Add opt-for-size core lib feature flag
Adds a feature flag to the core library that enables the possibility to have smaller implementations for certain algorithms.
So far, the core lib has traded performance for binary size. This is likely what most people want since they have big simd-capable machines. However, people on small machines, like embedded devices, don't enjoy the potential speedup of the bigger algorithms, but do have to pay for them. These microcontrollers often only have 16-1024kB of flash memory.
This PR is the result of some talks with project members like `@Amanieu` at RustNL.
There are some open questions of how this is eventually stabilized, but it's a similar question as with the existing `panic_immediate_abort` feature.
Speaking as someone from the embedded side, we'd rather have this unstable for a while as opposed to not having it at all. In the meantime we can try to use it and also add additional PRs to the core lib that uses the feature flag in areas where we find benefit.
Open questions from my side:
- Is this a good feature name?
- `panic_immediate_abort` is fairly verbose, so I went with something equally verbose
- It's easy to refactor later
- I've added the feature to `std` and `alloc` as well as they might benefit too. Do we agree?
- I expect these to get less usage out of the flag since most size-constraint projects don't use these libraries often.
library/backtrace also declares a feature called `gimli-symbolize` which
appear used, but the feature in std with the same name is unused, so
remove it.
Extending `std` to get the last error number for HermitOS.
HermitOS is a tier 3 platform and this PR changes only files,
wich are related to the tier 3 platform.
- Some comment fixes.
- Make some functions unsafe.
- Make helpers module private.
- Rebase on master
- Update r-efi to v4.2.0
Signed-off-by: Ayush Singh <ayushsingh1325@gmail.com>
Basic alloc support on Xous is supported by the `dlmalloc` crate. This
necessitates bumping the dlmalloc version to 0.2.4.
Signed-off-by: Sean Cross <sean@xobs.io>
reduce deps for windows-msvc targets for backtrace
(eventually) mirrors https://github.com/rust-lang/backtrace-rs/pull/543
Some dependencies of backtrace don't used on windows-msvc targets, so exclude them:
miniz_oxide (+ adler)
addr2line (+ gimli)
object (+ memchr)
This saves about 30kb of std.dll + 17.5mb of rlibs
Expose `compiler-builtins-weak-intrinsics` feature for `-Zbuild-std`
This was added in rust-lang/compiler-builtins#526 to force all compiler-builtins intrinsics to use weak linkage.
STD support for PSVita
This PR adds std support for `armv7-sony-vita-newlibeabihf` target.
The work here is fairly similar to #95897, just for a different target platform.
This depends on the following pull requests:
rust-lang/backtrace-rs#523rust-lang/libc#3209
