From: Rui Ueyama <ruiu@google.com>
Date: Wed, 31 Jul 2013 17:45:48 +0000 (+0000)
Subject: [PECOFF] Add a comment about .bss section.
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3361fa49f5b110a36cf10be3800e15566c53bf19;p=platform%2Fupstream%2Fllvm.git

[PECOFF] Add a comment about .bss section.

llvm-svn: 187505
---

diff --git a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
index 64a1f6c..d7d8176 100644
--- a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
+++ b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
@@ -579,6 +579,15 @@ private:
 };
 
 // \brief A BSSSectionChunk represents a .bss section.
+//
+// Seems link.exe does not emit .bss section but instead merges it with .data
+// section. In COFF, if the size of the section in the header is greater than
+// the size of the actual data on disk, the section on memory is zero-padded.
+// That's why .bss can be merge with .data just by appending it at the end of
+// the section.
+//
+// The executable with .bss is also valid and easier to understand. So we chose
+// to create .bss in LLD.
 class BssSectionChunk : public SectionChunk {
 public:
   // BSS section does not have contents, so write should be no-op.