TYPE DESCRIPTOR MANAGEMENT FOR FROZEN OBJECTS

• US 20100058304A1
• Filed: 09/03/2008
• Published: 03/04/2010
• Est. Priority Date: 09/03/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Martin, Rudi, Pardoe, Andrew, Dussud, Patrick H., Magruder, Michael M., Hall, Simon J., Sollich, Peter F., Talluri, Madhusudhan, Peschel-Gallee, Frank V., Mosier, Scott D.
• Granted Patent: US 8,316,357 B2
• Time in Patent Office: Days
• US Class Current: 717/159
• CPC Class Codes: G06F 8/315 Object-oriented languages
• CPC Class Codes: G06F 8/437 Type checking
• CPC Class Codes: G06F 9/44557 Code layout in executable memory

Abstract

The efficient use of type descriptors with frozen objects. A frozen object might actually include several type descriptors, a primary type descriptor that is canonical according to a set of canonicalization rules, and an auxiliary type descriptor that is not identical to the primary type descriptor. The auxiliary type descriptor may be used to access the canonical type descriptor. When performing an operation, if the auxiliary type descriptor can be used to perform the operation, then that auxiliary type descriptor may be used. If the canonical type descriptor is to be used to perform the operation, the auxiliary type descriptor is used to gain access to the canonical primary type descriptor. The primary type descriptor is then used to perform the operation.

Claims

1. A computer program product comprising one or more computer-readable media having thereon an executable module, the executable module comprising:

a frozen object that is an instance of a type canonically described by a canonical type descriptor that conforms to a set of canonicalization rules;

an auxiliary type descriptor that is not identical to the canonical type descriptor, but that also serves as a type descriptor for the frozen object, at least for some of operations that use type descriptors for the type;

wherein the frozen object is directly or indirectly associated with the auxiliary type descriptor and the canonical type descriptor.

2. A computer program product in accordance with claim 1, wherein the one or more computer-readable media is physical memory and/or storage media.

3. A computer program product in accordance with claim 2, wherein the canonical type descriptor is not present within the executable module.

4. A computer program product in accordance with claim 3, wherein the canonical type descriptor is present on the computer program product.

5. A computer program product in accordance with claim 2, wherein the frozen object is associated with the auxiliary type descriptor by including a pointer that points to the auxiliary type descriptor.

6. A computer program product in accordance with claim 2, wherein the indirection component is a component that may be written to at run-time to thereby cause the indirection component to point to the canonicalized type descriptor without causing the indirection component or a portion thereof to become private.

7. A computer program product in accordance with claim 2, wherein the indirection component is a component that may be written to once at run-time to thereby cause the indirection component to point to the canonicalized type descriptor without causing the indirection component or a portion thereof to become private.

8. A computer program product in accordance with claim 2, wherein the indirection component is an import address table.

9. A method for performing one or more type operations using a plurality of type descriptions corresponding to the frozen object, the plurality of type descriptions including a canonical type descriptor that conforms to a set of canonicalization rules, the method comprising:

for a first set of one of more operations, an act of determining that the auxiliary type descriptor will be sufficient to perform the operation, and an act of using the auxiliary type descriptor, and not the canonical type descriptor, to perform the operation; and

for a second set of one or more operations, an act of determining that the auxiliary type descriptor will not be sufficient to perform the operation, an act of using the auxiliary type descriptor to access the canonical type descriptor; and

an act of using the canonical type descriptor to perform the operation.

10. A method in accordance with claim 9, wherein the act of using the auxiliary type descriptor to access the canonical type descriptor comprises:

an act of accessing a pointer within the auxiliary type descriptor, wherein the pointer points directly or indirectly to the canonical type descriptor.

11. A method in accordance with claim 9, wherein the act of using the auxiliary type descriptor to access the canonical type descriptor comprises:

an act of accessing a pointer within the auxiliary type descriptor, wherein the pointer points directly or indirectly to an indirection component that includes a pointer that points directly or indirectly to the canonical type descriptor; and

an act of using the pointer that is in the indirection component to access the canonical type descriptor.

12. A method in accordance with claim 11, further comprising an act of preparing to use the indirection component to allow access to the canonical type descriptor.

13. A method in accordance with claim 12, wherein the act of preparing comprises:

an act of determining a type that corresponds to the indirection component;

an act of determining that the type corresponds to the canonical type descriptor; and

an act of modifying the indirection component to include the pointer to the canonical type descriptor.

14. A method in accordance with claim 9, wherein at least one of the second set of operations includes a comparison of a type of the frozen object to the type of another object.

15. A method in accordance with claim 9, wherein at least one of the first set of operations requires that there only be one level of indirection between the frozen object and the type descriptor that is used to perform the operation.

16. A method in accordance with claim 9, wherein at least one of the first set of operations is a virtual-call operation.

17. A method in accordance with claim 9, wherein at least one of the first set of operations is an interface-call operation.

18. A computer program product comprising one or more computer-readable media having thereon the following:

a defining module that includes a first compiled image that contains a primary type description corresponding to a type;

a referring module that includes a second compiled image that contains a frozen object, an auxiliary type descriptor, and an association between the frozen object and the auxiliary type descriptor;

an indirection component through which the auxiliary type descriptor is associated with the primary type descriptor; and

an operations management component that is configured to determine whether the auxiliary type descriptor is sufficient to perform an operation, or whether the primary type descriptor is need to perform the operation, and if it is determined that the primary type descriptor is needed, using the auxiliary type descriptor to locate and access the primary type descriptor through the indirection component.

19. A computer program product in accordance with claim 18, wherein the one or more computer-executable instructions is/are physical memory and/or storage media.

20. A computer program product in accordance with claim 19, wherein the indirection component may be modified at least once without making any portion of the indirection component private.