Crash on IR Generation in LLVM DenseMap, but it happens only in some configurations (Patch included)

[bc-lee]

Description

I'm currently compiling Swift in Fedora, and I encountered a crash during IR generation, but it occurs only in some configurations.

Steps to reproduce

1. Create a docker container with fedora 39 and start it
2. Install dependencies
3. Clone swift release/5.9 branch
4. Build

Detailed build scripts are here

Expected result

Build succeeds, though some tests may fail

Actual result

In some cases, build fails.

Cases that do not crash

• (x86_64) Fedora 39 with Fedora 39's Clang (17.0.6) link
• (x86_64) Fedora 39 with Clang 17.0.6 built from source link
• (aarch64) Fedora 39 with Clang included in Swift 5.8.1 link

Cases that crash

• (aarch64) Fedora 39 with Fedora 39's Clang (17.0.6) link, link2
• (aarch64) Fedora 39 with Clang 17.0.6 built from source link

The crash stack trace is as follows:

swift-frontend: /builddir/build/BUILD/swift-source/llvm-project/llvm/include/llvm/ADT/DenseMap.h:408: void llvm::DenseMapBase<llvm::DenseMap<swift::irgen::LinkEntity, llvm::Function *>, swift::irgen::LinkEntity, llvm::Function *, llvm::DenseMapInfo<swift::irgen::LinkEntity>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function *>>::moveFromOldBuckets(BucketT *, BucketT *) [DerivedT = llvm::DenseMap<swift::irgen::LinkEntity, llvm::Function *>, KeyT = swift::irgen::LinkEntity, ValueT = llvm::Function *, KeyInfoT = llvm::DenseMapInfo<swift::irgen::LinkEntity>, BucketT = llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function *>]: Assertion `!FoundVal && "Key already in new map?"' failed.
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.	Program arguments: /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend -frontend -c /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/Contains.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/FirstRange.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/Ranges.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/Replace.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/Split.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/StartsWith.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Algorithms/Trim.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Consumers/CollectionConsumer.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Consumers/FixedPatternConsumer.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Consumers/ManyConsumer.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Consumers/PredicateConsumer.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/FirstMatch.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/MatchReplace.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/MatchResult.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/Matches.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/MatchingCollectionConsumer.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Matching/MatchingCollectionSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/CollectionSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/ConsumerSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/NaivePatternSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/PatternOrEmpty.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/PredicateSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Algorithms/Searchers/ZSearcher.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/ByteCodeGen.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Capture.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Compiler.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/ConsumerInterface.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Backtracking.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Consume.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Engine.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/InstPayload.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Instruction.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/MEBuilder.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/MEBuiltins.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/MECapture.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/MEProgram.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/MEQuantify.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Metrics.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Processor.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Registers.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Structuralize.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Tracing.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Executor.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/MatchingOptions.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/PrintAsPattern.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/ASTConversion.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/AnyRegexOutput.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/Core.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/CustomComponents.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/DSLTree.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/Match.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Regex/Options.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/ASCII.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/CaseConversion.