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[DebugInfo][InstrRef] Index DebugVariables and some DILocations (#99318)

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A lot of time in LiveDebugValues is spent computing DenseMap keys for
DebugVariables, and they're made up of three pointers, so are large.
This patch installs an index for them: for the SSA and value-to-location
mapping parts of InstrRefBasedLDV we don't need to access things like
the variable declaration or the inlining site, so just use a uint32_t
identifier for each variable fragment that's tracked. The compile-time
performance improvements are substantial (almost 0.4% on the tracker).

About 80% of this patch is just replacing DebugVariable references with
DebugVariableIDs instead, however there are some larger consequences. We
spend lots of time fetching DILocations when emitting DBG_VALUE
instructions, so index those with the DebugVariables: this means all
DILocations on all new DBG_VALUE instructions will normalise to the
first-seen DILocation for the variable (which should be fine).

We also used to keep an ordering of when each variable was seen first in
a DBG_* instruction, in the AllVarsNumbering collection, so that we can
emit new DBG_* instructions in a stable order. We can hang this off the
DebugVariable index instead, so AllVarsNumbering is deleted.

Finally, rather than ordering by AllVarsNumbering just before DBG_*
instructions are linked into the output MIR, store instructions along
with their DebugVariableID, so that they can be sorted by that instead.
This commit is contained in:
Jeremy Morse
2024-07-18 15:04:02 +01:00
committed by GitHub
parent 684a61506a
commit 078198f310
4 changed files with 186 additions and 128 deletions
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201
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
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@@ -183,6 +183,7 @@ public:
/// information from it. (XXX make it const?)
MLocTracker *MTracker;
MachineFunction &MF;
const DebugVariableMap &DVMap;
bool ShouldEmitDebugEntryValues;
/// Record of all changes in variable locations at a block position. Awkwardly
@@ -191,7 +192,9 @@ public:
struct Transfer {
MachineBasicBlock::instr_iterator Pos; /// Position to insert DBG_VALUes
MachineBasicBlock *MBB; /// non-null if we should insert after.
SmallVector<MachineInstr *, 4> Insts; /// Vector of DBG_VALUEs to insert.
/// Vector of DBG_VALUEs to insert. Store with their DebugVariableID so that
/// they can be sorted into a stable order for emission at a later time.
SmallVector<std::pair<DebugVariableID, MachineInstr *>, 4> Insts;
};
/// Stores the resolved operands (machine locations and constants) and
@@ -227,15 +230,15 @@ public:
/// Map from LocIdxes to which DebugVariables are based that location.
/// Mantained while stepping through the block. Not accurate if
/// VarLocs[Idx] != MTracker->LocIdxToIDNum[Idx].
DenseMap<LocIdx, SmallSet<DebugVariable, 4>> ActiveMLocs;
DenseMap<LocIdx, SmallSet<DebugVariableID, 4>> ActiveMLocs;
/// Map from DebugVariable to it's current location and qualifying meta
/// information. To be used in conjunction with ActiveMLocs to construct
/// enough information for the DBG_VALUEs for a particular LocIdx.
DenseMap<DebugVariable, ResolvedDbgValue> ActiveVLocs;
DenseMap<DebugVariableID, ResolvedDbgValue> ActiveVLocs;
/// Temporary cache of DBG_VALUEs to be entered into the Transfers collection.
SmallVector<MachineInstr *, 4> PendingDbgValues;
SmallVector<std::pair<DebugVariableID, MachineInstr *>, 4> PendingDbgValues;
/// Record of a use-before-def: created when a value that's live-in to the
/// current block isn't available in any machine location, but it will be
@@ -244,12 +247,12 @@ public:
/// Value of this variable, def'd in block.
SmallVector<DbgOp> Values;
/// Identity of this variable.
DebugVariable Var;
DebugVariableID VarID;
/// Additional variable properties.
DbgValueProperties Properties;
UseBeforeDef(ArrayRef<DbgOp> Values, const DebugVariable &Var,
UseBeforeDef(ArrayRef<DbgOp> Values, DebugVariableID VarID,
const DbgValueProperties &Properties)
: Values(Values.begin(), Values.end()), Var(Var),
: Values(Values.begin(), Values.end()), VarID(VarID),
Properties(Properties) {}
};
@@ -260,15 +263,16 @@ public:
/// The set of variables that are in UseBeforeDefs and can become a location
/// once the relevant value is defined. An element being erased from this
/// collection prevents the use-before-def materializing.
