Reland D64327 [MC][ELF] Allow STT_SECTION referencing SHF_MERGE on REL targets

This drops a GNU gold workaround and reverts the revert commit rL366708.

  Before binutils 2.34, gold -O2 and above did not correctly handle R_386_GOTOFF to
  SHF_MERGE|SHF_STRINGS sections: https://sourceware.org/bugzilla/show_bug.cgi?id=16794

From the original review:

  ... it reduced the size of a big ARM-32 debug image by 33%. It contained ~68M
  of relocations symbols out of total ~71M symbols (96% of symbols table was
  generated for relocations with symbol).

-Wl,-O2 (and -Wl,-O3) is so rare that we should just lower the
optimization level for LLVM_LINKER_IS_GOLD rather than pessimizing all users.

1 files changed, 0 insertions, 5 deletions

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index 1ca9d0f..5a5692c 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -1389,11 +1389,6 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
     if (Flags & ELF::SHF_MERGE) {
       if (C != 0)
         return true;
-
-      // It looks like gold has a bug (http://sourceware.org/PR16794) and can
-      // only handle section relocations to mergeable sections if using RELA.
-      if (!hasRelocationAddend())
-        return true;
     }
 
     // Most TLS relocations use a got, so they need the symbol. Even those that