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authorNathan James <n.james93@hotmail.co.uk>2020-12-22 17:18:59 +0000
committerNathan James <n.james93@hotmail.co.uk>2020-12-22 17:18:59 +0000
commit5d10b8ad595da87bec8c66ad70a8daf86cd9266b (patch)
treea747c1a008110694bc7e374a780800c19ef55529 /llvm/unittests/ADT/SmallVectorTest.cpp
parentbe85b3e4324b5a03abd929815b7fc1c2184db97a (diff)
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[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.cpp25
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");