3 files changed, 30 insertions, 5 deletions
diff --git a/include/llvm/Transforms/IPO/FunctionImport.h b/include/llvm/Transforms/IPO/FunctionImport.h
index d7acbe883c5d..eaea092c9179 100644
--- a/include/llvm/Transforms/IPO/FunctionImport.h
+++ b/include/llvm/Transforms/IPO/FunctionImport.h
@@ -86,11 +86,15 @@ public:
 /// \p ExportLists contains for each Module the set of globals (GUID) that will
 /// be imported by another module, or referenced by such a function. I.e. this
 /// is the set of globals that need to be promoted/renamed appropriately.
+///
+/// \p DeadSymbols (optional) contains a list of GUID that are deemed "dead" and
+/// will be ignored for the purpose of importing.
 void ComputeCrossModuleImport(
     const ModuleSummaryIndex &Index,
     const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
     StringMap<FunctionImporter::ImportMapTy> &ImportLists,
-    StringMap<FunctionImporter::ExportSetTy> &ExportLists);
+    StringMap<FunctionImporter::ExportSetTy> &ExportLists,
+    const DenseSet<GlobalValue::GUID> *DeadSymbols = nullptr);
 
 /// Compute all the imports for the given module using the Index.
 ///
@@ -100,6 +104,13 @@ void ComputeCrossModuleImportForModule(
     StringRef ModulePath, const ModuleSummaryIndex &Index,
     FunctionImporter::ImportMapTy &ImportList);
 
+/// Compute all the symbols that are "dead": i.e these that can't be reached
+/// in the graph from any of the given symbols listed in
+/// \p GUIDPreservedSymbols.
+DenseSet<GlobalValue::GUID>
+computeDeadSymbols(const ModuleSummaryIndex &Index,
+                   const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols);
+
 /// Compute the set of summaries needed for a ThinLTO backend compilation of
 /// \p ModulePath.
 //
diff --git a/include/llvm/Transforms/IPO/LowerTypeTests.h b/include/llvm/Transforms/IPO/LowerTypeTests.h
index 23c59c199a3b..ca6e1b878dff 100644
--- a/include/llvm/Transforms/IPO/LowerTypeTests.h
+++ b/include/llvm/Transforms/IPO/LowerTypeTests.h
@@ -60,10 +60,6 @@ struct BitSetInfo {
 
   bool containsGlobalOffset(uint64_t Offset) const;
 
-  bool containsValue(const DataLayout &DL,
-                     const DenseMap<GlobalObject *, uint64_t> &GlobalLayout,
-                     Value *V, uint64_t COffset = 0) const;
-
   void print(raw_ostream &OS) const;
 };
 
diff --git a/include/llvm/Transforms/Utils/FunctionImportUtils.h b/include/llvm/Transforms/Utils/FunctionImportUtils.h
index 57b7d0fcd7cc..f18cd92310b4 100644
--- a/include/llvm/Transforms/Utils/FunctionImportUtils.h
+++ b/include/llvm/Transforms/Utils/FunctionImportUtils.h
@@ -40,9 +40,20 @@ class FunctionImportGlobalProcessing {
   /// as part of a different backend compilation process.
   bool HasExportedFunctions = false;
 
+  /// Set of llvm.*used values, in order to validate that we don't try
+  /// to promote any non-renamable values.
+  SmallPtrSet<GlobalValue *, 8> Used;
+
   /// Check if we should promote the given local value to global scope.
   bool shouldPromoteLocalToGlobal(const GlobalValue *SGV);
 
+#ifndef NDEBUG
+  /// Check if the given value is a local that can't be renamed (promoted).
+  /// Only used in assertion checking, and disabled under NDEBUG since the Used
+  /// set will not be populated.
+  bool isNonRenamableLocal(const GlobalValue &GV) const;
+#endif
+
   /// Helper methods to check if we are importing from or potentially
   /// exporting from the current source module.
   bool isPerformingImport() const { return GlobalsToImport != nullptr; }
@@ -82,6 +93,13 @@ public:
     // may be exported to another backend compilation.
     if (!GlobalsToImport)
       HasExportedFunctions = ImportIndex.hasExportedFunctions(M);
+
+#ifndef NDEBUG
+    // First collect those in the llvm.used set.
+    collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
+    // Next collect those in the llvm.compiler.used set.
+    collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ true);
+#endif
   }
 
   bool run();