[llvm][dwarfdump] Show name of referenced DW_TAG_APPLE_property (llvm…

…#165537)

This patch makes `dwarfdump` show the `DW_AT_APPLE_property_name` of a
referenced `DW_TAG_APPLE_property` (similar to how we show the name of a
referenced `DW_AT_type`). Eventually we'll extend this to the DWARFv6
property tags too.

Before:
```
0x00000013:     DW_TAG_APPLE_property
                  DW_AT_APPLE_property_name     ("propertyName")

0x0000001b:     DW_TAG_member
                  DW_AT_name    ("_ivar")
                  DW_AT_APPLE_property  (0x00000013)
```
After:
```
0x00000013:     DW_TAG_APPLE_property
                  DW_AT_APPLE_property_name     ("propertyName")

0x0000001b:     DW_TAG_member
                  DW_AT_name    ("_ivar")
                  DW_AT_APPLE_property  (0x00000013 "propertyName")
```

(cherry picked from commit 1e7c082)

llvm/lib/DebugInfo/DWARF/DWARFDie.cpp

@@ -107,6 +107,25 @@ static DWARFDie resolveReferencedType(DWARFDie D, DWARFFormValue F) {
   return D.getAttributeValueAsReferencedDie(F).resolveTypeUnitReference();
 }
 
+static llvm::Expected<llvm::StringRef>
+getApplePropertyName(const DWARFDie &PropDIE) {
+  if (!PropDIE)
+    return llvm::createStringError("invalid DIE");
+
+  if (PropDIE.getTag() != DW_TAG_APPLE_property)
+    return llvm::createStringError("not referencing a DW_TAG_APPLE_property");
+
+  auto PropNameForm = PropDIE.find(DW_AT_APPLE_property_name);
+  if (!PropNameForm)
+    return "";
+
+  auto NameOrErr = PropNameForm->getAsCString();
+  if (!NameOrErr)
+    return NameOrErr.takeError();
+
+  return *NameOrErr;
+}
+
 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
                           const DWARFAttribute &AttrValue, unsigned Indent,
                           DIDumpOptions DumpOpts) {
@@ -197,6 +216,15 @@ static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
             Die.getAttributeValueAsReferencedDie(FormValue).getName(
                 DINameKind::LinkageName))
       OS << Space << "\"" << Name << '\"';
+  } else if (Attr == DW_AT_APPLE_property) {
+    auto PropDIE = Die.getAttributeValueAsReferencedDie(FormValue);
+    if (auto PropNameOrErr = getApplePropertyName(PropDIE))
+      OS << Space << "\"" << *PropNameOrErr << '\"';
+    else
+      DumpOpts.RecoverableErrorHandler(createStringError(
+          errc::invalid_argument,
+          llvm::formatv("decoding DW_AT_APPLE_property_name: {}",
+                        toString(PropNameOrErr.takeError()))));
   } else if (Attr == DW_AT_type || Attr == DW_AT_containing_type) {
     DWARFDie D = resolveReferencedType(Die, FormValue);
     if (D && !D.isNULL()) {

