[DebugInfo] Support for DW_AT_associated and DW_AT_allocated.

Summary:
This support is needed for the Fortran array variables with pointer/allocatable
attribute. This support enables debugger to identify the status of variable
whether that is currently allocated/associated.

  for pointer array (before allocation/association)
  without DW_AT_associated

(gdb) pt ptr
type = integer (140737345375288:140737354129776)
(gdb) p ptr
value requires 35017956 bytes, which is more than max-value-size

  with DW_AT_associated

(gdb) pt ptr
type = integer (:)
(gdb) p ptr
$1 = <not associated>

  for allocatable array (before allocation)

  without DW_AT_allocated

(gdb) pt arr
type = integer (140737345375288:140737354129776)
(gdb) p arr
value requires 35017956 bytes, which is more than max-value-size

  with DW_AT_allocated

(gdb) pt arr
type = integer, allocatable (:)
(gdb) p arr
$1 = <not allocated>

    Testing
- unit test cases added
- check-llvm
- check-debuginfo

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D83544

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

@@ -1350,7 +1350,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     break;
   }
   case bitc::METADATA_COMPOSITE_TYPE: {
-    if (Record.size() < 16 || Record.size() > 18)
+    if (Record.size() < 16 || Record.size() > 20)
       return error("Invalid record");
 
     // If we have a UUID and this is not a forward declaration, lookup the
@@ -1375,6 +1375,8 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     Metadata *TemplateParams = nullptr;
     Metadata *Discriminator = nullptr;
     Metadata *DataLocation = nullptr;
+    Metadata *Associated = nullptr;
+    Metadata *Allocated = nullptr;
     auto *Identifier = getMDString(Record[15]);
     // If this module is being parsed so that it can be ThinLTO imported
     // into another module, composite types only need to be imported
@@ -1399,13 +1401,18 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
         Discriminator = getMDOrNull(Record[16]);
       if (Record.size() > 17)
         DataLocation = getMDOrNull(Record[17]);
+      if (Record.size() > 19) {
+        Associated = getMDOrNull(Record[18]);
+        Allocated = getMDOrNull(Record[19]);
+      }
     }
     DICompositeType *CT = nullptr;
     if (Identifier)
       CT = DICompositeType::buildODRType(
           Context, *Identifier, Tag, Name, File, Line, Scope, BaseType,
           SizeInBits, AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
-          VTableHolder, TemplateParams, Discriminator, DataLocation);
+          VTableHolder, TemplateParams, Discriminator, DataLocation, Associated,
+          Allocated);
 
     // Create a node if we didn't get a lazy ODR type.
     if (!CT)
@@ -1413,7 +1420,8 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
                            (Context, Tag, Name, File, Line, Scope, BaseType,
                             SizeInBits, AlignInBits, OffsetInBits, Flags,
                             Elements, RuntimeLang, VTableHolder, TemplateParams,
-                            Identifier, Discriminator, DataLocation));
+                            Identifier, Discriminator, DataLocation, Associated,
+                            Allocated));
     if (!IsNotUsedInTypeRef && Identifier)
       MetadataList.addTypeRef(*Identifier, *cast<DICompositeType>(CT));