Bug 921245 – media-video/rav1e-0.6.6 fails to compile on sparc: Assertion `DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"' failed.

• Status: CONFIRMED
• Product: Gentoo Linux

[Description matoro 2024-01-03 03:39:53 UTC]

With 1.71.1 this gets stuck on posix_spawn issues.  When bumping to 1.73.0 it reproducibly fails with the following LLVM assertion:

rustc: /var/tmp/portage/dev-lang/rust-1.73.0/work/rustc-1.73.0-src/src/llvm-project/llvm/lib/Analysis/ScalarEvolution.cpp:740: std::optional<int> CompareSCEVComplexity(llvm::EquivalenceClasses<const llvm::SCEV*>&, llvm::EquivalenceClasses<const llvm::Value*>&, const llvm::LoopInfo*, const llvm::SCEV*, const llvm::SCEV*, llvm::DominatorTree&, unsigned int): Assertion `DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"' failed.


Log taken with -j1 to make clear the exact failing command line.  I tried following some of the steps in https://rustc-dev-guide.rust-lang.org/backend/debugging.html but have not been able to get an LLVM bytecode dump that demonstrates the issue.

Reproducible: Always

[Comment 1 matoro 2024-01-03 03:41:34 UTC]

Created attachment 881350 [details]
build.log and emerge --info

[Comment 2 Sam James 2024-01-03 06:17:22 UTC]

CCing LLVM, Rust maintainers, because it's an assertion in there.