DenseSet<DebugVariable> UseBeforeDefVariables;
DenseSet<DebugVariableID> UseBeforeDefVariables;
const TargetRegisterInfo &TRI;
const BitVector &CalleeSavedRegs;
TransferTracker(const TargetInstrInfo *TII, MLocTracker *MTracker,
MachineFunction &MF, const TargetRegisterInfo &TRI,
MachineFunction &MF, const DebugVariableMap &DVMap,
const TargetRegisterInfo &TRI,
const BitVector &CalleeSavedRegs, const TargetPassConfig &TPC)
: TII(TII), MTracker(MTracker), MF(MF), TRI(TRI),
: TII(TII), MTracker(MTracker), MF(MF), DVMap(DVMap), TRI(TRI),
CalleeSavedRegs(CalleeSavedRegs) {
TLI = MF.getSubtarget().getTargetLowering();
auto &TM = TPC.getTM<TargetMachine>();
@@ -352,7 +356,7 @@ public:
/// determine the values used by Value.
void loadVarInloc(MachineBasicBlock &MBB, DbgOpIDMap &DbgOpStore,
const SmallVectorImpl<ValueLocPair> &ValueToLoc,
DebugVariable Var, DbgValue Value) {
DebugVariableID VarID, DbgValue Value) {
SmallVector<DbgOp> DbgOps;
SmallVector<ResolvedDbgOp> ResolvedDbgOps;
bool IsValueValid = true;
@@ -401,7 +405,7 @@ public:
static_cast<unsigned>(Num.getInst()));
continue;
}
recoverAsEntryValue(Var, Value.Properties, Num);
recoverAsEntryValue(VarID, Value.Properties, Num);
IsValueValid = false;
break;
}
@@ -419,8 +423,7 @@ public:
// Add UseBeforeDef entry for the last value to be defined in this block.
if (LastUseBeforeDef) {
addUseBeforeDef(Var, Value.Properties, DbgOps,
LastUseBeforeDef);
addUseBeforeDef(VarID, Value.Properties, DbgOps, LastUseBeforeDef);
return;
}
@@ -428,13 +431,15 @@ public:
// the transfer.
for (const ResolvedDbgOp &Op : ResolvedDbgOps)
if (!Op.IsConst)
ActiveMLocs[Op.Loc].insert(Var);
ActiveMLocs[Op.Loc].insert(VarID);
auto NewValue = ResolvedDbgValue{ResolvedDbgOps, Value.Properties};
auto Result = ActiveVLocs.insert(std::make_pair(Var, NewValue));
auto Result = ActiveVLocs.insert(std::make_pair(VarID, NewValue));
if (!Result.second)
Result.first->second = NewValue;
auto &[Var, DILoc] = DVMap.lookupDVID(VarID);
PendingDbgValues.push_back(
MTracker->emitLoc(ResolvedDbgOps, Var, Value.Properties));
std::make_pair(VarID, &*MTracker->emitLoc(ResolvedDbgOps, Var, DILoc,
Value.Properties)));
}
/// Load object with live-in variable values. \p mlocs contains the live-in
@@ -445,7 +450,7 @@ public:
/// FIXME: could just examine mloctracker instead of passing in \p mlocs?
void
loadInlocs(MachineBasicBlock &MBB, ValueTable &MLocs, DbgOpIDMap &DbgOpStore,
const SmallVectorImpl<std::pair<DebugVariable, DbgValue>> &VLocs,
const SmallVectorImpl<std::pair<DebugVariableID, DbgValue>> &VLocs,
unsigned NumLocs) {
ActiveMLocs.clear();
ActiveVLocs.clear();
@@ -506,11 +511,11 @@ public:
/// Record that \p Var has value \p ID, a value that becomes available
/// later in the function.
void addUseBeforeDef(const DebugVariable &Var,
void addUseBeforeDef(DebugVariableID VarID,
const DbgValueProperties &Properties,
const SmallVectorImpl<DbgOp> &DbgOps, unsigned Inst) {
UseBeforeDefs[Inst].emplace_back(DbgOps, Var, Properties);
UseBeforeDefVariables.insert(Var);
UseBeforeDefs[Inst].emplace_back(DbgOps, VarID, Properties);
UseBeforeDefVariables.insert(VarID);
}
/// After the instruction at index \p Inst and position \p pos has been
@@ -529,7 +534,7 @@ public:
// Populate ValueToLoc with illegal default mappings for every value used by
// any UseBeforeDef variables for this instruction.
for (auto &Use : MIt->second) {
if (!UseBeforeDefVariables.count(Use.Var))
if (!UseBeforeDefVariables.count(Use.VarID))
continue;
for (DbgOp &Op : Use.Values) {
@@ -568,7 +573,7 @@ public:
// Using the map of values to locations, produce a final set of values for
// this variable.
for (auto &Use : MIt->second) {
if (!UseBeforeDefVariables.count(Use.Var))
if (!UseBeforeDefVariables.count(Use.VarID))
continue;
SmallVector<ResolvedDbgOp> DbgOps;
@@ -591,8 +596,9 @@ public:
continue;
// Otherwise, we're good to go.
PendingDbgValues.push_back(
MTracker->emitLoc(DbgOps, Use.Var, Use.Properties));
auto &[Var, DILoc] = DVMap.lookupDVID(Use.VarID);
PendingDbgValues.push_back(std::make_pair(
Use.VarID, MTracker->emitLoc(DbgOps, Var, DILoc, Use.Properties)));
}
flushDbgValues(pos, nullptr);
}
@@ -642,7 +648,7 @@ public:
return Reg != SP && Reg != FP;
}
bool recoverAsEntryValue(const DebugVariable &Var,
bool recoverAsEntryValue(DebugVariableID VarID,
const DbgValueProperties &Prop,
const ValueIDNum &Num) {
// Is this variable location a candidate to be an entry value. First,
@@ -663,6 +669,8 @@ public:
DIExpr = *NonVariadicExpression;
}
auto &[Var, DILoc] = DVMap.lookupDVID(VarID);
// Is the variable appropriate for entry values (i.e., is a parameter).
