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/Transforms/LoopVectorize/conditional-assignment.ll b/llvm/test/Transforms/LoopVectorize/conditional-assignment.ll
index 454966e9613..8d820e277b2 100644
--- a/llvm/test/Transforms/LoopVectorize/conditional-assignment.ll
+++ b/llvm/test/Transforms/LoopVectorize/conditional-assignment.ll
@@ -6,7 +6,7 @@ target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.9.0"
 
 ; Function Attrs: nounwind ssp uwtable
-define void @conditional_store(i32* noalias nocapture %indices) #0 {
+define void @conditional_store(i32* noalias nocapture %indices) #0 !dbg !4 {
 entry:
   br label %for.body, !dbg !10
 
@@ -40,7 +40,7 @@ attributes #0 = { nounwind }
 !1 = !DIFile(filename: "source.c", directory: ".")
 !2 = !{}
 !3 = !{!4}
-!4 = distinct !DISubprogram(name: "conditional_store", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 1, file: !1, scope: !5, type: !6, function: void (i32*)* @conditional_store, variables: !2)
+!4 = distinct !DISubprogram(name: "conditional_store", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 1, file: !1, scope: !5, type: !6, variables: !2)
 !5 = !DIFile(filename: "source.c", directory: ".")
 !6 = !DISubroutineType(types: !2)
 !7 = !{i32 2, !"Dwarf Version", i32 2}