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[DebugInfo][NFC] Represent DbgValues with multiple ops in IRefLDV
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In preparation for allowing InstrRefBasedLDV to handle DBG_VALUE_LIST,
this patch updates the internal representation that it uses to represent
debug values to store a list of values. This is one of the more
significant changes in terms of line count, but is fairly simple and
should not affect the output of this pass.

Differential Revision: https://reviews.llvm.org/D128177
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@SLTozer
SLTozer committed Aug 22, 2022
1 parent 96fd3f2 commit b5ba5d2
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Showing 3 changed files with 598 additions and 284 deletions.
118 changes: 82 additions & 36 deletions llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
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Expand Up @@ -155,6 +155,8 @@ static cl::opt<unsigned>
cl::desc("livedebugvalues-stack-ws-limit"),
cl::init(250));

DbgOpID DbgOpID::UndefID = DbgOpID(0xffffffff);

/// Tracker for converting machine value locations and variable values into
/// variable locations (the output of LiveDebugValues), recorded as DBG_VALUEs
/// specifying block live-in locations and transfers within blocks.
Expand Down Expand Up @@ -259,7 +261,7 @@ class TransferTracker {
/// object fields to track variable locations as we step through the block.
/// FIXME: could just examine mloctracker instead of passing in \p mlocs?
void
loadInlocs(MachineBasicBlock &MBB, ValueTable &MLocs,
loadInlocs(MachineBasicBlock &MBB, ValueTable &MLocs, DbgOpIDMap &DbgOpStore,
const SmallVectorImpl<std::pair<DebugVariable, DbgValue>> &VLocs,
unsigned NumLocs) {
ActiveMLocs.clear();
Expand All @@ -284,9 +286,13 @@ class TransferTracker {

// Initialized the preferred-location map with illegal locations, to be
// filled in later.
for (const auto &VLoc : VLocs)
if (VLoc.second.Kind == DbgValue::Def)
ValueToLoc.insert({VLoc.second.ID, LocIdx::MakeIllegalLoc()});
for (const auto &VLoc : VLocs) {
if (VLoc.second.Kind == DbgValue::Def &&
!VLoc.second.getDbgOpID(0).isConst()) {
ValueToLoc.insert({DbgOpStore.find(VLoc.second.getDbgOpID(0)).ID,
LocIdx::MakeIllegalLoc()});
}
}

ActiveMLocs.reserve(VLocs.size());
ActiveVLocs.reserve(VLocs.size());
Expand Down Expand Up @@ -320,14 +326,16 @@ class TransferTracker {

// Now map variables to their picked LocIdxes.
for (const auto &Var : VLocs) {
if (Var.second.Kind == DbgValue::Const) {
DbgOpID OpID = Var.second.getDbgOpID(0);
DbgOp Op = DbgOpStore.find(OpID);
if (Var.second.Kind == DbgValue::Def && OpID.isConst()) {
PendingDbgValues.push_back(
emitMOLoc(*Var.second.MO, Var.first, Var.second.Properties));
emitMOLoc(Op.MO, Var.first, Var.second.Properties));
continue;
}

// If the value has no location, we can't make a variable location.
const ValueIDNum &Num = Var.second.ID;
const ValueIDNum &Num = Op.ID;
auto ValuesPreferredLoc = ValueToLoc.find(Num);
if (ValuesPreferredLoc->second.isIllegal()) {
// If it's a def that occurs in this block, register it as a
Expand Down Expand Up @@ -674,17 +682,43 @@ ValueIDNum ValueIDNum::EmptyValue = {UINT_MAX, UINT_MAX, UINT_MAX};
ValueIDNum ValueIDNum::TombstoneValue = {UINT_MAX, UINT_MAX, UINT_MAX - 1};

