Fixing a bug where debug info for a local variable gets emitted at file scope.

The patch was discussed in Phabricator. See:
http://llvm-reviews.chandlerc.com/D1281



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189649 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index fe50398..89e2059 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -3142,14 +3142,31 @@
 }
 
 /// EmitGlobalVariable - Emit information about a global variable.
-void CGDebugInfo::EmitGlobalVariable(llvm::GlobalVariable *Var,
+/// \param VarOrInit either the global variable itself or the initializer
+/// \param D the global declaration
+void CGDebugInfo::EmitGlobalVariable(llvm::Value *VarOrInit,
                                      const VarDecl *D) {
   assert(DebugKind >= CodeGenOptions::LimitedDebugInfo);
   // Create global variable debug descriptor.
   llvm::DIFile Unit = getOrCreateFile(D->getLocation());
   unsigned LineNo = getLineNumber(D->getLocation());
+  StringRef DeclName = D->getName();
+  StringRef LinkageName;
+  bool IsLocalToUnit = true;
 
-  setLocation(D->getLocation());
+  // For deferred global variables, the current source location is usually
+  // where they are being referenced. Do not change the current source location
+  // to the place where they are declared, lest we get a bogus line table.
+  // FIXME: maybe we do not need to set the source location here at all.
+  if (llvm::GlobalVariable *Var = dyn_cast<llvm::GlobalVariable>(VarOrInit)) {
+    setLocation(D->getLocation());
+    IsLocalToUnit = Var->hasInternalLinkage();
+    if (D->getDeclContext() && !isa<FunctionDecl>(D->getDeclContext())
+        && !isa<ObjCMethodDecl>(D->getDeclContext()))
+      LinkageName = Var->getName();
+    if (LinkageName == DeclName)
+      LinkageName = StringRef();
+  }
 
   QualType T = D->getType();
   if (T->isIncompleteArrayType()) {
@@ -3161,18 +3178,11 @@
     T = CGM.getContext().getConstantArrayType(ET, ConstVal,
                                               ArrayType::Normal, 0);
   }
-  StringRef DeclName = D->getName();
-  StringRef LinkageName;
-  if (D->getDeclContext() && !isa<FunctionDecl>(D->getDeclContext())
-      && !isa<ObjCMethodDecl>(D->getDeclContext()))
-    LinkageName = Var->getName();
-  if (LinkageName == DeclName)
-    LinkageName = StringRef();
   llvm::DIDescriptor DContext =
     getContextDescriptor(dyn_cast<Decl>(D->getDeclContext()));
   llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(
       DContext, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
-      Var->hasInternalLinkage(), Var,
+      IsLocalToUnit, VarOrInit,
       getOrCreateStaticDataMemberDeclarationOrNull(D));
   DeclCache.insert(std::make_pair(D->getCanonicalDecl(), llvm::WeakVH(GV)));
 }
@@ -3203,26 +3213,16 @@
                                 Var->hasInternalLinkage(), Var);
 }
 
-/// EmitGlobalVariable - Emit global variable's debug info.
-void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD,
-                                     llvm::Constant *Init) {
+/// EmitEnumConstant - Emit debug info for an enumerator constant
+void CGDebugInfo::EmitEnumConstant(const EnumConstantDecl *ECD)
+{
   assert(DebugKind >= CodeGenOptions::LimitedDebugInfo);
-  // Create the descriptor for the variable.
-  llvm::DIFile Unit = getOrCreateFile(VD->getLocation());
-  StringRef Name = VD->getName();
-  llvm::DIType Ty = getOrCreateType(VD->getType(), Unit);
-  if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(VD)) {
-    const EnumDecl *ED = cast<EnumDecl>(ECD->getDeclContext());
-    assert(isa<EnumType>(ED->getTypeForDecl()) && "Enum without EnumType?");
-    Ty = getOrCreateType(QualType(ED->getTypeForDecl(), 0), Unit);
-  }
-  // Do not use DIGlobalVariable for enums.
-  if (Ty.getTag() == llvm::dwarf::DW_TAG_enumeration_type)
-    return;
-  llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(
-      Unit, Name, Name, Unit, getLineNumber(VD->getLocation()), Ty, true, Init,
-      getOrCreateStaticDataMemberDeclarationOrNull(cast<VarDecl>(VD)));
-  DeclCache.insert(std::make_pair(VD->getCanonicalDecl(), llvm::WeakVH(GV)));
+  llvm::DIFile Unit = getOrCreateFile(ECD->getLocation());
+  llvm::DIType Ty = getOrCreateType(ECD->getType(), Unit);
+
+  const EnumDecl *ED = cast<EnumDecl>(ECD->getDeclContext());
+  assert(isa<EnumType>(ED->getTypeForDecl()) && "Enum without EnumType?");
+  Ty = getOrCreateType(QualType(ED->getTypeForDecl(), 0), Unit);
 }
 
 llvm::DIScope CGDebugInfo::getCurrentContextDescriptor(const Decl *D) {
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index a8ba14b..9642a83 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -264,13 +264,13 @@
                                             CGBuilderTy &Builder);
 
