[llvm] [Coroutines][LazyCallGraph] addSplitRefRecursiveFunctions allows spurious ref edges between new functions. (PR #116285)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/13821

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM-Unit :: Analysis/./AnalysisTests/79/171' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/b/1/llvm-clang-x86_64-expensive-checks-debian/build/unittests/Analysis/./AnalysisTests-LLVM-Unit-3491294-79-171.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=171 GTEST_SHARD_INDEX=79 /b/1/llvm-clang-x86_64-expensive-checks-debian/build/unittests/Analysis/./AnalysisTests
--

Note: This is test shard 80 of 171.
[==========] Running 4 tests from 4 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CtxProfAnalysisTest
[ RUN      ] CtxProfAnalysisTest.GetCallsiteIDNegativeTest
[       OK ] CtxProfAnalysisTest.GetCallsiteIDNegativeTest (0 ms)
[----------] 1 test from CtxProfAnalysisTest (0 ms total)

[----------] 1 test from LazyCallGraphTest
[ RUN      ] LazyCallGraphTest.AddSplitFunctions6
AnalysisTests: /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/lib/Analysis/LazyCallGraph.cpp:403: void llvm::LazyCallGraph::RefSCC::verify(): Assertion `Visited.contains(NodeToVisit) && "Cannot reach all nodes within RefSCC"' failed.
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  AnalysisTests   0x00000000011dbb47 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 39
1  AnalysisTests   0x00000000011d95cc llvm::sys::RunSignalHandlers() + 188
2  AnalysisTests   0x00000000011dc35a
3  libpthread.so.0 0x00007effb2dc5140
4  libc.so.6       0x00007effb28d9d51 gsignal + 321
5  libc.so.6       0x00007effb28c3537 abort + 291
6  libc.so.6       0x00007effb28c340f
7  libc.so.6       0x00007effb28d26d2
8  AnalysisTests   0x0000000000b677a8 llvm::LazyCallGraph::RefSCC::verify() + 3224
9  AnalysisTests   0x0000000000b76b0a llvm::LazyCallGraph::addSplitRefRecursiveFunctions(llvm::Function&, llvm::ArrayRef<llvm::Function*>) + 2234
10 AnalysisTests   0x000000000094e875
11 AnalysisTests   0x000000000160d74c testing::Test::Run() + 348
12 AnalysisTests   0x000000000160eba9 testing::TestInfo::Run() + 457
13 AnalysisTests   0x000000000160faa6 testing::TestSuite::Run() + 1014
14 AnalysisTests   0x0000000001623fed testing::internal::UnitTestImpl::RunAllTests() + 2909
15 AnalysisTests   0x000000000162334a testing::UnitTest::Run() + 90
16 AnalysisTests   0x00000000015edccc main + 140
17 libc.so.6       0x00007effb28c4d7a __libc_start_main + 234
18 AnalysisTests   0x000000000084b37a _start + 42

--
exit: -6
--
shard JSON output does not exist: /b/1/llvm-clang-x86_64-expensive-checks-debian/build/unittests/Analysis/./AnalysisTests-LLVM-Unit-3491294-79-171.json
********************


```

</details>

https://github.com/llvm/llvm-project/pull/116285