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AVX stream intrinsics signatures are incorrect, maybe unsound #575
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[-]_mm256_stream_si256 signature incorrect, maybe unsound[/-][+]AVX stream intrinsic signatures are incorrect, maybe unsound[/+]on Oct 3, 2018 - changed the title
[-]AVX stream intrinsic signatures are incorrect, maybe unsound[/-][+]AVX stream intrinsics signatures are incorrect, maybe unsound[/+]on Oct 3, 2018 - added a commit that references this issue
on Oct 3, 2018 Oh dear sounds bad! It may be the case though we can fix this without practical breakage. Want to send a PR and we can crater?
Will do.
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on Oct 5, 2018 - added a commit that references this issue
on Nov 2, 2018 Notice that
*const Tand*mut Tare equivalent in terms of UB, so this is not -- on its own -- unsound.However, it could lead to people using
&Ton the call site, and that would be unsound.Reacted by gnzlbg and Jonas SchievinkYes, we should just have had a single pointer type :/
Reacted by Juhan Oskar Hennoste and Suchir Kavi
In the intel intrinsics guide, the signature is:
but in Rust the signature is:
Note that the
mem_addrpointer isconstin Rust, but not in C. Since the only purpose of this function is to write through this pointer, it is probably unsound for it to take aconstpointer.EDIT:
_mm256_stream_pdand_mm256_stream_psalso have this same issue. The SSE_mm_stream_ps,_mm_stream_pd, and_mm_stream_piintrinsics correctly use*muthere.A tangential bug is that the intrinsic verification failed hard here, since the C intrinsics do not use
constpointers, it would have been safer to require these intrinsics to usemutpointers.