   /// EmitGlobalVariable - Emit information about a global variable.
-  void EmitGlobalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
+  void EmitGlobalVariable(llvm::Value *VarOrInit, const VarDecl *Decl);
 
   /// EmitGlobalVariable - Emit information about an objective-c interface.
   void EmitGlobalVariable(llvm::GlobalVariable *GV, ObjCInterfaceDecl *Decl);
 
-  /// EmitGlobalVariable - Emit global variable's debug info.
-  void EmitGlobalVariable(const ValueDecl *VD, llvm::Constant *Init);
+  /// EmitEnumConstant - Emit information about an enumerator constant
+  void EmitEnumConstant(const EnumConstantDecl *ECD);
 
   /// \brief - Emit C++ using directive.
   void EmitUsingDirective(const UsingDirectiveDecl &UD);
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 12aa0a2..31da6df 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -967,15 +967,9 @@
   // Emit as a constant.
   llvm::Constant *C = CGM.EmitConstantValue(result.Val, resultType, this);
 
-  // Make sure we emit a debug reference to the global variable.
-  // This should probably fire even for
-  if (isa<VarDecl>(value)) {
-    if (!getContext().DeclMustBeEmitted(cast<VarDecl>(value)))
-      EmitDeclRefExprDbgValue(refExpr, C);
-  } else {
-    assert(isa<EnumConstantDecl>(value));
-    EmitDeclRefExprDbgValue(refExpr, C);
-  }
+  // Make sure we emit a debug reference to the global variable or
+  // enumerator constant.
+  EmitValueDeclDbgValue(value, C);
 
   // If we emitted a reference constant, we need to dereference that.
   if (resultIsReference)
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 20352f9..c035723 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -1376,12 +1376,27 @@
   return EmitLValue(E).getAddress();
 }
 
-void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
-                                              llvm::Constant *Init) {
+void CodeGenFunction::EmitValueDeclDbgValue(const ValueDecl *Val,
+                                            llvm::Constant *Init) {
   assert (Init && "Invalid DeclRefExpr initializer!");
-  if (CGDebugInfo *Dbg = getDebugInfo())
-    if (CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
-      Dbg->EmitGlobalVariable(E->getDecl(), Init);
+  CGDebugInfo *Dbg = getDebugInfo();
+  if (!Dbg ||
+      CGM.getCodeGenOpts().getDebugInfo() < CodeGenOptions::LimitedDebugInfo)
+    return;
+
+  // Make sure we emit a debug reference to the global variable.
+  if (const VarDecl *VD = dyn_cast<VarDecl>(Val)) {
+    // Do not duplicate DIE entry for local variables; they are not deferred
+    // like global variables are.
+    if (VD->isFileVarDecl() && !getLangOpts().EmitAllDecls &&
+        !getContext().DeclMustBeEmitted(Val))
+      Dbg->EmitGlobalVariable(Init, VD);
+
+  // Make sure we emit a debug reference to an enumerator constant.
+  } else {
+    assert(isa<EnumConstantDecl>(Val));
+    Dbg->EmitEnumConstant(dyn_cast<EnumConstantDecl>(Val));
+  }
 }
 
 CodeGenFunction::PeepholeProtection
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 20c0b82..9913c68 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -2047,7 +2047,8 @@
   LValue EmitStmtExprLValue(const StmtExpr *E);
   LValue EmitPointerToDataMemberBinaryExpr(const BinaryOperator *E);
   LValue EmitObjCSelectorLValue(const ObjCSelectorExpr *E);
-  void   EmitDeclRefExprDbgValue(const DeclRefExpr *E, llvm::Constant *Init);
+  void   EmitValueDeclDbgValue(const ValueDecl *Val, llvm::Constant *Init);
+
 
   //===--------------------------------------------------------------------===//
   //                         Scalar Expression Emission