[libcxx-commits] [PATCH] D128146: [libc++] Use uninitialized algorithms for vector

[Louis Dionne via Phabricator via libcxx-commits]

ldionne added a comment.

In D128146#3699909 <https://reviews.llvm.org/D128146#3699909>, @vitalybuka wrote:

>> @vitalybuka This isn't unexpected. `-fno-inline` disables inlining, which is essential for a lot of other optimizations. Using `-fno-inline` pretty much defeats the optimizer: https://godbolt.org/z/zrE5o1WK1.
>
> I am more concerned about sanitizers
>
> https://godbolt.org/z/1x9qjGG19 Near LBB11_5 we have now __asan_memcpy per every "P", before it was for entire vector.
> I assume some additional improvement in instrumentation are possible, maybe replacing fixed short asan_memcpy with check/load/store. Or even optimizing asan_memcpy itself.
>
> But still maybe some ideas if it's solvable on libc++ level so we rely less on optimizations?

I suspect this might go away if we manually lowered `std::uninitialized_foo` to `memcpy` like we do for `std::copy` and `std::move`.


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