[PATCH] D27324: IPO: Introduce ThinLTOBitcodeWriter pass.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added a comment.

In https://reviews.llvm.org/D27324#612053, @pcc wrote:

> In https://reviews.llvm.org/D27324#612038, @mehdi_amini wrote:
>
> > Not reading any IR during ThinLTO is important, only if we really can do differently I'd consider it. But I'd look at every options/tradeoff before and make sure the design does not lock us in.
>
>
> I intend the amount of IR we read during ThinLTO to be minimal. Basically just the vtables and a small number of virtual functions (for vcall opt). The fact that we're reading IR seems less important than that we're reading less of it; I don't want to be in a situation where we keep adding things to the summary only to discover that we've just reinvented parts of the IR and we're just reading it via a "summary" code path.


(and incidentally, this is part of why I've been pushing on the typeless pointer work lately; it would allow us to strip a lot of useless data from the IR in these cases)


https://reviews.llvm.org/D27324