if (!isEntryValueVariable(Var, DIExpr))
return false;
@@ -676,9 +684,8 @@ public:
DIExpression::prepend(DIExpr, DIExpression::EntryValue);
Register Reg = MTracker->LocIdxToLocID[Num.getLoc()];
MachineOperand MO = MachineOperand::CreateReg(Reg, false);
PendingDbgValues.push_back(
emitMOLoc(MO, Var, {NewExpr, Prop.Indirect, false}));
PendingDbgValues.push_back(std::make_pair(
VarID, &*emitMOLoc(MO, Var, {NewExpr, Prop.Indirect, false})));
return true;
}
@@ -687,19 +694,20 @@ public:
DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
MI.getDebugLoc()->getInlinedAt());
DbgValueProperties Properties(MI);
DebugVariableID VarID = DVMap.getDVID(Var);
// Ignore non-register locations, we don't transfer those.
if (MI.isUndefDebugValue() ||
all_of(MI.debug_operands(),
[](const MachineOperand &MO) { return !MO.isReg(); })) {
auto It = ActiveVLocs.find(Var);
auto It = ActiveVLocs.find(VarID);
if (It != ActiveVLocs.end()) {
for (LocIdx Loc : It->second.loc_indices())
ActiveMLocs[Loc].erase(Var);
ActiveMLocs[Loc].erase(VarID);
ActiveVLocs.erase(It);
}
// Any use-before-defs no longer apply.
UseBeforeDefVariables.erase(Var);
UseBeforeDefVariables.erase(VarID);
return;
}
@@ -725,14 +733,15 @@ public:
SmallVectorImpl<ResolvedDbgOp> &NewLocs) {
DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
MI.getDebugLoc()->getInlinedAt());
DebugVariableID VarID = DVMap.getDVID(Var);
// Any use-before-defs no longer apply.
UseBeforeDefVariables.erase(Var);
UseBeforeDefVariables.erase(VarID);
// Erase any previous location.
auto It = ActiveVLocs.find(Var);
auto It = ActiveVLocs.find(VarID);
if (It != ActiveVLocs.end()) {
for (LocIdx Loc : It->second.loc_indices())
ActiveMLocs[Loc].erase(Var);
ActiveMLocs[Loc].erase(VarID);
}
// If there _is_ no new location, all we had to do was erase.
@@ -742,7 +751,7 @@ public:
return;
}
SmallVector<std::pair<LocIdx, DebugVariable>> LostMLocs;
SmallVector<std::pair<LocIdx, DebugVariableID>> LostMLocs;
for (ResolvedDbgOp &Op : NewLocs) {
if (Op.IsConst)
continue;
@@ -769,17 +778,17 @@ public:
for (const auto &LostMLoc : LostMLocs)
ActiveMLocs[LostMLoc.first].erase(LostMLoc.second);
LostMLocs.clear();
It = ActiveVLocs.find(Var);
It = ActiveVLocs.find(VarID);
ActiveMLocs[NewLoc.asU64()].clear();
VarLocs[NewLoc.asU64()] = MTracker->readMLoc(NewLoc);
}
ActiveMLocs[NewLoc].insert(Var);
ActiveMLocs[NewLoc].insert(VarID);
}
if (It == ActiveVLocs.end()) {
ActiveVLocs.insert(
std::make_pair(Var, ResolvedDbgValue(NewLocs, Properties)));
std::make_pair(VarID, ResolvedDbgValue(NewLocs, Properties)));
} else {
It->second.Ops.assign(NewLocs);
It->second.Properties = Properties;
@@ -822,21 +831,21 @@ public:
// explicitly undef, then stop here.
if (!NewLoc && !MakeUndef) {
// Try and recover a few more locations with entry values.
for (const auto &Var : ActiveMLocIt->second) {
auto &Prop = ActiveVLocs.find(Var)->second.Properties;
recoverAsEntryValue(Var, Prop, OldValue);
for (DebugVariableID VarID : ActiveMLocIt->second) {
auto &Prop = ActiveVLocs.find(VarID)->second.Properties;
recoverAsEntryValue(VarID, Prop, OldValue);
}
flushDbgValues(Pos, nullptr);
return;
}
// Examine all the variables based on this location.
DenseSet<DebugVariable> NewMLocs;
DenseSet<DebugVariableID> NewMLocs;
// If no new location has been found, every variable that depends on this
// MLoc is dead, so end their existing MLoc->Var mappings as well.
SmallVector<std::pair<LocIdx, DebugVariable>> LostMLocs;
for (const auto &Var : ActiveMLocIt->second) {
auto ActiveVLocIt = ActiveVLocs.find(Var);
SmallVector<std::pair<LocIdx, DebugVariableID>> LostMLocs;
for (DebugVariableID VarID : ActiveMLocIt->second) {
auto ActiveVLocIt = ActiveVLocs.find(VarID);
// Re-state the variable location: if there's no replacement then NewLoc
// is std::nullopt and a $noreg DBG_VALUE will be created. Otherwise, a
// DBG_VALUE identifying the alternative location will be emitted.