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/CharacterProps.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Comparison.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Decoding.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Encodings.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Formatting.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/NFC.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/NecessaryEvils.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/NumberParsing.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/ScalarProps.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Transcoding.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/UCD.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/Validation.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Unicode/WordBreaking.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/ASTBuilder.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/AsciiBitset.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/Misc.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/Protocols.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/RegexFactory.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/Traced.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/TypeVerification.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/TypedIndex.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Utility/TypedInt.swift /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/_CharacterClassModel.swift -supplementary-output-file-map /tmp/supplementaryOutputs-e5a39b -target aarch64-unknown-linux-gnu -Xllvm -aarch64-use-tbi -disable-objc-interop -sdk / -I /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/./lib/swift/linux -color-diagnostics -warn-implicit-overrides -enable-library-evolution -module-cache-path /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/./module-cache -module-link-name swift_StringProcessing -resource-dir /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/./lib/swift -static -swift-version 5 -tools-directory /builddir/build/BUILD/swift-source/build/buildbot_linux/llvm-linux-aarch64/./bin -O -library-level api -D SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY -D SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED -D SWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING -D SWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING -D SWIFT_ENABLE_EXPERIMENTAL_OBSERVATION -D SWIFT_RUNTIME_OS_VERSIONING -D SWIFT_STDLIB_ENABLE_UNICODE_DATA -D SWIFT_STDLIB_ENABLE_VECTOR_TYPES -D SWIFT_STDLIB_HAS_COMMANDLINE -D SWIFT_STDLIB_HAS_STDIN -D SWIFT_STDLIB_HAS_ENVIRON -D SWIFT_THREADING_LINUX -D SWIFT_ENABLE_REFLECTION -require-explicit-availability=ignore -enforce-exclusivity=unchecked -disable-autolinking-runtime-compatibility-concurrency -disable-objc-interop -public-autolink-library swift_RegexParser -enable-ossa-modules -enable-lexical-lifetimes=false -disable-implicit-concurrency-module-import -disable-implicit-string-processing-module-import -prespecialize-generic-metadata -define-availability "SwiftStdlib 9999:macOS 9999, iOS 9999, watchOS 9999, tvOS 9999" -define-availability "SwiftStdlib 5.0:macOS 10.14.4, iOS 12.2, watchOS 5.2, tvOS 12.2" -define-availability "SwiftStdlib 5.1:macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0" -define-availability "SwiftStdlib 5.2:macOS 10.15.4, iOS 13.4, watchOS 6.2, tvOS 13.4" -define-availability "SwiftStdlib 5.3:macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0" -define-availability "SwiftStdlib 5.4:macOS 11.3, iOS 14.5, watchOS 7.4, tvOS 14.5" -define-availability "SwiftStdlib 5.5:macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0" -define-availability "SwiftStdlib 5.6:macOS 12.3, iOS 15.4, watchOS 8.5, tvOS 15.4" -define-availability "SwiftStdlib 5.7:macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0" -define-availability "SwiftStdlib 5.8:macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4" -define-availability "SwiftStdlib 5.9:macOS 14.0, iOS 17.0, watchOS 10.0, tvOS 17.0" -define-availability "SwiftStdlib 5.10:macOS 9999, iOS 9999, watchOS 9999, tvOS 9999" -target-min-inlining-version min -plugin-path /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/lib/swift/host/plugins -plugin-path /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/local/lib/swift/host/plugins -Xcc -DSWIFT_STDLIB_HAS_ENVIRON -parse-as-library -module-name _StringProcessing -o /builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/stdlib/public/StringProcessing//LINUX/aarch64/_StringProcessing.o -runtime-compatibility-version none -disable-autolinking-runtime-compatibility-dynamic-replacements
1.	Swift version 5.9 (swift-5.9-RELEASE)
2.	Compiling with the current language version
3.	While evaluating request IRGenRequest(IR Generation for module _StringProcessing)
4.	While emitting metadata for 'OpCode' (at /builddir/build/BUILD/swift-source/swift-experimental-string-processing/Sources/_StringProcessing/Engine/Instruction.swift:25:3)
 #0 0x0000000006227760 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x6227760)
 #1 0x00000000062257d8 llvm::sys::RunSignalHandlers() (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x62257d8)
 #2 0x0000000006227b78 SignalHandler(int) Signals.cpp:0:0
 #3 0x0000ffff82aee7fc (linux-vdso.so.1+0x7fc)
 #4 0x0000ffff81e92280 __pthread_kill_implementation (/lib64/libc.so.6+0x92280)
