Relaxed Memory Model Zoo

Operational RC11 (ORC11)
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Operational RC11 ORC11

2019 · Dang, Jourdan, Kaiser, Dreyer · language, formal, operational · operational formalism

An operational version of RC11 (Operational RC11) developed for the RustBelt project. It underpins a program logic that was used to prove the soundness of several synchronisation primitives from the Rust standard library against the relaxed-memory semantics. Being equivalent to RC11, ORC11 is strictly stronger than the C++20 model Rust normatively ships (it forbids the out-of-thin-air, plain load-buffering and broken-release-sequence behaviours C++20 leaves open): it is the verification model RustBelt reasons against, a sound over-approximation of shipped Rust, not a model of its exact semantics.

Properties

Property vector survey-sourced — from Tables 1–2 of the Moiseenko et al. survey, except cells that cite a specific source.

Compilation optimal mapping to
  • yes x86
  • no POWER
  • no Armv7
  • no Armv8
Reordering sound
  • yes Store→Load
  • yes Store→Store
  • yes Load→Load
  • no Load→Store
Elimination sound
  • yes Store/Load
  • yes Store/Store
  • yes Load/Load
  • no Load/Store
Other local transformations
  • no Speculative load intro.
  • yes Roach motel
  • yes Strengthening
  • yes Trace preserving
  • no Common subexpr. elim.
Global transformations
  • yes Register promotion
  • yes Thread inlining
Reasoning guarantees
  • yes External DRF
  • yes Coherence
  • no No undefined behaviour
  • yes In-order execution
  • yes No out-of-thin-air

Ordering relationships

Equivalent to
  • Repaired C11 (RC11) — ORC11 is an operational version of RC11 developed for RustBelt to verify Rust standard-library synchronisation primitives against a program logic.

References

  • Hoang-Hai Dang, Jacques-Henri Jourdan, Jan-Oliver Kaiser, Derek Dreyer. RustBelt Meets Relaxed Memory. POPL 2020 (PACMPL vol. 4), 2019. doi:10.1145/3371102
  • Evgenii Moiseenko, Anton Podkopaev, Dmitrii Koznov. A Survey of Programming Language Memory Models. Programming and Computer Software 47(6), pp. 439–456, 2021. doi:10.1134/S0361768821060050