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[DenseMap] Introduce emplace_or_assign #138886

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Merged
merged 1 commit into from
May 8, 2025
Merged

[DenseMap] Introduce emplace_or_assign #138886

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16 changes: 16 additions & 0 deletions llvm/include/llvm/ADT/DenseMap.h
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Original file line number Diff line number Diff line change
Expand Up @@ -324,6 +324,22 @@ class DenseMapBase : public DebugEpochBase {
return Ret;
}

template <typename... Ts>
std::pair<iterator, bool> emplace_or_assign(const KeyT &Key, Ts &&...Args) {
auto Ret = try_emplace(Key, std::forward<Ts>(Args)...);
if (!Ret.second)
Ret.first->second = ValueT(std::forward<Ts>(Args)...);
return Ret;
}

template <typename... Ts>
std::pair<iterator, bool> emplace_or_assign(KeyT &&Key, Ts &&...Args) {
auto Ret = try_emplace(std::move(Key), std::forward<Ts>(Args)...);
if (!Ret.second)
Ret.first->second = ValueT(std::forward<Ts>(Args)...);
return Ret;
}

bool erase(const KeyT &Val) {
BucketT *TheBucket = doFind(Val);
if (!TheBucket)
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35 changes: 35 additions & 0 deletions llvm/unittests/ADT/DenseMapTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -545,6 +545,41 @@ TEST(DenseMapCustomTest, InsertOrAssignTest) {
EXPECT_EQ(1, CountCopyAndMove::MoveAssignments);
}

TEST(DenseMapCustomTest, EmplaceOrAssign) {
DenseMap<int, CountCopyAndMove> Map;

CountCopyAndMove::ResetCounts();
auto Try0 = Map.emplace_or_assign(3, 3);
EXPECT_TRUE(Try0.second);
EXPECT_EQ(0, CountCopyAndMove::TotalCopies());
EXPECT_EQ(0, CountCopyAndMove::TotalMoves());
EXPECT_EQ(1, CountCopyAndMove::ValueConstructions);

CountCopyAndMove::ResetCounts();
auto Try1 = Map.emplace_or_assign(3, 4);
EXPECT_FALSE(Try1.second);
EXPECT_EQ(0, CountCopyAndMove::TotalCopies());
EXPECT_EQ(1, CountCopyAndMove::ValueConstructions);
EXPECT_EQ(0, CountCopyAndMove::MoveConstructions);
EXPECT_EQ(1, CountCopyAndMove::MoveAssignments);

int Key = 5;
CountCopyAndMove::ResetCounts();
auto Try2 = Map.emplace_or_assign(Key, 3);
EXPECT_TRUE(Try2.second);
EXPECT_EQ(0, CountCopyAndMove::TotalCopies());
EXPECT_EQ(0, CountCopyAndMove::TotalMoves());
EXPECT_EQ(1, CountCopyAndMove::ValueConstructions);

CountCopyAndMove::ResetCounts();
auto Try3 = Map.emplace_or_assign(Key, 4);
EXPECT_FALSE(Try3.second);
EXPECT_EQ(0, CountCopyAndMove::TotalCopies());
EXPECT_EQ(1, CountCopyAndMove::ValueConstructions);
EXPECT_EQ(0, CountCopyAndMove::MoveConstructions);
EXPECT_EQ(1, CountCopyAndMove::MoveAssignments);
}

// Make sure DenseMap works with StringRef keys.
TEST(DenseMapCustomTest, StringRefTest) {
DenseMap<StringRef, int> M;
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