[PATCH] D126642: [Clang] NFCI: Repurpose HasExtParameterInfos for HasExtraBitfields

Tue May 31 08:39:49 PDT 2022

erichkeane added a comment.

In D126642#3547496 <https://reviews.llvm.org/D126642#3547496>, @sdesmalen wrote:

> In D126642#3547284 <https://reviews.llvm.org/D126642#3547284>, @erichkeane wrote:
>
>> I'm not sure I'm grokking hte difference between the ExtraBitfields and ExtParamInfos here.
>
> The reason I repurposed the bit was because I previously tried adding a bit to `unsigned ExtInfo : 13;` but that fails
>
>   static_assert(sizeof(*this) <= 8 + sizeof(ExtQualsTypeCommonBase), "changing bitfields changed sizeof(Type)!");

Right, yeah.  One thing to consider: `ExtInfo` was 'first', and so it got to keep the 'in bitfield bits'. However, much of what is in there is, IMO, not something that is used often enough to be worth having in there.  Of the bits being used there, I think 'NoReturn' is the only one used with any regularity (other than perhaps 'this call' in Windows-32-bit machines).  I wonder if we should consider moving as much of that as possible over.

> so perhaps incorrectly I assumed I couldn't add any new bits to FunctionType and thought I'd repurpose this one bit, because it's only ever used for FunctionProtoType (never for FunctionNoProtoType).
>
> But I now realised I can just add an extra bit, so that we can leave this bit as-is. What do you think?

I think there is probably value to that, yes.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126642/new/

https://reviews.llvm.org/D126642