[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

10 files changed, 22 insertions, 30 deletions

diff --git a/llvm/test/Linker/Inputs/mdlocation.ll b/llvm/test/Linker/Inputs/mdlocation.ll
index 2d166971a70..0f6a162bdba 100644
--- a/llvm/test/Linker/Inputs/mdlocation.ll
+++ b/llvm/test/Linker/Inputs/mdlocation.ll
@@ -4,7 +4,7 @@ define void @foo1() !dbg !0 {
 
 !named = !{!1, !2, !3, !4, !5}
 
-!0 = distinct !DISubprogram(file: !7, scope: !7, line: 1, name: "foo", type: !9)
+!0 = distinct !DISubprogram(file: !7, scope: !7, line: 1, name: "foo", type: !9, unit: !6)
 
 !1 = !DILocation(line: 3, column: 7, scope: !10)
 !2 = !DILocation(line: 3, column: 7, scope: !10, inlinedAt: !1)
@@ -14,7 +14,7 @@ define void @foo1() !dbg !0 {
 !5 = distinct !DILocation(line: 3, column: 7, scope: !10, inlinedAt: !4)
 
 !llvm.dbg.cu = !{!6}
-!6 = distinct !DICompileUnit(language: DW_LANG_C89, file: !7, subprograms: !{!0})
+!6 = distinct !DICompileUnit(language: DW_LANG_C89, file: !7)
 !7 = !DIFile(filename: "source.c", directory: "/dir")
 
 !llvm.module.flags = !{!8}
diff --git a/llvm/test/Linker/Inputs/only-needed-debug-metadata.ll b/llvm/test/Linker/Inputs/only-needed-debug-metadata.ll
index 6ae5b2cac72..a944c8ab932 100644
--- a/llvm/test/Linker/Inputs/only-needed-debug-metadata.ll
+++ b/llvm/test/Linker/Inputs/only-needed-debug-metadata.ll
@@ -12,11 +12,10 @@ define void @bar() !dbg !4 {
 !llvm.module.flags = !{!7, !8}
 !llvm.ident = !{!9}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, subprograms: !3)
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
 !1 = !DIFile(filename: "linkused.b.c", directory: ".")
 !2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 5, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized: true, variables: !2)
+!4 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 5, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized: true, unit: !0, variables: !2)
 !5 = !DISubroutineType(types: !6)
 !6 = !{null}
 !7 = !{i32 2, !"Dwarf Version", i32 4}
diff --git a/llvm/test/Linker/Inputs/pr26037.ll b/llvm/test/Linker/Inputs/pr26037.ll
index c4ecaaab36c..a1a024f1906 100644
--- a/llvm/test/Linker/Inputs/pr26037.ll
+++ b/llvm/test/Linker/Inputs/pr26037.ll
@@ -9,11 +9,10 @@ entry:
 !llvm.module.flags = !{!8, !9}
 !llvm.ident = !{!10}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, subprograms: !3)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
 !1 = !DIFile(filename: "main.cc", directory: "")
 !2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
 !5 = !DISubroutineType(types: !6)
 !6 = !{!7}
 !7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
diff --git a/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll b/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
index e33c7b468c1..7598ab159eb 100644
--- a/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
+++ b/llvm/test/Linker/Inputs/replaced-function-matches-first-subprogram.ll
@@ -12,11 +12,10 @@ entry:
 !llvm.module.flags = !{!8, !9, !10}
 !llvm.ident = !{!11}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)", isOptimized: false, emissionKind: LineTablesOnly, file: !1, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.6.0 (trunk 224193) (llvm/trunk 224197)", isOptimized: false, emissionKind: LineTablesOnly, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
 !1 = !DIFile(filename: "t2.cpp", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2")
 !2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "foo", line: 2, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 2, file: !5, scope: !6, type: !7, variables: !2)
+!4 = distinct !DISubprogram(name: "foo", line: 2, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 2, file: !5, scope: !6, type: !7, variables: !2)
 !5 = !DIFile(filename: "../t.h", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2")
 !6 = !DIFile(filename: "../t.h", directory: "/Users/dexonsmith/data/llvm/staging/test/Linker/repro/d2")
 !7 = !DISubroutineType(types: !2)
diff --git a/llvm/test/Linker/Inputs/subprogram-linkonce-weak.ll b/llvm/test/Linker/Inputs/subprogram-linkonce-weak.ll
index 3fc8b375de6..29d06515e42 100644
--- a/llvm/test/Linker/Inputs/subprogram-linkonce-weak.ll
+++ b/llvm/test/Linker/Inputs/subprogram-linkonce-weak.ll
@@ -10,7 +10,7 @@ declare i32 @fastadd(i32, i32)
 !0 = !{i32 2, !"Debug Info Version", i32 3}
 
