sink DebugCompressionType into MC for exposing to clang

This is a preparatory change to expose the debug compression style to
clang.  It requires exposing the enumeration and passing the actual
value through to the backend from the frontend in actual value form
rather than a boolean that selects the GNU style of debug info
compression.

Minor tweak to the ELF Object Writer to use a variable for re-used
values.  Add an assertion that debug information format is one of the
two currently known types if debug information is being compressed.

llvm-svn: 305038

1 files changed, 10 insertions, 6 deletions

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 9954d6f6bd6..4d139132df4 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -1020,18 +1020,24 @@ void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
   MCSectionELF &Section = static_cast<MCSectionELF &>(Sec);
   StringRef SectionName = Section.getSectionName();
 
+  auto &MC = Asm.getContext();
+  const auto &MAI = MC.getAsmInfo();
+
   // Compressing debug_frame requires handling alignment fragments which is
   // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow
   // for writing to arbitrary buffers) for little benefit.
   bool CompressionEnabled =
-      Asm.getContext().getAsmInfo()->compressDebugSections() !=
-      DebugCompressionType::DCT_None;
+      MAI->compressDebugSections() != DebugCompressionType::None;
   if (!CompressionEnabled || !SectionName.startswith(".debug_") ||
       SectionName == ".debug_frame") {
     Asm.writeSectionData(&Section, Layout);
     return;
   }
 
+  assert((MAI->compressDebugSections() == DebugCompressionType::Z ||
+          MAI->compressDebugSections() == DebugCompressionType::GNU) &&
+         "expected zlib or zlib-gnu style compression");
+
   SmallVector<char, 128> UncompressedData;
   raw_svector_ostream VecOS(UncompressedData);
   raw_pwrite_stream &OldStream = getStream();
@@ -1048,8 +1054,7 @@ void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
     return;
   }
 
-  bool ZlibStyle = Asm.getContext().getAsmInfo()->compressDebugSections() ==
-                   DebugCompressionType::DCT_Zlib;
+  bool ZlibStyle = MAI->compressDebugSections() == DebugCompressionType::Z;
   if (!maybeWriteCompression(UncompressedData.size(), CompressedContents,
                              ZlibStyle, Sec.getAlignment())) {
     getStream() << UncompressedData;
@@ -1061,8 +1066,7 @@ void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
     Section.setFlags(Section.getFlags() | ELF::SHF_COMPRESSED);
   else
     // Add "z" prefix to section name. This is zlib-gnu style.
-    Asm.getContext().renameELFSection(&Section,
-                                      (".z" + SectionName.drop_front(1)).str());
+    MC.renameELFSection(&Section, (".z" + SectionName.drop_front(1)).str());
   getStream() << CompressedContents;
 }