OT Bytecode Attributes

These pages describe the bytecode attributes which are generated by the OT/J compiler to hold all that information that cannot be directly translated to normal Java bytecode.

Most of this information is needed by the Object Teams Runtime Environment (OTRE) in order to perform its loadtime bytecode transformations.

Some information is used by the compiler when reading pre-compiled teams and roles.

General notes

As in the Java Virtual Machine Specification (§4) the format of attributes is specified by pseudo-structures written in a C-like struct notation.

Attributes are used in the ClassFile (JVM Spec. §4.1), field_info (JVM Spec. §4.5), method_info (JVM Spec. §4.6), and Code_attribute (JVM Spec. §4.7.3) structures of the class file format. All attributes have the following general format:

    attribute_info {
        u2 attribute_name_index;
        u4 attribute_length;
        u1 info[attribute_length];
    }

In the following the value of every item_name_index item must be a valid index into the constant_pool table, and the entry at that index must be a CONSTANT_Utf8_info (JVM Spec. §4.4.7) structure denoting the item_name info.

(This documentation is work in progress)

TODO:

• mention otlistclass

Full list of attributes

In the following list a mark OTRE indicates an attribute that is used by the OTRE and Compiler indicates an attribute that the compiler uses when reading a compiled class file of a team or role type.

Attribute	OTRE	Compiler	remark
AnchorUsageRanks		X
BaseClassTags			obsolete since 1.4.0 / 0.7.0, fully removed in 0.7.1
BoundClassesHierarchy	X
CallinFlags	X	X
CallinMethodMappings	X	X
CallinParamMappings	X
CallinPrecedence	X	X
CallinRoleBaseBindings	X
CalloutMappings		X
CopyInheritanceSrc		X
InheritedRoles	X
Modifiers		X
OTDynCallinBindings	(OTDyn)		only used by ASM-based new dynamic OTRE
OTClassFlags	X	X
OTCompilerVersion	X	X
OTSpecialAccess	X	X
PlayedBy	X	X
ReferencedTeams	X
RoleFiles		X
RoleLocalTypes		X
SourceDebugExtension			Debugger only
StaticReplaceBindings	X

Team level attributes

• /BaseClassTags
• /BoundClassesHierarchy
• /CallinPrecedence
• /CallinRoleBaseBindings
• /OTClassFlags
• /OTSpecialAccess

Role level attributes

• /CallinMethodMappings
• /OTClassFlags
• /PlayedBy

Other types level attributes

• /ReferencedTeams

Method level attributes

• /CallinFlags
• /CallinParamMappings
• /Modifiers

Field level attributes

• /AnchorUsageRanks
• /Modifiers

Multi level attributes

• /OTClassFlags
• /OTSpecialAccess

Change History

Changed in version 0.7.1

• Base type reference in /CallinRoleBaseBindings may use the prefix "^" to denote an interface.
• Fully removed obsolete attribute /BaseClassTags

Changed in version 0.7.0

none

Changed in version 1.4.0 (from objectteams.org)

• /CallinMethodMappings: obsolete flag QUERY has been removed

Changed in version 1.3.2 (from objectteams.org)

• New attribute /AnchorUsageRanks

Changed in version 1.3.1 (from objectteams.org)

none