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, 2 insertions, 2 deletions

diff --git a/llvm/test/CodeGen/ARM/debug-info-blocks.ll b/llvm/test/CodeGen/ARM/debug-info-blocks.ll
index bd5c51e2039..2e68b04dc5c 100644
--- a/llvm/test/CodeGen/ARM/debug-info-blocks.ll
+++ b/llvm/test/CodeGen/ARM/debug-info-blocks.ll
@@ -27,7 +27,7 @@ declare void @llvm.dbg.value(metadata, i64, metadata, metadata) nounwind readnon
 
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
 
-define hidden void @foobar_func_block_invoke_0(i8* %.block_descriptor, %0* %loadedMydata, [4 x i32] %bounds.coerce0, [4 x i32] %data.coerce0) ssp {
+define hidden void @foobar_func_block_invoke_0(i8* %.block_descriptor, %0* %loadedMydata, [4 x i32] %bounds.coerce0, [4 x i32] %data.coerce0) ssp !dbg !23 {
   %1 = alloca %0*, align 4
   %bounds = alloca %struct.CR, align 4
   %data = alloca %struct.CR, align 4
@@ -118,7 +118,7 @@ define hidden void @foobar_func_block_invoke_0(i8* %.block_descriptor, %0* %load
 !20 = !DIFile(filename: "header4.h", directory: "/Volumes/Sandbox/llvm")
 !21 = !{!22}
 !22 = !DIEnumerator(name: "Eleven", value: 0) ; [ DW_TAG_enumerator ]
-!23 = distinct !DISubprogram(name: "foobar_func_block_invoke_0", line: 609, isLocal: true, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 609, file: !152, scope: !24, type: !25, function: void (i8*, %0*, [4 x i32], [4 x i32])* @foobar_func_block_invoke_0)
+!23 = distinct !DISubprogram(name: "foobar_func_block_invoke_0", line: 609, isLocal: true, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, scopeLine: 609, file: !152, scope: !24, type: !25)
 !24 = !DIFile(filename: "MyLibrary.m", directory: "/Volumes/Sandbox/llvm")
 !25 = !DISubroutineType(types: !26)
 !26 = !{null}