llc crash generating type die

[demoitem]

llc crashes generating debug code with the context die null.

crashtrace.txt

prog.ll.txt

[llvmbot]

@llvm/issue-subscribers-debuginfo

Author: peter mckinna (demoitem)

llc crashes generating debug code with the context die null.

crashtrace.txt

prog.ll.txt

[OCHyams]

Reduced a bit more to:

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!13, !14}

!0 = distinct !DICompileUnit(language: DW_LANG_Modula3, file: !1, producer: "cm3", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "Main.m3", directory: "/")
!2 = !{!3}
!3 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "End", scope: !4, file: !1, line: 1, size: 8, align: 8, elements: !9)
!4 = distinct !DILexicalBlock(scope: !5, file: !1, line: 32)
!5 = distinct !DISubprogram(name: "Crash", linkageName: "Main__Crash", scope: !1, file: !1, line: 27, type: !6, scopeLine: 27, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !0, retainedNodes: !9)
!6 = !DISubroutineType(types: !7)
!7 = !{null}
!9 = !{}
!13 = !{i32 2, !"Dwarf Version", i32 4}
!14 = !{i32 2, !"Debug Info Version", i32 3}

It looks like it's the fact that the type (!3) is scoped to a block (!4) that is tripping up LLVM - for example if you change the type's scope to !5 it doesn't crash.

FWIW, it looks like both Clang and GCC put block-scoped types in C++ in the function scope in DWARF: https://godbolt.org/z/8vr6jPn5x

With a quick scan I can't see anything in the LangRef that says types shouldn't be scoped to lexical blocks in metadata. It may be a case of unusual/unexpected input that hasn't been tested before, but if it's actually not allowed for some reason, then it should be reported in a friendlier way than a crash, e.g. in the verifier.

[demoitem]

I’m not surprised but some languages let you declare constant, vars and types in a lexical block and I thought dwarf allows this. I could put everything at file scope but could run into name clashes at the very least.

…

On Tue, 7 Oct 2025 at 10:55 pm, Orlando Cazalet-Hyams < ***@***.***> wrote: *OCHyams* left a comment (llvm/llvm-project#151619) <#151619 (comment)> Reduced a bit more to: !llvm.dbg.cu = !{!0}!llvm.module.flags = !{!13, !14} !0 = distinct !DICompileUnit(language: DW_LANG_Modula3, file: !1, producer: "cm3", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)!1 = !DIFile(filename: "Main.m3", directory: "/")!2 = !{!3}!3 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "End", scope: !4, file: !1, line: 1, size: 8, align: 8, elements: !9)!4 = distinct !DILexicalBlock(scope: !5, file: !1, line: 32)!5 = distinct !DISubprogram(name: "Crash", linkageName: "Main__Crash", scope: !1, file: !1, line: 27, type: !6, scopeLine: 27, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !0, retainedNodes: !9)!6 = !DISubroutineType(types: !7)!7 = !{null}!9 = !{}!13 = !{i32 2, !"Dwarf Version", i32 4}!14 = !{i32 2, !"Debug Info Version", i32 3} It looks like it's the fact that the type (!3) is scoped to a block (!4) that is tripping up LLVM - if you change the types scope to !5 it doesn't crash. FWIW, it looks like both Clang and GCC put block-scoped types in C++ in the function scope in DWARF: https://godbolt.org/z/8vr6jPn5x — Reply to this email directly, view it on GitHub <#151619 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABALZX2EPPYWB46XZ32ICU33WOS2NAVCNFSM6AAAAACC3NVD72VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGNZWGU2TCMBWHE> . You are receiving this because you authored the thread.Message ID: ***@***.***>