llvm/test/tools/llvm-dwarfdump/AArch64/DW_AT_APPLE_property.s

@@ -0,0 +1,126 @@
+# Checks that we correctly display the DW_AT_APPLE_property_name of a
+# referenced DW_TAG_APPLE_property.
+#
+# RUN: llvm-mc -triple=aarch64--darwin -filetype=obj -o %t.o < %s
+# RUN: not llvm-dwarfdump %t.o 2> %t.errs.txt | FileCheck %s
+# RUN: FileCheck %s --check-prefix=ERRORS < %t.errs.txt 
+
+# CHECK: 0x[[PROP_REF:[0-9a-f]+]]: DW_TAG_APPLE_property
+# CHECK-NEXT: DW_AT_APPLE_property_name ("autoSynthProp")
+#
+# CHECK: 0x[[NO_NAME_PROP:[0-9a-f]+]]: DW_TAG_APPLE_property
+# CHECK-NOT: DW_AT_APPLE_property_name
+#
+# CHECK: 0x[[INVALID_STRP:[0-9a-f]+]]: DW_TAG_APPLE_property
+# CHECK-NEXT: DW_AT_APPLE_property_name
+#
+# CHECK: DW_TAG_member
+# CHECK:   DW_AT_APPLE_property  (0x[[PROP_REF]] "autoSynthProp")
+# CHECK:   DW_AT_APPLE_property  (0x[[NO_NAME_PROP]] "")
+# CHECK:   DW_AT_APPLE_property  (0x{{.*}})
+# CHECK:   DW_AT_APPLE_property  (0x{{.*}})
+# CHECK:   DW_AT_APPLE_property  (0x[[INVALID_STRP]])
+
+# ERRORS: error: decoding DW_AT_APPLE_property_name: not referencing a DW_TAG_APPLE_property
+# ERRORS: error: decoding DW_AT_APPLE_property_name: invalid DIE
+# ERRORS: error: decoding DW_AT_APPLE_property_name: DW_FORM_strp offset 102 is beyond .debug_str bounds
+
+	.section	__DWARF,__debug_abbrev,regular,debug
+Lsection_abbrev:
+	.byte	1                               ; Abbreviation Code
+	.byte	17                              ; DW_TAG_compile_unit
+	.byte	1                               ; DW_CHILDREN_yes
+	.byte	114                             ; DW_AT_str_offsets_base
+	.byte	23                              ; DW_FORM_sec_offset
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	2                               ; Abbreviation Code
+	.byte	19                              ; DW_TAG_structure_type
+	.byte	1                               ; DW_CHILDREN_yes
+	.byte	3                               ; DW_AT_name
+	.byte	37                              ; DW_FORM_strx1
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	3                               ; Abbreviation Code
+	.ascii	"\200\204\001"                  ; DW_TAG_APPLE_property
+	.byte	0                               ; DW_CHILDREN_no
+	.ascii	"\350\177"                      ; DW_AT_APPLE_property_name
+	.byte	37                              ; DW_FORM_strx1
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	4                               ; Abbreviation Code
+	.ascii	"\200\204\001"                  ; DW_TAG_APPLE_property
+	.byte	0                               ; DW_CHILDREN_no
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	5                               ; Abbreviation Code
+	.ascii	"\200\204\001"                  ; DW_TAG_APPLE_property
+	.byte	0                               ; DW_CHILDREN_no
+	.ascii	"\350\177"                      ; DW_AT_APPLE_property_name
+	.byte	14                              ; DW_FORM_strp
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	6                               ; Abbreviation Code
+	.byte	13                              ; DW_TAG_member
+	.byte	0                               ; DW_CHILDREN_no
+	.byte	3                               ; DW_AT_name
+	.byte	37                              ; DW_FORM_strx1
+	.ascii	"\355\177"                      ; DW_AT_APPLE_property
+	.byte	19                              ; DW_FORM_ref4
+	.ascii	"\355\177"                      ; DW_AT_APPLE_property
+	.byte	19                              ; DW_FORM_ref4
+	.ascii	"\355\177"                      ; DW_AT_APPLE_property
+	.byte	19                              ; DW_FORM_ref4
+	.ascii	"\355\177"                      ; DW_AT_APPLE_property
+	.byte	19                              ; DW_FORM_ref4
+	.ascii	"\355\177"                      ; DW_AT_APPLE_property
+	.byte	19                              ; DW_FORM_ref4
+	.byte	0                               ; EOM(1)
+	.byte	0                               ; EOM(2)
+	.byte	0                               ; EOM(3)
+	.section	__DWARF,__debug_info,regular,debug
+Lsection_info:
+Lcu_begin0:
+Lset0 = Ldebug_info_end0-Ldebug_info_start0 ; Length of Unit
+	.long	Lset0
+Ldebug_info_start0:
+	.short	5                               ; DWARF version number
+	.byte	1                               ; DWARF Unit Type
+	.byte	8                               ; Address Size (in bytes)
+Lset1 = Lsection_abbrev-Lsection_abbrev ; Offset Into Abbrev. Section
+	.long	Lset1
+	.byte	1                               ; Abbrev [1] DW_TAG_compile_unit
+Lset2 = Lstr_offsets_base0-Lsection_str_off ; DW_AT_str_offsets_base
+	.long	Lset2
+	.byte	2                               ; Abbrev [2] DW_TAG_structure_type
+	.byte	2                               ; DW_AT_name
+	.byte	3                               ; Abbrev [3] DW_TAG_APPLE_property
+	.byte	0                               ; DW_AT_APPLE_property_name
+	.byte	4                               ; Abbrev [4] DW_TAG_APPLE_property
+	.byte	5                               ; Abbrev [5] DW_TAG_APPLE_property
+	.long	102                             ; DW_AT_APPLE_property_name
+	.byte	6                               ; Abbrev [6] DW_TAG_member
+	.byte	1                               ; DW_AT_name
+	.long	19                              ; DW_AT_APPLE_property
+	.long	21                              ; DW_AT_APPLE_property
+	.long	17                              ; DW_AT_APPLE_property
+	.long	0                               ; DW_AT_APPLE_property
+	.long	22                              ; DW_AT_APPLE_property
+	.byte	0                               ; End Of Children Mark
+	.byte	0                               ; End Of Children Mark
+Ldebug_info_end0:
+	.section	__DWARF,__debug_str_offs,regular,debug
+Lsection_str_off:
+	.long	16                              ; Length of String Offsets Set
+	.short	5
+	.short	0
+Lstr_offsets_base0:
+	.section	__DWARF,__debug_str,regular,debug
+Linfo_string:
+	.asciz	"autoSynthProp"                 ; string offset=0
+	.asciz	"_var"                          ; string offset=14
+	.asciz	"Foo"                           ; string offset=19
+	.section	__DWARF,__debug_str_offs,regular,debug
+	.long	0
+	.long	14
+	.long	19