From 3c06bcb519683814425b7d23a1604ec806fcc83a Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Thu, 7 Jan 2016 03:14:59 +0000
Subject: [PATCH] [Linker] Also treat a DIImportedEntity scope DISubprogram as
 needed.

Follow-up to r257000: DIImportedEntity can reach a DISubprogram via
its entity, but also via its scope. Handle the latter case as well.

PR26037.

llvm-svn: 257019
---
 lib/Linker/IRMover.cpp |  4 +++-
 test/Linker/pr26037.ll | 36 ++++++++++++++++++++++--------------
 2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/lib/Linker/IRMover.cpp b/lib/Linker/IRMover.cpp
index aadaa73ae3d..16de0ec88f4 100644
--- a/lib/Linker/IRMover.cpp
+++ b/lib/Linker/IRMover.cpp
@@ -1212,7 +1212,7 @@ void IRLinker::findNeededSubprograms(ValueToValueMapTy &ValueMap) {
     auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
     assert(CU && "Expected valid compile unit");
     // Ensure that we don't remove subprograms referenced by DIImportedEntity.
-    // It is not legal to have a DIImportedEntity with a null entity.
+    // It is not legal to have a DIImportedEntity with a null entity or scope.
     // FIXME: The DISubprogram for functions not linked in but kept due to
     // being referenced by a DIImportedEntity should also get their
     // IsDefinition flag is unset.
@@ -1220,6 +1220,8 @@ void IRLinker::findNeededSubprograms(ValueToValueMapTy &ValueMap) {
     for (auto *IE : CU->getImportedEntities()) {
       if (auto *SP = dyn_cast<DISubprogram>(IE->getEntity()))
         ImportedEntitySPs.insert(SP);
+      if (auto *SP = dyn_cast<DISubprogram>(IE->getScope()))
+        ImportedEntitySPs.insert(SP);
     }
     for (auto *Op : CU->getSubprograms()) {
       // Unless we were doing function importing and deferred metadata linking,
diff --git a/test/Linker/pr26037.ll b/test/Linker/pr26037.ll
index dcf47a300a2..aa089a8922c 100644
--- a/test/Linker/pr26037.ll
+++ b/test/Linker/pr26037.ll
@@ -2,29 +2,37 @@
 ; RUN: llvm-as %p/Inputs/pr26037.ll -o %t2.bc
 ; RUN: llvm-link -S -only-needed %t2.bc %t.bc | FileCheck %s
 
-; CHECK: distinct !DISubprogram(name: "a"
-; CHECK: !DIImportedEntity({{.*}}, entity:
+; CHECK: [[A:![0-9]+]] = distinct !DISubprogram(name: "a"
+; CHECK: [[B:![0-9]+]] = distinct !DISubprogram(name: "b"
+; CHECK: !DIImportedEntity({{.*}}, scope: [[B]], entity: [[A]]
 
 define void @_ZN1A1aEv() #0 !dbg !4 {
 entry:
-  ret void, !dbg !13
+  ret void, !dbg !14
+}
+
+define void @_ZN1A1bEv() #0 !dbg !8 {
+entry:
+  ret void, !dbg !15
 }
 
 !llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!10, !11}
-!llvm.ident = !{!12}
+!llvm.module.flags = !{!11, !12}
+!llvm.ident = !{!13}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, imports: !8)
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, imports: !9)
 !1 = !DIFile(filename: "a2.cc", directory: "")
 !2 = !{}
-!3 = !{!4}
-!4 = distinct !DISubprogram(name: "a", linkageName: "_ZN1A1aEv", scope: !5, file: !1, line: 5, type: !6, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!3 = !{!4, !8}
+!4 = distinct !DISubprogram(name: "a", linkageName: "_ZN1A1aEv", scope: !5, file: !1, line: 7, type: !6, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
 !5 = !DINamespace(name: "A", scope: null, file: !1, line: 1)
 !6 = !DISubroutineType(types: !7)
 !7 = !{null}
-!8 = !{!9}
-!9 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0, entity: !4, line: 2)
-!10 = !{i32 2, !"Dwarf Version", i32 4}
-!11 = !{i32 2, !"Debug Info Version", i32 3}
-!12 = !{!"clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)"}
-!13 = !DILocation(line: 6, column: 1, scope: !4)
+!8 = distinct !DISubprogram(name: "b", linkageName: "_ZN1A1bEv", scope: !5, file: !1, line: 8, type: !6, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!9 = !{!10}
+!10 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !8, entity: !4, line: 8)
+!11 = !{i32 2, !"Dwarf Version", i32 4}
+!12 = !{i32 2, !"Debug Info Version", i32 3}
+!13 = !{!"clang version 3.8.0 (trunk 256934) (llvm/trunk 256936)"}
+!14 = !DILocation(line: 7, column: 12, scope: !4)
+!15 = !DILocation(line: 8, column: 24, scope: !8)