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[SelectionDAG] Use poison instead of undef for dbg.values #127915

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Merged
merged 1 commit into from
Mar 3, 2025
Merged

[SelectionDAG] Use poison instead of undef for dbg.values #127915

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24 changes: 12 additions & 12 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1385,12 +1385,12 @@ static bool handleDanglingVariadicDebugInfo(SelectionDAG &DAG,
DebugLoc DL, unsigned Order,
SmallVectorImpl<Value *> &Values,
DIExpression *Expression) {
// For variadic dbg_values we will now insert an undef.
// For variadic dbg_values we will now insert poison.
// FIXME: We can potentially recover these!
SmallVector<SDDbgOperand, 2> Locs;
for (const Value *V : Values) {
auto *Undef = UndefValue::get(V->getType());
Locs.push_back(SDDbgOperand::fromConst(Undef));
auto *Poison = PoisonValue::get(V->getType());
Locs.push_back(SDDbgOperand::fromConst(Poison));
}
SDDbgValue *SDV = DAG.getDbgValueList(Variable, Expression, Locs, {},
/*IsIndirect=*/false, DL, Order,
Expand All @@ -1409,9 +1409,9 @@ void SelectionDAGBuilder::addDanglingDebugInfo(SmallVectorImpl<Value *> &Values,
return;
}
// TODO: Dangling debug info will eventually either be resolved or produce
// an Undef DBG_VALUE. However in the resolution case, a gap may appear
// a poison DBG_VALUE. However in the resolution case, a gap may appear
// between the original dbg.value location and its resolved DBG_VALUE,
// which we should ideally fill with an extra Undef DBG_VALUE.
// which we should ideally fill with an extra poison DBG_VALUE.
assert(Values.size() == 1);
DanglingDebugInfoMap[Values[0]].emplace_back(Var, Expr, DL, Order);
}
Expand Down Expand Up @@ -1489,9 +1489,9 @@ void SelectionDAGBuilder::resolveDanglingDebugInfo(const Value *V,
} else {
LLVM_DEBUG(dbgs() << "Dropping debug info for " << printDDI(V, DDI)
<< "\n");
auto Undef = UndefValue::get(V->getType());
auto Poison = PoisonValue::get(V->getType());
auto SDV =
DAG.getConstantDbgValue(Variable, Expr, Undef, DL, DbgSDNodeOrder);
DAG.getConstantDbgValue(Variable, Expr, Poison, DL, DbgSDNodeOrder);
DAG.AddDbgValue(SDV, false);
}
}
Expand Down Expand Up @@ -1554,11 +1554,11 @@ void SelectionDAGBuilder::salvageUnresolvedDbgValue(const Value *V,
}

// This was the final opportunity to salvage this debug information, and it
// couldn't be done. Place an undef DBG_VALUE at this location to terminate
// couldn't be done. Place a poison DBG_VALUE at this location to terminate
// any earlier variable location.
assert(OrigV && "V shouldn't be null");
auto *Undef = UndefValue::get(OrigV->getType());
auto *SDV = DAG.getConstantDbgValue(Var, Expr, Undef, DL, SDNodeOrder);
auto *Poison = PoisonValue::get(OrigV->getType());
auto *SDV = DAG.getConstantDbgValue(Var, Expr, Poison, DL, SDNodeOrder);
DAG.AddDbgValue(SDV, false);
LLVM_DEBUG(dbgs() << "Dropping debug value info for:\n "
<< printDDI(OrigV, DDI) << "\n");
Expand Down Expand Up @@ -6180,10 +6180,10 @@ bool SelectionDAGBuilder::EmitFuncArgumentDbgValue(
Expr, Offset, RegFragmentSizeInBits);
Offset += RegAndSize.second;
// If a valid fragment expression cannot be created, the variable's
// correct value cannot be determined and so it is set as Undef.
// correct value cannot be determined and so it is set as poison.
if (!FragmentExpr) {
SDDbgValue *SDV = DAG.getConstantDbgValue(
Variable, Expr, UndefValue::get(V->getType()), DL, SDNodeOrder);
Variable, Expr, PoisonValue::get(V->getType()), DL, SDNodeOrder);
DAG.AddDbgValue(SDV, false);
continue;
}
Expand Down