#ifndef NDEBUG
void DbgValue::dump(const MLocTracker *MTrack) const {
if (Kind == Const) {
MO->dump();
} else if (Kind == NoVal) {
dbgs() << "NoVal(" << BlockNo << ")";
} else if (Kind == VPHI) {
dbgs() << "VPHI(" << BlockNo << "," << MTrack->IDAsString(ID) << ")";
void ResolvedDbgOp::dump(const MLocTracker *MTrack) const {
if (IsConst) {
dbgs() << MO;
} else {
assert(Kind == Def);
dbgs() << MTrack->LocIdxToName(Loc);
}
}
void DbgOp::dump(const MLocTracker *MTrack) const {
if (IsConst) {
dbgs() << MO;
} else if (!isUndef()) {
dbgs() << MTrack->IDAsString(ID);
}
}
void DbgOpID::dump(const MLocTracker *MTrack, const DbgOpIDMap *OpStore) const {
if (!OpStore) {
dbgs() << "ID(" << asU32() << ")";
} else {
OpStore->find(*this).dump(MTrack);
}
}
void DbgValue::dump(const MLocTracker *MTrack,
const DbgOpIDMap *OpStore) const {
if (Kind == NoVal) {
dbgs() << "NoVal(" << BlockNo << ")";
} else if (Kind == VPHI || Kind == Def) {
if (Kind == VPHI)
dbgs() << "VPHI(" << BlockNo << ",";
else
dbgs() << "Def(";
for (unsigned Idx = 0; Idx < getDbgOpIDs().size(); ++Idx) {
getDbgOpID(Idx).dump(MTrack, OpStore);
if (Idx != 0)
dbgs() << ",";
}
dbgs() << ")";
}
if (Properties.Indirect)
dbgs() << " indir";
if (Properties.DIExpr)
Expand Down Expand Up @@ -1076,8 +1110,9 @@ bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
// contribute to locations in this block, but don't propagate further.
// Interpret it like a DBG_VALUE $noreg.
if (MI.isDebugValueList()) {
SmallVector<DbgOpID> EmptyDebugOps;
if (VTracker)
VTracker->defVar(MI, Properties, None);
VTracker->defVar(MI, Properties, EmptyDebugOps);
if (TTracker)
TTracker->redefVar(MI, Properties, None);
return true;
Expand All @@ -1094,16 +1129,21 @@ bool InstrRefBasedLDV::transferDebugValue(const MachineInstr &MI) {
// locations are already solved, and we report this DBG_VALUE and the value
// it refers to to VLocTracker.
if (VTracker) {
if (MO.isReg()) {
// Feed defVar the new variable location, or if this is a
// DBG_VALUE $noreg, feed defVar None.
if (MO.getReg())
VTracker->defVar(MI, Properties, MTracker->readReg(MO.getReg()));
else
VTracker->defVar(MI, Properties, None);
} else if (MO.isImm() || MO.isFPImm() || MO.isCImm()) {
VTracker->defVar(MI, MO);
SmallVector<DbgOpID> DebugOps;
// Feed defVar the new variable location, or if this is a DBG_VALUE $noreg,
// feed defVar None.
if (!MI.isUndefDebugValue()) {
// There should be no undef registers here, as we've screened for undef
// debug values.
if (MO.isReg()) {
DebugOps.push_back(DbgOpStore.insert(MTracker->readReg(MO.getReg())));
} else if (MO.isImm() || MO.isFPImm() || MO.isCImm()) {
DebugOps.push_back(DbgOpStore.insert(MO));
} else {
llvm_unreachable("Unexpected debug operand type.");
}
}
VTracker->defVar(MI, Properties, DebugOps);
}

// If performing final tracking of transfers, report this variable definition
Expand Down Expand Up @@ -1287,8 +1327,11 @@ bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI,
// for DBG_INSTR_REFs as DBG_VALUEs (just, the former can refer to values that
// aren't immediately available).
DbgValueProperties Properties(Expr, false, false);
SmallVector<DbgOpID> DbgOpIDs;
if (NewID)
DbgOpIDs.push_back(DbgOpStore.insert(*NewID));
if (VTracker)
VTracker->defVar(MI, Properties, NewID);
VTracker->defVar(MI, Properties, DbgOpIDs);

// If we're on the final pass through the function, decompose this INSTR_REF
// into a plain DBG_VALUE.
Expand Down Expand Up @@ -1334,6 +1377,7 @@ bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI,
// FoundLoc is None.
// (XXX -- could morph the DBG_INSTR_REF in the future).
MachineInstr *DbgMI = MTracker->emitLoc(FoundLoc, V, Properties);

