Simplify compression API by decompressing into a SmallVector rather than a MemoryBuffer

This avoids an extra copy during decompression and avoids the use of
MemoryBuffer which is a weirdly esoteric device that includes unrelated
concepts like "file name" (its rather generic name is a bit misleading).

Similar refactoring of zlib::compress coming up.

llvm-svn: 205676

2 files changed, 7 insertions, 6 deletions

diff --git a/llvm/lib/DebugInfo/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARFContext.cpp
index 60c5f6ab56d..a287cf9edb2 100644
--- a/llvm/lib/DebugInfo/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARFContext.cpp
@@ -637,14 +637,15 @@ DWARFContextInMemory::DWARFContextInMemory(object::ObjectFile *Obj)
       if (!zlib::isAvailable() ||
           !consumeCompressedDebugSectionHeader(data, OriginalSize))
         continue;
-      std::unique_ptr<MemoryBuffer> UncompressedSection;
-      if (zlib::uncompress(data, UncompressedSection, OriginalSize) !=
-          zlib::StatusOK)
+      UncompressedSections.resize(UncompressedSections.size() + 1);
+      if (zlib::uncompress(data, UncompressedSections.back(), OriginalSize) !=
+          zlib::StatusOK) {
+        UncompressedSections.pop_back();
         continue;
+      }
       // Make data point to uncompressed section contents and save its contents.
       name = name.substr(1);
-      data = UncompressedSection->getBuffer();
-      UncompressedSections.push_back(std::move(UncompressedSection));
+      data = UncompressedSections.back();
     }
 
     StringRef *SectionData =
diff --git a/llvm/lib/DebugInfo/DWARFContext.h b/llvm/lib/DebugInfo/DWARFContext.h
index ad6841ae9e3..6d1ae921cec 100644
--- a/llvm/lib/DebugInfo/DWARFContext.h
+++ b/llvm/lib/DebugInfo/DWARFContext.h
@@ -242,7 +242,7 @@ class DWARFContextInMemory : public DWARFContext {
   StringRef RangeDWOSection;
   StringRef AddrSection;
 
-  SmallVector<std::unique_ptr<MemoryBuffer>, 4> UncompressedSections;
+  SmallVector<SmallString<32>, 4> UncompressedSections;
 
 public:
   DWARFContextInMemory(object::ObjectFile *);