[DebugInfo] [DWARFv5] Collect calling convention info for C++ types during codegen

[vleschuk]

Summary

When generating debug info collect information on calling convention for types (http://www.dwarfstd.org/ShowIssue.php?issue=141215.1) and pass it to backend.

[dblaikie]

Be best to avoid having to 'fixup' the argabi after the fact - and instead build the type with the right argabi from the get-go.

lib/CodeGen/CGDebugInfo.cpp

955–957

Could you file a bug/feature request with the DWARF committee? & maybe we could/should use an implementation defined extension value here? (assuming the DW_CC set has an implementation defined space - which I really hope it does)

test/CodeGenCXX/debug-info-type-calling-conventions.cpp

11–12

I'd probably make this a struct (and drop the 'public:' section since it'll be the default then) - since it doesn't seem to matter here.

[vleschuk]

test/CodeGenCXX/debug-info-type-calling-conventions.cpp

11–12

Will do when I fix this bug: http://lists.llvm.org/pipermail/llvm-dev/2017-February/110557.html

[aprantl]

lib/CodeGen/CGDebugInfo.cpp

955–957

Plenty:
DW_CC_lo_user 0x40
DW_CC_hi_user 0xff

lib/CodeGen/CGDebugInfo.h

void CollectRecordFields(const RecordDecl *Decl, llvm::DIFile *F,
                            SmallVectorImpl<llvm::Metadata *> &E,
                            llvm::DICompositeType *RecordTy);
 
   /// If the C++ class has vtable info then insert appropriate debug
   /// info entry in EltTys vector.
   void CollectVTableInfo(const CXXRecordDecl *Decl, llvm::DIFile *F,
                          SmallVectorImpl<llvm::Metadata *> &EltTys,
                          llvm::DICompositeType *RecordTy);
+
+  void CollectArgABIInfo(const CXXRecordDecl *Decl,
+                         llvm::DICompositeType *RecordTy);
   /// @}
 
   /// Create a new lexical block node and push it on the stack.
   void CreateLexicalBlock(SourceLocation Loc);
 
 public:
   CGDebugInfo(CodeGenModule &CGM);
   ~CGDebugInfo();

lib/CodeGen/CGDebugInfo.cpp

static unsigned getDwarfCC(CallingConv CC) {
   case CC_PreserveMost:
   case CC_PreserveAll:
   case CC_X86RegCall:
     return 0;
   }
   return 0;
 }
 
+static llvm::dwarf::CallingConvention getArgABI(const CodeGenModule &CGM,
+                                                const CXXRecordDecl *CXXDecl) {
+  switch (CGM.getCXXABI().getRecordArgABI(CXXDecl)) {
+  case CGCXXABI::RAA_Default:
+    return llvm::dwarf::DW_CC_pass_by_value;
+  case CGCXXABI::RAA_Indirect:
+    return llvm::dwarf::DW_CC_pass_by_reference;
+  case CGCXXABI::RAA_DirectInMemory:
+    // DWARFv5 doesn't specify explicit DW_CC_* value for this case,
+    // thus we just return 'normal' here.
+    return llvm::dwarf::DW_CC_normal;
+  }
+  return llvm::dwarf::DW_CC_normal;
+}
+
 llvm::DIType *CGDebugInfo::CreateType(const FunctionType *Ty,
                                       llvm::DIFile *Unit) {
   SmallVector<llvm::Metadata *, 16> EltTys;
 
   // Add the result type at least.
   EltTys.push_back(getOrCreateType(Ty->getReturnType(), Unit));
 
   // Set up remainder of arguments if there is a prototype.
void CGDebugInfo::CollectVTableInfo(const CXXRecordDecl *RD, llvm::DIFile *Unit,
 
   unsigned Size = CGM.getContext().getTypeSize(CGM.getContext().VoidPtrTy);
   llvm::DIType *VPtrMember = DBuilder.createMemberType(
       Unit, getVTableName(RD), Unit, 0, Size, 0, 0,
       llvm::DINode::FlagArtificial, VPtrTy);
   EltTys.push_back(VPtrMember);
 }
 
+void CGDebugInfo::CollectArgABIInfo(const CXXRecordDecl *Decl,
+                                    llvm::DICompositeType *RecordTy) {
+  DBuilder.replaceArgABI(RecordTy, getArgABI(CGM, Decl));
+}
+
 llvm::DIType *CGDebugInfo::getOrCreateRecordType(QualType RTy,
                                                  SourceLocation Loc) {
   assert(DebugKind >= codegenoptions::LimitedDebugInfo);
   llvm::DIType *T = getOrCreateType(RTy, getOrCreateFile(Loc));
   return T;
 }
 
 llvm::DIType *CGDebugInfo::getOrCreateInterfaceType(QualType D,
llvm::DIType *CGDebugInfo::CreateTypeDefinition(const RecordType *Ty) {
   // Note: The split of CXXDecl information here is intentional, the
   // gdb tests will depend on a certain ordering at printout. The debug
   // information offsets are still correct if we merge them all together
   // though.
   const auto *CXXDecl = dyn_cast<CXXRecordDecl>(RD);
   if (CXXDecl) {
     CollectCXXBases(CXXDecl, DefUnit, EltTys, FwdDecl);
     CollectVTableInfo(CXXDecl, DefUnit, EltTys, FwdDecl);
+    CollectArgABIInfo(CXXDecl, FwdDecl);
   }
 
   // Collect data fields (including static variables and any initializers).
   CollectRecordFields(RD, DefUnit, EltTys, FwdDecl);
   if (CXXDecl)
     CollectCXXMemberFunctions(CXXDecl, DefUnit, EltTys, FwdDecl);
 
   LexicalBlockStack.pop_back();

test/CodeGenCXX/debug-info-type-calling-conventions.cpp

+// RUN: %clang_cc1 %s -dwarf-version=5 -std=c++11 -debug-info-kind=limited -emit-llvm -o - | FileCheck %s
+
+struct DefaultDtor {
+  ~DefaultDtor() = default;
+};
+
+void f(DefaultDtor arg) {}
+
+// CHECK: !DICompositeType({{.*}}name: "DefaultDtor"{{.*}}argABI: DW_CC_pass_by_value
+
+class UserDtor {
+public:
+  ~UserDtor() {}
+};
+
+void f(UserDtor arg) {}
+
+// CHECK: !DICompositeType({{.*}}name: "UserDtor"{{.*}}argABI: DW_CC_pass_by_reference