LTO: Do summary-based prevailing symbol resolution at --lto-O0.

Prevailing symbol resolution is necessary for correctness. Without
this we can end up dropping a referenced linkonce symbol from the link.

Differential Revision: https://reviews.llvm.org/D33570

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303939 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 13 deletions

diff --git a/lib/LTO/LTO.cpp b/lib/LTO/LTO.cpp
index c69f3855a19..780f3b713ff 100644
--- a/lib/LTO/LTO.cpp
+++ b/lib/LTO/LTO.cpp
@@ -1002,10 +1002,6 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
         ExportedGUIDs.insert(GUID);
     }
 
-    auto isPrevailing = [&](GlobalValue::GUID GUID,
-                            const GlobalValueSummary *S) {
-      return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();
-    };
     auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
       const auto &ExportList = ExportLists.find(ModuleIdentifier);
       return (ExportList != ExportLists.end() &&
@@ -1013,17 +1009,20 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
              ExportedGUIDs.count(GUID);
     };
     thinLTOInternalizeAndPromoteInIndex(ThinLTO.CombinedIndex, isExported);
-
-    auto recordNewLinkage = [&](StringRef ModuleIdentifier,
-                                GlobalValue::GUID GUID,
-                                GlobalValue::LinkageTypes NewLinkage) {
-      ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
-    };
-
-    thinLTOResolveWeakForLinkerInIndex(ThinLTO.CombinedIndex, isPrevailing,
-                                       recordNewLinkage);
   }
 
+  auto isPrevailing = [&](GlobalValue::GUID GUID,
+                          const GlobalValueSummary *S) {
+    return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();
+  };
+  auto recordNewLinkage = [&](StringRef ModuleIdentifier,
+                              GlobalValue::GUID GUID,
+                              GlobalValue::LinkageTypes NewLinkage) {
+    ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
+  };
+  thinLTOResolveWeakForLinkerInIndex(ThinLTO.CombinedIndex, isPrevailing,
+                                     recordNewLinkage);
+
   std::unique_ptr<ThinBackendProc> BackendProc =
       ThinLTO.Backend(Conf, ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
                       AddStream, Cache);