Fix for "DICompileUnit not listed in llvm.dbg.cu" verification error after ...

...cloning a function from a different module

Currently when a function with debug info is cloned from a different module, the 
cloned function may have hanging DICompileUnits, so that the module with the 
cloned function fails debug info verification.

The proposed fix inserts all DICompileUnits reachable from the cloned function 
to "llvm.dbg.cu" metadata operands of the cloned function module. 

Reviewed By: aprantl, efriedma

Differential Revision: https://reviews.llvm.org/D66510

Patch by Oleg Pliss (Oleg.Pliss@azul.com)

llvm-svn: 370265

1 files changed, 14 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/CloneModule.cpp b/llvm/lib/Transforms/Utils/CloneModule.cpp
index 71e39e9..2c8c3ab 100644
--- a/llvm/lib/Transforms/Utils/CloneModule.cpp
+++ b/llvm/lib/Transforms/Utils/CloneModule.cpp
@@ -181,13 +181,25 @@ std::unique_ptr<Module> llvm::CloneModule(
   }
 
   // And named metadata....
+  const auto* LLVM_DBG_CU = M.getNamedMetadata("llvm.dbg.cu");
   for (Module::const_named_metadata_iterator I = M.named_metadata_begin(),
                                              E = M.named_metadata_end();
        I != E; ++I) {
     const NamedMDNode &NMD = *I;
     NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
-    for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
-      NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
+    if (&NMD == LLVM_DBG_CU) {
+      // Do not insert duplicate operands.
+      SmallPtrSet<const void*, 8> Visited;
+      for (const auto* Operand : NewNMD->operands())
+        Visited.insert(Operand);
+      for (const auto* Operand : NMD.operands()) {
+        auto* MappedOperand = MapMetadata(Operand, VMap);
+        if (Visited.insert(MappedOperand).second)
+          NewNMD->addOperand(MappedOperand);
+      }
+    } else
+      for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
+        NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
   }
 
   return New;