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[Coverage] Improve readability by using a struct. NFC. 

llvm-svn: 306340
This commit is contained in:
Vedant Kumar 2017-06-26 22:33:06 +00:00
parent 3923c0c46b
commit 71b3d721fd
2 changed files with 30 additions and 24 deletions
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12
llvm/include/llvm/ProfileData/Coverage/CoverageMapping.h
View File

@ -168,13 +168,21 @@ class CounterExpressionBuilder {
/// expression is added to the builder's collection of expressions.
Counter get(const CounterExpression &E);
/// Represents a term in a counter expression tree.
struct Term {
unsigned CounterID;
int Factor;
Term(unsigned CounterID, int Factor)
: CounterID(CounterID), Factor(Factor) {}
};
/// \brief Gather the terms of the expression tree for processing.
///
/// This collects each addition and subtraction referenced by the counter into
/// a sequence that can be sorted and combined to build a simplified counter
/// expression.
void extractTerms(Counter C, int Sign,
SmallVectorImpl<std::pair<unsigned, int>> &Terms);
void extractTerms(Counter C, int Sign, SmallVectorImpl<Term> &Terms);
/// \brief Simplifies the given expression tree
/// by getting rid of algebraically redundant operations.

42
llvm/lib/ProfileData/Coverage/CoverageMapping.cpp
View File

@ -54,26 +54,26 @@ Counter CounterExpressionBuilder::get(const CounterExpression &E) {
return Counter::getExpression(I);
}
void CounterExpressionBuilder::extractTerms(
Counter C, int Sign, SmallVectorImpl<std::pair<unsigned, int>> &Terms) {
void CounterExpressionBuilder::extractTerms(Counter C, int Factor,
SmallVectorImpl<Term> &Terms) {
switch (C.getKind()) {
case Counter::Zero:
break;
case Counter::CounterValueReference:
Terms.push_back(std::make_pair(C.getCounterID(), Sign));
Terms.emplace_back(C.getCounterID(), Factor);
break;
case Counter::Expression:
const auto &E = Expressions[C.getExpressionID()];
extractTerms(E.LHS, Sign, Terms);
extractTerms(E.RHS, E.Kind == CounterExpression::Subtract ? -Sign : Sign,
Terms);
extractTerms(E.LHS, Factor, Terms);
extractTerms(
E.RHS, E.Kind == CounterExpression::Subtract ? -Factor : Factor, Terms);
break;
}
}
Counter CounterExpressionBuilder::simplify(Counter ExpressionTree) {
// Gather constant terms.
SmallVector<std::pair<unsigned, int>, 32> Terms;
SmallVector<Term, 32> Terms;
extractTerms(ExpressionTree, +1, Terms);
// If there are no terms, this is just a zero. The algorithm below assumes at
@ -82,17 +82,15 @@ Counter CounterExpressionBuilder::simplify(Counter ExpressionTree) {
return Counter::getZero();
// Group the terms by counter ID.
std::sort(Terms.begin(), Terms.end(),
[](const std::pair<unsigned, int> &LHS,
const std::pair<unsigned, int> &RHS) {
return LHS.first < RHS.first;
std::sort(Terms.begin(), Terms.end(), [](const Term &LHS, const Term &RHS) {
return LHS.CounterID < RHS.CounterID;
});
// Combine terms by counter ID to eliminate counters that sum to zero.
auto Prev = Terms.begin();
for (auto I = Prev + 1, E = Terms.end(); I != E; ++I) {
if (I->first == Prev->first) {
Prev->second += I->second;
if (I->CounterID == Prev->CounterID) {
Prev->Factor += I->Factor;
continue;
}
++Prev;
@ -103,24 +101,24 @@ Counter CounterExpressionBuilder::simplify(Counter ExpressionTree) {
Counter C;
// Create additions. We do this before subtractions to avoid constructs like
// ((0 - X) + Y), as opposed to (Y - X).
for (auto Term : Terms) {
if (Term.second <= 0)
for (auto T : Terms) {
if (T.Factor <= 0)
continue;
for (int I = 0; I < Term.second; ++I)
for (int I = 0; I < T.Factor; ++I)
if (C.isZero())
C = Counter::getCounter(Term.first);
C = Counter::getCounter(T.CounterID);
else
C = get(CounterExpression(CounterExpression::Add, C,
Counter::getCounter(Term.first)));
Counter::getCounter(T.CounterID)));
}
// Create subtractions.
for (auto Term : Terms) {
if (Term.second >= 0)
for (auto T : Terms) {
if (T.Factor >= 0)
continue;
for (int I = 0; I < -Term.second; ++I)
for (int I = 0; I < -T.Factor; ++I)
C = get(CounterExpression(CounterExpression::Subtract, C,
Counter::getCounter(Term.first)));
Counter::getCounter(T.CounterID)));
}
return C;
}