 #5 0x0000ffff81e45800 gsignal (/lib64/libc.so.6+0x45800)
 #6 0x0000ffff81e30288 abort (/lib64/libc.so.6+0x30288)
 #7 0x0000ffff81e3e56c __assert_fail_base (/lib64/libc.so.6+0x3e56c)
 #8 0x0000ffff81e3e5e0 __assert_perror_fail (/lib64/libc.so.6+0x3e5e0)
 #9 0x0000000000a52368 llvm::DenseMapBase<llvm::DenseMap<swift::irgen::LinkEntity, llvm::Function*, llvm::DenseMapInfo<swift::irgen::LinkEntity, void>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>>, swift::irgen::LinkEntity, llvm::Function*, llvm::DenseMapInfo<swift::irgen::LinkEntity, void>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>>::moveFromOldBuckets(llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>*, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>*) DLangDemangle.cpp:0:0
#10 0x0000000000a521f4 llvm::DenseMap<swift::irgen::LinkEntity, llvm::Function*, llvm::DenseMapInfo<swift::irgen::LinkEntity, void>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>>::grow(unsigned int) DLangDemangle.cpp:0:0
#11 0x0000000000a52148 llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>* llvm::DenseMapBase<llvm::DenseMap<swift::irgen::LinkEntity, llvm::Function*, llvm::DenseMapInfo<swift::irgen::LinkEntity, void>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>>, swift::irgen::LinkEntity, llvm::Function*, llvm::DenseMapInfo<swift::irgen::LinkEntity, void>, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>>::InsertIntoBucketImpl<swift::irgen::LinkEntity>(swift::irgen::LinkEntity const&, swift::irgen::LinkEntity const&, llvm::detail::DenseMapPair<swift::irgen::LinkEntity, llvm::Function*>*) DLangDemangle.cpp:0:0
#12 0x0000000000a49a88 swift::irgen::IRGenModule::getAddrOfValueWitness(swift::CanType, swift::irgen::ValueWitness, swift::ForDefinition_t) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0xa49a88)
#13 0x0000000000b3d4d8 addValueWitness(swift::irgen::IRGenModule&, swift::irgen::ConstantStructBuilder&, swift::irgen::ValueWitness, swift::irgen::FixedPacking, swift::CanType, swift::SILType, swift::irgen::TypeInfo const&, llvm::Optional<(anonymous namespace)::BoundGenericTypeCharacteristics>) GenValueWitness.cpp:0:0
#14 0x0000000000b3cc70 addValueWitnessesForAbstractType(swift::irgen::IRGenModule&, swift::irgen::ConstantStructBuilder&, swift::CanType, bool&) GenValueWitness.cpp:0:0
#15 0x0000000000b3c894 swift::irgen::emitValueWitnessTable(swift::irgen::IRGenModule&, swift::CanType, bool, bool) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0xb3c894)
#16 0x0000000000ab9620 swift::irgen::emitEnumMetadata(swift::irgen::IRGenModule&, swift::EnumDecl*) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0xab9620)
#17 0x0000000000a390bc swift::irgen::IRGenerator::emitLazyDefinitions() (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0xa390bc)
#18 0x0000000000908c90 swift::IRGenRequest::evaluate(swift::Evaluator&, swift::IRGenDescriptor) const (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x908c90)
#19 0x000000000095ba7c swift::GeneratedModule swift::SimpleRequest<swift::IRGenRequest, swift::GeneratedModule (swift::IRGenDescriptor), (swift::RequestFlags)9>::callDerived<0ul>(swift::Evaluator&, std::integer_sequence<unsigned long, 0ul>) const DLangDemangle.cpp:0:0
#20 0x0000000000917c6c llvm::Expected<swift::IRGenRequest::OutputType> swift::Evaluator::getResultUncached<swift::IRGenRequest>(swift::IRGenRequest const&) DLangDemangle.cpp:0:0
#21 0x0000000000909bb4 swift::performIRGeneration(swift::ModuleDecl*, swift::IRGenOptions const&, swift::TBDGenOptions const&, std::unique_ptr<swift::SILModule, std::default_delete<swift::SILModule>>, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::ArrayRef<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>, llvm::GlobalVariable**) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x909bb4)
#22 0x00000000005ce0b8 generateIR(swift::IRGenOptions const&, swift::TBDGenOptions const&, std::unique_ptr<swift::SILModule, std::default_delete<swift::SILModule>>, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, llvm::GlobalVariable*&, llvm::ArrayRef<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>) FrontendTool.cpp:0:0
#23 0x00000000005ca3fc performCompileStepsPostSILGen(swift::CompilerInstance&, std::unique_ptr<swift::SILModule, std::default_delete<swift::SILModule>>, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, swift::PrimarySpecificPaths const&, int&, swift::FrontendObserver*) FrontendTool.cpp:0:0
#24 0x00000000005c979c swift::performCompileStepsPostSema(swift::CompilerInstance&, int&, swift::FrontendObserver*) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x5c979c)
#25 0x00000000005db6c4 withSemanticAnalysis(swift::CompilerInstance&, swift::FrontendObserver*, llvm::function_ref<bool (swift::CompilerInstance&)>, bool) FrontendTool.cpp:0:0
#26 0x00000000005cbb8c performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) FrontendTool.cpp:0:0
#27 0x00000000005cad78 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x5cad78)
#28 0x000000000044d6a0 swift::mainEntry(int, char const**) (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x44d6a0)
#29 0x0000ffff81e309dc __libc_start_call_main (/lib64/libc.so.6+0x309dc)
#30 0x0000ffff81e30ab0 __libc_start_main@GLIBC_2.17 (/lib64/libc.so.6+0x30ab0)
#31 0x000000000044c530 _start (/builddir/build/BUILD/swift-source/build/buildbot_linux/swift-linux-aarch64/bin/swift-frontend+0x44c530)

