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[NFC]Do not use recursion for CounterMappingContext::evaluate #66961

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merged 1 commit into from
Sep 22, 2023
Merged

[NFC]Do not use recursion for CounterMappingContext::evaluate #66961

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74 changes: 54 additions & 20 deletions llvm/lib/ProfileData/Coverage/CoverageMapping.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -167,27 +167,61 @@ void CounterMappingContext::dump(const Counter &C, raw_ostream &OS) const {
}

Expected<int64_t> CounterMappingContext::evaluate(const Counter &C) const {
switch (C.getKind()) {
case Counter::Zero:
return 0;
case Counter::CounterValueReference:
if (C.getCounterID() >= CounterValues.size())
return errorCodeToError(errc::argument_out_of_domain);
return CounterValues[C.getCounterID()];
case Counter::Expression: {
if (C.getExpressionID() >= Expressions.size())
return errorCodeToError(errc::argument_out_of_domain);
const auto &E = Expressions[C.getExpressionID()];
Expected<int64_t> LHS = evaluate(E.LHS);
if (!LHS)
return LHS;
Expected<int64_t> RHS = evaluate(E.RHS);
if (!RHS)
return RHS;
return E.Kind == CounterExpression::Subtract ? *LHS - *RHS : *LHS + *RHS;
}
struct StackElem {
Counter ICounter;
int64_t LHS = 0;
enum {
KNeverVisited = 0,
KVisitedOnce = 1,
KVisitedTwice = 2,
} VisitCount = KNeverVisited;
};

std::stack<StackElem> CounterStack;
CounterStack.push({C});

int64_t LastPoppedValue;

while (!CounterStack.empty()) {
StackElem &Current = CounterStack.top();

switch (Current.ICounter.getKind()) {
case Counter::Zero:
LastPoppedValue = 0;
CounterStack.pop();
break;
case Counter::CounterValueReference:
if (Current.ICounter.getCounterID() >= CounterValues.size())
return errorCodeToError(errc::argument_out_of_domain);
LastPoppedValue = CounterValues[Current.ICounter.getCounterID()];
CounterStack.pop();
break;
case Counter::Expression: {
if (Current.ICounter.getExpressionID() >= Expressions.size())
return errorCodeToError(errc::argument_out_of_domain);
const auto &E = Expressions[Current.ICounter.getExpressionID()];
if (Current.VisitCount == StackElem::KNeverVisited) {
CounterStack.push(StackElem{E.LHS});
Current.VisitCount = StackElem::KVisitedOnce;
} else if (Current.VisitCount == StackElem::KVisitedOnce) {
Current.LHS = LastPoppedValue;
CounterStack.push(StackElem{E.RHS});
Current.VisitCount = StackElem::KVisitedTwice;
} else {
int64_t LHS = Current.LHS;
int64_t RHS = LastPoppedValue;
LastPoppedValue =
E.Kind == CounterExpression::Subtract ? LHS - RHS : LHS + RHS;
CounterStack.pop();
}
break;
}
default:
llvm_unreachable("Unhandled CounterKind");
}
}
llvm_unreachable("Unhandled CounterKind");

return LastPoppedValue;
}

unsigned CounterMappingContext::getMaxCounterID(const Counter &C) const {
Expand Down