[llvm] [DebugInfo] Report errors when DWARFUnitHeader::applyIndexEntry fails (PR #89156)

[Alex Langford via llvm-commits]

https://github.com/bulbazord created https://github.com/llvm/llvm-project/pull/89156

Motivation: LLDB is able to report errors about these scenarios whereas LLVM's DWARF parser only gives a boolean success/fail. I want to migrate LLDB to using LLVM's DWARFUnitHeader class, but I don't want to lose some of the error reporting, so I'm adding it to the LLVM class first.

>From ce40cc22d0ad193849efa6ef919adf04e4d5820e Mon Sep 17 00:00:00 2001
From: Alex Langford <alangford at apple.com>
Date: Wed, 17 Apr 2024 16:26:47 -0700
Subject: [PATCH] [DebugInfo] Report errors when
 DWARFUnitHeader::applyIndexEntry fails

Motivation: LLDB is able to report errors about these scenarios whereas
LLVM's DWARF parser only gives a boolean success/fail. I want to migrate
LLDB to using LLVM's DWARFUnitHeader class, but I don't want to lose
some of the error reporting, so I'm adding it to the LLVM class first.
---
 llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h |  2 +-
 llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp        | 30 ++++++++++++++-----
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
index f20e71781f46be..80c27aea893123 100644
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFUnit.h
@@ -85,7 +85,7 @@ class DWARFUnitHeader {
                 uint64_t *offset_ptr, DWARFSectionKind SectionKind);
   // For units in DWARF Package File, remember the index entry and update
   // the abbreviation offset read by extract().
-  bool applyIndexEntry(const DWARFUnitIndex::Entry *Entry);
+  Error applyIndexEntry(const DWARFUnitIndex::Entry *Entry);
   uint64_t getOffset() const { return Offset; }
   const dwarf::FormParams &getFormParams() const { return FormParams; }
   uint16_t getVersion() const { return FormParams.Version; }
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index 9f455fa7e96a7e..985566ad329f63 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -98,8 +98,12 @@ void DWARFUnitVector::addUnitsImpl(
         if (!IndexEntry)
           IndexEntry = Index.getFromOffset(Header.getOffset());
       }
-      if (IndexEntry && !Header.applyIndexEntry(IndexEntry))
-        return nullptr;
+      if (IndexEntry) {
+        if (Error ApplicationErr = Header.applyIndexEntry(IndexEntry)) {
+          Context.getWarningHandler()(std::move(ApplicationErr));
+          return nullptr;
+        }
+      }
       std::unique_ptr<DWARFUnit> U;
       if (Header.isTypeUnit())
         U = std::make_unique<DWARFTypeUnit>(Context, InfoSection, Header, DA,
@@ -334,21 +338,33 @@ Error DWARFUnitHeader::extract(DWARFContext &Context,
   return Error::success();
 }
 
-bool DWARFUnitHeader::applyIndexEntry(const DWARFUnitIndex::Entry *Entry) {
+Error DWARFUnitHeader::applyIndexEntry(const DWARFUnitIndex::Entry *Entry) {
   assert(Entry);
   assert(!IndexEntry);
   IndexEntry = Entry;
   if (AbbrOffset)
-    return false;
+    return createStringError(errc::invalid_argument,
+                             "DWARF package unit from offset 0x%8.8" PRIx64
+                             " has a non-zero abbreviation offset",
+                             Offset);
+
   auto *UnitContrib = IndexEntry->getContribution();
   if (!UnitContrib ||
       UnitContrib->getLength() != (getLength() + getUnitLengthFieldByteSize()))
-    return false;
+    return createStringError(errc::invalid_argument,
+                             "DWARF package unit at offset 0x%8.8" PRIx64
+                             "has an inconsistent index",
+                             Offset);
+
   auto *AbbrEntry = IndexEntry->getContribution(DW_SECT_ABBREV);
   if (!AbbrEntry)
-    return false;
+    return createStringError(errc::invalid_argument,
+                             "DWARF package unit at offset 0x%8.8 " PRIx64
+                             " mising abbreviation column",
+                             Offset);
+
   AbbrOffset = AbbrEntry->getOffset();
-  return true;
+  return Error::success();
 }
 
 Error DWARFUnit::extractRangeList(uint64_t RangeListOffset,