ArchSemArm: machine-checked LSE fence-redundancy over UMArm.ob - #212
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sebpop wants to merge 1 commit into
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ArchSemArm: machine-checked LSE fence-redundancy over UMArm.ob#212sebpop wants to merge 1 commit into
sebpop wants to merge 1 commit into
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With the acq-rel AMO full-barrier clause present, prove against UMArm.ob:
- LSE (e.g. SWPAL): the leading and trailing DMB fences OCaml emits around an
atomic RMW add no ob edge the AMO does not already add (redundant);
- LL/SC (ldaxr/stlxr): the store-exclusive release is lxsx, not amo, so the
clause does not fire and the trailing fence is load-bearing.
Print Assumptions reports only stdpp functional_extensionality (no Admitted, no
added axiom). Motivation: the OCaml runtime (ocaml/ocaml#14936) drops these
redundant fences around LSE atomics on AArch64.
Collaborator
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I think this will require rebasing onto main because of the GitHub CI fixes. |
Collaborator
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@sebpop, Sorry for the delay I was on leave. This proof is really nice, although there are some things that should be cleaned-up before merging, I think. In particular, using “clause 135” to designate a line in a herd file is really confusing and really not robust if herd model is updated (even by adding irrelevant stuff). Before looking at it further, I'd really like to talk be email or if possible over a call. I couldn't find your email. Can you email me at |
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With the acq-rel AMO full-barrier clause present, prove against UMArm.ob:
Print Assumptions reports only stdpp functional_extensionality (no Admitted, no added axiom). Motivation: the OCaml runtime (ocaml/ocaml#14936) drops these redundant fences around LSE atomics on AArch64.