 !llvm.dbg.cu = !{!1}
-!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, subprograms: !{!3}, emissionKind: FullDebug)
+!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, emissionKind: FullDebug)
 !2 = !DIFile(filename: "foo.c", directory: "/path/to/dir")
-!3 = distinct !DISubprogram(file: !2, scope: !2, line: 51, name: "foo", type: !4)
+!3 = distinct !DISubprogram(file: !2, scope: !2, line: 51, name: "foo", type: !4, unit: !1)
 !4 = !DISubroutineType(types: !{})
diff --git a/llvm/test/Linker/Inputs/thinlto_funcimport_debug.ll b/llvm/test/Linker/Inputs/thinlto_funcimport_debug.ll
index a06c715f801..cc76d8ae29e 100644
--- a/llvm/test/Linker/Inputs/thinlto_funcimport_debug.ll
+++ b/llvm/test/Linker/Inputs/thinlto_funcimport_debug.ll
@@ -22,11 +22,10 @@ attributes #2 = { nounwind }
 !llvm.module.flags = !{!8, !9}
 !llvm.ident = !{!10}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, subprograms: !3)
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251407) (llvm/trunk 251401)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
 !1 = !DIFile(filename: "dbg_main.c", directory: ".")
 !2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, variables: !2)
+!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0, variables: !2)
 !5 = !DISubroutineType(types: !6)
 !6 = !{!7}
 !7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
diff --git a/llvm/test/Linker/Inputs/type-unique-inheritance-a.ll b/llvm/test/Linker/Inputs/type-unique-inheritance-a.ll
index baacba38a84..14c78097e42 100644
--- a/llvm/test/Linker/Inputs/type-unique-inheritance-a.ll
+++ b/llvm/test/Linker/Inputs/type-unique-inheritance-a.ll
@@ -66,7 +66,7 @@ attributes #1 = { nounwind readnone }
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!19, !25}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git f54e02f969d02d640103db73efc30c45439fceab) (http://llvm.org/git/llvm.git 284353b55896cb1babfaa7add7c0a363245342d2)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, subprograms: !14, globals: !2, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git f54e02f969d02d640103db73efc30c45439fceab) (http://llvm.org/git/llvm.git 284353b55896cb1babfaa7add7c0a363245342d2)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, globals: !2, imports: !2)
 !1 = !DIFile(filename: "foo.cpp", directory: "/Users/mren/c_testing/type_unique_air/inher")
 !2 = !{}
 !3 = !{!4, !8}
@@ -80,8 +80,7 @@ attributes #1 = { nounwind readnone }
 !11 = !DIDerivedType(tag: DW_TAG_member, name: "b", line: 4, size: 32, align: 32, flags: DIFlagPrivate, file: !9, scope: !"_ZTS4Base", baseType: !12)
 !12 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !13 = !DIDerivedType(tag: DW_TAG_member, name: "x", line: 4, size: 32, align: 32, offset: 32, flags: DIFlagPrivate, file: !5, scope: !"_ZTS1A", baseType: !12)
-!14 = !{!15}
-!15 = distinct !DISubprogram(name: "f", linkageName: "_Z1fi", line: 5, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 5, file: !1, scope: !16, type: !17, variables: !2)
+!15 = distinct !DISubprogram(name: "f", linkageName: "_Z1fi", line: 5, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 5, file: !1, scope: !16, type: !17, variables: !2)
 !16 = !DIFile(filename: "foo.cpp", directory: "/Users/mren/c_testing/type_unique_air/inher")
 !17 = !DISubroutineType(types: !18)
 !18 = !{null, !12}
diff --git a/llvm/test/Linker/Inputs/type-unique-inheritance-b.ll b/llvm/test/Linker/Inputs/type-unique-inheritance-b.ll
index fa88fa368bb..e1f5893d35b 100644
--- a/llvm/test/Linker/Inputs/type-unique-inheritance-b.ll
+++ b/llvm/test/Linker/Inputs/type-unique-inheritance-b.ll
@@ -40,7 +40,7 @@ attributes #3 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "n
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!27, !38}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git f54e02f969d02d640103db73efc30c45439fceab) (http://llvm.org/git/llvm.git 284353b55896cb1babfaa7add7c0a363245342d2)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, subprograms: !19, globals: !2, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git f54e02f969d02d640103db73efc30c45439fceab) (http://llvm.org/git/llvm.git 284353b55896cb1babfaa7add7c0a363245342d2)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, globals: !2, imports: !2)
 !1 = !DIFile(filename: "bar.cpp", directory: "/Users/mren/c_testing/type_unique_air/inher")
 !2 = !{}
 !3 = !{!4, !11, !15}
@@ -59,12 +59,11 @@ attributes #3 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "n
 !16 = !{!17}
 !17 = !DIDerivedType(tag: DW_TAG_member, name: "b", line: 4, size: 32, align: 32, flags: DIFlagPrivate, file: !5, scope: !"_ZTS4Base", baseType: !8)
 !18 = !DIDerivedType(tag: DW_TAG_member, name: "x", line: 4, size: 32, align: 32, offset: 32, flags: DIFlagPrivate, file: !12, scope: !"_ZTS1A", baseType: !8)
-!19 = !{!20, !24}
