[llvm] 210c485 - [LiveDebugValues] Encode a location in VarLoc IDs, NFC [2/3]
Vedant Kumar via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 27 12:40:00 PST 2020
Author: Vedant Kumar
Date: 2020-02-27T12:39:47-08:00
New Revision: 210c4853de20c36da207dfc5f524e0d7f013eec4
URL: https://github.com/llvm/llvm-project/commit/210c4853de20c36da207dfc5f524e0d7f013eec4
DIFF: https://github.com/llvm/llvm-project/commit/210c4853de20c36da207dfc5f524e0d7f013eec4.diff
LOG: [LiveDebugValues] Encode a location in VarLoc IDs, NFC [2/3]
This is part 2 of a 3-part series to address a compile-time explosion
issue in LiveDebugValues.
---
Each VarLoc has a unique ID: this ID is used to look up a VarLoc in the
VarLocMap, and to virtually insert a VarLoc into a VarLocSet. Instead of
inserting the VarLoc /itself/ into the VarLocSet, we insert just the ID,
because this can be represented efficiently with a SparseBitVector.
This change introduces LocIndex, a layer of abstraction on top of VarLoc
IDs. Prior to this change, an ID was just an index into a vector. With
this change, an ID encodes both an index /and/ a register location. The
type-checker ensures that conversions to and from LocIndex are correct.
For the moment the register location is always 0 (undef). We have plenty
of bits left over to encode physregs, stack slots, and other locations
in the future.
Differential Revision: https://reviews.llvm.org/D74985
Added:
Modified:
llvm/lib/CodeGen/LiveDebugValues.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues.cpp
index 259604adb5c0..f2949694d06d 100644
--- a/llvm/lib/CodeGen/LiveDebugValues.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -112,6 +112,32 @@ namespace {
using DefinedRegsSet = SmallSet<Register, 32>;
+/// A type-checked pair of {Register Location (or 0), Index}, used to index
+/// into a \ref VarLocMap. This can be efficiently converted to a 64-bit int
+/// for insertion into a \ref VarLocSet, and efficiently converted back. The
+/// type-checker helps ensure that the conversions aren't lossy.
+///
+/// Why encode a location /into/ the VarLocMap index? This makes it possible
+/// to find the open VarLocs killed by a register def very quickly. This is a
+/// performance-critical operation for LiveDebugValues.
+struct LocIndex {
+ uint32_t Location; // Physical registers live in the range [1;2^30) (see
+ // \ref MCRegister), so we have plenty of range left here
+ // to encode non-register locations.
+ uint32_t Index;
+
+ LocIndex(uint32_t Location, uint32_t Index)
+ : Location(Location), Index(Index) {}
+
+ uint64_t getAsRawInteger() const {
+ return (static_cast<uint64_t>(Location) << 32) | Index;
+ }
+
+ static LocIndex fromRawInteger(uint64_t ID) {
+ return {static_cast<uint32_t>(ID >> 32), static_cast<uint32_t>(ID)};
+ }
+};
+
class LiveDebugValues : public MachineFunctionPass {
private:
const TargetRegisterInfo *TRI;
@@ -407,12 +433,23 @@ class LiveDebugValues : public MachineFunctionPass {
}
};
- using VarLocMap = UniqueVector<VarLoc>;
+ class VarLocMap {
+ UniqueVector<VarLoc> VarLocs;
+
+ public:
+ LocIndex insert(const VarLoc &VL) {
+ uint32_t Index = VarLocs.insert(VL);
+ return {0, Index};
+ }
+
+ const VarLoc &operator[](LocIndex ID) const { return VarLocs[ID.Index]; }
+ };
+
using VarLocSet = SparseBitVector<>;
using VarLocInMBB = SmallDenseMap<const MachineBasicBlock *, VarLocSet>;
struct TransferDebugPair {
MachineInstr *TransferInst; /// Instruction where this transfer occurs.
- unsigned LocationID; /// Location number for the transfer dest.
+ LocIndex LocationID; /// Location number for the transfer dest.
};
using TransferMap = SmallVector<TransferDebugPair, 4>;
@@ -441,9 +478,9 @@ class LiveDebugValues : public MachineFunctionPass {
class OpenRangesSet {
VarLocSet VarLocs;
// Map the DebugVariable to recent primary location ID.
