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

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll b/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
index 721cc3ce0e1..39575311b4b 100644
--- a/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
+++ b/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
@@ -34,7 +34,7 @@ declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #2
 
 ; Function Attrs: nounwind
-define void @_Z3fn4v() #0 {
+define void @_Z3fn4v() #0 !dbg !21 {
 entry:
 ; Test that the dbg.declare is moved together with the alloca.
 ; CHECK: define void @_Z3fn5v()
@@ -61,7 +61,7 @@ _Z3fn31A.exit:                                    ; preds = %entry, %if.then.i
 }
 
 ; Function Attrs: noreturn nounwind
-define void @_Z3fn5v() #3 {
+define void @_Z3fn5v() #3 !dbg !24 {
 entry:
   br label %while.body, !dbg !55
 
@@ -97,16 +97,16 @@ attributes #3 = { noreturn nounwind }
 !12 = !{!13}
 !13 = !DISubrange(count: 2)
 !14 = !{!15, !21, !24}
-!15 = distinct !DISubprogram(name: "fn3", linkageName: "_Z3fn31A", line: 6, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 6, file: !5, scope: !16, type: !17, function: void (%struct.A*)* @_Z3fn31A, variables: !19)
+!15 = distinct !DISubprogram(name: "fn3", linkageName: "_Z3fn31A", line: 6, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 6, file: !5, scope: !16, type: !17, variables: !19)
 !16 = !DIFile(filename: "test.cpp", directory: "")
 !17 = !DISubroutineType(types: !18)
 !18 = !{null, !"_ZTS1A"}
 !19 = !{!20}
 !20 = !DILocalVariable(name: "p1", line: 6, arg: 1, scope: !15, file: !16, type: !"_ZTS1A")
-!21 = distinct !DISubprogram(name: "fn4", linkageName: "_Z3fn4v", line: 11, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 11, file: !5, scope: !16, type: !22, function: void ()* @_Z3fn4v, variables: !2)
+!21 = distinct !DISubprogram(name: "fn4", linkageName: "_Z3fn4v", line: 11, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 11, file: !5, scope: !16, type: !22, variables: !2)
 !22 = !DISubroutineType(types: !23)
 !23 = !{null}
-!24 = distinct !DISubprogram(name: "fn5", linkageName: "_Z3fn5v", line: 13, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 13, file: !5, scope: !16, type: !22, function: void ()* @_Z3fn5v, variables: !2)
+!24 = distinct !DISubprogram(name: "fn5", linkageName: "_Z3fn5v", line: 13, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 13, file: !5, scope: !16, type: !22, variables: !2)
 !25 = !{!26, !27}
 !26 = !DIGlobalVariable(name: "a", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !"_ZTS1A", variable: %struct.A* @a)
 !27 = !DIGlobalVariable(name: "b", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !"_ZTS1A", variable: %struct.A* @b)