[llvm] [DebugInfo][InstrRef] Index DebugVariables and some DILocations (PR #99318)
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 18 05:05:21 PDT 2024
https://github.com/jmorse updated https://github.com/llvm/llvm-project/pull/99318
>From 7b425960c2ad9797330218aa6ed91bd3ee3a32ec Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Wed, 19 Jun 2024 13:15:18 +0000
Subject: [PATCH 1/2] [InstrRef] Index DebugVariables and some DILocations
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 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.
As a consequence of deleting AllVarsNumbering, the order that DBG_*
instructions are outputted in can change: we now produce a total order
based on RPO exploration of the function, not exploring in normal
block-order. That causes the DBG_* instructions in
live-debug-values-fragments.mir to change order. These differences don't
affect the meaning of the debug-info, but will cause slightly different
ordered output, hence this isn't an NFC patch. Downstream tests that fail
because of ordering changes /should/ be able to just update the order with
no ill effects.
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.
---
.../LiveDebugValues/InstrRefBasedImpl.cpp | 201 +++++++++---------
.../LiveDebugValues/InstrRefBasedImpl.h | 105 ++++++---
.../MIR/X86/live-debug-values-fragments.mir | 12 +-
llvm/unittests/CodeGen/InstrRefLDVTest.cpp | 3 +-
4 files changed, 189 insertions(+), 132 deletions(-)
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
index 555cbb7a507f4..dbb21344c72d0 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -183,6 +183,7 @@ class TransferTracker {
/// 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 @@ class TransferTracker {
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 @@ class TransferTracker {
/// 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 @@ class TransferTracker {
/// 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 @@ class TransferTracker {
/// 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>();
@@ -345,7 +349,7 @@ class TransferTracker {
/// determine the values used by Value.
void loadVarInloc(MachineBasicBlock &MBB, DbgOpIDMap &DbgOpStore,
const DenseMap<ValueIDNum, LocationAndQuality> &ValueToLoc,
- DebugVariable Var, DbgValue Value) {
+ DebugVariableID VarID, DbgValue Value) {
SmallVector<DbgOp> DbgOps;
SmallVector<ResolvedDbgOp> ResolvedDbgOps;
bool IsValueValid = true;
@@ -386,7 +390,7 @@ class TransferTracker {
static_cast<unsigned>(Num.getInst()));
continue;
}
- recoverAsEntryValue(Var, Value.Properties, Num);
+ recoverAsEntryValue(VarID, Value.Properties, Num);
IsValueValid = false;
break;
}
@@ -404,8 +408,7 @@ class TransferTracker {
// 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;
}
@@ -413,13 +416,15 @@ class TransferTracker {
// 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
@@ -430,7 +435,7 @@ class TransferTracker {
/// 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();
@@ -486,11 +491,11 @@ class TransferTracker {
/// 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
@@ -509,7 +514,7 @@ class TransferTracker {
// 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) {
@@ -548,7 +553,7 @@ class TransferTracker {
// 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;
@@ -571,8 +576,9 @@ class TransferTracker {
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);
}
@@ -622,7 +628,7 @@ class TransferTracker {
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,
@@ -643,6 +649,8 @@ class TransferTracker {
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;
@@ -656,9 +664,8 @@ class TransferTracker {
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;
}
@@ -667,19 +674,20 @@ class TransferTracker {
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;
}
@@ -705,14 +713,15 @@ class TransferTracker {
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.
@@ -722,7 +731,7 @@ class TransferTracker {
return;
}
- SmallVector<std::pair<LocIdx, DebugVariable>> LostMLocs;
+ SmallVector<std::pair<LocIdx, DebugVariableID>> LostMLocs;
for (ResolvedDbgOp &Op : NewLocs) {
if (Op.IsConst)
continue;
@@ -749,17 +758,17 @@ class TransferTracker {
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;
@@ -802,21 +811,21 @@ class TransferTracker {
// 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.
@@ -835,19 +844,21 @@ class TransferTracker {
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);
}
}
@@ -871,8 +882,8 @@ class TransferTracker {
// 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
@@ -895,17 +906,18 @@ class TransferTracker {
// 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);
@@ -1156,11 +1168,9 @@ 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)
@@ -1706,7 +1716,8 @@ 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);
}
}
@@ -1715,9 +1726,11 @@ 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;
}
@@ -3092,7 +3105,8 @@ 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) {
@@ -3167,7 +3181,7 @@ 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) {
@@ -3181,7 +3195,7 @@ 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));
}
@@ -3191,7 +3205,7 @@ 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;
}
@@ -3264,7 +3278,7 @@ 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) {
@@ -3326,9 +3340,11 @@ 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.
