUses(LiveRange &LR, unsigned Reg, unsigned LaneMask = ~0u);
public:
LiveRangeCalc() : MF(nullptr), MRI(nullptr), Indexes(nullptr),
/// single existing value, Alloc may be null.
///
/// PhysReg, when set, is used to verify live-in lists on basic blocks.
- void extend(LiveRange &LR, SlotIndex Kill, unsigned PhysReg,
- LiveOutData &LiveOuts);
+ void extend(LiveRange &LR, SlotIndex Kill, unsigned PhysReg = 0);
- void extend(LiveRange &LR, SlotIndex Kill) {
- extend(LR, Kill, 0, MainLiveOutData);
- }
-
- /// createDeadDefs - Create a dead def in LI for every def operand of Reg.
- /// Each instruction defining Reg gets a new VNInfo with a corresponding
- /// minimal live range.
- void createDeadDefs(LiveRange &LR, unsigned Reg);
+ /// Calculates liveness for the uses/defs of a given registers. The results
+ /// are written to @p LR.
+ void calculate(LiveRange &LR, unsigned Reg, bool IgnoreUses);
- /// Subregister aware version of createDeadDefs(LiveRange &LR, unsigned Reg).
- /// If subregister liveness tracking is enabled new subranges are created as
- /// necessary when subregister defs are found. As with
- /// createDeadDefs(LiveRange &LR, unsigned Reg) new short live segments are
- /// created for every def of LI.reg. The new segments start and end at the
- /// defining instruction (hence the name "DeadDef").
- void createDeadDefs(LiveInterval &LI);
-
- /// extendToUses - Extend the live range of LI to reach all uses of Reg.
- ///
- /// All uses must be jointly dominated by existing liveness. PHI-defs are
- /// inserted as needed to preserve SSA form.
- void extendToUses(LiveRange &LR, unsigned Reg);
-
- /// Subregister aware version of extendToUses(LiveRange &LR, unsigned Reg).
- /// If subregister liveness tracking is enabled new subranges are created
- /// as necessary when subregister uses are found. As with
- /// extendToUses(LiveRange &LR, unsigned Reg) the segments existing at the
- /// defs are extend until they reach all uses. New value numbers are created
- /// at CFG joins as necessary (SSA construction).
- void extendToUses(LiveInterval &LI);
+ /// Calculates liveness for the register specified in live interval @p LI.
+ /// Creates subregister live ranges as needed if subreg liveness tracking is
+ /// enabled.
+ void calculate(LiveInterval &LI);
//===--------------------------------------------------------------------===//
// Low-level interface.
/// VNI may be null only if MBB is a live-through block also passed to
/// addLiveInBlock().
void setLiveOutValue(MachineBasicBlock *MBB, VNInfo *VNI) {
- MainLiveOutData.setLiveOutValue(MBB, VNI);
+ Seen.set(MBB->getNumber());
+ Map[MBB] = LiveOutPair(VNI, nullptr);
}
/// addLiveInBlock - Add a block with an unknown live-in value. This
///
/// Every predecessor of a live-in block must have been given a value with
/// setLiveOutValue, the value may be null for live-trough blocks.
- void calculateValues(LiveOutData &LiveOuts);
-
- void calculateValues() {
- calculateValues(MainLiveOutData);
- }
+ void calculateValues();
};
} // end namespace llvm
projects / oota-llvm.git / commitdiff