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Avoid codegen for Result::into_ok in lang_start by Mark-Simulacrum · Pull Reques...
source link: https://github.com/rust-lang/rust/pull/88988
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This extra codegen seems to be the cause for the regressions in max-rss on #86034. While LLVM will certainly optimize the dead code away, avoiding it's generation in the first place seems good, particularly when it is so simple.
#86034 produced this diff for a simple fn main() {}. With this PR, that diff becomes limited to just a few extra IR instructions -- no extra functions.
Note that these are pre-optimization; LLVM surely will eliminate this during optimization. However, that optimization can end up generating more work and bump memory usage, and this eliminates that.
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