rnk added inline comments.
================ Comment at: clang/lib/CodeGen/CodeGenModule.cpp:4290-4293 - // Do not set COMDAT attribute for CUDA/HIP stub functions to prevent - // them being "merged" by the COMDAT Folding linker optimization. - if (D.hasAttr<CUDAGlobalAttr>()) - return false; ---------------- rnk wrote: > tra wrote: > > This was added in D63277 specifically to deal with comdat-related issue on > > windows. > > > > We do need to have unique addresses for each kernel stub. Placing stubs > > into comdat may allow them to be merged into one and that would be a > > problem. > > https://docs.microsoft.com/en-us/cpp/build/reference/opt-optimizations?view=vs-2019 > > > > > > @rnk,@kpyzhov -- how do we make sure that identical functions are placed in > > comdat (needed for templates) but do not get comdat-folded with `/OPT:ICF`? > > > These are readonly global variables. I believe MSVC's ICF implementation > changed behavior here a few times over the years. I think the current state > is that they don't merge such globals. If you are using LLD, you can use safe > ICF to avoid merging such globals. > > @zequanwu reviewed the state of ICF in LLD in the last year, so he may know > more about the current status, and he may be more helpful if you have more > questions. > > Finally, you could mark these globals as mutable if you really want to block > ICF. That will work reliably with any linker. Broadly, I think this change is correct. If I had reviewed D63277, I probably would have objected to it and not approved it. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D112492/new/ https://reviews.llvm.org/D112492 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