- SmallDenseMap<DebugVariable, unsigned, 8> Vars;
+ SmallDenseMap<DebugVariable, LocIndex, 8> Vars;
// Map the DebugVariable to recent backup location ID.
- SmallDenseMap<DebugVariable, unsigned, 8> EntryValuesBackupVars;
+ SmallDenseMap<DebugVariable, LocIndex, 8> EntryValuesBackupVars;
OverlapMap &OverlappingFragments;
public:
@@ -459,17 +496,18 @@ class LiveDebugValues : public MachineFunctionPass {
void erase(const VarLocSet &KillSet, const VarLocMap &VarLocIDs);
/// Insert a new range into the set.
- void insert(unsigned VarLocID, const VarLoc &VL);
+ void insert(LocIndex VarLocID, const VarLoc &VL);
/// Insert a set of ranges.
void insertFromLocSet(const VarLocSet &ToLoad, const VarLocMap &Map) {
- for (unsigned Id : ToLoad) {
- const VarLoc &VarL = Map[Id];
- insert(Id, VarL);
+ for (uint64_t ID : ToLoad) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ const VarLoc &VarL = Map[Idx];
+ insert(Idx, VarL);
}
}
- llvm::Optional<unsigned> getEntryValueBackup(DebugVariable Var);
+ llvm::Optional<LocIndex> getEntryValueBackup(DebugVariable Var);
/// Empty the set.
void clear() {
@@ -517,7 +555,7 @@ class LiveDebugValues : public MachineFunctionPass {
VarLoc::SpillLoc extractSpillBaseRegAndOffset(const MachineInstr &MI);
void insertTransferDebugPair(MachineInstr &MI, OpenRangesSet &OpenRanges,
TransferMap &Transfers, VarLocMap &VarLocIDs,
- unsigned OldVarID, TransferKind Kind,
+ LocIndex OldVarID, TransferKind Kind,
unsigned NewReg = 0);
void transferDebugValue(const MachineInstr &MI, OpenRangesSet &OpenRanges,
@@ -617,8 +655,8 @@ void LiveDebugValues::OpenRangesSet::erase(const VarLoc &VL) {
auto *EraseFrom = VL.isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars;
auto It = EraseFrom->find(VarToErase);
if (It != EraseFrom->end()) {
- unsigned ID = It->second;
- VarLocs.reset(ID);
+ LocIndex ID = It->second;
+ VarLocs.reset(ID.getAsRawInteger());
EraseFrom->erase(It);
}
};
@@ -648,23 +686,23 @@ void LiveDebugValues::OpenRangesSet::erase(const VarLoc &VL) {
void LiveDebugValues::OpenRangesSet::erase(const VarLocSet &KillSet,
const VarLocMap &VarLocIDs) {
VarLocs.intersectWithComplement(KillSet);
- for (unsigned ID : KillSet) {
- const VarLoc *VL = &VarLocIDs[ID];
+ for (uint64_t ID : KillSet) {
+ const VarLoc *VL = &VarLocIDs[LocIndex::fromRawInteger(ID)];
auto *EraseFrom = VL->isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars;
EraseFrom->erase(VL->Var);
}
}
-void LiveDebugValues::OpenRangesSet::insert(unsigned VarLocID,
+void LiveDebugValues::OpenRangesSet::insert(LocIndex VarLocID,
const VarLoc &VL) {
auto *InsertInto = VL.isEntryBackupLoc() ? &EntryValuesBackupVars : &Vars;
- VarLocs.set(VarLocID);
+ VarLocs.set(VarLocID.getAsRawInteger());
InsertInto->insert({VL.Var, VarLocID});
}
/// Return the Loc ID of an entry value backup location, if it exists for the
/// variable.
