[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>

llvm-svn: 266446

1 files changed, 4 insertions, 5 deletions

diff --git a/llvm/test/DebugInfo/Generic/2010-05-03-OriginDIE.ll b/llvm/test/DebugInfo/Generic/2010-05-03-OriginDIE.ll
index 5561b7e1994..fb6e082e768 100644
--- a/llvm/test/DebugInfo/Generic/2010-05-03-OriginDIE.ll
+++ b/llvm/test/DebugInfo/Generic/2010-05-03-OriginDIE.ll
@@ -52,21 +52,21 @@ declare void @uuid_LtoB(i8*, i8*)
 !llvm.module.flags = !{!41}
 !0 = !DILocation(line: 808, scope: !1)
 !1 = distinct !DILexicalBlock(line: 807, column: 0, file: !39, scope: !2)
-!2 = distinct !DISubprogram(name: "gpt2gpm", linkageName: "gpt2gpm", line: 807, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, file: !39, scope: null, type: !5)
+!2 = distinct !DISubprogram(name: "gpt2gpm", linkageName: "gpt2gpm", line: 807, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !4, file: !39, scope: null, type: !5)
 !3 = !DIFile(filename: "G.c", directory: "/tmp")
-!4 = distinct !DICompileUnit(language: DW_LANG_C89, producer: "llvm-gcc", isOptimized: true, emissionKind: FullDebug, file: !39, enums: !18, retainedTypes: !18, subprograms: !40)
+!4 = distinct !DICompileUnit(language: DW_LANG_C89, producer: "llvm-gcc", isOptimized: true, emissionKind: FullDebug, file: !39, enums: !18, retainedTypes: !18)
 !5 = !DISubroutineType(types: !6)
 !6 = !{null}
 !7 = !DILocation(line: 810, scope: !1)
 !8 = !DILocalVariable(name: "data", line: 201, arg: 1, scope: !9, file: !10, type: !11)
-!9 = distinct !DISubprogram(name: "_OSSwapInt64", linkageName: "_OSSwapInt64", line: 202, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, file: !10, scope: null, type: !5)
+!9 = distinct !DISubprogram(name: "_OSSwapInt64", linkageName: "_OSSwapInt64", line: 202, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !4, file: !10, scope: null, type: !5)
 !10 = !DIFile(filename: "OSByteOrder.h", directory: "/usr/include/libkern/ppc")
 !11 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint64_t", line: 59, file: !36, scope: !3, baseType: !13)
 !12 = !DIFile(filename: "stdint.h", directory: "/usr/4.2.1/include")
 !13 = !DIBasicType(tag: DW_TAG_base_type, name: "long long unsigned int", size: 64, align: 64, encoding: DW_ATE_unsigned)
 !14 = !DILocation(line: 202, scope: !9, inlinedAt: !7)
 !15 = !DILocalVariable(name: "base", line: 92, arg: 2, scope: !16, file: !10, type: !17)
-!16 = distinct !DISubprogram(name: "OSReadSwapInt64", linkageName: "OSReadSwapInt64", line: 95, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, file: !38, scope: null, type: !5)
+!16 = distinct !DISubprogram(name: "OSReadSwapInt64", linkageName: "OSReadSwapInt64", line: 95, isLocal: true, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !4, file: !38, scope: null, type: !5)
 !17 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 32, align: 32, file: !39, scope: !3, baseType: null)
 !18 = !{}
 !19 = !DILocalVariable(name: "byteOffset", line: 94, arg: 3, scope: !16, file: !10, type: !20)
@@ -90,5 +90,4 @@ declare void @uuid_LtoB(i8*, i8*)
 !37 = !DIFile(filename: "types.h", directory: "/usr/include/ppc")
 !38 = !DIFile(filename: "OSByteOrder.h", directory: "/usr/include/libkern/ppc")
 !39 = !DIFile(filename: "G.c", directory: "/tmp")
-!40 = !{!2, !9, !16}
 !41 = !{i32 1, !"Debug Info Version", i32 3}