[Cloning] Fix to cloning DISubprograms.

When trying to enable -debug-info-kind=constructor there was an assert
that occurs during debug info cloning ("mismatched subprogram between
llvm.dbg.value variable and !dbg attachment").
It appears that during llvm::CloneFunctionInto, a DISubprogram could be
duplicated when MapMetadata is called, and then added to the MD map again
when DIFinder gets a list of subprograms. This results in two different
versions of the DISubprogram.

This patch switches the order so that the DIFinder subprograms are
added before MapMetadata is called.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46784

Differential Revision: https://reviews.llvm.org/D86185

1 files changed, 13 insertions, 11 deletions

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index 957e402..3225495 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -137,16 +137,6 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
       MD[SP].reset(SP);
   }
 
-  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
-  OldFunc->getAllMetadata(MDs);
-  for (auto MD : MDs) {
-    NewFunc->addMetadata(
-        MD.first,
-        *MapMetadata(MD.second, VMap,
-                     ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
-                     TypeMapper, Materializer));
-  }
-
   // Everything else beyond this point deals with function instructions,
   // so if we are dealing with a function declaration, we're done.
   if (OldFunc->isDeclaration())
@@ -162,7 +152,6 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
   // Loop over all of the basic blocks in the function, cloning them as
   // appropriate.  Note that we save BE this way in order to handle cloning of
   // recursive functions into themselves.
-  //
   for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
        BI != BE; ++BI) {
     const BasicBlock &BB = *BI;
@@ -201,6 +190,19 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
   for (DIType *Type : DIFinder.types())
     VMap.MD()[Type].reset(Type);
 
+  // Duplicate the metadata that is attached to the cloned function.
+  // Subprograms/CUs/types that were already mapped to themselves won't be
+  // duplicated.
+  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
+  OldFunc->getAllMetadata(MDs);
+  for (auto MD : MDs) {
+    NewFunc->addMetadata(
+        MD.first,
+        *MapMetadata(MD.second, VMap,
+                     ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
+                     TypeMapper, Materializer));
+  }
+
   // Loop over all of the instructions in the function, fixing up operand
   // references as we go.  This uses VMap to do all the hard work.
   for (Function::iterator BB =