[COFF] Add support for the .secidx directive

Reviewed at http://llvm-reviews.chandlerc.com/D2445

llvm-svn: 197826
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
index 6da4142..31dc110 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
@@ -65,6 +65,9 @@
     if (Is64Bit)
       return COFF::IMAGE_REL_AMD64_ADDR64;
     llvm_unreachable("unsupported relocation type");
+  case FK_SecRel_2:
+    return Is64Bit ? COFF::IMAGE_REL_AMD64_SECTION
+                   : COFF::IMAGE_REL_I386_SECTION;
   case FK_SecRel_4:
     return Is64Bit ? COFF::IMAGE_REL_AMD64_SECREL : COFF::IMAGE_REL_I386_SECREL;
   default: