[ELF] Do not merge sections in case of relocatable object generation

Do not merge sections if generating a relocatable object. It makes
the code simpler because we do not need to update relocations addends
to reflect changes introduced by merging. Instead of that we write
such "merge" sections into separate OutputSections and keep SHF_MERGE
/ SHF_STRINGS flags and sh_entsize value to be able to perform merging
later during a final linking.

Differential Revision: http://reviews.llvm.org/D25066

llvm-svn: 283300

1 files changed, 9 insertions, 0 deletions

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index cd29311ccdc..35626092349 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -177,6 +177,15 @@ bool elf::ObjectFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
   if (Config->Optimize == 0)
     return false;
 
+  // Do not merge sections if generating a relocatable object. It makes
+  // the code simpler because we do not need to update relocation addends
+  // to reflect changes introduced by merging. Instead of that we write
+  // such "merge" sections into separate OutputSections and keep SHF_MERGE
+  // / SHF_STRINGS flags and sh_entsize value to be able to perform merging
+  // later during a final linking.
+  if (Config->Relocatable)
+    return false;
+
   // A mergeable section with size 0 is useless because they don't have
   // any data to merge. A mergeable string section with size 0 can be
   // argued as invalid because it doesn't end with a null character.