TTracker->PendingDbgValues.push_back(DbgMI);
TTracker->flushDbgValues(MI.getIterator(), nullptr);
return true;
Expand Down Expand Up @@ -2397,7 +2441,7 @@ Optional<ValueIDNum> InstrRefBasedLDV::pickVPHILoc(
return None;
const DbgValue &OutVal = *OutValIt->second;

if (OutVal.Kind == DbgValue::Const || OutVal.Kind == DbgValue::NoVal)
if (OutVal.getDbgOpID(0).isConst() || OutVal.Kind == DbgValue::NoVal)
// Consts and no-values cannot have locations we can join on.
return None;

Expand All @@ -2410,8 +2454,8 @@ Optional<ValueIDNum> InstrRefBasedLDV::pickVPHILoc(
// present. Do the same for VPHIs where we know the VPHI value.
if (OutVal.Kind == DbgValue::Def ||
(OutVal.Kind == DbgValue::VPHI && OutVal.BlockNo != MBB.getNumber() &&
OutVal.ID != ValueIDNum::EmptyValue)) {
ValueIDNum ValToLookFor = OutVal.ID;
!OutVal.getDbgOpID(0).isUndef())) {
ValueIDNum ValToLookFor = DbgOpStore.find(OutVal.getDbgOpID(0)).ID;
// Search the live-outs of the predecessor for the specified value.
for (unsigned int I = 0; I < NumLocs; ++I) {
if (MOutLocs[ThisBBNum][I] == ValToLookFor)
Expand Down Expand Up @@ -2543,7 +2587,7 @@ bool InstrRefBasedLDV::vlocJoin(
return false;
if (V.second->Kind == DbgValue::NoVal)
return false;
if (V.second->Kind == DbgValue::Const && FirstVal.Kind != DbgValue::Const)
if (!V.second->hasJoinableLocOps(FirstVal))
return false;
}

Expand All @@ -2556,7 +2600,7 @@ bool InstrRefBasedLDV::vlocJoin(
// If both values are not equal but have equal non-empty IDs then they refer
// to the same value from different sources (e.g. one is VPHI and the other
// is Def), which does not cause disagreement.
if (V.second->ID != ValueIDNum::EmptyValue && V.second->ID == FirstVal.ID)
if (V.second->hasIdenticalValidLocOps(FirstVal))
continue;

// Eliminate if a backedge feeds a VPHI back into itself.
Expand Down Expand Up @@ -2807,8 +2851,9 @@ void InstrRefBasedLDV::buildVLocValueMap(
pickVPHILoc(*MBB, Var, LiveOutIdx, MOutLocs, Preds);

if (ValueNum) {
InLocsChanged |= LiveIn->ID != *ValueNum;
LiveIn->ID = *ValueNum;
DbgOpID ValueID = DbgOpStore.insert(*ValueNum);
InLocsChanged |= LiveIn->getDbgOpID(0) != ValueID;
LiveIn->setDbgOpIDs(ValueID);
}
}

Expand Down Expand Up @@ -2878,8 +2923,7 @@ void InstrRefBasedLDV::buildVLocValueMap(
DbgValue *BlockLiveIn = LiveInIdx[MBB];
if (BlockLiveIn->Kind == DbgValue::NoVal)
continue;
if (BlockLiveIn->Kind == DbgValue::VPHI &&
BlockLiveIn->ID == ValueIDNum::EmptyValue)
if (BlockLiveIn->isUnjoinedPHI())
continue;
if (BlockLiveIn->Kind == DbgValue::VPHI)
BlockLiveIn->Kind = DbgValue::Def;
Expand Down Expand Up @@ -3070,7 +3114,8 @@ bool InstrRefBasedLDV::depthFirstVLocAndEmit(
// instructions, installing transfers.
MTracker->reset();
MTracker->loadFromArray(MInLocs[BBNum], BBNum);
TTracker->loadInlocs(MBB, MInLocs[BBNum], Output[BBNum], NumLocs);
TTracker->loadInlocs(MBB, MInLocs[BBNum], DbgOpStore, Output[BBNum],
NumLocs);

CurBB = BBNum;
CurInst = 1;
Expand Down Expand Up @@ -3368,6 +3413,7 @@ bool InstrRefBasedLDV::ExtendRanges(MachineFunction &MF,
OverlapFragments.clear();
SeenFragments.clear();
SeenDbgPHIs.clear();
DbgOpStore.clear();

return Changed;
}
Expand Down

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