@@ -855,19 +864,21 @@ public:
replace_copy(ActiveVLocIt->second.Ops, DbgOps.begin(), OldOp, NewOp);
}
PendingDbgValues.push_back(MTracker->emitLoc(DbgOps, Var, Properties));
auto &[Var, DILoc] = DVMap.lookupDVID(VarID);
PendingDbgValues.push_back(std::make_pair(
VarID, &*MTracker->emitLoc(DbgOps, Var, DILoc, Properties)));
// Update machine locations <=> variable locations maps. Defer updating
// ActiveMLocs to avoid invalidating the ActiveMLocIt iterator.
if (!NewLoc) {
for (LocIdx Loc : ActiveVLocIt->second.loc_indices()) {
if (Loc != MLoc)
LostMLocs.emplace_back(Loc, Var);
LostMLocs.emplace_back(Loc, VarID);
}
ActiveVLocs.erase(ActiveVLocIt);
} else {
ActiveVLocIt->second.Ops = DbgOps;
NewMLocs.insert(Var);
NewMLocs.insert(VarID);
}
}
@@ -891,8 +902,8 @@ public:
// Commit ActiveMLoc changes.
ActiveMLocIt->second.clear();
if (!NewMLocs.empty())
for (auto &Var : NewMLocs)
ActiveMLocs[*NewLoc].insert(Var);
for (DebugVariableID VarID : NewMLocs)
ActiveMLocs[*NewLoc].insert(VarID);
}
/// Transfer variables based on \p Src to be based on \p Dst. This handles
@@ -915,17 +926,18 @@ public:
// For each variable based on Src; create a location at Dst.
ResolvedDbgOp SrcOp(Src);
ResolvedDbgOp DstOp(Dst);
for (const auto &Var : MovingVars) {
auto ActiveVLocIt = ActiveVLocs.find(Var);
for (DebugVariableID VarID : MovingVars) {
auto ActiveVLocIt = ActiveVLocs.find(VarID);
assert(ActiveVLocIt != ActiveVLocs.end());
// Update all instances of Src in the variable's tracked values to Dst.
std::replace(ActiveVLocIt->second.Ops.begin(),
ActiveVLocIt->second.Ops.end(), SrcOp, DstOp);
MachineInstr *MI = MTracker->emitLoc(ActiveVLocIt->second.Ops, Var,
auto &[Var, DILoc] = DVMap.lookupDVID(VarID);
MachineInstr *MI = MTracker->emitLoc(ActiveVLocIt->second.Ops, Var, DILoc,
ActiveVLocIt->second.Properties);
PendingDbgValues.push_back(MI);
PendingDbgValues.push_back(std::make_pair(VarID, MI));
}
ActiveMLocs[Src].clear();
flushDbgValues(Pos, nullptr);
@@ -1176,11 +1188,9 @@ LLVM_DUMP_METHOD void MLocTracker::dump_mloc_map() {
MachineInstrBuilder
MLocTracker::emitLoc(const SmallVectorImpl<ResolvedDbgOp> &DbgOps,
const DebugVariable &Var,
const DebugVariable &Var, const DILocation *DILoc,
const DbgValueProperties &Properties) {
DebugLoc DL = DILocation::get(Var.getVariable()->getContext(), 0, 0,
Var.getVariable()->getScope(),
const_cast<DILocation *>(Var.getInlinedAt()));
DebugLoc DL = DebugLoc(DILoc);
const MCInstrDesc &Desc = Properties.IsVariadic
? TII.get(TargetOpcode::DBG_VALUE_LIST)
@@ -1726,7 +1736,8 @@ bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI,
LastUseBeforeDef = std::max(LastUseBeforeDef, NewID.getInst());
}
if (IsValidUseBeforeDef) {
TTracker->addUseBeforeDef(V, {MI.getDebugExpression(), false, true},
DebugVariableID VID = DVMap.insertDVID(V, MI.getDebugLoc().get());
TTracker->addUseBeforeDef(VID, {MI.getDebugExpression(), false, true},
DbgOps, LastUseBeforeDef);
}
}
@@ -1735,9 +1746,11 @@ bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI,
// This DBG_VALUE is potentially a $noreg / undefined location, if
// FoundLoc is illegal.
// (XXX -- could morph the DBG_INSTR_REF in the future).
MachineInstr *DbgMI = MTracker->emitLoc(NewLocs, V, Properties);
MachineInstr *DbgMI =
MTracker->emitLoc(NewLocs, V, MI.getDebugLoc().get(), Properties);
DebugVariableID ID = DVMap.getDVID(V);
TTracker->PendingDbgValues.push_back(DbgMI);
TTracker->PendingDbgValues.push_back(std::make_pair(ID, DbgMI));
TTracker->flushDbgValues(MI.getIterator(), nullptr);
return true;
}
@@ -3112,7 +3125,8 @@ void InstrRefBasedLDV::getBlocksForScope(
}
void InstrRefBasedLDV::buildVLocValueMap(
const DILocation *DILoc, const SmallSet<DebugVariable, 4> &VarsWeCareAbout,
const DILocation *DILoc,
const SmallSet<DebugVariableID, 4> &VarsWeCareAbout,
SmallPtrSetImpl<MachineBasicBlock *> &AssignBlocks, LiveInsT &Output,
FuncValueTable &MOutLocs, FuncValueTable &MInLocs,
SmallVectorImpl<VLocTracker> &AllTheVLocs) {
@@ -3188,7 +3202,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
// between blocks. This keeps the locality of working on one lexical scope at
// at time, but avoids re-processing variable values because some other
// variable has been assigned.
