Pretty-printing of dicuEmissionKind

[langston-barrett]

The LLVM disassembler will print the numeric field EmissionKind as a string:

• https://github.com/llvm-mirror/llvm/blob/release_40/lib/IR/DebugInfoMetadata.cpp#L413
• https://github.com/llvm-mirror/llvm/blob/release_60/lib/IR/DebugInfoMetadata.cpp#L449

(See also the functions just above those). This prevents the output of llvm-disasm from matching that of llvm-dis, at least on LLVM 6.0.

C++ source

int main()
{
  return 0;
}

llvm-dis output (LLVM 6)

source_filename = "cpp-examples/test.cpp"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define i32 @main() #0 !dbg !8 {
  %1 = alloca i32, align 4
  store i32 0, i32* %1, align 4
  ret i32 0, !dbg !12
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}

!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.1 (tags/RELEASE_601/final)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "cpp-examples/test.cpp", directory: "/home/siddharthist/code/llvm-pretty-bc-parser")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 7, !"PIC Level", i32 2}
!7 = !{!"clang version 6.0.1 (tags/RELEASE_601/final)"}
!8 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !9, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!9 = !DISubroutineType(types: !10)
!10 = !{!11}
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !DILocation(line: 3, column: 3, scope: !8)

llvm-disasm output

target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
define i32 @main() !dbg !8 {
; <label>: 0
  %1 = alloca i32, align 4
  store i32 0, i32* %1, align 4
  ret i32 0, !dbg !DILocation(line: 3, column: 3, scope: !8)
}
!llvm.dbg.cu = !{!0}
!llvm.ident = !{!7}
!llvm.module.flags = !{!3, !4, !5, !6}

!0 = distinct !DICompileUnit(language: 4, file: !1, producer: "clang version 6.0.1 (tags/RELEASE_601/final)", isOptimized: false, flags: "", runtimeVersion: 0, emissionKind: 1, enums: !2, dwoId: 0)
!1 = !DIFile(filename: "cpp-examples/test.cpp", directory: "/home/siddharthist/code/llvm-pretty-bc-parser")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 7, !"PIC Level", i32 2}
!7 = !{!"clang version 6.0.1 (tags/RELEASE_601/final)"}
!8 = distinct !DISubprogram(scope: !DIFile(filename: "cpp-examples/test.cpp", directory: "/home/siddharthist/code/llvm-pretty-bc-parser"), name: "main", file: !DIFile(filename: "cpp-examples/test.cpp", directory: "/home/siddharthist/code/llvm-pretty-bc-parser"), line: 1, type: !11, isLocal: false, isDefinition: true, scopeLine: 2, virtuality: 0, virtualIndex: 0, flags: 256, isOptimized: false, templateParams: !DICompileUnit(language: 4, file: !1, producer: "clang version 6.0.1 (tags/RELEASE_601/final)", isOptimized: false, flags: "", runtimeVersion: 0, emissionKind: 1, enums: !2, dwoId: 0))
!9 = !DIBasicType(tag: 36, name: "int", size: 32, align: 0, encoding: 5)
!10 = !{!9}
!11 = distinct !DISubroutineType(flags: 0, types: !10)