iains added a comment. In D137059#3898239 <https://reviews.llvm.org/D137059#3898239>, @ChuanqiXu wrote:
> In D137059#3896661 <https://reviews.llvm.org/D137059#3896661>, @dblaikie > wrote: > >> Could you link to the email/discourse discussion about supporting this mode >> (I think you've linked it in other discussions, be good to have it for >> reference here & Probably in the other review)? (I'm wondering if we need a >> new flag for this, or if it'll be OK to change the driver behavior to always >> coalesce the .cppm->.pcm->.o path into a single step, for instance - I >> realize this is a somewhat breaking change but may be acceptable given that >> modules aren't widely deployed yet) > > Done. From my reading, in that discourse discussing, we're not talking about > to add the new flags. I add the flag since I don't want the `.pcm` file > pollutes the user space accidentally. > >> if it'll be OK to change the driver behavior to always coalesce the >> .cppm->.pcm->.o path into a single step > > I am not sure what you mean. Do you talk about to forbidden the original > 2-phase compilation model? If so, I think it is definitely the wrong > direction. The 2-phase compilation model should be the correct direction in > the long term since it has higher parallelism. I am not convinced about this second point as motivation for this direction; it comes with some significant resource tradeoffs (compared with the proposed [near] future version of producing the PCM and the object from one invocation of the FE): - it requires multiple instantiations of the FE - it blocks the objective of reducing the content of module interfaces (so that they only contain the information that pertains to the interface) - since requiring source -> pcm, pcm -> object means that the PCM has to contain all the information necessary to generate the object. - in terms of parallelism, the interface PCM has to be generated and distributed - the parsing and serialisation has to be complete before the PCM can be distributed; that process is the same regardless of whether the FE invocation also produces an object. So, I would suggest that we would move to a single invocation of the compiler to produce the PCM and object as the default; if the user has a specific reason to want to do the two jobs separately then thay could still do so ( -fmodule-only / --precompile ) at the expense of two invocations as now, Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D137059/new/ https://reviews.llvm.org/D137059 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
