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InstrProf: Avoid linear search in a hot loop

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Every time we were adding or removing an expression when generating a
coverage mapping we were doing a linear search to try and deduplicate
the list. The indices in the list are important, so we can't just
replace it by a DenseMap entirely, but an auxilliary DenseMap for fast
lookup massively improves the performance issues I was seeing here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218892 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Justin Bogner 2014-10-02 17:14:18 +00:00
parent f3cd10bdc3
commit d76512681e
2 changed files with 41 additions and 10 deletions
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40
include/llvm/ProfileData/CoverageMapping.h
View File

@ -16,6 +16,8 @@
#define LLVM_PROFILEDATA_COVERAGEMAPPING_H_
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/raw_ostream.h"
#include <system_error>
@ -91,10 +93,6 @@ struct CounterExpression {
CounterExpression(ExprKind Kind, Counter LHS, Counter RHS)
: Kind(Kind), LHS(LHS), RHS(RHS) {}
bool operator==(const CounterExpression &Other) const {
return Kind == Other.Kind && LHS == Other.LHS && RHS == Other.RHS;
}
};
/// \brief A Counter expression builder is used to construct the
@ -102,7 +100,9 @@ struct CounterExpression {
/// and simplifies algebraic expressions.
class CounterExpressionBuilder {
/// \brief A list of all the counter expressions
llvm::SmallVector<CounterExpression, 16> Expressions;
std::vector<CounterExpression> Expressions;
/// \brief A lookup table for the index of a given expression.
llvm::DenseMap<CounterExpression, unsigned> ExpressionIndices;
/// \brief Return the counter which corresponds to the given expression.
///
@ -370,6 +370,36 @@ public:
};
} // end namespace coverage
/// \brief Provide DenseMapInfo for CounterExpression
template<> struct DenseMapInfo<coverage::CounterExpression> {
static inline coverage::CounterExpression getEmptyKey() {
using namespace coverage;
return CounterExpression(CounterExpression::ExprKind::Subtract,
Counter::getCounter(~0U),
Counter::getCounter(~0U));
}
static inline coverage::CounterExpression getTombstoneKey() {
using namespace coverage;
return CounterExpression(CounterExpression::ExprKind::Add,
Counter::getCounter(~0U),
Counter::getCounter(~0U));
}
static unsigned getHashValue(const coverage::CounterExpression &V) {
return static_cast<unsigned>(
hash_combine(V.Kind, V.LHS.getKind(), V.LHS.getCounterID(),
V.RHS.getKind(), V.RHS.getCounterID()));
}
static bool isEqual(const coverage::CounterExpression &LHS,
const coverage::CounterExpression &RHS) {
return LHS.Kind == RHS.Kind && LHS.LHS == RHS.LHS && LHS.RHS == RHS.RHS;
}
};
} // end namespace llvm
#endif // LLVM_PROFILEDATA_COVERAGEMAPPING_H_

11
lib/ProfileData/CoverageMapping.cpp
View File

@ -28,12 +28,13 @@ using namespace coverage;
#define DEBUG_TYPE "coverage-mapping"
Counter CounterExpressionBuilder::get(const CounterExpression &E) {
for (unsigned I = 0, S = Expressions.size(); I < S; ++I) {
if (Expressions[I] == E)
return Counter::getExpression(I);
}
auto It = ExpressionIndices.find(E);
if (It != ExpressionIndices.end())
return Counter::getExpression(It->second);
unsigned I = Expressions.size();
Expressions.push_back(E);
return Counter::getExpression(Expressions.size() - 1);
ExpressionIndices[E] = I;
return Counter::getExpression(I);
}
void CounterExpressionBuilder::extractTerms(