[Dwarf] DW_TAG_unspecified_type is a type tag.

[JDevlieghere]

Summary

This fixes an incorrect verifier error for a DW_AT_type pointing to DW_TAG_unspecified_type.

error: DIE has DW_AT_type with incompatible tag DW_TAG_unspecified_type

rdar://54059283

[probinson]

This doesn't seem complete. And it's hard to tell, because the list is mostly but not entirely in numeric order.
Mostly it's missing the new v5 type tags (coarray, dynamic, atomic, immutable) which is probably my fault, but some older ones also appear to be missing (restrict, shared).

[aprantl]

FYI. You can derive the complete list by scanning for DW_AT_type in DWARF 5 Appendix A, Table A.1.

[probinson]

In D65914#1621248, @aprantl wrote:

FYI. You can derive the complete list by scanning for DW_AT_type in DWARF 5 Appendix A, Table A.1.

? not really. Any tag that is a type qualifier will have DW_AT_type, but also anything else that simply has a type (DW_TAG_constant, etc).

I do think that the regex DW_TAG_*_type will find all of them.

[aprantl]

In D65914#1621427, @probinson wrote:

In D65914#1621248, @aprantl wrote:

FYI. You can derive the complete list by scanning for DW_AT_type in DWARF 5 Appendix A, Table A.1.

? not really. Any tag that is a type qualifier will have DW_AT_type, but also anything else that simply has a type (DW_TAG_constant, etc).

I do think that the regex DW_TAG_*_type will find all of them.

I'm probably misunderstanding something here, but DW_TAG_constant *is* listed in Appendix A as allowing a DW_AT_type attribute, so are all the DW_TAG_*_type tags.

[probinson]

In D65914#1621471, @aprantl wrote:

In D65914#1621427, @probinson wrote:

In D65914#1621248, @aprantl wrote:

FYI. You can derive the complete list by scanning for DW_AT_type in DWARF 5 Appendix A, Table A.1.

? not really. Any tag that is a type qualifier will have DW_AT_type, but also anything else that simply has a type (DW_TAG_constant, etc).

I do think that the regex DW_TAG_*_type will find all of them.

I'm probably misunderstanding something here, but DW_TAG_constant *is* listed in Appendix A as allowing a DW_AT_type attribute, so are all the DW_TAG_*_type tags.

is-a versus has-a? We want the isType(Tag T) predicate to return true for the tags that DW_AT_type is allowed to *point to* (i.e. whether the tag is-a type), not those tags that permit DW_AT_type as an attribute (i.e., those that have-a type).

[aprantl]

Got it! I misunderstood the purpose of this function.

[JDevlieghere]

Add missing type tags and sort the list alphabetically.

[aprantl]

llvm/include/llvm/BinaryFormat/Dwarf.h

118

Looking at the LHS, I think that the list was *meant* to be sorted by encoding value (cf. Table 7.3) which could make it easier to check whether some new group of TAGs have been added. I'm fine either way... Alphabetical also has its advantages.

[aprantl]

llvm/include/llvm/BinaryFormat/Dwarf.h

118

The *nicest* way to implement this might be to add a new IS_TYPE field to the TAG macro in Dwarf.def and then generate this switch statement.

[JDevlieghere]

Make type part of the def file.

[aprantl]

Neat. Thanks!

llvm/include/llvm/BinaryFormat/Dwarf.h

#include "llvm/BinaryFormat/Dwarf.def"
   DW_TAG_lo_user = 0x4080,
   DW_TAG_hi_user = 0xffff,
   DW_TAG_user_base = 0x1000 ///< Recommended base for user tags.
 };
 
 inline bool isType(Tag T) {
   switch (T) {
   case DW_TAG_array_type:
+  case DW_TAG_atomic_type:
+  case DW_TAG_base_type:
   case DW_TAG_class_type:
-  case DW_TAG_interface_type:
+  case DW_TAG_coarray_type:
+  case DW_TAG_const_type:
+  case DW_TAG_dynamic_type:
   case DW_TAG_enumeration_type:
+  case DW_TAG_file_type:
+  case DW_TAG_immutable_type:
+  case DW_TAG_interface_type:
+  case DW_TAG_packed_type:
   case DW_TAG_pointer_type:
+  case DW_TAG_ptr_to_member_type:
   case DW_TAG_reference_type:
+  case DW_TAG_restrict_type:
   case DW_TAG_rvalue_reference_type:
+  case DW_TAG_set_type:
+  case DW_TAG_shared_type:
   case DW_TAG_string_type:
   case DW_TAG_structure_type:
+  case DW_TAG_subrange_type:
   case DW_TAG_subroutine_type:
+  case DW_TAG_thrown_type:
+  case DW_TAG_typedef:
   case DW_TAG_union_type:
-  case DW_TAG_ptr_to_member_type:
-  case DW_TAG_set_type:
-  case DW_TAG_subrange_type:
-  case DW_TAG_base_type:
-  case DW_TAG_const_type:
-  case DW_TAG_file_type:
-  case DW_TAG_packed_type:
+  case DW_TAG_unspecified_type:
   case DW_TAG_volatile_type:
-  case DW_TAG_typedef:
     return true;
   default:
     return false;
   }
 }
 
 /// Attributes.
 enum Attribute : uint16_t {

llvm/test/DebugInfo/X86/template.ll

 ; REQUIRES: object-emission
 
 ; RUN: llc -mtriple=x86_64-linux -O0 -filetype=obj < %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: llc -mtriple=x86_64-linux -O0 -filetype=obj < %s | not llvm-dwarfdump -verify - | FileCheck %s --check-prefix VERIFY
 
 ; IR generated with `clang++ -g -emit-llvm -S` from the following code:
 ; template<int x, int*, template<typename> class y, decltype(nullptr) n, int ...z>  int func() {
 ;  var<int> = 5;
 ;  return var<int>;
 ; }
 ; template<typename> struct y_impl { struct nested { }; };
 ; int glbl = func<3, &glbl, y_impl, nullptr, 1, 2>();
 ; y_impl<int>::nested n;
 
+; VERIFY-NOT: error: DIE has DW_AT_type with incompatible tag DW_TAG_unspecified_type
+; VERIFY: error: DIEs have overlapping address ranges
+
 ; CHECK: [[INT:0x[0-9a-f]*]]:{{ *}}DW_TAG_base_type
 ; CHECK-NEXT: DW_AT_name{{.*}} = "int"
 
 ; CHECK: DW_TAG_structure_type
 ; CHECK: DW_AT_name{{.*}}"y_impl<int>"
 ; CHECK-NOT: {{TAG|NULL}}
 ; CHECK: DW_TAG_template_type_parameter