for (const auto &Var : VarsWeCareAbout) {
for (DebugVariableID VarID : VarsWeCareAbout) {
// Re-initialize live-ins and live-outs, to clear the remains of previous
// variables live-ins / live-outs.
for (unsigned int I = 0; I < NumBlocks; ++I) {
@@ -3202,7 +3216,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
SmallPtrSet<MachineBasicBlock *, 32> DefBlocks;
for (const MachineBasicBlock *ExpMBB : BlocksToExplore) {
auto &TransferFunc = AllTheVLocs[ExpMBB->getNumber()].Vars;
if (TransferFunc.contains(Var))
if (TransferFunc.contains(VarID))
DefBlocks.insert(const_cast<MachineBasicBlock *>(ExpMBB));
}
@@ -3212,7 +3226,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
// only one value definition, things are very simple.
if (DefBlocks.size() == 1) {
placePHIsForSingleVarDefinition(MutBlocksToExplore, *DefBlocks.begin(),
AllTheVLocs, Var, Output);
AllTheVLocs, VarID, Output);
continue;
}
@@ -3285,7 +3299,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
// Do transfer function.
auto &VTracker = AllTheVLocs[MBB->getNumber()];
auto TransferIt = VTracker.Vars.find(Var);
auto TransferIt = VTracker.Vars.find(VarID);
if (TransferIt != VTracker.Vars.end()) {
// Erase on empty transfer (DBG_VALUE $noreg).
if (TransferIt->second.Kind == DbgValue::Undef) {
@@ -3347,9 +3361,11 @@ void InstrRefBasedLDV::buildVLocValueMap(
continue;
if (BlockLiveIn->Kind == DbgValue::VPHI)
BlockLiveIn->Kind = DbgValue::Def;
auto &[Var, DILoc] = DVMap.lookupDVID(VarID);
assert(BlockLiveIn->Properties.DIExpr->getFragmentInfo() ==
Var.getFragment() && "Fragment info missing during value prop");
Output[MBB->getNumber()].push_back(std::make_pair(Var, *BlockLiveIn));
Var.getFragment() &&
"Fragment info missing during value prop");
Output[MBB->getNumber()].push_back(std::make_pair(VarID, *BlockLiveIn));
}
} // Per-variable loop.
@@ -3360,7 +3376,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
void InstrRefBasedLDV::placePHIsForSingleVarDefinition(
const SmallPtrSetImpl<MachineBasicBlock *> &InScopeBlocks,
MachineBasicBlock *AssignMBB, SmallVectorImpl<VLocTracker> &AllTheVLocs,
const DebugVariable &Var, LiveInsT &Output) {
DebugVariableID VarID, LiveInsT &Output) {
// If there is a single definition of the variable, then working out it's
// value everywhere is very simple: it's every block dominated by the
// definition. At the dominance frontier, the usual algorithm would:
@@ -3373,7 +3389,7 @@ void InstrRefBasedLDV::placePHIsForSingleVarDefinition(
// Pick out the variables value from the block transfer function.
VLocTracker &VLocs = AllTheVLocs[AssignMBB->getNumber()];
auto ValueIt = VLocs.Vars.find(Var);
auto ValueIt = VLocs.Vars.find(VarID);
const DbgValue &Value = ValueIt->second;
// If it's an explicit assignment of "undef", that means there is no location
@@ -3388,7 +3404,7 @@ void InstrRefBasedLDV::placePHIsForSingleVarDefinition(
if (!DomTree->properlyDominates(AssignMBB, ScopeBlock))
continue;
Output[ScopeBlock->getNumber()].push_back({Var, Value});
Output[ScopeBlock->getNumber()].push_back({VarID, Value});
}
// All blocks that aren't dominated have no live-in value, thus no variable
@@ -3515,9 +3531,9 @@ bool InstrRefBasedLDV::depthFirstVLocAndEmit(
const ScopeToVarsT &ScopeToVars, ScopeToAssignBlocksT &ScopeToAssignBlocks,
LiveInsT &Output, FuncValueTable &MOutLocs, FuncValueTable &MInLocs,
SmallVectorImpl<VLocTracker> &AllTheVLocs, MachineFunction &MF,
DenseMap<DebugVariable, unsigned> &AllVarsNumbering,
const TargetPassConfig &TPC) {
TTracker = new TransferTracker(TII, MTracker, MF, *TRI, CalleeSavedRegs, TPC);
TTracker =
new TransferTracker(TII, MTracker, MF, DVMap, *TRI, CalleeSavedRegs, TPC);
unsigned NumLocs = MTracker->getNumLocs();
VTracker = nullptr;
@@ -3622,31 +3638,24 @@ bool InstrRefBasedLDV::depthFirstVLocAndEmit(
if (MInLocs.hasTableFor(*MBB))
EjectBlock(*MBB);
return emitTransfers(AllVarsNumbering);
return emitTransfers();
}
bool InstrRefBasedLDV::emitTransfers(
DenseMap<DebugVariable, unsigned> &AllVarsNumbering) {
bool InstrRefBasedLDV::emitTransfers() {
// Go through all the transfers recorded in the TransferTracker -- this is
// both the live-ins to a block, and any movements of values that happen
// in the middle.
for (const auto &P : TTracker->Transfers) {
for (auto &P : TTracker->Transfers) {
// We have to insert DBG_VALUEs in a consistent order, otherwise they
// appear in DWARF in different orders. Use the order that they appear
// when walking through each block / each instruction, stored in
// AllVarsNumbering.
