[dwarfdump] Fix off-by-one bug in accelerator table extractor.

This fixes a bug where the verifier was complaining about empty
accelerator tables. When the table is empty, its size is not a valid
offset as it points after the end of the section.

This patch also makes the extractor return llvm:Error instead of bool
for better error reporting in the verifier.

Differential revision: https://reviews.llvm.org/D41063

rdar://35932007

llvm-svn: 320399

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 414959c7a5c..a5defa90eb3 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -672,7 +672,8 @@ getAccelTable(std::unique_ptr<DWARFAcceleratorTable> &Cache,
   DWARFDataExtractor AccelSection(Obj, Section, IsLittleEndian, 0);
   DataExtractor StrData(StringSection, IsLittleEndian, 0);
   Cache.reset(new DWARFAcceleratorTable(AccelSection, StrData));
-  Cache->extract();
+  if (Error E = Cache->extract())
+    llvm::consumeError(std::move(E));
   return *Cache;
 }