Revert "[IR] Remove the DIExpression field from DIGlobalVariable."

This reverts commit 289920 (again).
I forgot to implement a Bitcode upgrade for the case where a DIGlobalVariable
has not DIExpression. Unfortunately it is not possible to safely upgrade
these variables without adding a flag to the bitcode record indicating which
version they are.
My plan of record is to roll the planned follow-up patch that adds a
unit: field to DIGlobalVariable into this patch before recomitting.
This way we only need one Bitcode upgrade for both changes (with a
version flag in the bitcode record to safely distinguish the record
formats).

Sorry for the churn!

llvm-svn: 289982

1 files changed, 7 insertions, 14 deletions

diff --git a/llvm/lib/IR/Metadata.cpp b/llvm/lib/IR/Metadata.cpp
index 1d193045923..adc91573a7f 100644
--- a/llvm/lib/IR/Metadata.cpp
+++ b/llvm/lib/IR/Metadata.cpp
@@ -1419,15 +1419,9 @@ void GlobalObject::copyMetadata(const GlobalObject *Other, unsigned Offset) {
     // If an offset adjustment was specified we need to modify the DIExpression
     // to prepend the adjustment:
     // !DIExpression(DW_OP_plus, Offset, [original expr])
-    auto *Attachment = MD.second;
     if (Offset != 0 && MD.first == LLVMContext::MD_dbg) {
-      DIGlobalVariable *GV = dyn_cast<DIGlobalVariable>(Attachment);
-      DIExpression *E = nullptr;
-      if (!GV) {
-        auto *GVE = cast<DIGlobalVariableExpression>(Attachment);
-        GV = GVE->getVariable();
-        E = GVE->getExpression();
-      }
+      DIGlobalVariable *GV = cast<DIGlobalVariable>(MD.second);
+      DIExpression *E = GV->getExpr();
       ArrayRef<uint64_t> OrigElements;
       if (E)
         OrigElements = E->getElements();
@@ -1435,10 +1429,9 @@ void GlobalObject::copyMetadata(const GlobalObject *Other, unsigned Offset) {
       Elements[0] = dwarf::DW_OP_plus;
       Elements[1] = Offset;
       std::copy(OrigElements.begin(), OrigElements.end(), Elements.begin() + 2);
-      E = DIExpression::get(getContext(), Elements);
-      Attachment = DIGlobalVariableExpression::get(getContext(), GV, E);
+      GV->replaceExpr(DIExpression::get(getContext(), Elements));
     }
-    addMetadata(MD.first, *Attachment);
+    addMetadata(MD.first, *MD.second);
   }
 }
 
@@ -1459,14 +1452,14 @@ DISubprogram *Function::getSubprogram() const {
   return cast_or_null<DISubprogram>(getMetadata(LLVMContext::MD_dbg));
 }
 
-void GlobalVariable::addDebugInfo(DIGlobalVariableExpression *GV) {
+void GlobalVariable::addDebugInfo(DIGlobalVariable *GV) {
   addMetadata(LLVMContext::MD_dbg, *GV);
 }
 
 void GlobalVariable::getDebugInfo(
-    SmallVectorImpl<DIGlobalVariableExpression *> &GVs) const {
+    SmallVectorImpl<DIGlobalVariable *> &GVs) const {
   SmallVector<MDNode *, 1> MDs;
   getMetadata(LLVMContext::MD_dbg, MDs);
   for (MDNode *MD : MDs)
-    GVs.push_back(cast<DIGlobalVariableExpression>(MD));
+    GVs.push_back(cast<DIGlobalVariable>(MD));
 }