Linux dropped `linux/scc.h` from Linux 7.1, which breaks building
compiler-rt when sanitizers enabled. Upstream fixed this for LLVM 23.
This PR cherry-picks the fix for the other LLVM packages in Nixpkgs.
see f8a025c964.
this commit backports that same change to LLVM 22. the fix is not
available upstream since LLVM 22 is EOL, but we can pick the patch
from the Rust fork of LLVM, as that is currently on version 22.1.
Several LLVM versions have a bug in SelectionDAG that causes
miscompilations around conditional poisions. This was exposed due to
Rust 1.97.0 exercising the involved code path heavily and generating
segfaulting code, but the bug existed beforehand as well. The patch was
made to LLVM 23, but the tests have many conflicts, so this is a manual
backport. This backport was made by:
- applying the code change to `llvm/lib`
- hand-updating `test/CodeGen/Mips/cmov.ll` with the same diff as the PR
- updating the rest with `utils/update_llc_test_checks.py` from the LLVM
source tree, and verifying the diff against the one in the PR.
The last step made this a rather large and gnarly patch, but it's mostly
mechanical.
Rust issue: https://github.com/rust-lang/rust/issues/159035
LLVM issue: https://github.com/llvm/llvm-project/issues/208611
LLVM PR: https://github.com/llvm/llvm-project/pull/208683
Scope:
- Combination of
- Textual matches of "baseNameOf (toString"
- Redundant toString calls I've found with my latest
"lazy paths" nix branch as they force lazy fetches into
the store. More info and new PR soon.
- Only cases I believe are worthwhile or easily determined
I've determined the validity by
- testing llvmPackages instantiation
- figuring out which types can pass into any particular
toString call - "human fuzzy type checker"
Behavior considerations by type:
- `path`: converted back to a string *without* context
`baseNameOf` does not copy things to the store on its own,
equivalent to its behavior for string inputs
- `null`: converted to `""` -> may be valid input!
ok if "" would not have been acceptable anyway
- `string` itself: passed through identically -> trivial
- `attrset` with `outPath`: same coercion as built into
the `baseNameOf` function -> trivial
- other atomic types: generally not sensible inputs to
`baseNameOf` -> fuzzy but true
