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llvm-project/llvm/test/DebugInfo/Generic/discriminated-union.ll

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Add DWARF for discriminated unions n Rust, an enum that carries data in the variants is, essentially, a discriminated union. Furthermore, the Rust compiler will perform space optimizations on such enums in some situations. Previously, DWARF for these constructs was emitted using a hack (a magic field name); but this approach stopped working when more space optimizations were added in https://github.com/rust-lang/rust/pull/45225. This patch changes LLVM to allow discriminated unions to be represented in DWARF. It adds createDiscriminatedUnionType and createDiscriminatedMemberType to DIBuilder and then arranges for this to be emitted using DWARF's DW_TAG_variant_part and DW_TAG_variant. Note that DWARF requires that a discriminated union be represented as a structure with a variant part. However, as Rust only needs to emit pure discriminated unions, this is what I chose to expose on DIBuilder. Patch by Tom Tromey! Differential Revision: https://reviews.llvm.org/D42082 llvm-svn: 324426
2018-02-07 07:45:59 +08:00
; REQUIRES: object-emission
; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
; Check for a variant part that has two members, one of which has a
; discriminant value.
; CHECK: DW_TAG_variant_part
; CHECK-NOT: TAG
; CHECK: DW_AT_discr [DW_FORM_ref4] (cu + {{0x[0-9a-fA-F]+}} => {[[OFFSET:0x[0-9a-fA-F]+]]})
; CHECK-NOT: TAG
; CHECK: [[OFFSET]]: DW_TAG_member
; CHECK: DW_AT_type
; CHECK: DW_AT_alignment
; CHECK: DW_AT_data_member_location [DW_FORM_data1] (0x00)
; CHECK: DW_AT_artificial [DW_FORM_flag_present] (true)
; CHECK: DW_TAG_variant
; CHECK: DW_TAG_member
; CHECK: DW_AT_type
; CHECK: DW_AT_alignment
; CHECK: DW_AT_data_member_location [DW_FORM_data1] (0x00)
; CHECK: DW_TAG_variant
; CHECK: DW_AT_discr_value [DW_FORM_data1] (0x00)
; CHECK: DW_TAG_member
; CHECK: DW_AT_type
; CHECK: DW_AT_alignment
; CHECK: DW_AT_data_member_location [DW_FORM_data1] (0x00)
%F = type { [0 x i8], {}*, [8 x i8] }
%"F::Nope" = type {}
define internal void @_ZN2e34main17h934ff72f9a38d4bbE() unnamed_addr #0 !dbg !5 {
start:
%qq = alloca %F, align 8
call void @llvm.dbg.declare(metadata %F* %qq, metadata !10, metadata !28), !dbg !29
%0 = bitcast %F* %qq to {}**, !dbg !29
store {}* null, {}** %0, !dbg !29
%1 = bitcast %F* %qq to %"F::Nope"*, !dbg !29
ret void, !dbg !30
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
attributes #0 = { nounwind uwtable }
!llvm.module.flags = !{!0, !1}
!llvm.dbg.cu = !{!2}
!0 = !{i32 1, !"PIE Level", i32 2}
!1 = !{i32 2, !"Debug Info Version", i32 3}
!2 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !3, producer: "clang LLVM (rustc version 1.24.0-dev)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4)
!3 = !DIFile(filename: "e3.rs", directory: "/home/tromey/Rust")
!4 = !{}
[DebugInfoMetadata] Move main subprogram DIFlag into DISPFlags Moving subprogram specific flags into DISPFlags makes IR code more readable. In addition, we provide free space in DIFlags for other 'non-subprogram-specific' debug info flags. Patch by Djordje Todorovic. Differential Revision: https://reviews.llvm.org/D59288 llvm-svn: 356454
2019-03-19 21:49:03 +08:00
!5 = distinct !DISubprogram(name: "main", linkageName: "_ZN2e34mainE", scope: !6, file: !3, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagMainSubprogram, isOptimized: false, unit: !2, templateParams: !4, retainedNodes: !4)
Add DWARF for discriminated unions n Rust, an enum that carries data in the variants is, essentially, a discriminated union. Furthermore, the Rust compiler will perform space optimizations on such enums in some situations. Previously, DWARF for these constructs was emitted using a hack (a magic field name); but this approach stopped working when more space optimizations were added in https://github.com/rust-lang/rust/pull/45225. This patch changes LLVM to allow discriminated unions to be represented in DWARF. It adds createDiscriminatedUnionType and createDiscriminatedMemberType to DIBuilder and then arranges for this to be emitted using DWARF's DW_TAG_variant_part and DW_TAG_variant. Note that DWARF requires that a discriminated union be represented as a structure with a variant part. However, as Rust only needs to emit pure discriminated unions, this is what I chose to expose on DIBuilder. Patch by Tom Tromey! Differential Revision: https://reviews.llvm.org/D42082 llvm-svn: 324426
2018-02-07 07:45:59 +08:00
!6 = !DINamespace(name: "e3", scope: null)
!7 = !DIFile(filename: "<unknown>", directory: "")
!8 = !DISubroutineType(types: !9)
!9 = !{null}
!10 = !DILocalVariable(name: "qq", scope: !11, file: !3, line: 3, type: !12, align: 8)
!11 = distinct !DILexicalBlock(scope: !5, file: !3, line: 3, column: 4)
!12 = !DICompositeType(tag: DW_TAG_structure_type, name: "F", scope: !6, file: !7, size: 128, align: 64, elements: !13, identifier: "7ce1efff6b82281ab9ceb730566e7e20")
!13 = !{!14}
!14 = !DICompositeType(tag: DW_TAG_variant_part, name: "", scope: !12, file: !7, size: 128, align: 64, elements: !16, identifier: "7ce1efff6b82281ab9ceb730566e7e20", discriminator: !15)
!15 = !DIDerivedType(tag: DW_TAG_member, scope: !14, file: !7, baseType: !27, size: 64, align: 64, flags: DIFlagArtificial)
!16 = !{!17, !24}
!17 = !DIDerivedType(tag: DW_TAG_member, scope: !14, file: !7, baseType: !18, size: 128, align: 64)
!18 = !DICompositeType(tag: DW_TAG_structure_type, name: "Yep", scope: !12, file: !7, size: 128, align: 64, elements: !19, identifier: "7ce1efff6b82281ab9ceb730566e7e20::Yep")
!19 = !{!20, !22}
!20 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !18, file: !7, baseType: !21, size: 8, align: 8, offset: 64)
!21 = !DIBasicType(name: "u8", size: 8, encoding: DW_ATE_unsigned)
!22 = !DIDerivedType(tag: DW_TAG_member, name: "__1", scope: !18, file: !7, baseType: !23, size: 64, align: 64)
!23 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&u8", baseType: !21, size: 64, align: 64)
!24 = !DIDerivedType(tag: DW_TAG_member, scope: !14, file: !7, baseType: !25, size: 128, align: 64, extraData: i64 0)
!25 = !DICompositeType(tag: DW_TAG_structure_type, name: "Nope", scope: !12, file: !7, size: 128, align: 64, elements: !4, identifier: "7ce1efff6b82281ab9ceb730566e7e20::Nope")
!27 = !DIBasicType(name: "u64", size: 64, encoding: DW_ATE_unsigned)
!28 = !DIExpression()
!29 = !DILocation(line: 3, scope: !11)
!30 = !DILocation(line: 4, scope: !5)