[PATCH] D86310: [X86] Align i128 to 16 bytes in x86-64 datalayout

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

I'm not personally involved with any workflows that care about autoupgrade, so I'm not really invested in ensuring it's stable.  If everyone agrees the impact is small enough that we're willing to just break autoupgrade to the extent it's relevant, I'll withdraw my objection.

> As for the longer term solution to this problem, instead of permitting mixed data layouts of data layout customization, IMO LLVM structs should explicitly encode field offsets. LLVM would still have APIs to assist frontends with producing semi-C-compatible struct layouts, in so much as we do today.

I agree with the general sentiment that we want less dependence on alignment specified in the datalayout.  Not sure about the exact design of that for structs... if IR moves in the direction people are proposing, the notion of a "struct" with a memory layout will likely go away altogether.  (If we remove struct types form global variables and GEPs, there's very little left that actually cares about the layout of structs in memory.)


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  https://reviews.llvm.org/D86310/new/

https://reviews.llvm.org/D86310