From d6b67eb15c3640c38d2e12f83373def07ca6fae9 Mon Sep 17 00:00:00 2001
From: Greg Clayton <gclayton@apple.com>
Date: Mon, 27 Nov 2017 22:12:44 +0000
Subject: [PATCH] Fixed the ability to recursively get an attribute value from
 a DWARFDie.

The previous implementation would only look 1 DW_AT_specification or DW_AT_abstract_origin deep. This means DWARFDie::getName() would fail in certain cases. I ran into such a case while creating a tool that used the LLVM DWARF parser to generate a symbolication format so I have seen this in the wild.

Differential Revision: https://reviews.llvm.org/D40156

llvm-svn: 319104
---
 llvm/lib/DebugInfo/DWARF/DWARFDie.cpp                 | 19 +++++++++----------
 llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp |  9 +++++++--
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index 6dd5ecb..c4bb225 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -306,17 +306,16 @@ Optional<DWARFFormValue>
 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
   if (!isValid())
     return None;
-  auto Die = *this;
-  if (auto Value = Die.find(Attrs))
-    return Value;
-  if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
-    Die = D;
-  if (auto Value = Die.find(Attrs))
-    return Value;
-  if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
-    Die = D;
-  if (auto Value = Die.find(Attrs))
+  if (auto Value = find(Attrs))
     return Value;
+  if (auto Die = getAttributeValueAsReferencedDie(DW_AT_abstract_origin)) {
+    if (auto Value = Die.findRecursively(Attrs))
+      return Value;
+  }
+  if (auto Die = getAttributeValueAsReferencedDie(DW_AT_specification)) {
+    if (auto Value = Die.findRecursively(Attrs))
+      return Value;
+  }
   return None;
 }
 
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
index 4786cc2..cdccd9f 100644
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp
@@ -1287,12 +1287,16 @@ TEST(DWARFDebugInfo, TestFindRecurse) {
     auto CUDie = CU.getUnitDIE();
     auto FuncSpecDie = CUDie.addChild(DW_TAG_subprogram);
     auto FuncAbsDie = CUDie.addChild(DW_TAG_subprogram);
+    // Put the linkage name in a second abstract origin DIE to ensure we
+    // recurse through more than just one DIE when looking for attributes.
+    auto FuncAbsDie2 = CUDie.addChild(DW_TAG_subprogram);
     auto FuncDie = CUDie.addChild(DW_TAG_subprogram);
     auto VarAbsDie = CUDie.addChild(DW_TAG_variable);
     auto VarDie = CUDie.addChild(DW_TAG_variable);
     FuncSpecDie.addAttribute(DW_AT_name, DW_FORM_strp, SpecDieName);
-    FuncAbsDie.addAttribute(DW_AT_linkage_name, DW_FORM_strp, SpecLinkageName);
+    FuncAbsDie2.addAttribute(DW_AT_linkage_name, DW_FORM_strp, SpecLinkageName);
     FuncAbsDie.addAttribute(DW_AT_specification, DW_FORM_ref4, FuncSpecDie);
+    FuncAbsDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4, FuncAbsDie2);
     FuncDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4, FuncAbsDie);
     VarAbsDie.addAttribute(DW_AT_name, DW_FORM_strp, AbsDieName);
     VarDie.addAttribute(DW_AT_abstract_origin, DW_FORM_ref4, VarAbsDie);
@@ -1314,7 +1318,8 @@ TEST(DWARFDebugInfo, TestFindRecurse) {
 
   auto FuncSpecDie = CUDie.getFirstChild();
   auto FuncAbsDie = FuncSpecDie.getSibling();
-  auto FuncDie = FuncAbsDie.getSibling();
+  auto FuncAbsDie2 = FuncAbsDie.getSibling();
+  auto FuncDie = FuncAbsDie2.getSibling();
   auto VarAbsDie = FuncDie.getSibling();
   auto VarDie = VarAbsDie.getSibling();
 
-- 
2.7.4