[PECOFF] Fix parallel read bug.

InputElement::parse() may recursively call WinLinkDriver::parse() to handle
.drectve section contents, and if /defaultlib option exists in the section,
the driver will mutate the input graph to add a new input file to the graph.
So the access to input graph needs to be protected with mutext.

llvm-svn: 204285

1 files changed, 7 insertions, 3 deletions

diff --git a/lld/include/lld/Driver/WinLinkInputGraph.h b/lld/include/lld/Driver/WinLinkInputGraph.h
index 9c798007124..4d5e4339037 100644
--- a/lld/include/lld/Driver/WinLinkInputGraph.h
+++ b/lld/include/lld/Driver/WinLinkInputGraph.h
@@ -66,10 +66,14 @@ public:
 
   /// \brief Parse the group members.
   error_code parse(const LinkingContext &ctx, raw_ostream &diagnostics) override {
+    auto *pctx = (PECOFFLinkingContext *)(&ctx);
+    error_code ec = error_code::success();
+    pctx->lock();
     for (auto &elem : _elements)
-      if (error_code ec = elem->parse(ctx, diagnostics))
-        return ec;
-    return error_code::success();
+      if ((ec = elem->parse(ctx, diagnostics)))
+        break;
+    pctx->unlock();
+    return ec;
   }
 };