-llvm::Optional<unsigned>
+llvm::Optional<LocIndex>
LiveDebugValues::OpenRangesSet::getEntryValueBackup(DebugVariable Var) {
auto It = EntryValuesBackupVars.find(Var);
if (It != EntryValuesBackupVars.end())
@@ -689,8 +727,8 @@ void LiveDebugValues::printVarLocInMBB(const MachineFunction &MF,
if (L.empty())
continue;
Out << "MBB: " << BB.getNumber() << ":\n";
- for (unsigned VLL : L) {
- const VarLoc &VL = VarLocIDs[VLL];
+ for (uint64_t VLL : L) {
+ const VarLoc &VL = VarLocIDs[LocIndex::fromRawInteger(VLL)];
Out << " Var: " << VL.Var.getVariable()->getName();
Out << " MI: ";
VL.dump(TRI, Out);
@@ -757,8 +795,8 @@ bool LiveDebugValues::removeEntryValue(const MachineInstr &MI,
}
if (TrySalvageEntryValue) {
- for (unsigned ID : OpenRanges.getVarLocs()) {
- const VarLoc &VL = VarLocIDs[ID];
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ const VarLoc &VL = VarLocIDs[LocIndex::fromRawInteger(ID)];
if (!VL.isEntryBackupLoc())
continue;
@@ -801,7 +839,6 @@ void LiveDebugValues::transferDebugValue(const MachineInstr &MI,
}
}
- unsigned ID;
if (isDbgValueDescribedByReg(MI) || MI.getOperand(0).isImm() ||
MI.getOperand(0).isFPImm() || MI.getOperand(0).isCImm()) {
// Use normal VarLoc constructor for registers and immediates.
@@ -809,7 +846,7 @@ void LiveDebugValues::transferDebugValue(const MachineInstr &MI,
// End all previous ranges of VL.Var.
OpenRanges.erase(VL);
- ID = VarLocIDs.insert(VL);
+ LocIndex ID = VarLocIDs.insert(VL);
// Add the VarLoc to OpenRanges from this DBG_VALUE.
OpenRanges.insert(ID, VL);
} else if (MI.hasOneMemOperand()) {
@@ -827,12 +864,15 @@ void LiveDebugValues::emitEntryValues(MachineInstr &MI,
VarLocMap &VarLocIDs,
TransferMap &Transfers,
SparseBitVector<> &KillSet) {
- for (unsigned ID : KillSet) {
- if (!VarLocIDs[ID].Var.getVariable()->isParameter())
+ for (uint64_t ID : KillSet) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ const VarLoc &VL = VarLocIDs[Idx];
+ if (!VL.Var.getVariable()->isParameter())
continue;
- auto DebugVar = VarLocIDs[ID].Var;
- auto EntryValBackupID = OpenRanges.getEntryValueBackup(DebugVar);
+ auto DebugVar = VL.Var;
+ Optional<LocIndex> EntryValBackupID =
+ OpenRanges.getEntryValueBackup(DebugVar);
// If the parameter has the entry value backup, it means we should
// be able to use its entry value.
@@ -842,7 +882,7 @@ void LiveDebugValues::emitEntryValues(MachineInstr &MI,
const VarLoc &EntryVL = VarLocIDs[*EntryValBackupID];
VarLoc EntryLoc =
VarLoc::CreateEntryLoc(EntryVL.MI, LS, EntryVL.Expr, EntryVL.Loc.RegNo);
- unsigned EntryValueID = VarLocIDs.insert(EntryLoc);
+ LocIndex EntryValueID = VarLocIDs.insert(EntryLoc);
Transfers.push_back({&MI, EntryValueID});
OpenRanges.insert(EntryValueID, EntryLoc);
}
@@ -855,12 +895,12 @@ void LiveDebugValues::emitEntryValues(MachineInstr &MI,
/// otherwise it is variable's location on the stack.
void LiveDebugValues::insertTransferDebugPair(
MachineInstr &MI, OpenRangesSet &OpenRanges, TransferMap &Transfers,
- VarLocMap &VarLocIDs, unsigned OldVarID, TransferKind Kind,
+ VarLocMap &VarLocIDs, LocIndex OldVarID, TransferKind Kind,
unsigned NewReg) {
const MachineInstr *DebugInstr = &VarLocIDs[OldVarID].MI;
auto ProcessVarLoc = [&MI, &OpenRanges, &Transfers, &VarLocIDs](VarLoc &VL) {
- unsigned LocId = VarLocIDs.insert(VL);
+ LocIndex LocId = VarLocIDs.insert(VL);
// Close this variable's previous location range.
OpenRanges.erase(VL);
@@ -961,8 +1001,9 @@ void LiveDebugValues::transferRegisterDef(
}
// For performance reasons, it's critical to iterate over the open var locs
// at most once.
