ABataev added inline comments.
================ Comment at: llvm/lib/Frontend/OpenMPIRBuilder.cpp:228 + getOrCreateThreadID(getOrCreateIdent(SrcLocStr))}; + bool UseCancelBarrier = !ForceSimpleCall && CancellationBlock; + Value *Result = Builder.CreateCall( ---------------- jdoerfert wrote: > ABataev wrote: > > jdoerfert wrote: > > > ABataev wrote: > > > > jdoerfert wrote: > > > > > ABataev wrote: > > > > > > jdoerfert wrote: > > > > > > > ABataev wrote: > > > > > > > > jdoerfert wrote: > > > > > > > > > ABataev wrote: > > > > > > > > > > Maybe add an assert when the cancellation version is > > > > > > > > > > requested but the cancellation block is not set? Instead of > > > > > > > > > > the generating simple version of barrier. > > > > > > > > > The interface doesn't work that way as we do not know here if > > > > > > > > > the cancellation was requested except if the block was set. > > > > > > > > > That is basically the flag (and I expect it to continue to be > > > > > > > > > that way). > > > > > > > > Maybe instead of `ForceSimpleBarrier` add a flag > > > > > > > > `EmitCancelBarrier` and if it set to true, always emit cancel > > > > > > > > barrier, otherwise always emit simple barrier? And add an > > > > > > > > assertion for non-set cancellation block or even accept it as a > > > > > > > > parameter here. > > > > > > > > > > > > > > > > Also, what if we have inner exception handling in the region? > > > > > > > > Will you handle the cleanup correctly in case of the > > > > > > > > cancelation barrier? > > > > > > > > Maybe instead of ForceSimpleBarrier add a flag > > > > > > > > EmitCancelBarrier and if it set to true, always emit cancel > > > > > > > > barrier, otherwise always emit simple barrier? And add an > > > > > > > > assertion for non-set cancellation block or even accept it as a > > > > > > > > parameter here. > > > > > > > > > > > > > > What is the difference in moving some of the boolean logic to the > > > > > > > caller? Also, we have test to verify we get cancellation barriers > > > > > > > if we need them, both unit tests and clang lit tests. > > > > > > > > > > > > > > > > > > > > > > Also, what if we have inner exception handling in the region? > > > > > > > > Will you handle the cleanup correctly in case of the > > > > > > > > cancelation barrier? > > > > > > > > > > > > > > I think so. Right now through the code in clang that does the set > > > > > > > up of the cancellation block, later through callbacks but we only > > > > > > > need that for regions where we actually go out of some scope, > > > > > > > e.g., parallel. > > > > > > 1. I'm just thinking about future users of thus interface. It woild > > > > > > be good if we could provide safe interface for all the users, not > > > > > > only clang. > > > > > > 2. Exit out of the OpenMP region is not allowed. But you may have > > > > > > inner try...catch or just simple compound statement with local vars > > > > > > that require constructors/destructors. And the cancellation barrier > > > > > > may exit out of these regions. And you need to call all required > > > > > > destructors. You'd better to think about it now, not later. > > > > > > 2. [...] You'd better to think about it now, not later. > > > > > > > > > > First, I do think about it now and I hope this was not an insinuation > > > > > to suggest otherwise. > > > > > > > > > > > 1. I'm just thinking about future users of thus interface. It woild > > > > > > be good if we could provide safe interface for all the users, not > > > > > > only clang. > > > > > > 2. Exit out of the OpenMP region is not allowed. But you may have > > > > > > inner try...catch or just simple compound statement with local vars > > > > > > that require constructors/destructors. And the cancellation barrier > > > > > > may exit out of these regions. And you need to call all required > > > > > > destructors. > > > > > > > > > > Generally speaking, we shall not add features that we cannot use or > > > > > test with the assumption we will use them in the future. This is > > > > > suggested by the LLVM best practices. If you have specific changes in > > > > > mind that are testable and better than what I suggested so far, > > > > > please bring them forward. You can also bring forward suggestions on > > > > > how it might look in the future but without a real use case now it is > > > > > not practical to block a review based on that, given that we can > > > > > change the interface once the time has come. > > > > > > > > > > I said before, we will need callbacks for destructors, actual > > > > > handling of cancellation blocks, and there are various other features > > > > > missing right now. Nevertheless, we cannot build them into the > > > > > current interface, or even try to prepare for all of them, while > > > > > keeping the patches small and concise. > > > > It won't work for clang, I'm afraid. You need a list of desructors > > > > here. But clang uses recursive codegen and it is very hard to walk over > > > > the call tree and gather all required destructors into a list. At > > > > least, it will require significant rework in clang frontend. > > > > Instead of generating the branch to cancellation block in the builder, > > > > I would suggest to call a single callback function provided by the > > > > frontend, which will generate correct branch over a chain of the > > > > destructor blocks. In this case, you won't need this cancellation block > > > > at all. This is what I meant when said that you need to think about > > > > this problem right now. That current solution is not very suitable for > > > > the use in the frontend. > > > > It won't work for clang, > > > > > > It won't work in the future or it does not work now? If the latter, do > > > you have a mwe to show the problem? > > 1. Both. > > 2. What is mwe? Sure, will simple test tomorrow. > both what? > A simple test is what I wanted, thx. Both - it won't work now and in tbe future it is going to be very hard to adapt clang to this interface. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D69785/new/ https://reviews.llvm.org/D69785 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
