Round table was held on 2023/5/11 at EuroLLVM 2023
- around ±10 persons attending
- getelementptr with a signed vs unsigned index => depends on the how the index is defined in c/c++
-
status of full restrict patches and ptr_provenance patches
- ptr_provenance: ⚙ D111159 [UnknownProvenance] Introduce UnknownProvenance constant
- All 14 patches have been reviewed and accepted - thank you !
- full_restrict: rebase ongoing, a number of known issues still need to be fixed.
- opaque pointers made the rebasing ‘interesting’
- a number of issues found by: experiments with rust (Nikita), flang (Slavia), other external feedback and internal testing.
- Discussion about what the patches are resolving (next to the local restrict support) and if it is the right way
⚙ D143129 [GVN] Restrict equality propagation for pointers - [GVN] Restrict equality propagation for pointers- Can be fixed with the ptr_provenance patches, by separating ptr provenance and ptr value.
- Can also be fixed by not allowing the propagation.
- More info about full restrict, see presentation at US LLVM Dev 2021:
- Given the availability of the patches (since 2018) and that no one came up with an alternative,
the consensus is to continue with the upstreaming. - Current plan to go forward :
- Continue the rebasing (Done: ⚙ D69542 Full Restrict Support - single patch ; ptr_provenance: still to publish)
- Provide fixes for the known issues
- Start providing separate patches again for full restrict, to start the detailed review process
- Once the llvm-17 branch is created, apply the approved ptr_provenance patches (should be around end of July)
- ptr_provenance: ⚙ D111159 [UnknownProvenance] Introduce UnknownProvenance constant
- Other inputs from the past weeks:
- In last LLVM Alias Analysis Technical Call (LLVM AA TechCall) (<2023-05-23 Tue>), but also on discourse, it became again clear that other parties
are also still interested in the patches and are willing to provide help. Thank you !
- In last LLVM Alias Analysis Technical Call (LLVM AA TechCall) (<2023-05-23 Tue>), but also on discourse, it became again clear that other parties
- next LLVM AA Tech Call is on June 6, 2023, 19h00 CET:
Thanks,
Jeroen Dobbelaere