Add template type and value parameter metadata nodes to template variable specializations.

[ormris]

Summary

Depends on LLVM patch: D46138

Resolves https://bugs.llvm.org/show_bug.cgi?id=22119

[probinson]

lib/CodeGen/CGDebugInfo.cpp

3023

Naively it looks like it should be possible to put the local into a scope under the if:

if (isa<...>(VD)) {
  llvm::DINodeArray parameterNodes = CollectVarTemplateParams(VD, &*Unit);
  templateParameters = parameterNodes.get();
}

but you told me this caused crashes. I don't understand that, as templateParameters is itself a formal parameter, so you're really returning the node array to the caller?
(My understanding is at least partly hampered by being unable to find the definition of DINodeArray, if somebody can point it out that would be helpful.)

[ormris]

Thanks for spotting that @probinson. Will update.

[ormris]

After some further inspection, support for the LLVM side of patch needs a few significant additions. Abandoning this revision.

lib/CodeGen/CGDebugInfo.h

#include "clang/Basic/OpenCLImageTypes.def"
   llvm::DINodeArray CollectTemplateParams(const TemplateParameterList *TPList,
                                           ArrayRef<TemplateArgument> TAList,
                                           llvm::DIFile *Unit);
   /// A helper function to collect debug info for function template
   /// parameters.
   llvm::DINodeArray CollectFunctionTemplateParams(const FunctionDecl *FD,
                                                   llvm::DIFile *Unit);
 
+  /// A helper function to collect debug info for function template
+  /// parameters.
+  llvm::DINodeArray CollectVarTemplateParams(const VarDecl *VD,
+                                             llvm::DIFile *Unit);
+
   /// A helper function to collect debug info for template
   /// parameters.
   llvm::DINodeArray
   CollectCXXTemplateParams(const ClassTemplateSpecializationDecl *TS,
                            llvm::DIFile *F);
 
   llvm::DIType *createFieldType(StringRef name, QualType type,
                                 SourceLocation loc, AccessSpecifier AS,
void collectFunctionDeclProps(GlobalDecl GD, llvm::DIFile *Unit,
                                 StringRef &Name, StringRef &LinkageName,
                                 llvm::DIScope *&FDContext,
                                 llvm::DINodeArray &TParamsArray,
                                 llvm::DINode::DIFlags &Flags);
 
   /// Collect various properties of a VarDecl.
   void collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
                            unsigned &LineNo, QualType &T, StringRef &Name,
-                           StringRef &LinkageName, llvm::DIScope *&VDContext);
+                           StringRef &LinkageName,
+                           llvm::MDTuple *&templateParameters,
+                           llvm::DIScope *&VDContext);
 
   /// Allocate a copy of \p A using the DebugInfoNames allocator
   /// and return a reference to it. If multiple arguments are given the strings
   /// are concatenated.
   StringRef internString(StringRef A, StringRef B = StringRef()) {
     char *Data = DebugInfoNames.Allocate<char>(A.size() + B.size());
     if (!A.empty())
       std::memcpy(Data, A.data(), A.size());

lib/CodeGen/CGDebugInfo.cpp

 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/Path.h"
 using namespace clang;
 using namespace clang::CodeGen;
 
 static uint32_t getTypeAlignIfRequired(const Type *Ty, const ASTContext &Ctx) {
const TemplateParameterList *TList = FD->getTemplateSpecializationInfo()
                                              ->getTemplate()
                                              ->getTemplateParameters();
     return CollectTemplateParams(
         TList, FD->getTemplateSpecializationArgs()->asArray(), Unit);
   }
   return llvm::DINodeArray();
 }
 
+llvm::DINodeArray CGDebugInfo::CollectVarTemplateParams(const VarDecl *VL,
+                                                        llvm::DIFile *Unit) {
+  if (auto *TS = dyn_cast<VarTemplateSpecializationDecl>(VL)) {
+    if (TS->getSpecializedTemplateOrPartial()
+            .is<VarTemplatePartialSpecializationDecl *>()) {
+      const TemplateParameterList *TList =
+          TS->getSpecializedTemplateOrPartial()
+              .get<VarTemplatePartialSpecializationDecl *>()
+              ->getTemplateParameters();
+      return CollectTemplateParams(TList, TS->getTemplateArgs().asArray(),
+                                   Unit);
+    }
+
+    if (TS->getSpecializedTemplateOrPartial().is<VarTemplateDecl *>()) {
+      const TemplateParameterList *TList = TS->getSpecializedTemplateOrPartial()
+                                               .get<VarTemplateDecl *>()
+                                               ->getTemplateParameters();
+      return CollectTemplateParams(TList, TS->getTemplateArgs().asArray(),
+                                   Unit);
+    }
+  }
+  return llvm::DINodeArray();
+}
+
 llvm::DINodeArray CGDebugInfo::CollectCXXTemplateParams(
     const ClassTemplateSpecializationDecl *TSpecial, llvm::DIFile *Unit) {
   // Always get the full list of parameters, not just the ones from
   // the specialization.
   TemplateParameterList *TPList =
       TSpecial->getSpecializedTemplate()->getTemplateParameters();
   const TemplateArgumentList &TAList = TSpecial->getTemplateArgs();
   return CollectTemplateParams(TPList, TAList.asArray(), Unit);
if (DebugKind >= codegenoptions::LimitedDebugInfo) {
     // Collect template parameters.
     TParamsArray = CollectFunctionTemplateParams(FD, Unit);
   }
 }
 
