rnk added a comment.

In D106585#2905663 <https://reviews.llvm.org/D106585#2905663>, @dblaikie wrote:

> In D106585#2902588 <https://reviews.llvm.org/D106585#2902588>, @dblaikie 
> wrote:
>
>> Preserving existing behavior sounds OK - maybe some comment about that it 
>> might be good to remove so the next person who looks at it knows there's 
>> something not-quite-fully-reasoned here (& the comment about GCC's 
>> representation choice still seems off - GCC does use the signedness of the 
>> enumerators, not only the enumeration).
>
> @rnk - any thoughts on the comments? (the existing comment about GCC's 
> emission seems incorrect to me (or subtly correct, but probably easy to 
> misunderstand) - GCC does use different DWARF encodings for negative 
> enumerators, depending on the enumerator) And seems like a comment about how 
> this is maybe confusing/in need of some more touch-up might be handy for the 
> next reader? (specifically that the current DWARF backend ignores the 
> "isUnsigned" flag entirely, and relies on the signedness of the enumerator's 
> underlying type instead - so maybe we could remove the isUnsigned flag?)

I wasn't aware that the backend ignored this info. If that's the case, then I 
think we can carry the signedness over from the enumerator, update the enum2 
IRgen test, and someone can update the DWARF backend later if they want to 
match GCC more closely. I think C and GCC's behavior is driven by a desire to 
make enumerators behave as close as possible to an integer literal macro 
definition, which could explain the per-enumerator signedness, similar to how 
certain ways of spelling a literal affect its type.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106585/new/

https://reviews.llvm.org/D106585

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