@@ -3339,7 +3355,7 @@ 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:
@@ -3352,7 +3368,7 @@ 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
@@ -3367,7 +3383,7 @@ 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
@@ -3486,9 +3502,9 @@ 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;
@@ -3593,31 +3609,24 @@ 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
@@ -3626,7 +3635,7 @@ 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);
}
}
@@ -3681,7 +3690,7 @@ 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);
@@ -3738,10 +3747,6 @@ 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;
@@ -3760,16 +3765,15 @@ 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;
@@ -3793,7 +3797,7 @@ 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;
@@ -3812,6 +3816,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
SeenFragments.clear();
SeenDbgPHIs.clear();
DbgOpStore.clear();
+ DVMap.clear();
return Changed;
}
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
index 6d77a6972f09b..5417e2a59cb25 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
@@ -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 @@ class MLocTracker {
/// 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 +1041,44 @@ 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: this is less true now).
/// 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 +1100,15 @@ class VLocTracker {
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 +1139,7 @@ class InstrRefBasedLDV : public LDVImpl {
/// 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 +1152,8 @@ class InstrRefBasedLDV : public LDVImpl {
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 +1247,11 @@ class InstrRefBasedLDV : public LDVImpl {
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 +1382,9 @@ class InstrRefBasedLDV : public LDVImpl {
/// 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 +1433,7 @@ class InstrRefBasedLDV : public LDVImpl {
/// 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 +1466,8 @@ class InstrRefBasedLDV : public LDVImpl {
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 +1487,14 @@ class InstrRefBasedLDV : public LDVImpl {
/// 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,
diff --git a/llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir b/llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir
index b54c748ac9e84..637d11838df0e 100644
--- a/llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir
+++ b/llvm/test/DebugInfo/MIR/X86/live-debug-values-fragments.mir
@@ -15,16 +15,16 @@
#
# CHECK-LABEL: foo
# 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-SAME: !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 32)
-# CHECK-SAME: $ecx, $r8d
-# CHECK-NEXT: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
+# CHECK: DBG_VALUE $ebx, $noreg, !{{[0-9]+}},
# CHECK-SAME: !DIExpression(DW_OP_LLVM_fragment, 32, 32)
# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
# CHECK-SAME: !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 32, 32)
# CHECK-SAME: $ebx, $r10d
+# CHECK-NEXT: DBG_VALUE $ecx, $noreg, !{{[0-9]+}},
+# CHECK-SAME: !DIExpression(DW_OP_LLVM_fragment, 0, 32)
+# CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]+}},
+# CHECK-SAME: !DIExpression({{[^)]+}}, DW_OP_LLVM_fragment, 0, 32)
+# CHECK-SAME: $ecx, $r8d
# CHECK-NEXT: XOR32rr
# CHECK-NEXT: RET64
#
diff --git a/llvm/unittests/CodeGen/InstrRefLDVTest.cpp b/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
index 306a97c3149cc..50a8cb97ae061 100644
--- a/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
+++ b/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
@@ -55,6 +55,7 @@ class InstrRefLDVTest : public testing::Test {
DIBasicType *LongInt;
DIExpression *EmptyExpr;
LiveDebugValues::OverlapMap Overlaps;
+ LiveDebugValues::DebugVariableMap DVMap;
DebugLoc OutermostLoc, InBlockLoc, NotNestedBlockLoc, InlinedLoc;
@@ -176,7 +177,7 @@ class InstrRefLDVTest : public testing::Test {
void addVTracker() {
ASSERT_TRUE(LDV);
- VTracker = std::make_unique<VLocTracker>(Overlaps, EmptyExpr);
+ VTracker = std::make_unique<VLocTracker>(DVMap, Overlaps, EmptyExpr);
LDV->VTracker = &*VTracker;
}
>From a8e0b77460dd1548a6c319acfc0adfefbbe55377 Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Thu, 18 Jul 2024 13:00:54 +0100
Subject: [PATCH 2/2] expand upon a comment
---
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
index 5417e2a59cb25..3da6887852a23 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h
@@ -1045,7 +1045,8 @@ class VLocTracker {
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. (FIXME: this is less true now).
+ /// 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
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