Project:Toolchain/LTO
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Plan
- Add
filter-lto
toflag-o-matic.eclass
- Trivial glob is a bit messy but also matches stuff like -fno-lto, hence this is needed (e.g. bug #838115)
- Needs to handle non-obvious flags which require LTO (e.g. bug #853280)
- Review blockers of the LTO tracker (bug #618550) and fix appropriately
- Review list of failures from the gentooLTO overlay and fix appropriately
- Formulate a policy on USE=lto
- Likely will mean "workarounds are needed in build system" and not "upstream support LTO for this package"
- How can we express the latter though? Many of us would be happy using LTO where we know upstream support it
- See https://marc.info/?l=gentoo-project&m=161957141921902&w=2
Signs a package is unsafe
- Any
-Wodr
warnings - Any
-Wlto-type-mismatch
warnings - Any
-Wstrict-aliasing
warnings - Test failures with LTO but passes without
- Failure to build with e.g. multiple LTO partitions
Other distros
- Debian plans to default to LTO either for bookworm or bookworm+1.
- Fedora has defaulted to LTO since Fedora 33 (2021)
- openSUSE defaulted to LTO in 2019