[clang] [llvm] [CoroSplit] Erase trivially dead allocas after spilling (PR #189295)

Sun Mar 29 22:21:41 PDT 2026

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-darwin` running on `doug-worker-3` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/23/builds/18895

<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 'Clang :: CodeGenCXX/ubsan-coroutines.cpp' FAILED ********************
Exit Code: -6

Command Output (stdout):
--
# RUN: at line 3
/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang -cc1 -internal-isystem /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/lib/clang/23/include -nostdsysteminc -emit-obj -std=c++2a -fsanitize=null /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/CodeGenCXX/ubsan-coroutines.cpp -o /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/tools/clang/test/CodeGenCXX/Output/ubsan-coroutines.cpp.tmp.o
# executed command: /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang -cc1 -internal-isystem /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/lib/clang/23/include -nostdsysteminc -emit-obj -std=c++2a -fsanitize=null /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/CodeGenCXX/ubsan-coroutines.cpp -o /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/tools/clang/test/CodeGenCXX/Output/ubsan-coroutines.cpp.tmp.o
# .---command stderr------------
# | Assertion failed: (hasUseList()), function materialized_use_begin, file Value.h, line 358.
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
# | Stack dump:
# | 0.	Program arguments: /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang -cc1 -internal-isystem /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/lib/clang/23/include -nostdsysteminc -emit-obj -std=c++2a -fsanitize=null /Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/CodeGenCXX/ubsan-coroutines.cpp -o /Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/tools/clang/test/CodeGenCXX/Output/ubsan-coroutines.cpp.tmp.o
# | 1.	<eof> parser at end of file
# | 2.	Optimizer
# | 3.	Running pass "coro-cond(coro-early,cgscc(coro-split),coro-cleanup,globaldce)" on module "/Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/CodeGenCXX/ubsan-coroutines.cpp"
# | 4.	Running pass "cgscc(coro-split)" on module "/Volumes/RAMDisk/buildbot-root/x86_64-darwin/llvm-project/clang/test/CodeGenCXX/ubsan-coroutines.cpp"
# | 5.	While splitting coroutine @_ZN9awaitable5awaitEv
# |  #0 0x000000010c2cd148 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x101b5c148)
# |  #1 0x000000010c2ca317 llvm::sys::RunSignalHandlers() (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x101b59317)
# |  #2 0x000000010c2cdd67 SignalHandler(int, __siginfo*, void*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x101b5cd67)
# |  #3 0x000000010c2cdbcd SignalHandlerTerminate(int, __siginfo*, void*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x101b5cbcd)
# |  #4 0x00007ff80af57fdd (/usr/lib/system/libsystem_platform.dylib+0x7ff80046afdd)
# |  #5 0x0000000400000001
# |  #6 0x00007ff80ae4ea69 (/usr/lib/system/libsystem_c.dylib+0x7ff800361a69)
# |  #7 0x00007ff80ae4dd58 (/usr/lib/system/libsystem_c.dylib+0x7ff800360d58)
# |  #8 0x000000011095f313 llvm::coro::BaseABI::buildCoroutineFrame(bool) (.cold.29) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1061ee313)
# |  #9 0x000000010db3a809 llvm::coro::BaseABI::buildCoroutineFrame(bool) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1033c9809)
# | #10 0x000000010db4aa90 doSplitCoroutine(llvm::Function&, llvm::SmallVectorImpl<llvm::Function*>&, llvm::coro::BaseABI&, llvm::TargetTransformInfo&, bool) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1033d9a90)
# | #11 0x000000010db49661 llvm::CoroSplitPass::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1033d8661)
# | #12 0x000000010d610592 llvm::detail::PassModel<llvm::LazyCallGraph::SCC, llvm::CoroSplitPass, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x102e9f592)
# | #13 0x000000010ac78163 llvm::PassManager<llvm::LazyCallGraph::SCC, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x100507163)
# | #14 0x000000010b9d53f2 llvm::detail::PassModel<llvm::LazyCallGraph::SCC, llvm::PassManager<llvm::LazyCallGraph::SCC, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&>::run(llvm::LazyCallGraph::SCC&, llvm::AnalysisManager<llvm::LazyCallGraph::SCC, llvm::LazyCallGraph&>&, llvm::LazyCallGraph&, llvm::CGSCCUpdateResult&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1012643f2)
# | #15 0x000000010ac79888 llvm::ModuleToPostOrderCGSCCPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x100508888)
# | #16 0x000000010a7cbb52 llvm::detail::PassModel<llvm::Module, llvm::ModuleToPostOrderCGSCCPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x10005ab52)
# | #17 0x000000010b7f42c8 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1010832c8)
# | #18 0x000000010db2bc54 llvm::CoroConditionalWrapper::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1033bac54)
# | #19 0x000000010d603cd2 llvm::detail::PassModel<llvm::Module, llvm::CoroConditionalWrapper, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x102e92cd2)
# | #20 0x000000010b7f42c8 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1010832c8)
# | #21 0x000000010c8e366f (anonymous namespace)::EmitAssemblyHelper::RunOptimizationPipeline(clang::BackendAction, std::__1::unique_ptr<llvm::raw_pwrite_stream, std::__1::default_delete<llvm::raw_pwrite_stream>>&, std::__1::unique_ptr<llvm::ToolOutputFile, std::__1::default_delete<llvm::ToolOutputFile>>&, clang::BackendConsumer*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x10217266f)
# | #22 0x000000010c8d97c1 clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::__1::unique_ptr<llvm::raw_pwrite_stream, std::__1::default_delete<llvm::raw_pwrite_stream>>, clang::BackendConsumer*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1021687c1)
# | #23 0x000000010cc8cec6 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x10251bec6)
# | #24 0x000000010e0f95b9 clang::ParseAST(clang::Sema&, bool, bool) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1039885b9)
# | #25 0x000000010d1f660a clang::FrontendAction::Execute() (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x102a8560a)
# | #26 0x000000010d16256d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1029f156d)
# | #27 0x000000010d2b260b clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x102b4160b)
# | #28 0x000000010a7780ae cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1000070ae)
# | #29 0x000000010a7752b1 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1000042b1)
# | #30 0x000000010a7743d9 clang_main(int, char**, llvm::ToolContext const&) (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x1000033d9)
# | #31 0x000000010a783016 main (/Volumes/RAMDisk/buildbot-root/x86_64-darwin/build/bin/clang-23+0x100012016)
...

```

</details>

https://github.com/llvm/llvm-project/pull/189295