SmallVector<std::pair<unsigned, MachineInstr *>> Insts;
for (MachineInstr *MI : P.Insts) {
DebugVariable Var(MI->getDebugVariable(), MI->getDebugExpression(),
MI->getDebugLoc()->getInlinedAt());
Insts.emplace_back(AllVarsNumbering.find(Var)->second, MI);
}
llvm::sort(Insts, llvm::less_first());
// DVMap.
llvm::sort(P.Insts, llvm::less_first());
// Insert either before or after the designated point...
if (P.MBB) {
MachineBasicBlock &MBB = *P.MBB;
for (const auto &Pair : Insts)
for (const auto &Pair : P.Insts)
MBB.insert(P.Pos, Pair.second);
} else {
// Terminators, like tail calls, can clobber things. Don't try and place
@@ -3655,7 +3664,7 @@ bool InstrRefBasedLDV::emitTransfers(
continue;
MachineBasicBlock &MBB = *P.Pos->getParent();
for (const auto &Pair : Insts)
for (const auto &Pair : P.Insts)
MBB.insertAfterBundle(P.Pos, Pair.second);
}
}
@@ -3710,7 +3719,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
initialSetup(MF);
MLocTransfer.resize(MaxNumBlocks);
vlocs.resize(MaxNumBlocks, VLocTracker(OverlapFragments, EmptyExpr));
vlocs.resize(MaxNumBlocks, VLocTracker(DVMap, OverlapFragments, EmptyExpr));
SavedLiveIns.resize(MaxNumBlocks);
produceMLocTransferFunction(MF, MLocTransfer, MaxNumBlocks);
@@ -3766,10 +3775,6 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
MTracker->reset();
}
// Number all variables in the order that they appear, to be used as a stable
// insertion order later.
DenseMap<DebugVariable, unsigned> AllVarsNumbering;
// Map from one LexicalScope to all the variables in that scope.
ScopeToVarsT ScopeToVars;
@@ -3788,16 +3793,15 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
auto *VTracker = &vlocs[MBB->getNumber()];
// Collect each variable with a DBG_VALUE in this block.
for (auto &idx : VTracker->Vars) {
const auto &Var = idx.first;
const DILocation *ScopeLoc = VTracker->Scopes[Var];
DebugVariableID VarID = idx.first;
const DILocation *ScopeLoc = VTracker->Scopes[VarID];
assert(ScopeLoc != nullptr);
auto *Scope = LS.findLexicalScope(ScopeLoc);
// No insts in scope -> shouldn't have been recorded.
assert(Scope != nullptr);
AllVarsNumbering.insert(std::make_pair(Var, AllVarsNumbering.size()));
ScopeToVars[Scope].insert(Var);
ScopeToVars[Scope].insert(VarID);
ScopeToAssignBlocks[Scope].insert(VTracker->MBB);
ScopeToDILocation[Scope] = ScopeLoc;
++VarAssignCount;
@@ -3821,7 +3825,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
// the "else" block of this condition.
Changed = depthFirstVLocAndEmit(
MaxNumBlocks, ScopeToDILocation, ScopeToVars, ScopeToAssignBlocks,
SavedLiveIns, MOutLocs, MInLocs, vlocs, MF, AllVarsNumbering, *TPC);
SavedLiveIns, MOutLocs, MInLocs, vlocs, MF, *TPC);
}
delete MTracker;
@@ -3840,6 +3844,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
SeenFragments.clear();
SeenDbgPHIs.clear();
DbgOpStore.clear();
DVMap.clear();
return Changed;
}

106
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
View File

@@ -35,6 +35,44 @@ class DbgOpIDMap;
using namespace llvm;
using DebugVariableID = unsigned;
using VarAndLoc = std::pair<DebugVariable, const DILocation *>;
/// Mapping from DebugVariable to/from a unique identifying number. Each
/// DebugVariable consists of three pointers, and after a small amount of
/// work to identify overlapping fragments of variables we mostly only use
/// DebugVariables as identities of variables. It's much more compile-time
/// efficient to use an ID number instead, which this class provides.
class DebugVariableMap {
DenseMap<DebugVariable, unsigned> VarToIdx;
SmallVector<VarAndLoc> IdxToVar;
public:
DebugVariableID getDVID(const DebugVariable &Var) const {
auto It = VarToIdx.find(Var);
assert(It != VarToIdx.end());
return It->second;
}
DebugVariableID insertDVID(DebugVariable &Var, const DILocation *Loc) {
unsigned Size = VarToIdx.size();
auto ItPair = VarToIdx.insert({Var, Size});
if (ItPair.second) {
IdxToVar.push_back({Var, Loc});
return Size;
}
return ItPair.first->second;
}
const VarAndLoc &lookupDVID(DebugVariableID ID) const { return IdxToVar[ID]; }
void clear() {
VarToIdx.clear();
IdxToVar.clear();
}
};
/// Handle-class for a particular "location". This value-type uniquely
/// symbolises a register or stack location, allowing manipulation of locations
/// without concern for where that location is. Practically, this allows us to
@@ -985,7 +1023,7 @@ public:
/// information in \pProperties, for variable Var. Don't insert it anywhere,
/// just return the builder for it.
