[libcxx-commits] [libcxx] [libc++] Optimize vector::emplace_back (PR #218658)

[Liza Burakova via libcxx-commits]

liza371 wrote:

@ldionne yes that's correct. We're building with `-O2` on most releases, and one some small android releases we build with `-Os` and we also see a regression there.

I did just attempt a build with `-O1` and actually see roughly the same size increase.

Size diff w/ `-O1`: https://chrome-supersize.firebaseapp.com/viewer.html?load_url=https%3A%2F%2Fstorage.googleapis.com%2Fchrome-supersize%2Foneoffs%2Fb16984ce99c702355a5b2b4c52574e82cec41fb9_ec81d14a14d102f226169100abb31fffd83ca985.sizediff&group_by=template

Size diff w/ `-O2`: https://chrome-supersize.firebaseapp.com/viewer.html?load_url=https%3A%2F%2Fstorage.googleapis.com%2Fchrome-supersize%2Foneoffs%2Fb16984ce99c702355a5b2b4c52574e82cec41fb9_704a5fc995977400ff5b7760f5f27e64e6db6a25.sizediff&group_by=template

These are both without the `emplace_back` patch that just merged.

https://github.com/llvm/llvm-project/pull/218658