core: Remove panics from some Layout methods#49884
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Could we add a comment here as to why we have this unsafe code? Otherwise I worry someone will remove it down the line since it feels unnecessary.
Either way, I feel like it's unfortunate we have to do this :/
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…mulacrum core: Remove panics from some `Layout` methods `Layout` is often used at the core of allocation APIs and is as a result pretty sensitive to codegen in various circumstances. I was profiling `-C opt-level=z` with a wasm project recently and noticed that the `unwrap()` wasn't removed inside of `Layout`, causing the program to be much larger than it otherwise would be. If inlining were more aggressive LLVM would have figured out that the panic could be eliminated, but in general the methods here can't panic in the first place! As a result this commit makes the following tweaks: * Removes `unwrap()` and replaces it with `unsafe` in `Layout::new` and `Layout::for_value`. For posterity though a debug assertion was left behind. * Removes an `unwrap()` in favor of `?` in the `repeat` method. The comment indicating that the function call couldn't panic wasn't quite right in that if `alloc_size` becomes too large and if `align` is high enough it could indeed cause a panic. This'll hopefully mean that panics never get introduced into code in the first place, ensuring that `opt-level=z` is closer to `opt-level=s` in this regard.
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☔ The latest upstream changes (presumably #49669) made this pull request unmergeable. Please resolve the merge conflicts. |
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`Layout` is often used at the core of allocation APIs and is as a result pretty sensitive to codegen in various circumstances. I was profiling `-C opt-level=z` with a wasm project recently and noticed that the `unwrap()` wasn't removed inside of `Layout`, causing the program to be much larger than it otherwise would be. If inlining were more aggressive LLVM would have figured out that the panic could be eliminated, but in general the methods here can't panic in the first place! As a result this commit makes the following tweaks: * Removes `unwrap()` and replaces it with `unsafe` in `Layout::new` and `Layout::for_value`. For posterity though a debug assertion was left behind. * Removes an `unwrap()` in favor of `?` in the `repeat` method. The comment indicating that the function call couldn't panic wasn't quite right in that if `alloc_size` becomes too large and if `align` is high enough it could indeed cause a panic. This'll hopefully mean that panics never get introduced into code in the first place, ensuring that `opt-level=z` is closer to `opt-level=s` in this regard.
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core: Remove panics from some `Layout` methods `Layout` is often used at the core of allocation APIs and is as a result pretty sensitive to codegen in various circumstances. I was profiling `-C opt-level=z` with a wasm project recently and noticed that the `unwrap()` wasn't removed inside of `Layout`, causing the program to be much larger than it otherwise would be. If inlining were more aggressive LLVM would have figured out that the panic could be eliminated, but in general the methods here can't panic in the first place! As a result this commit makes the following tweaks: * Removes `unwrap()` and replaces it with `unsafe` in `Layout::new` and `Layout::for_value`. For posterity though a debug assertion was left behind. * Removes an `unwrap()` in favor of `?` in the `repeat` method. The comment indicating that the function call couldn't panic wasn't quite right in that if `alloc_size` becomes too large and if `align` is high enough it could indeed cause a panic. This'll hopefully mean that panics never get introduced into code in the first place, ensuring that `opt-level=z` is closer to `opt-level=s` in this regard.
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Layoutis often used at the core of allocation APIs and is as a result prettysensitive to codegen in various circumstances. I was profiling
-C opt-level=zwith a wasm project recently and noticed that the
unwrap()wasn't removedinside of
Layout, causing the program to be much larger than it otherwisewould be. If inlining were more aggressive LLVM would have figured out that the
panic could be eliminated, but in general the methods here can't panic in the
first place!
As a result this commit makes the following tweaks:
unwrap()and replaces it withunsafeinLayout::newandLayout::for_value. For posterity though a debug assertion was left behind.unwrap()in favor of?in therepeatmethod. The commentindicating that the function call couldn't panic wasn't quite right in that if
alloc_sizebecomes too large and ifalignis high enough it could indeedcause a panic.
This'll hopefully mean that panics never get introduced into code in the first
place, ensuring that
opt-level=zis closer toopt-level=sin this regard.