MC/Mach-O/x86_64: Add a new hook for checking whether a particular section can
be diced into atoms, and adjust getAtom() to take this into account.
 - This fixes relocations to symbols in fixed size literal sections, for
   example.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103532 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 65e3571..8ec927e 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -297,6 +297,12 @@
   if (!SD->getFragment())
     return 0;
 
+  // Non-linker visible symbols in sections which can't be atomized have no
+  // defining atom.
+  if (!getBackend().isSectionAtomizable(
+        SD->getFragment()->getParent()->getSection()))
+    return 0;
+
   // Otherwise, return the atom for the containing fragment.
   return SD->getFragment()->getAtom();
 }