1 files changed, 25 insertions, 38 deletions

diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 517e2dc8ebe0..df090c5990e6 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -11,7 +11,6 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/Triple.h"
 #include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfoMetadata.h"
@@ -28,6 +27,7 @@
 #include "llvm/Object/ModuleSymbolTable.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
+#include "llvm/TargetParser/Triple.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
 #include <optional>
 #include <utility>
@@ -409,6 +409,10 @@ class IRLinker {
   std::vector<GlobalValue *> Worklist;
   std::vector<std::pair<GlobalValue *, Value*>> RAUWWorklist;
 
+  /// Set of globals with eagerly copied metadata that may require remapping.
+  /// This remapping is performed after metadata linking.
+  DenseSet<GlobalObject *> UnmappedMetadata;
+
   void maybeAdd(GlobalValue *GV) {
     if (ValuesToLink.insert(GV).second)
       Worklist.push_back(GV);
@@ -750,8 +754,11 @@ GlobalValue *IRLinker::copyGlobalValueProto(const GlobalValue *SGV,
 
   if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) {
     // Metadata for global variables and function declarations is copied eagerly.
-    if (isa<GlobalVariable>(SGV) || SGV->isDeclaration())
+    if (isa<GlobalVariable>(SGV) || SGV->isDeclaration()) {
       NewGO->copyMetadata(cast<GlobalObject>(SGV), 0);
+      if (SGV->isDeclaration() && NewGO->hasMetadata())
+        UnmappedMetadata.insert(NewGO);
+    }
   }
 
   // Remove these copied constants in case this stays a declaration, since
@@ -1056,6 +1063,10 @@ Expected<Constant *> IRLinker::linkGlobalValueProto(GlobalValue *SGV,
   // as well.
   if (Function *F = dyn_cast<Function>(NewGV))
     if (auto Remangled = Intrinsic::remangleIntrinsicFunction(F)) {
+      // Note: remangleIntrinsicFunction does not copy metadata and as such
+      // F should not occur in the set of objects with unmapped metadata.
+      // If this assertion fails then remangleIntrinsicFunction needs updating.
+      assert(!UnmappedMetadata.count(F) && "intrinsic has unmapped metadata");
       NewGV->eraseFromParent();
       NewGV = *Remangled;
       NeedsRenaming = false;
@@ -1200,39 +1211,7 @@ void IRLinker::prepareCompileUnitsForImport() {
     // size inefficient.
     CU->replaceGlobalVariables(nullptr);
 
-    // Imported entities only need to be mapped in if they have local
-    // scope, as those might correspond to an imported entity inside a
-    // function being imported (any locally scoped imported entities that
-    // don't end up referenced by an imported function will not be emitted
-    // into the object). Imported entities not in a local scope
-    // (e.g. on the namespace) only need to be emitted by the originating
-    // module. Create a list of the locally scoped imported entities, and
-    // replace the source CUs imported entity list with the new list, so
-    // only those are mapped in.
-    // FIXME: Locally-scoped imported entities could be moved to the
-    // functions they are local to instead of listing them on the CU, and
-    // we would naturally only link in those needed by function importing.
-    SmallVector<TrackingMDNodeRef, 4> AllImportedModules;
-    bool ReplaceImportedEntities = false;
-    for (auto *IE : CU->getImportedEntities()) {
-      DIScope *Scope = IE->getScope();
-      assert(Scope && "Invalid Scope encoding!");
-      if (isa<DILocalScope>(Scope))
-        AllImportedModules.emplace_back(IE);
-      else
-        ReplaceImportedEntities = true;
-    }
-    if (ReplaceImportedEntities) {
-      if (!AllImportedModules.empty())
-        CU->replaceImportedEntities(MDTuple::get(
-            CU->getContext(),
-            SmallVector<Metadata *, 16>(AllImportedModules.begin(),
-                                        AllImportedModules.end())));
-      else
-        // If there were no local scope imported entities, we can map
-        // the whole list to nullptr.
-        CU->replaceImportedEntities(nullptr);
-    }
+    CU->replaceImportedEntities(nullptr);
   }
 }
 
@@ -1651,6 +1630,13 @@ Error IRLinker::run() {
   // are properly remapped.
   linkNamedMDNodes();
 
+  // Clean up any global objects with potentially unmapped metadata.
+  // Specifically declarations which did not become definitions.
+  for (GlobalObject *NGO : UnmappedMetadata) {
+    if (NGO->isDeclaration())
+      Mapper.remapGlobalObjectMetadata(*NGO);
+  }
+
   if (!IsPerformingImport && !SrcM->getModuleInlineAsm().empty()) {
     // Append the module inline asm string.
     DstM.appendModuleInlineAsm(adjustInlineAsm(SrcM->getModuleInlineAsm(),
@@ -1671,15 +1657,16 @@ Error IRLinker::run() {
 
   // Reorder the globals just added to the destination module to match their
   // original order in the source module.
-  Module::GlobalListType &Globals = DstM.getGlobalList();
   for (GlobalVariable &GV : SrcM->globals()) {
     if (GV.hasAppendingLinkage())
       continue;
     Value *NewValue = Mapper.mapValue(GV);
     if (NewValue) {
       auto *NewGV = dyn_cast<GlobalVariable>(NewValue->stripPointerCasts());
-      if (NewGV)
-        Globals.splice(Globals.end(), Globals, NewGV->getIterator());
+      if (NewGV) {
+        NewGV->removeFromParent();
+        DstM.insertGlobalVariable(NewGV);
+      }
     }
   }