MachineInstrBuilder emitLoc(const SmallVectorImpl<ResolvedDbgOp> &DbgOps,
const DebugVariable &Var,
const DebugVariable &Var, const DILocation *DILoc,
const DbgValueProperties &Properties);
};
@@ -1003,38 +1041,45 @@ using OverlapMap =
/// identified.
class VLocTracker {
public:
/// Ref to function-wide map of DebugVariable <=> ID-numbers.
DebugVariableMap &DVMap;
/// Map DebugVariable to the latest Value it's defined to have.
/// Needs to be a MapVector because we determine order-in-the-input-MIR from
/// the order in this container.
/// the order in this container. (FIXME: likely no longer true as the ordering
/// is now provided by DebugVariableMap).
/// We only retain the last DbgValue in each block for each variable, to
/// determine the blocks live-out variable value. The Vars container forms the
/// transfer function for this block, as part of the dataflow analysis. The
/// movement of values between locations inside of a block is handled at a
/// much later stage, in the TransferTracker class.
MapVector<DebugVariable, DbgValue> Vars;
SmallDenseMap<DebugVariable, const DILocation *, 8> Scopes;
MapVector<DebugVariableID, DbgValue> Vars;
SmallDenseMap<DebugVariableID, const DILocation *, 8> Scopes;
MachineBasicBlock *MBB = nullptr;
const OverlapMap &OverlappingFragments;
DbgValueProperties EmptyProperties;
public:
VLocTracker(const OverlapMap &O, const DIExpression *EmptyExpr)
: OverlappingFragments(O), EmptyProperties(EmptyExpr, false, false) {}
VLocTracker(DebugVariableMap &DVMap, const OverlapMap &O,
const DIExpression *EmptyExpr)
: DVMap(DVMap), OverlappingFragments(O),
EmptyProperties(EmptyExpr, false, false) {}
void defVar(const MachineInstr &MI, const DbgValueProperties &Properties,
const SmallVectorImpl<DbgOpID> &DebugOps) {
assert(MI.isDebugValueLike());
DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
MI.getDebugLoc()->getInlinedAt());
// Either insert or fetch an ID number for this variable.
DebugVariableID VarID = DVMap.insertDVID(Var, MI.getDebugLoc().get());
DbgValue Rec = (DebugOps.size() > 0)
? DbgValue(DebugOps, Properties)
: DbgValue(Properties, DbgValue::Undef);
// Attempt insertion; overwrite if it's already mapped.
auto Result = Vars.insert(std::make_pair(Var, Rec));
auto Result = Vars.insert(std::make_pair(VarID, Rec));
if (!Result.second)
Result.first->second = Rec;
Scopes[Var] = MI.getDebugLoc().get();
Scopes[VarID] = MI.getDebugLoc().get();
considerOverlaps(Var, MI.getDebugLoc().get());
}
@@ -1056,13 +1101,15 @@ public:
DebugVariable Overlapped(Var.getVariable(), OptFragmentInfo,
Var.getInlinedAt());
// Produce an ID number for this overlapping fragment of a variable.
DebugVariableID OverlappedID = DVMap.insertDVID(Overlapped, Loc);
DbgValue Rec = DbgValue(EmptyProperties, DbgValue::Undef);
// Attempt insertion; overwrite if it's already mapped.
auto Result = Vars.insert(std::make_pair(Overlapped, Rec));
auto Result = Vars.insert(std::make_pair(OverlappedID, Rec));
if (!Result.second)
Result.first->second = Rec;
Scopes[Overlapped] = Loc;
Scopes[OverlappedID] = Loc;
}
}
@@ -1093,7 +1140,7 @@ public:
/// variables to their values.
using LiveIdxT = DenseMap<const MachineBasicBlock *, DbgValue *>;
using VarAndLoc = std::pair<DebugVariable, DbgValue>;
using VarAndLoc = std::pair<DebugVariableID, DbgValue>;
/// Type for a live-in value: the predecessor block, and its value.
using InValueT = std::pair<MachineBasicBlock *, DbgValue *>;
@@ -1106,7 +1153,8 @@ public:
using ScopeToDILocT = DenseMap<const LexicalScope *, const DILocation *>;
/// Mapping from lexical scopes to variables in that scope.
using ScopeToVarsT = DenseMap<const LexicalScope *, SmallSet<DebugVariable, 4>>;
using ScopeToVarsT =
DenseMap<const LexicalScope *, SmallSet<DebugVariableID, 4>>;
/// Mapping from lexical scopes to blocks where variables in that scope are
/// assigned. Such blocks aren't necessarily "in" the lexical scope, it's
@@ -1200,6 +1248,11 @@ private:
DbgOpIDMap DbgOpStore;
/// Mapping between DebugVariables and unique ID numbers. This is a more
/// efficient way to represent the identity of a variable, versus a plain
/// DebugVariable.
