From 5d10b8ad595da87bec8c66ad70a8daf86cd9266b Mon Sep 17 00:00:00 2001 From: Nathan James Date: Tue, 22 Dec 2020 17:18:59 +0000 Subject: [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 --- llvm/unittests/ADT/SmallVectorTest.cpp | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'llvm/unittests/ADT/SmallVectorTest.cpp') 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 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 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"); -- cgit v1.1