- for (unsigned ID : OpenRanges.getVarLocs()) {
- unsigned Reg = VarLocIDs[ID].isDescribedByReg();
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ unsigned Reg = VarLocIDs[Idx].isDescribedByReg();
if (!Reg)
continue;
@@ -1081,8 +1122,9 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
VarLocSet KillSet;
if (isSpillInstruction(MI, MF)) {
Loc = extractSpillBaseRegAndOffset(MI);
- for (unsigned ID : OpenRanges.getVarLocs()) {
- const VarLoc &VL = VarLocIDs[ID];
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ const VarLoc &VL = VarLocIDs[Idx];
if (VL.Kind == VarLoc::SpillLocKind && VL.Loc.SpillLocation == *Loc) {
// This location is overwritten by the current instruction -- terminate
// the open range, and insert an explicit DBG_VALUE $noreg.
@@ -1096,7 +1138,7 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
// where they are located; it's best to fix handle overwrites now.
KillSet.set(ID);
VarLoc UndefVL = VarLoc::CreateCopyLoc(VL.MI, LS, 0);
- unsigned UndefLocID = VarLocIDs.insert(UndefVL);
+ LocIndex UndefLocID = VarLocIDs.insert(UndefVL);
Transfers.push_back({&MI, UndefLocID});
}
}
@@ -1119,19 +1161,20 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
<< "\n");
}
// Check if the register or spill location is the location of a debug value.
- for (unsigned ID : OpenRanges.getVarLocs()) {
- if (TKind == TransferKind::TransferSpill &&
- VarLocIDs[ID].isDescribedByReg() == Reg) {
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ const VarLoc &VL = VarLocIDs[Idx];
+ if (TKind == TransferKind::TransferSpill && VL.isDescribedByReg() == Reg) {
LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
- << VarLocIDs[ID].Var.getVariable()->getName() << ")\n");
+ << VL.Var.getVariable()->getName() << ")\n");
} else if (TKind == TransferKind::TransferRestore &&
- VarLocIDs[ID].Kind == VarLoc::SpillLocKind &&
- VarLocIDs[ID].Loc.SpillLocation == *Loc) {
+ VL.Kind == VarLoc::SpillLocKind &&
+ VL.Loc.SpillLocation == *Loc) {
LLVM_DEBUG(dbgs() << "Restoring Register " << printReg(Reg, TRI) << '('
- << VarLocIDs[ID].Var.getVariable()->getName() << ")\n");
+ << VL.Var.getVariable()->getName() << ")\n");
} else
continue;
- insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID, TKind,
+ insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, Idx, TKind,
Reg);
return;
}
@@ -1176,17 +1219,19 @@ void LiveDebugValues::transferRegisterCopy(MachineInstr &MI,
// a parameter describing only a moving of the value around, rather then
// modifying it, we are still able to use the entry value if needed.
if (isRegOtherThanSPAndFP(*DestRegOp, MI, TRI)) {
- for (unsigned ID : OpenRanges.getVarLocs()) {
- if (VarLocIDs[ID].getEntryValueBackupReg() == SrcReg) {
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ const VarLoc &VL = VarLocIDs[Idx];
+ if (VL.getEntryValueBackupReg() == SrcReg) {
LLVM_DEBUG(dbgs() << "Copy of the entry value: "; MI.dump(););
- VarLoc EntryValLocCopyBackup = VarLoc::CreateEntryCopyBackupLoc(
- VarLocIDs[ID].MI, LS, VarLocIDs[ID].Expr, DestReg);
+ VarLoc EntryValLocCopyBackup =
+ VarLoc::CreateEntryCopyBackupLoc(VL.MI, LS, VL.Expr, DestReg);
// Stop tracking the original entry value.
- OpenRanges.erase(VarLocIDs[ID]);
+ OpenRanges.erase(VL);
// Start tracking the entry value copy.