DebugVariableMap DVMap;
/// True if we need to examine call instructions for stack clobbers. We
/// normally assume that they don't clobber SP, but stack probes on Windows
/// do.
@@ -1330,9 +1383,9 @@ private:
/// performance as it doesn't have to find the dominance frontier between
/// different assignments.
void placePHIsForSingleVarDefinition(
const SmallPtrSetImpl<MachineBasicBlock *> &InScopeBlocks,
MachineBasicBlock *MBB, SmallVectorImpl<VLocTracker> &AllTheVLocs,
const DebugVariable &Var, LiveInsT &Output);
const SmallPtrSetImpl<MachineBasicBlock *> &InScopeBlocks,
MachineBasicBlock *MBB, SmallVectorImpl<VLocTracker> &AllTheVLocs,
DebugVariableID Var, LiveInsT &Output);
/// Calculate the iterated-dominance-frontier for a set of defs, using the
/// existing LLVM facilities for this. Works for a single "value" or
@@ -1381,7 +1434,7 @@ private:
/// scope, but which do contain DBG_VALUEs, which VarLocBasedImpl tracks
/// locations through.
void buildVLocValueMap(const DILocation *DILoc,
const SmallSet<DebugVariable, 4> &VarsWeCareAbout,
const SmallSet<DebugVariableID, 4> &VarsWeCareAbout,
SmallPtrSetImpl<MachineBasicBlock *> &AssignBlocks,
LiveInsT &Output, FuncValueTable &MOutLocs,
FuncValueTable &MInLocs,
@@ -1414,10 +1467,8 @@ private:
const SmallVectorImpl<const MachineBasicBlock *> &BlockOrders);
/// Take collections of DBG_VALUE instructions stored in TTracker, and
/// install them into their output blocks. Preserves a stable order of
/// DBG_VALUEs produced (which would otherwise cause nondeterminism) through
/// the AllVarsNumbering order.
bool emitTransfers(DenseMap<DebugVariable, unsigned> &AllVarsNumbering);
/// install them into their output blocks.
bool emitTransfers();
/// Boilerplate computation of some initial sets, artifical blocks and
/// RPOT block ordering.
@@ -1437,13 +1488,14 @@ private:
/// block information can be fully computed before exploration finishes,
/// allowing us to emit it and free data structures earlier than otherwise.
/// It's also good for locality.
bool depthFirstVLocAndEmit(
unsigned MaxNumBlocks, const ScopeToDILocT &ScopeToDILocation,
const ScopeToVarsT &ScopeToVars, ScopeToAssignBlocksT &ScopeToBlocks,
LiveInsT &Output, FuncValueTable &MOutLocs, FuncValueTable &MInLocs,
SmallVectorImpl<VLocTracker> &AllTheVLocs, MachineFunction &MF,
DenseMap<DebugVariable, unsigned> &AllVarsNumbering,
const TargetPassConfig &TPC);
bool depthFirstVLocAndEmit(unsigned MaxNumBlocks,
const ScopeToDILocT &ScopeToDILocation,
const ScopeToVarsT &ScopeToVars,
ScopeToAssignBlocksT &ScopeToBlocks,
LiveInsT &Output, FuncValueTable &MOutLocs,
FuncValueTable &MInLocs,
SmallVectorImpl<VLocTracker> &AllTheVLocs,
MachineFunction &MF, const TargetPassConfig &TPC);
bool ExtendRanges(MachineFunction &MF, MachineDominatorTree *DomTree,
TargetPassConfig *TPC, unsigned InputBBLimit,

4
llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir
View File

@@ -17,12 +17,12 @@
# CHECK-LABEL: bb.3.bb3:
# CHECK: DBG_VALUE $ecx, $noreg, !{{[0-9]+}},
# CHECK-SAME: !DIExpression(DW_OP_LLVM_fragment, 0, 32)
# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
# CHECK-SAME: !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 32)
# CHECK-SAME: $ecx, $r8d
# CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
# CHECK-SAME: !DIExpression(DW_OP_LLVM_fragment, 32, 32)
# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
# CHECK-SAME: !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
# CHECK-SAME: $ebx, $r10d
# CHECK-NEXT: XOR32rr

3
llvm/unittests/CodeGen/InstrRefLDVTest.cpp
View File

@@ -55,6 +55,7 @@ public:
DIBasicType *LongInt;
DIExpression *EmptyExpr;
LiveDebugValues::OverlapMap Overlaps;
LiveDebugValues::DebugVariableMap DVMap;
DebugLoc OutermostLoc, InBlockLoc, NotNestedBlockLoc, InlinedLoc;
@@ -176,7 +177,7 @@ public:
void addVTracker() {
ASSERT_TRUE(LDV);
VTracker = std::make_unique<VLocTracker>(Overlaps, EmptyExpr);
VTracker = std::make_unique<VLocTracker>(DVMap, Overlaps, EmptyExpr);
LDV->VTracker = &*VTracker;
}