llvm/test/Assembler/drop-debug-info.ll
Adrian Prantl 4eeaa0da04 [PR27284] Reverse the ownership between DICompileUnit and DISubprogram.
Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.

Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.

Motivation
----------

Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.

We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.

Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.

http://reviews.llvm.org/D19034
<rdar://problem/25256815>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266446 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-15 15:57:41 +00:00

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LLVM

; RUN: llvm-as < %s -o %t.bc 2>&1 >/dev/null | FileCheck -check-prefix=WARN %s
; RUN: llvm-dis < %t.bc | FileCheck %s
; RUN: verify-uselistorder < %t.bc
define i32 @main() !dbg !4 {
entry:
%retval = alloca i32, align 4
store i32 0, i32* %retval
ret i32 0, !dbg !12
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!9}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.5 (trunk 195495) (llvm/trunk 195495:195504M)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "../llvm/tools/clang/test/CodeGen/debug-info-version.c", directory: "/Users/manmanren/llvm_gmail/release")
!2 = !{i32 0}
!4 = distinct !DISubprogram(name: "main", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !6, variables: !2)
!5 = !DIFile(filename: "../llvm/tools/clang/test/CodeGen/debug-info-version.c", directory: "/Users/manmanren/llvm_gmail/release")
!6 = !DISubroutineType(types: !7)
!7 = !{!8}
!8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!9 = !{i32 2, !"Dwarf Version", i32 2}
!12 = !DILocation(line: 4, scope: !4)
; WARN: warning: ignoring debug info with an invalid version (0)
; CHECK-NOT: !dbg
; CHECK-NOT: !llvm.dbg.cu