- unsigned EntryValCopyLocID = VarLocIDs.insert(EntryValLocCopyBackup);
+ LocIndex EntryValCopyLocID = VarLocIDs.insert(EntryValLocCopyBackup);
OpenRanges.insert(EntryValCopyLocID, EntryValLocCopyBackup);
break;
}
@@ -1196,9 +1241,10 @@ void LiveDebugValues::transferRegisterCopy(MachineInstr &MI,
if (!SrcRegOp->isKill())
return;
- for (unsigned ID : OpenRanges.getVarLocs()) {
- if (VarLocIDs[ID].isDescribedByReg() == SrcReg) {
- insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, ID,
+ for (uint64_t ID : OpenRanges.getVarLocs()) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ if (VarLocIDs[Idx].isDescribedByReg() == SrcReg) {
+ insertTransferDebugPair(MI, OpenRanges, Transfers, VarLocIDs, Idx,
TransferKind::TransferCopy, DestReg);
return;
}
@@ -1212,11 +1258,11 @@ bool LiveDebugValues::transferTerminator(MachineBasicBlock *CurMBB,
const VarLocMap &VarLocIDs) {
bool Changed = false;
- LLVM_DEBUG(for (unsigned ID
+ LLVM_DEBUG(for (uint64_t ID
: OpenRanges.getVarLocs()) {
// Copy OpenRanges to OutLocs, if not already present.
dbgs() << "Add to OutLocs in MBB #" << CurMBB->getNumber() << ": ";
- VarLocIDs[ID].dump(TRI);
+ VarLocIDs[LocIndex::fromRawInteger(ID)].dump(TRI);
});
VarLocSet &VLS = OutLocs[CurMBB];
Changed = VLS != OpenRanges.getVarLocs();
@@ -1340,9 +1386,12 @@ bool LiveDebugValues::join(
LLVM_DEBUG({
if (!InLocsT.empty()) {
- for (auto ID : InLocsT)
+ for (uint64_t ID : InLocsT)
dbgs() << " gathered candidate incoming var: "
- << VarLocIDs[ID].Var.getVariable()->getName() << "\n";
+ << VarLocIDs[LocIndex::fromRawInteger(ID)]
+ .Var.getVariable()
+ ->getName()
+ << "\n";
}
});
@@ -1353,11 +1402,12 @@ bool LiveDebugValues::join(
VarLocSet KillSet;
bool IsArtificial = ArtificialBlocks.count(&MBB);
if (!IsArtificial) {
- for (auto ID : InLocsT) {
- if (!VarLocIDs[ID].dominates(MBB)) {
+ for (uint64_t ID : InLocsT) {
+ LocIndex Idx = LocIndex::fromRawInteger(ID);
+ if (!VarLocIDs[Idx].dominates(MBB)) {
KillSet.set(ID);
LLVM_DEBUG({
- auto Name = VarLocIDs[ID].Var.getVariable()->getName();
+ auto Name = VarLocIDs[Idx].Var.getVariable()->getName();
dbgs() << " killing " << Name << ", it doesn't dominate MBB\n";
});
}
@@ -1410,10 +1460,10 @@ void LiveDebugValues::flushPendingLocs(VarLocInMBB &PendingInLocs,
auto &MBB = const_cast<MachineBasicBlock &>(*Iter.first);
VarLocSet &Pending = Iter.second;
- for (unsigned ID : Pending) {
+ for (uint64_t ID : Pending) {
// The ID location is live-in to MBB -- work out what kind of machine
// location it is and create a DBG_VALUE.
- const VarLoc &DiffIt = VarLocIDs[ID];
+ const VarLoc &DiffIt = VarLocIDs[LocIndex::fromRawInteger(ID)];
if (DiffIt.isEntryBackupLoc())
continue;
MachineInstr *MI = DiffIt.BuildDbgValue(*MBB.getParent());
@@ -1502,7 +1552,7 @@ void LiveDebugValues::recordEntryValue(const MachineInstr &MI,
DIExpression *NewExpr =
DIExpression::prepend(MI.getDebugExpression(), DIExpression::EntryValue);
VarLoc EntryValLocAsBackup = VarLoc::CreateEntryBackupLoc(MI, LS, NewExpr);
- unsigned EntryValLocID = VarLocIDs.insert(EntryValLocAsBackup);
+ LocIndex EntryValLocID = VarLocIDs.insert(EntryValLocAsBackup);
OpenRanges.insert(EntryValLocID, EntryValLocAsBackup);
}
More information about the llvm-commits
mailing list