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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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11
lib/ProfileData/CoverageMapping.cpp
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@ -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(