Fix the bitcode upgrade for DIGlobalVariable in a DIImportedEntity context.

The bitcode upgrade for DIGlobalVariable unconditionally wrapped
DIGlobalVariables in a DIGlobalVariableExpression. When a
DIGlobalVariable is referenced by a DIImportedEntity, however, this is
wrong. This patch fixes the bitcode upgrade by deferring the creation
of DIGlobalVariableExpressions until we know the context of the
DIGlobalVariable.

<rdar://problem/30134279>

Differential Revision: https://reviews.llvm.org/D29349

llvm-svn: 294318

1 files changed, 51 insertions, 5 deletions

diff --git a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
index 7df0a2ed906..41985e2590c 100644
--- a/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
+++ b/llvm/lib/Bitcode/Reader/MetadataLoader.cpp
@@ -451,6 +451,7 @@ class MetadataLoader::MetadataLoaderImpl {
 
   bool StripTBAA = false;
   bool HasSeenOldLoopTags = false;
+  bool NeedUpgradeToDIGlobalVariableExpression = false;
 
   /// True if metadata is being parsed for a module being ThinLTO imported.
   bool IsImporting = false;
@@ -476,6 +477,45 @@ class MetadataLoader::MetadataLoaderImpl {
     CUSubprograms.clear();
   }
 
+  /// Upgrade old-style bare DIGlobalVariables to DIGlobalVariableExpressions.
+  void upgradeCUVariables() {
+    if (!NeedUpgradeToDIGlobalVariableExpression)
+      return;
+
+    // Upgrade list of variables attached to the CUs.
+    if (NamedMDNode *CUNodes = TheModule.getNamedMetadata("llvm.dbg.cu"))
+      for (unsigned I = 0, E = CUNodes->getNumOperands(); I != E; ++I) {
+        auto *CU = cast<DICompileUnit>(CUNodes->getOperand(I));
+        if (auto *GVs = dyn_cast_or_null<MDTuple>(CU->getRawGlobalVariables()))
+          for (unsigned I = 0; I < GVs->getNumOperands(); I++)
+            if (auto *GV =
+                    dyn_cast_or_null<DIGlobalVariable>(GVs->getOperand(I))) {
+              auto *DGVE =
+                  DIGlobalVariableExpression::getDistinct(Context, GV, nullptr);
+              GVs->replaceOperandWith(I, DGVE);
+            }
+      }
+
+    // Upgrade variables attached to globals.
+    for (auto &GV : TheModule.globals()) {
+      SmallVector<MDNode *, 1> MDs, NewMDs;
+      GV.getMetadata(LLVMContext::MD_dbg, MDs);
+      GV.eraseMetadata(LLVMContext::MD_dbg);
+      for (auto *MD : MDs)
+        if (auto *DGV = dyn_cast_or_null<DIGlobalVariable>(MD)) {
+          auto *DGVE =
+              DIGlobalVariableExpression::getDistinct(Context, DGV, nullptr);
+          GV.addMetadata(LLVMContext::MD_dbg, *DGVE);
+        } else
+          GV.addMetadata(LLVMContext::MD_dbg, *MD);
+    }
+  }
+
+  void upgradeDebugInfo() {
+    upgradeCUSubprograms();
+    upgradeCUVariables();
+  }
+
 public:
   MetadataLoaderImpl(BitstreamCursor &Stream, Module &TheModule,
                      BitcodeReaderValueList &ValueList,
@@ -729,7 +769,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseMetadata(bool ModuleLevel) {
       // Reading the named metadata created forward references and/or
       // placeholders, that we flush here.
       resolveForwardRefsAndPlaceholders(Placeholders);
-      upgradeCUSubprograms();
+      upgradeDebugInfo();
       // Return at the beginning of the block, since it is easy to skip it
       // entirely from there.
       Stream.ReadBlockEnd(); // Pop the abbrev block context.
@@ -753,7 +793,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseMetadata(bool ModuleLevel) {
       return error("Malformed block");
     case BitstreamEntry::EndBlock:
       resolveForwardRefsAndPlaceholders(Placeholders);
-      upgradeCUSubprograms();
+      upgradeDebugInfo();
       return Error::success();
     case BitstreamEntry::Record:
       // The interesting case.
@@ -1424,11 +1464,17 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
            getDITypeRefOrNull(Record[6]), Record[7], Record[8],
            getMDOrNull(Record[10]), AlignInBits));
 
-      auto *DGVE = DIGlobalVariableExpression::getDistinct(Context, DGV, Expr);
-      MetadataList.assignValue(DGVE, NextMetadataNo);
-      NextMetadataNo++;
+      DIGlobalVariableExpression *DGVE = nullptr;
+      if (Attach || Expr)
+        DGVE = DIGlobalVariableExpression::getDistinct(Context, DGV, Expr);
+      else
+        NeedUpgradeToDIGlobalVariableExpression = true;
       if (Attach)
         Attach->addDebugInfo(DGVE);
+
+      auto *MDNode = Expr ? cast<Metadata>(DGVE) : cast<Metadata>(DGV);
+      MetadataList.assignValue(MDNode, NextMetadataNo);
+      NextMetadataNo++;
     } else
       return error("Invalid record");