mehdi_amini added a comment. In https://reviews.llvm.org/D28404#640170, @probinson wrote:
> In https://reviews.llvm.org/D28404#640090, @mehdi_amini wrote: > > > In https://reviews.llvm.org/D28404#640046, @probinson wrote: > > > > > "I don't care" doesn't seem like much of a principle. > > > > > > Long version is: "There is no use-case, no users, so I don't have much > > motivation to push it forward for the only sake of completeness". Does it > > sound enough of a principle like that? > > > No. You still need to have adequate justification for your use case, which I > think you do not. I don't follow your logic. IIUC, you asked about "why not supporting `O1/O2/O3`" ; how is *not supporting* these because their not useful / don't have use-case related to "supporting `O0` is useful"? > > >>> Optnone does not equal -O0. It is a debugging aid for the programmer, >>> because debugging optimized code sucks. If you have an LTO-built >>> application and want to de-optimize parts of it to aid with debugging, then >>> you can use the pragma, as originally intended. >> >> Having to modifying the source isn't friendly. Not being able to honor -O0 >> during LTO is not user-friendly. > > IMO, '-O0' and '-flto' are conflicting options and therefore not deserving of > special support. You're advocating for *rejecting* O0 built module at link-time? We'd still need to detect this though. Status-quo isn't acceptable. Also, that's not practicable: what if I have an LTO static library for which I don't have the source, now if I build my own file with -O0 -flto I can't link anymore. > In my experience, modifying source is by far simpler than hacking a build > system to make a special case for compiler options for one module in an > application. (If you have a way to build Clang with everything done LTO > except one module built with -O0, on Linux with ninja, I would be very > curious to hear how you do that.) Static library, separated projects, etc. We have tons of users... >>> I don't think `-c -O0` should get this not-entirely-O0-like behavior. >> >> What is "not-entirely"? And why do you think that? > > "Not entirely" means that running the -O0 pipeline, and running an > optimization pipeline but asking some subset of passes to turn themselves > off, does not get you the same result. And I think that because I'm the one > who put 'optnone' upstream in the first place. The case that particularly > sticks in my memory is the register allocator, but I believe there are passes > at every stage that do not turn themselves off for optnone. That's orthogonal: you're saying we are not handling it correctly yet, I'm just moving toward *fixing* all these. https://reviews.llvm.org/D28404 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
