Skip to content

[ADT] Fix the initial size calculation of SmallDenseMap #158458

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Sep 14, 2025
Merged

[ADT] Fix the initial size calculation of SmallDenseMap #158458

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
aab3145
[ADT] Fix the initial size calculation of SmallDenseMap
kazutakahirata Sep 14, 2025
b0d2b31
Address a comment.
kazutakahirata Sep 14, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 4 additions & 7 deletions llvm/include/llvm/ADT/DenseMap.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -887,11 +887,7 @@ class SmallDenseMap
AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;

public:
explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
if (NumInitBuckets > InlineBuckets)
NumInitBuckets = llvm::bit_ceil(NumInitBuckets);
init(NumInitBuckets);
}
explicit SmallDenseMap(unsigned InitialReserve = 0) { init(InitialReserve); }

SmallDenseMap(const SmallDenseMap &other) : BaseT() {
init(0);
Expand All @@ -905,7 +901,7 @@ class SmallDenseMap

template <typename InputIt>
SmallDenseMap(const InputIt &I, const InputIt &E) {
init(NextPowerOf2(std::distance(I, E)));
init(std::distance(I, E));
this->insert(I, E);
}

Expand Down Expand Up @@ -1017,7 +1013,8 @@ class SmallDenseMap
this->BaseT::copyFrom(other);
}

void init(unsigned InitBuckets) {
void init(unsigned InitNumEntries) {
auto InitBuckets = BaseT::getMinBucketToReserveForEntries(InitNumEntries);
Small = true;
if (InitBuckets > InlineBuckets) {
Small = false;
Expand Down
69 changes: 69 additions & 0 deletions llvm/unittests/ADT/DenseMapTest.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -962,4 +962,73 @@ TEST(DenseMapCustomTest, PairPrinting) {
EXPECT_EQ(R"({ (1, "one"), (2, "two") })", ::testing::PrintToString(Map));
}

TEST(DenseMapCustomTest, InitSize) {
constexpr unsigned ElemSize = sizeof(std::pair<int *, int>);

{
DenseMap<int *, int> Map;
EXPECT_EQ(ElemSize * 0U, Map.getMemorySize());
}
{
DenseMap<int *, int> Map(0);
EXPECT_EQ(ElemSize * 0U, Map.getMemorySize());
}
{
DenseMap<int *, int> Map(1);
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
DenseMap<int *, int> Map(2);
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
DenseMap<int *, int> Map(3);
EXPECT_EQ(ElemSize * 8U, Map.getMemorySize());
}
{
int A, B;
DenseMap<int *, int> Map = {{&A, 1}, {&B, 2}};
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
int A, B, C;
DenseMap<int *, int> Map = {{&A, 1}, {&B, 2}, {&C, 3}};
EXPECT_EQ(ElemSize * 8U, Map.getMemorySize());
}
}

TEST(SmallDenseMapCustomTest, InitSize) {
constexpr unsigned ElemSize = sizeof(std::pair<int *, int>);
{
SmallDenseMap<int *, int> Map;
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
SmallDenseMap<int *, int> Map(0);
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
SmallDenseMap<int *, int> Map(1);
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
SmallDenseMap<int *, int> Map(2);
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
SmallDenseMap<int *, int> Map(3);
EXPECT_EQ(ElemSize * 8U, Map.getMemorySize());
}
{
int A, B;
SmallDenseMap<int *, int> Map = {{&A, 1}, {&B, 2}};
EXPECT_EQ(ElemSize * 4U, Map.getMemorySize());
}
{
int A, B, C;
SmallDenseMap<int *, int> Map = {{&A, 1}, {&B, 2}, {&C, 3}};
EXPECT_EQ(ElemSize * 8U, Map.getMemorySize());
}
}

} // namespace
Loading