Fix crash bug on Windows.

Mutating the DenseMap here seems to cause the Windows executable
to crash. Don't use operator[] to access possibly nonexistent key.

llvm-svn: 218548

1 files changed, 4 insertions, 2 deletions

diff --git a/lld/lib/Core/Resolver.cpp b/lld/lib/Core/Resolver.cpp
index ba1f67cc8e7..eb445ff0365 100644
--- a/lld/lib/Core/Resolver.cpp
+++ b/lld/lib/Core/Resolver.cpp
@@ -305,8 +305,10 @@ void Resolver::markLive(const Atom *atom) {
   if (const DefinedAtom *defAtom = dyn_cast<DefinedAtom>(atom)) {
     for (const Reference *ref : *defAtom)
       markLive(ref->target());
-    for (const Atom *target : _reverseRef[defAtom])
-      markLive(target);
+    auto it = _reverseRef.find(defAtom);
+    if (it != _reverseRef.end())
+      for (const Atom *target : it->second)
+        markLive(target);
   }
 }