Relevant discussion can be found at: https://lists.llvm.org/pipermail/llvm-dev/2021-January/148197.html
In the existing design, An SCC that contains a coroutine will go through the folloing passes:
Inliner -> CoroSplitPass (fake) -> FunctionSimplificationPipeline -> Inliner -> CoroSplitPass (real) -> FunctionSimplificationPipeline
The first CoroSplitPass doesn't do anything other than putting the SCC back to the queue so that the entire pipeline can repeat.
As you can see, we run Inliner twice on the SCC consecutively without doing any real split, which is unnecessary and likely unintended.
What we really wanted is this:
Inliner -> FunctionSimplificationPipeline -> CoroSplitPass -> FunctionSimplificationPipeline
(note that we don't really need to run Inliner again on the ramp function after split).
Hence the way we do it here is to move CoroSplitPass to the end of the CGSCC pipeline, make it once for real, insert the newly generated SCCs (the clones) back to the pipeline so that they can be optimized, and also add a function simplification pipeline after CoroSplit to optimize the post-split ramp function.
This approach also conforms to how the new pass manager works instead of relying on an adhoc post split cleanup, making it ready for full switch to new pass manager eventually.
By looking at some of the changes to the tests, we can already observe that this changes allows for more optimizations applied to coroutines.
Reviewed By: aeubanks, ChuanqiXu
Differential Revision: https://reviews.llvm.org/D95807
CoroElide pass works only when a post-split coroutine is inlined into another post-split coroutine.
In O0, there is no inlining after CoroSplit, and hence no CoroElide can happen.
It's useless to put CoroElide pass in the O0 pipeline and it will never be triggered (unless I miss anything).
Differential Revision: https://reviews.llvm.org/D105066
Printing pass manager invocations is fairly verbose and not super
useful.
This allows us to remove DebugLogging from pass managers and PassBuilder
since all logging (aside from analysis managers) goes through
instrumentation now.
This has the downside of never being able to print the top level pass
manager via instrumentation, but that seems like a minor downside.
Reviewed By: ychen
Differential Revision: https://reviews.llvm.org/D101797
Summary:
This patch addresses https://bugs.llvm.org/show_bug.cgi?id=46256
The spec of coroutine requires that the expression co_await promise.final_suspend() shall not be potentially-throwing.
To check this, we recursively look at every call (including Call, MemberCall, OperatorCall and Constructor) in all code
generated by the final suspend, and ensure that the callees are declared with noexcept. We also look at any returned data
type that requires explicit destruction, and check their destructors for noexcept.
This patch does not check declarations with dependent types yet, which will be done in future patches.
Updated all tests to add noexcept to the required functions, and added a dedicated test for this patch.
This patch might start to cause existing codebase fail to compile because most people may not have been strict in tagging
all the related functions noexcept.
Reviewers: lewissbaker, modocache, junparser
Reviewed By: modocache
Subscribers: arphaman, junparser, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D82029
Summary:
Depends on https://reviews.llvm.org/D71902.
The last in a series of six patches that ports the LLVM coroutines
passes to the new pass manager infrastructure.
This patch has Clang schedule the new coroutines passes when the
`-fexperimental-new-pass-manager` option is used. With this and the
previous 5 patches, Clang is capable of building and successfully
running the test suite of large coroutines projects such as
https://github.com/lewissbaker/cppcoro with
`ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER=On`.
Reviewers: GorNishanov, lewissbaker, chandlerc, junparser
Subscribers: EricWF, cfe-commits, llvm-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D71903
Xun Li