-!20 = distinct !DISubprogram(name: "g", linkageName: "_Z1gi", line: 4, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 4, file: !1, scope: !21, type: !22, variables: !2)
+!20 = distinct !DISubprogram(name: "g", linkageName: "_Z1gi", line: 4, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 4, file: !1, scope: !21, type: !22, variables: !2)
 !21 = !DIFile(filename: "bar.cpp", directory: "/Users/mren/c_testing/type_unique_air/inher")
 !22 = !DISubroutineType(types: !23)
 !23 = !{null, !8}
-!24 = distinct !DISubprogram(name: "main", line: 9, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 9, file: !1, scope: !21, type: !25, variables: !2)
+!24 = distinct !DISubprogram(name: "main", line: 9, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 9, file: !1, scope: !21, type: !25, variables: !2)
 !25 = !DISubroutineType(types: !26)
 !26 = !{!8}
 !27 = !{i32 2, !"Dwarf Version", i32 2}
diff --git a/llvm/test/Linker/Inputs/type-unique-simple2-a.ll b/llvm/test/Linker/Inputs/type-unique-simple2-a.ll
index da8656ee9de..8451a1667eb 100644
--- a/llvm/test/Linker/Inputs/type-unique-simple2-a.ll
+++ b/llvm/test/Linker/Inputs/type-unique-simple2-a.ll
@@ -63,7 +63,7 @@ attributes #1 = { nounwind readnone }
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!16, !22}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git 8a3f9e46cb988d2c664395b21910091e3730ae82) (http://llvm.org/git/llvm.git 4699e9549358bc77824a59114548eecc3f7c523c)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, subprograms: !11, globals: !2, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git 8a3f9e46cb988d2c664395b21910091e3730ae82) (http://llvm.org/git/llvm.git 4699e9549358bc77824a59114548eecc3f7c523c)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, globals: !2, imports: !2)
 !1 = !DIFile(filename: "foo.cpp", directory: ".")
 !2 = !{}
 !3 = !{!4}
@@ -74,8 +74,7 @@ attributes #1 = { nounwind readnone }
 !8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !9 = !DIDerivedType(tag: DW_TAG_member, name: "b", line: 3, size: 64, align: 64, offset: 64, file: !5, scope: !"_ZTS4Base", baseType: !10)
 !10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS4Base")
-!11 = !{!12}
-!12 = distinct !DISubprogram(name: "f", linkageName: "_Z1fi", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 3, file: !1, scope: !13, type: !14, variables: !2)
+!12 = distinct !DISubprogram(name: "f", linkageName: "_Z1fi", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 3, file: !1, scope: !13, type: !14, variables: !2)
 !13 = !DIFile(filename: "foo.cpp", directory: ".")
 !14 = !DISubroutineType(types: !15)
 !15 = !{null, !8}
diff --git a/llvm/test/Linker/Inputs/type-unique-simple2-b.ll b/llvm/test/Linker/Inputs/type-unique-simple2-b.ll
index b1324de7fe2..eefc5de77ed 100644
--- a/llvm/test/Linker/Inputs/type-unique-simple2-b.ll
+++ b/llvm/test/Linker/Inputs/type-unique-simple2-b.ll
@@ -36,7 +36,7 @@ attributes #3 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "n
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!19, !28}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git 8a3f9e46cb988d2c664395b21910091e3730ae82) (http://llvm.org/git/llvm.git 4699e9549358bc77824a59114548eecc3f7c523c)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, subprograms: !11, globals: !2, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.4 (http://llvm.org/git/clang.git 8a3f9e46cb988d2c664395b21910091e3730ae82) (http://llvm.org/git/llvm.git 4699e9549358bc77824a59114548eecc3f7c523c)", isOptimized: false, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !3, globals: !2, imports: !2)
 !1 = !DIFile(filename: "bar.cpp", directory: ".")
 !2 = !{}
 !3 = !{!4}
@@ -47,12 +47,11 @@ attributes #3 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "n
 !8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
 !9 = !DIDerivedType(tag: DW_TAG_member, name: "b", line: 3, size: 64, align: 64, offset: 64, file: !5, scope: !"_ZTS4Base", baseType: !10)
 !10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS4Base")
-!11 = !{!12, !16}
-!12 = distinct !DISubprogram(name: "g", linkageName: "_Z1gi", line: 4, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 4, file: !1, scope: !13, type: !14, variables: !2)
+!12 = distinct !DISubprogram(name: "g", linkageName: "_Z1gi", line: 4, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 4, file: !1, scope: !13, type: !14, variables: !2)
 !13 = !DIFile(filename: "bar.cpp", directory: ".")
 !14 = !DISubroutineType(types: !15)
 !15 = !{null, !8}
-!16 = distinct !DISubprogram(name: "main", line: 7, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 7, file: !1, scope: !13, type: !17, variables: !2)
+!16 = distinct !DISubprogram(name: "main", line: 7, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 7, file: !1, scope: !13, type: !17, variables: !2)
 !17 = !DISubroutineType(types: !18)
 !18 = !{!8}
 !19 = !{i32 2, !"Dwarf Version", i32 2}