llvm-project/llvm/test/Linker/2009-09-03-mdnode2.ll
Adrian Prantl 75819aedf6 [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
2016-04-15 15:57:41 +00:00

29 lines
1.1 KiB
LLVM

; This file is used by 2009-09-03-mdnode.ll, so it doesn't actually do anything itself
;
; RUN: true
define i32 @f(...) nounwind {
entry:
%retval = alloca i32 ; <i32*> [#uses=1]
call void @llvm.dbg.func.start(metadata !0)
br label %return
return: ; preds = %entry
%0 = load i32, i32* %retval ; <i32> [#uses=1]
call void @llvm.dbg.stoppoint(i32 3, i32 1, metadata !1)
call void @llvm.dbg.region.end(metadata !0)
ret i32 %0
}
declare void @llvm.dbg.func.start(metadata) nounwind readnone
declare void @llvm.dbg.stoppoint(i32, i32, metadata) nounwind readnone
declare void @llvm.dbg.region.end(metadata) nounwind readnone
!llvm.dbg.cu = !{!1}
!0 = distinct !DISubprogram(name: "f", linkageName: "f", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: false, unit: !1, scope: !1)
!1 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "ellcc 0.1.0", isOptimized: true, emissionKind: FullDebug, file: !2)
!2 = !DIFile(filename: "b.c", directory: "/home/rich/ellcc/test/source")