[PATCH] D72932: [ARM] Follow AACPS standard for volatile bit-fields access width

[Diogo N. Sampaio via Phabricator via cfe-commits]

dnsampaio added a comment.

In D72932#1829716 <https://reviews.llvm.org/D72932#1829716>, @ostannard wrote:

> Why are you doing this in CodeGen, rather than adjusting the existing layout code in CGRecordLowering? Doing it this way will result in AdjustAAPCSBitfieldLValue being called for every access to the bitfield, rather than just once. This is probably more fragile too, because it's spreading the logic across multiple parts of the codebase, and has to undo some of the layout done by CGRecordLowering.


@ostannard Indeed, after looking at the `CGRecordLayout` I am not kind for doing this change. It will require changing all possible initializations, with a sensible value. And either way, codegen will also need to change, to define the address, it must know if it is volatile or not. I don't believe that recomputing it a every access would pose much of an overhead, perhaps we can leave it as a TODO to move it there?


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