DI: Reverse direction of subprogram -> function edge.
Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.
For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.
This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.
Since this is an IR change, a bitcode upgrade has been provided.
Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.
Differential Revision: http://reviews.llvm.org/D14265
llvm-svn: 252219
diff --git a/llvm/test/DebugInfo/X86/arguments.ll b/llvm/test/DebugInfo/X86/arguments.ll
index 3288fca..8b39027 100644
--- a/llvm/test/DebugInfo/X86/arguments.ll
+++ b/llvm/test/DebugInfo/X86/arguments.ll
@@ -29,7 +29,7 @@
%struct.foo = type { i32 }
; Function Attrs: nounwind uwtable
-define void @_Z4func3fooS_(%struct.foo* %f, %struct.foo* %g) #0 {
+define void @_Z4func3fooS_(%struct.foo* %f, %struct.foo* %g) #0 !dbg !4 {
entry:
call void @llvm.dbg.declare(metadata %struct.foo* %f, metadata !19, metadata !DIExpression()), !dbg !20
call void @llvm.dbg.declare(metadata %struct.foo* %g, metadata !21, metadata !DIExpression()), !dbg !20
@@ -53,7 +53,7 @@
!1 = !DIFile(filename: "scratch.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
!2 = !{}
!3 = !{!4}
-!4 = distinct !DISubprogram(name: "func", linkageName: "_Z4func3fooS_", line: 6, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 6, file: !1, scope: !5, type: !6, function: void (%struct.foo*, %struct.foo*)* @_Z4func3fooS_, variables: !2)
+!4 = distinct !DISubprogram(name: "func", linkageName: "_Z4func3fooS_", line: 6, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 6, file: !1, scope: !5, type: !6, variables: !2)
!5 = !DIFile(filename: "scratch.cpp", directory: "/usr/local/google/home/blaikie/dev/scratch")
!6 = !DISubroutineType(types: !7)
!7 = !{null, !8, !8}