Tacet 82b38e83cf [ASan][libc++] Optimization of container annotations (#76082) ...

This commit implements conditional compilation for ASan helper code.

As convey to me by @EricWF, string benchmarks with UBSan have been
experiencing significant performance hit after the commit with ASan
string annotations. This is likely due to the fact that no-op ASan code
is not optimized out with UBSan. To address this issue, this commit
conditionalizes the inclusion of ASan helper function bodies using
`#ifdef` directives. This approach allows us to selectively include only
the ASan code when it's actually required, thereby enhancing
optimizations and improving performance.

While issue was noticed in string benchmarks, I expect same overhead
(just less noticeable) in other containers, therefore `std::vector` and
`std::deque` have same changes.

To see impact of that change run `string.libcxx.out` with UBSan and
`--benchmark_filter=BM_StringAssign` or
`--benchmark_filter=BM_StringConstruct`.

2023-12-21 17:26:10 -05:00

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