[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
diff --git a/llvm/test/DebugInfo/Generic/accel-table-hash-collisions.ll b/llvm/test/DebugInfo/Generic/accel-table-hash-collisions.ll
index 614c0b9..477d5c8 100644
--- a/llvm/test/DebugInfo/Generic/accel-table-hash-collisions.ll
+++ b/llvm/test/DebugInfo/Generic/accel-table-hash-collisions.ll
@@ -69,7 +69,7 @@
!llvm.module.flags = !{!17, !18, !19}
!llvm.ident = !{!20}
-!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.7.0 (trunk 231548) (llvm/trunk 231547)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, subprograms: !2, globals: !3, imports: !2)
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.7.0 (trunk 231548) (llvm/trunk 231547)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !3, imports: !2)
!1 = !DIFile(filename: "hash-collisions.c", directory: "/tmp")
!2 = !{}
!3 = !{!4, !6, !7, !8, !9, !10, !11, !12, !13, !14, !15, !16}