Patch

The crash occurred in LLVM DenseMap, and I found that it was caused by the following code.

swift/lib/IRGen/GenDecl.cpp

Line 5451 in 9d03337

llvm::Function *IRGenModule::getAddrOfValueWitness(CanType abstractType,

/// Returns the address of a value-witness function.
llvm::Function *IRGenModule::getAddrOfValueWitness(CanType abstractType,
                                                   ValueWitness index,
                                                ForDefinition_t forDefinition) {
  LinkEntity entity = LinkEntity::forValueWitness(abstractType, index);

  llvm::Function *&entry = GlobalFuncs[entity];
  if (entry) {
    if (forDefinition) updateLinkageForDefinition(*this, entry, entity);
    return entry;
  }

  auto signature = getValueWitnessSignature(index);
  LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
  entry = createFunction(*this, link, signature);
  return entry;
}

From what I understand, the GlobalFuncs is a DenseMap that maps LinkEntity to llvm::Function*. operator [] finds the value for the key, and if it doesn't exist, it creates a new value and returns it.
It seems that this code is logically correct, but somehow it crashes. I think this is because the entity is not unique, but I'm not sure.

Instead of using operator [], I changed the code to use find and insert as follows.

/// Returns the address of a value-witness function.
llvm::Function *IRGenModule::getAddrOfValueWitness(CanType abstractType,
                                                   ValueWitness index,
                                                ForDefinition_t forDefinition) {
  LinkEntity entity = LinkEntity::forValueWitness(abstractType, index);

  auto found = GlobalFuncs.find(entity);
  llvm::Function *entry = nullptr;
  if (found != GlobalFuncs.end()) {
    entry = found->second;
    if (forDefinition) updateLinkageForDefinition(*this, entry, entity);
    return entry;
  }

  auto signature = getValueWitnessSignature(index);
  LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
  entry = createFunction(*this, link, signature);
  GlobalFuncs.insert({entity, entry});
  return entry;
}

(Full patch is here. It might need adjustments to apply to the main branch.)

With this patch, the crash is resolved, and the build succeeds.

• (aarch64) Fedora 39 with Fedora 39's Clang (17.0.6) link
• (aarch64) Fedora 39 with Clang 17.0.6 built from source link