[llvm] [llvm][DebugInfo][ObjC] Make sure we link backing ivars to their DW_TAG_APPLE_property (PR #165409)

[Michael Buch via llvm-commits]

https://github.com/Michael137 updated https://github.com/llvm/llvm-project/pull/165409

>From 93fa594efb77397891f9c02d22b716ac152550c8 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Tue, 28 Oct 2025 14:27:46 +0000
Subject: [PATCH] [llvm][DebugInfo][ObjC] Make sure we link backing ivars to
 their DW_TAG_APPLE_property

Depends on:
* https://github.com/llvm/llvm-project/pull/165373

When an Objective-C property has a backing ivar, we would previously not add a `DW_AT_APPLE_property` to the ivar's `DW_TAG_member`. This is what was intended based on the [Objective-C DebugInfo docs](https://github.com/llvm/llvm-project/blob/main/llvm/docs/SourceLevelDebugging.rst#proposal) but is not what LLVM currently generates.

LLDB currently doesn't ever try linking the `ObjCPropertyDecl`s to their `ObjCIvarDecl`s, but if we wanted to, this debug-info patch is a pre-requisite.
---
 llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp    |  2 +-
 llvm/test/DebugInfo/Generic/objc-property.ll | 26 ++++++++++++--------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index e40fb768027b8..7d7588c89fae2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1109,7 +1109,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
           constructMemberDIE(Buffer, DDTy);
         }
       } else if (auto *Property = dyn_cast<DIObjCProperty>(Element)) {
-        DIE &ElemDie = createAndAddDIE(Property->getTag(), Buffer);
+        DIE &ElemDie = createAndAddDIE(Property->getTag(), Buffer, Property);
         StringRef PropertyName = Property->getName();
         addString(ElemDie, dwarf::DW_AT_APPLE_property_name, PropertyName);
         if (Property->getType())
diff --git a/llvm/test/DebugInfo/Generic/objc-property.ll b/llvm/test/DebugInfo/Generic/objc-property.ll
index 6dd0e01017780..d624f69d97b04 100644
--- a/llvm/test/DebugInfo/Generic/objc-property.ll
+++ b/llvm/test/DebugInfo/Generic/objc-property.ll
@@ -3,20 +3,20 @@
 ; CHECK: DW_TAG_structure_type
 ; CHECK:   DW_AT_name ("Foo")
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[AUTO_SYNTH:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("autoSynthProp")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[SYNTH:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("synthProp")
 ; CHECK:     DW_AT_APPLE_property_attribute
 ; CHECK-SAME: DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
 ; FIXME: this should have a DW_AT_APPLE_property_getter tag
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[GET:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customGetterProp")
 ; CHECK:     DW_AT_APPLE_property_setter   ("customGetter")
 ; CHECK:     DW_AT_APPLE_property_attribute
@@ -24,7 +24,7 @@
 ; CHECK-SAME: DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
 ; FIXME: this should have a DW_AT_APPLE_property_setter tag
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[SET:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customSetterProp")
 ; CHECK:     DW_AT_APPLE_property_getter   ("customSetter:")
 ; CHECK:     DW_AT_APPLE_property_attribute
@@ -32,7 +32,7 @@
 ; CHECK-SAME: DW_APPLE_PROPERTY_setter, DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
 ; FIXME: the DW_AT_APPLE_property_(getter|setter) values are inverted
-; CHECK:   DW_TAG_APPLE_property
+; CHECK:   0x[[ACCESSORS:[0-9a-f]+]]: DW_TAG_APPLE_property
 ; CHECK:     DW_AT_APPLE_property_name ("customAccessorsProp")
 ; CHECK:     DW_AT_APPLE_property_getter   ("customSetter:")
 ; CHECK:     DW_AT_APPLE_property_setter   ("customGetter")
@@ -40,15 +40,21 @@
 ; CHECK-SAME: DW_APPLE_PROPERTY_getter, DW_APPLE_PROPERTY_assign, DW_APPLE_PROPERTY_readwrite,
 ; CHECK-SAME: DW_APPLE_PROPERTY_setter, DW_APPLE_PROPERTY_atomic, DW_APPLE_PROPERTY_unsafe_unretained
 ;
-; FIXME: missing link between DW_TAG_member and the associated DW_TAG_APPLE_property
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("someBackingIvar")
+; CHECK:     DW_AT_APPLE_property (0x[[SYNTH]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_autoSynthProp")
+; CHECK:     DW_AT_APPLE_property (0x[[AUTO_SYNTH]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_customGetterProp")
+; CHECK:     DW_AT_APPLE_property (0x[[GET]])
+;
 ; CHECK:   DW_TAG_member
-; CHECK-NOT: DW_AT_APPLE_property
+; CHECK:     DW_AT_name ("_customSetterProp")
+; CHECK:     DW_AT_APPLE_property (0x[[SET]])
 
 !llvm.module.flags = !{!0, !1}
 !llvm.dbg.cu = !{!2}