jhuber6 added a comment. In D129694#3708214 <https://reviews.llvm.org/D129694#3708214>, @ssquare08 wrote:
> If that's the preference I can make changes as suggested. You mentioned CUDA > and HIP mangle the declaration directly. To me it looks like they mangle it > on host and device separately. Is that not correct? If so, can you point me > to the source you are referring to? You're right, they mangle them separately like in https://godbolt.org/z/r6hG4brqx, this is most likely because they already had separate "device side" names. For OpenMP we currently just use the same name for the variable on the host and device side like in https://godbolt.org/z/eaGo9qsW3 where we just use the same kernel names. Thinking again, I'm still wondering if there's any utility in keeping the names separate. Correct me if I'm wrong, but the host-side variable should be able to remain internal so this mangled device name shouldn't show up in the final executable. In that case the only benefit is slightly nicer IR, which I'm not super concerned with. ================ Comment at: clang/lib/CodeGen/TargetInfo.cpp:9439 const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M) const { + // Make sure any variable with OpenMP declare target is visible to runtime + // except for those with hidden visibility ---------------- ssquare08 wrote: > jhuber6 wrote: > > jhuber6 wrote: > > > ssquare08 wrote: > > > > jhuber6 wrote: > > > > > Just spitballing, is it possible to do this when we make the global > > > > > instead? > > > > This is something I was wondering as well. In > > > > CodeGenModule::GetOrCreateLLVMGlobal, when it creates a new global > > > > variable, it always uses the llvm::GlobalValue::ExternalLinkage. Seems > > > > like this changes somewhere later to internal for static globals. Do > > > > you know where that would be? > > > I'm not exactly sure, I remember deleting some code in D117806 that did > > > something like that, albeit incorrectly. But I'm not sure if you'd have > > > the necessary information to check whether or not there are updates > > > attached to it. We don't want to externalize things if we don't need to, > > > otherwise we'd get a lot of our device runtime variables with external > > > visibility that now can't be optimized out. > > Were you able to find a place for this when we generate the variable? You > > should be able to do something similar to the patch above if it's a declare > > target static to force it to have external visibility, but as mentioned > > before I would prefer we only do this if necessary which might take some > > extra analysis. > If you are asking about the GV, it is created in > 'CodeGenModule::GetOrCreateLLVMGlobal' with external linkage always. > ``` > auto *GV = new llvm::GlobalVariable( > getModule(), Ty, false, llvm::GlobalValue::ExternalLinkage, nullptr, > MangledName, nullptr, llvm::GlobalVariable::NotThreadLocal, > getContext().getTargetAddressSpace(DAddrSpace)); > ``` > The linkage, however, changes in 'CodeGenModule::EmitGlobalVarDefinition' > based on the information VarDecl > > ``` > llvm::GlobalValue::LinkageTypes Linkage = > getLLVMLinkageVarDefinition(D, GV->isConstant()); > ``` > > Maybe you are suggesting changing the linkage information in 'VarDecl' itself? Yes, the patch I linked previously did something like that where it set the `LinkageValue` based on some information. Although I'm not sure if it would be excessively difficult to try to prune definitions that don't need to be externalized. I haven't looked too deep into this, but I believe CUDA does this inside of `adjustGVALinkageForAttributes`, there we also check some variable called `CUDADeviceVarODRUsedByHost` that I'm assuming tracks if we need to bother externalizing this. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D129694/new/ https://reviews.llvm.org/D129694 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
