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author | Nathan James <n.james93@hotmail.co.uk> | 2020-12-22 17:18:59 +0000 |
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committer | Nathan James <n.james93@hotmail.co.uk> | 2020-12-22 17:18:59 +0000 |
commit | 5d10b8ad595da87bec8c66ad70a8daf86cd9266b (patch) | |
tree | a747c1a008110694bc7e374a780800c19ef55529 /llvm/unittests/ADT/SmallVectorTest.cpp | |
parent | be85b3e4324b5a03abd929815b7fc1c2184db97a (diff) | |
download | llvm-5d10b8ad595da87bec8c66ad70a8daf86cd9266b.zip llvm-5d10b8ad595da87bec8c66ad70a8daf86cd9266b.tar.gz llvm-5d10b8ad595da87bec8c66ad70a8daf86cd9266b.tar.bz2 |
[ADT] Add resize_for_overwrite method to SmallVector.
Analagous to the std::make_(unqiue|shared)_for_overwrite added in c++20.
If T is POD, and the container gets larger, any new values added wont be initialized.
This is useful when using SmallVector as a buffer where its planned to overwrite any potential new values added.
If T is not POD, `new (Storage) T` functions identically to `new (Storage) T()` so this will function identically to `resize(size_type)`.
Reviewed By: dexonsmith
Differential Revision: https://reviews.llvm.org/D93532
Diffstat (limited to 'llvm/unittests/ADT/SmallVectorTest.cpp')
-rw-r--r-- | llvm/unittests/ADT/SmallVectorTest.cpp | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/llvm/unittests/ADT/SmallVectorTest.cpp b/llvm/unittests/ADT/SmallVectorTest.cpp index 957412f..e02c3e7 100644 --- a/llvm/unittests/ADT/SmallVectorTest.cpp +++ b/llvm/unittests/ADT/SmallVectorTest.cpp @@ -341,6 +341,31 @@ TYPED_TEST(SmallVectorTest, ResizeFillTest) { this->assertValuesInOrder(this->theVector, 3u, 77, 77, 77); } +TEST(SmallVectorTest, ResizeForOverwrite) { + { + // Heap allocated storage. + SmallVector<unsigned, 0> V; + V.push_back(5); + V.pop_back(); + V.resize_for_overwrite(V.size() + 1); + EXPECT_EQ(5, V.back()); + V.pop_back(); + V.resize(V.size() + 1); + EXPECT_EQ(0, V.back()); + } + { + // Inline storage. + SmallVector<unsigned, 2> V; + V.push_back(5); + V.pop_back(); + V.resize_for_overwrite(V.size() + 1); + EXPECT_EQ(5, V.back()); + V.pop_back(); + V.resize(V.size() + 1); + EXPECT_EQ(0, V.back()); + } +} + // Overflow past fixed size. TYPED_TEST(SmallVectorTest, OverflowTest) { SCOPED_TRACE("OverflowTest"); |