[PATCH] D54755: [DebugInfo] IR/Bitcode changes for DISubprogram flags

[Duncan P. N. Exon Smith via Phabricator via llvm-commits]

dexonsmith added a comment.

In D54755#1313098 <https://reviews.llvm.org/D54755#1313098>, @probinson wrote:

> In D54755#1313064 <https://reviews.llvm.org/D54755#1313064>, @probinson wrote:
>
> > In D54755#1312971 <https://reviews.llvm.org/D54755#1312971>, @aprantl wrote:
> >
> > > While I was updating some internal testcases I wondered: why is DIFlagPrototype not a DISPFlag? Does this flag make sense on something other than functions?
> >
> >
> > Because I was not interested in moving existing flags from the old word to the new word in the first round.  There are others that probably apply only to subprograms:
> >  NoReturn, MainSubprogram; probably Thunk, All CallsDescribed; maybe Trivial, Explicit.
> >  Really we should do some kind of audit, and do a bulk move in one go so we can minimize the bitcode-upgrade pain.
>
>
> One additional problem is that the existing flags are exposed as part of the public API, i.e. to front-ends, so we'll need to work out how to avoid Bad Stuff(tm) if we repurpose any existing flag bits.


Another option here is not to merge them at all in bitcode (I didn't consider this before).  You can add an abbreviation for a fixed-width field of 1 bit each:
https://llvm.org/docs/BitCodeFormat.html#fixed-width-value


Repository:
  rL LLVM

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https://reviews.llvm.org/D54755