Adjust comments regarding non-relocated abbrev offset in debug_info.dwo

I'm not sure the comment in the implementation really adds a lot of
value (it's clear that we emit zero when no symbol is provided, but it
doesn't explain why we would do that). Happy to iterate.

llvm-svn: 205386

2 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 9deb2f50f57..11345eb288a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2709,7 +2709,9 @@ DwarfTypeUnit *DwarfDebug::constructSkeletonTU(DwarfTypeUnit *TU) {
 // compile units that would normally be in debug_info.
 void DwarfDebug::emitDebugInfoDWO() {
   assert(useSplitDwarf() && "No split dwarf debug info?");
-  InfoHolder.emitUnits(this, nullptr);
+  // Don't pass an abbrev symbol, using a constant zero instead so as not to
+  // emit relocations into the dwo file.
+  InfoHolder.emitUnits(this, /* AbbrevSymbol */nullptr);
 }
 
 // Emit the .debug_abbrev.dwo section for separated dwarf. This contains the
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index dc3917b5857..97f251086ae 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -2040,7 +2040,7 @@ void DwarfUnit::emitHeader(const MCSymbol *ASectionSym) const {
   if (ASectionSym)
     Asm->EmitSectionOffset(ASectionSym, ASectionSym);
   else
-    // Use a constant value in the dwo file, to avoid relocations
+    // Use a constant value when no symbol is provided.
     Asm->EmitInt32(0);
   Asm->OutStreamer.AddComment("Address Size (in bytes)");
   Asm->EmitInt8(Asm->getDataLayout().getPointerSize());