[ThinLTO/WPD] Ensure devirtualized targets use promoted symbol when necessary

Summary:
This fixes a hole in the handling of devirtualized targets that were
local but need promoting due to devirtualization in another module. We
were not correctly referencing the promoted symbol in some cases. Make
sure the code that updates the name also looks at the ExportedGUIDs set
by utilizing a callback that checks all conditions (the callback
utilized by the internalization/promotion code).

Reviewers: pcc, davidxl, hiraditya

Subscribers: mehdi_amini, Prazek, inglorion, steven_wu, dexonsmith, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68159

llvm-svn: 373485

1 files changed, 6 insertions, 5 deletions

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index 9e16cba44fd..6c5858b942a 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -1304,11 +1304,6 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
     ComputeCrossModuleImport(ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
                              ImportLists, ExportLists);
 
-  // Update local devirtualized targets that were exported by cross-module
-  // importing
-  updateIndexWPDForExports(ThinLTO.CombinedIndex, ExportLists,
-                           LocalWPDTargetsMap);
-
   // Figure out which symbols need to be internalized. This also needs to happen
   // at -O0 because summary-based DCE is implemented using internalization, and
   // we must apply DCE consistently with the full LTO module in order to avoid
@@ -1338,6 +1333,12 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
             ExportList->second.count(GUID)) ||
            ExportedGUIDs.count(GUID);
   };
+
+  // Update local devirtualized targets that were exported by cross-module
+  // importing or by other devirtualizations marked in the ExportedGUIDs set.
+  updateIndexWPDForExports(ThinLTO.CombinedIndex, isExported,
+                           LocalWPDTargetsMap);
+
   auto isPrevailing = [&](GlobalValue::GUID GUID,
                           const GlobalValueSummary *S) {
     return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();