 void CGDebugInfo::collectVarDeclProps(const VarDecl *VD, llvm::DIFile *&Unit,
                                       unsigned &LineNo, QualType &T,
                                       StringRef &Name, StringRef &LinkageName,
+                                      llvm::MDTuple *&templateParameters,
                                       llvm::DIScope *&VDContext) {
   Unit = getOrCreateFile(VD->getLocation());
   LineNo = getLineNumber(VD->getLocation());
 
   setLocation(VD->getLocation());
 
   T = VD->getType();
   if (T->isIncompleteArrayType()) {
     // CodeGen turns int[] into int[1] so we'll do the same here.
     llvm::APInt ConstVal(32, 1);
     QualType ET = CGM.getContext().getAsArrayType(T)->getElementType();
 
     T = CGM.getContext().getConstantArrayType(ET, ConstVal,
                                               ArrayType::Normal, 0);
   }
 
   Name = VD->getName();
   if (VD->getDeclContext() && !isa<FunctionDecl>(VD->getDeclContext()) &&
       !isa<ObjCMethodDecl>(VD->getDeclContext()))
     LinkageName = CGM.getMangledName(VD);
   if (LinkageName == Name)
     LinkageName = StringRef();
 
+  llvm::DINodeArray parameterNodes;
+
+  if (isa<VarTemplateSpecializationDecl>(VD))
+    parameterNodes = CollectVarTemplateParams(VD, &*Unit);
+
+  templateParameters = parameterNodes.get();
+
   // Since we emit declarations (DW_AT_members) for static members, place the
   // definition of those static members in the namespace they were declared in
   // in the source code (the lexical decl context).
   // FIXME: Generalize this for even non-member global variables where the
   // declaration and definition may have different lexical decl contexts, once
   // we have support for emitting declarations of (non-member) global variables.
   const DeclContext *DC = VD->isStaticDataMember() ? VD->getLexicalDeclContext()
                                                    : VD->getDeclContext();

 llvm::DIGlobalVariable *
 CGDebugInfo::getGlobalVariableForwardDeclaration(const VarDecl *VD) {
   QualType T;
   StringRef Name, LinkageName;
   SourceLocation Loc = VD->getLocation();
   llvm::DIFile *Unit = getOrCreateFile(Loc);
   llvm::DIScope *DContext = Unit;
   unsigned Line = getLineNumber(Loc);
+  llvm::MDTuple *templateParameters = nullptr;
 
-  collectVarDeclProps(VD, Unit, Line, T, Name, LinkageName, DContext);
+  collectVarDeclProps(VD, Unit, Line, T, Name, LinkageName, templateParameters,
+                      DContext);
   auto Align = getDeclAlignIfRequired(VD, CGM.getContext());
   auto *GV = DBuilder.createTempGlobalVariableFwdDecl(
       DContext, Name, LinkageName, Unit, Line, getOrCreateType(T, Unit),
-      !VD->isExternallyVisible(), nullptr, Align);
+      !VD->isExternallyVisible(), nullptr, templateParameters, Align);
   FwdDeclReplaceMap.emplace_back(
       std::piecewise_construct,
       std::make_tuple(cast<VarDecl>(VD->getCanonicalDecl())),
       std::make_tuple(static_cast<llvm::Metadata *>(GV)));
   return GV;
 }
 
 llvm::DINode *CGDebugInfo::getDeclarationOrDefinition(const Decl *D) {
return Var->addDebugInfo(
         cast<llvm::DIGlobalVariableExpression>(Cached->second));
 
   // Create global variable debug descriptor.
   llvm::DIFile *Unit = nullptr;
   llvm::DIScope *DContext = nullptr;
   unsigned LineNo;
   StringRef DeclName, LinkageName;
   QualType T;
-  collectVarDeclProps(D, Unit, LineNo, T, DeclName, LinkageName, DContext);
+  llvm::MDTuple *templateParameters;
+  collectVarDeclProps(D, Unit, LineNo, T, DeclName, LinkageName,
+                      templateParameters, DContext);
 
   // Attempt to store one global variable for the declaration - even if we
   // emit a lot of fields.
   llvm::DIGlobalVariableExpression *GVE = nullptr;
 
   // If this is an anonymous union then we'll want to emit a global
   // variable for each member of the anonymous union so that it's possible
   // to find the name of any field in the union.
if (T->isUnionType() && DeclName.empty()) {
     unsigned AddressSpace =
         CGM.getContext().getTargetAddressSpace(D->getType());
     AppendAddressSpaceXDeref(AddressSpace, Expr);
 
