1 files changed, 43 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/Analysis.cpp b/llvm/lib/CodeGen/Analysis.cpp
index 292142b..ef40548 100644
--- a/llvm/lib/CodeGen/Analysis.cpp
+++ b/llvm/lib/CodeGen/Analysis.cpp
@@ -650,6 +650,49 @@ bool llvm::canBeOmittedFromSymbolTable(const GlobalValue *GV) {
   return !GS.IsCompared;
 }
 
+// FIXME: make this a proper option
+static bool CanUseCopyRelocWithPIE = false;
+
+bool llvm::shouldAssumeDSOLocal(Reloc::Model RM, const Triple &TT,
+                                const Module &M, const GlobalValue *GV) {
+  // DLLImport explicitly marks the GV as external.
+  if (GV && GV->hasDLLImportStorageClass())
+    return false;
+
+  // Every other GV is local on COFF
+  if (TT.isOSBinFormatCOFF())
+    return true;
+
+  if (RM == Reloc::Static)
+    return true;
+
+  if (GV && (GV->hasLocalLinkage() || !GV->hasDefaultVisibility()))
+    return true;
+
+  if (TT.isOSBinFormatELF()) {
+    assert(RM != Reloc::DynamicNoPIC);
+    // Some linkers can use copy relocations with pie executables.
+    if (M.getPIELevel() != PIELevel::Default) {
+      if (CanUseCopyRelocWithPIE)
+        return true;
+
+      // If the symbol is defined, it cannot be preempted.
+      if (GV && !GV->isDeclarationForLinker())
+        return true;
+      return false;
+    }
+
+    // ELF supports preemption of other symbols.
+    return false;
+  }
+
+  assert(TT.isOSBinFormatMachO());
+  if (GV && GV->isStrongDefinitionForLinker())
+    return true;
+
+  return false;
+}
+
 static void collectFuncletMembers(
     DenseMap<const MachineBasicBlock *, int> &FuncletMembership, int Funclet,
     const MachineBasicBlock *MBB) {