smallvector.h: bake reserve() into the non-boost SmallVector implementation#4385
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danmar merged 1 commit intocppcheck-opensource:mainfrom Aug 20, 2022
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This changes bakes the
reserve()call into the non-boost implementationSmallVectorconstruction as it would cause a performance regression with theboost::small_vectorimplementation (see #3919).I tested the build with Clang, GCC, MinGW and Visual Studio.
Replacing the
std::vector+resreve()appraoch withSmallVectorinvisitAstNodes()will now yield the same performance when using Clang.In case of GCC the code actually gets faster since (according to valgrind) it was previously using
std::vector<>::reserve(unsigned long)whereas it now usesoperator new(unsigned long)just like Clang does. Possibly another issue to report upstream.Clang 14
2,481,264,505->2,481,270,375GCC 12
2,388,141,113->2,359,483,453This patch does not replace the usage yet - that still requires a few more tests and is handled via #3919.