     GVE = DBuilder.createGlobalVariableExpression(
         DContext, DeclName, LinkageName, Unit, LineNo, getOrCreateType(T, Unit),
         Var->hasLocalLinkage(),
         Expr.empty() ? nullptr : DBuilder.createExpression(Expr),
-        getOrCreateStaticDataMemberDeclarationOrNull(D), Align);
+        getOrCreateStaticDataMemberDeclarationOrNull(D), templateParameters,
+        Align);
     Var->addDebugInfo(GVE);
   }
   DeclCache[D->getCanonicalDecl()].reset(GVE);
 }
 
 void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD, const APValue &Init) {
   assert(DebugKind >= codegenoptions::LimitedDebugInfo);
   if (VD->hasAttr<NoDebugAttr>())
if (CGM.getContext().getTypeSize(VD->getType()) <= 64) {
     // FIXME: Add a representation for integer constants wider than 64 bits.
     if (Init.isInt())
       InitExpr =
           DBuilder.createConstantValueExpression(Init.getInt().getExtValue());
     else if (Init.isFloat())
       InitExpr = DBuilder.createConstantValueExpression(
           Init.getFloat().bitcastToAPInt().getZExtValue());
   }
+
+  llvm::MDTuple *templateParameters = nullptr;
+  llvm::DINodeArray parameterNodes;
+
+  if (isa<VarTemplateSpecializationDecl>(VD))
+    if (VarD)
+      parameterNodes = CollectVarTemplateParams(VarD, &*Unit);
+
+  templateParameters = parameterNodes.get();
+
   GV.reset(DBuilder.createGlobalVariableExpression(
       DContext, Name, StringRef(), Unit, getLineNumber(VD->getLocation()), Ty,
       true, InitExpr, getOrCreateStaticDataMemberDeclarationOrNull(VarD),
-      Align));
+      templateParameters, Align));
 }
 
 llvm::DIScope *CGDebugInfo::getCurrentContextDescriptor(const Decl *D) {
   if (!LexicalBlockStack.empty())
     return LexicalBlockStack.back();
   llvm::DIScope *Mod = getParentModuleOrNull(D);
   return getContextDescriptor(D, Mod ? Mod : TheCU);
 }

test/CodeGenCXX/debug-info-template-member.cpp

 inline int add3(int x) {
   return MyClass().add<3>(x); // even though add<3> is ODR used, don't emit it since we don't codegen it
 }
 
 // The compile unit pulls in the global variables first.
 // CHECK: [[X]] = !DIGlobalVariableExpression(var: [[XV:.*]], expr: !DIExpression())
 // CHECK: [[XV]] = distinct !DIGlobalVariable(name: "x",
 // CHECK-SAME:                                type: ![[OUTER_FOO_INNER_ID:[0-9]+]]
+//
+// CHECK: {{![0-9]+}} = distinct !DIGlobalVariable(
+// CHECK-SAME: name: "var"
+// CHECK-SAME: templateParams: {{![0-9]+}}
+// CHECK: !DITemplateTypeParameter(name: "T", type: [[TY:![0-9]+]])
+// CHECK: {{![0-9]+}} = distinct !DIGlobalVariable(
+// CHECK-SAME: name: "var"
+// CHECK-SAME: templateParams: {{![0-9]+}}
+// CHECK: !DITemplateTypeParameter(name: "P", type: {{![0-9]+}})
+// CHECK: {{![0-9]+}} = distinct !DIGlobalVariable(
+// CHECK-SAME: name: "varray"
+// CHECK-SAME: templateParams: {{![0-9]+}}
+// CHECK: !DITemplateValueParameter(name: "N", type: [[TY]], value: i32 1)
 
 // CHECK: ![[OUTER_FOO_INNER_ID:[0-9]*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "inner"{{.*}}, identifier:
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "foo"
 // CHECK-SAME:             elements: [[FOO_MEM:![0-9]*]]
 // CHECK-SAME:             identifier: "_ZTS3foo"
 // CHECK: [[FOO_MEM]] = !{[[FOO_FUNC:![0-9]*]]}
 // CHECK: [[FOO_FUNC]] = !DISubprogram(name: "func", linkageName: "_ZN3foo4funcEN5outerIS_E5innerE",
 // CHECK-SAME:                         type: [[FOO_FUNC_TYPE:![0-9]*]]

 
 // Check that the member function template specialization and implicit special
 // members (the default ctor) refer to their class by scope, even though they
 // didn't appear in the class's member list (C_MEM). This prevents the functions
 // from being added to type units, while still appearing in the type
 // declaration/reference in the compile unit.
 // CHECK: !DISubprogram(name: "MyClass"
 // CHECK-SAME:          scope: [[C]]
+
+template <typename T>
+T var = T();
+template <typename P>
+P var<P *> = P();
+template <typename T, int N>
+T varray[N];
+void f3() {
+  var<int> = 1;
+  var<int *> = 1;
+  varray<int, 1>[0] = 1;
+}