Design of tags for lookup of non-volatile registers

• US 6,119,206 A
• Filed: 07/12/1996
• Issued: 09/12/2000
• Est. Priority Date: 02/12/1996
• Status: Expired due to Term

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Miller, Terrence C., Delagi, Bruce A., Tatkar, Vijay K., Zucker, Joel Steven
• Primary Examiner(s): Cabeca, John W.
• Assistant Examiner(s): RANSOM, DAVID BRYAN
• Application Number:
  US08/680,575
• Time in Patent Office: 1,523 Days
• Field of Search: 395/200.3, 395/200.31, 395/200.32, 395/200.34, 395/200.35, 395/200.43, 395/200.45, 395/672, 395/674, 711/147, 711/165, 711/202, 711/203, 711/209, 711/170, 767/2, 702/101
• US Class Current: 711/147
• CPC Class Codes: G06F 11/3612 by runtime analysis performance monitoring G06F11/3466

Abstract

Stack tracebacks are performed in debugging and exception handling routines, and involve providing the values of non-volatile registers at the time of entry into each function in a call chain. One stack traceback technique includes performing the following two steps for each virtual address at which a function call in the call chain is made: (1) locating the tag section whose virtual address range includes the virtual address; and (2) locating a tag in the tag section found in step (1), whose virtual address range includes the virtual address. The tag found in step (2) indicates which of the values, if any, respectively held by the non-volatile registers upon entry to the particular function in which the above function call is made, are stored in a stack frame for the particular function at the time of the function call.

Claims

1. A computer-implemented method for locating information that applies to a particular address in a program comprising:

locating a particular set of data that applies to a particular object, the particular object being either a primary object or a shared object that is loaded into an address space during execution of the program, each object includes a set of compiled instructions and occupies a respective address range;

determining a particular address range to which the particular set of data applies;

determining whether the particular address range includes the particular address; and

if the particular address range includes the particular address, searching the particular set of data for the information that applies to the particular address.

2. The method of claim 1, wherein the information that applies to the particular address indicates that the particular address corresponds to a particular line of source code for the program.

3. The method of claim 1, wherein the information that applies to the particular address indicates that the particular address corresponds to a particular block of source code for the program.

4. The method of claim 1, wherein the information that applies to the particular address indicates that the particular address corresponds to a particular function of the program.

5. The method of claim 1, wherein each set of data is independent of the address space of the object to which the set of data applies.

6. The method of claim 1 wherein the step of locating a particular set of data includes:

searching a linked list of structures, wherein each structure in the linked list is associated with a respective primary or shared object and is inserted into the linked list when the respective object is loaded into the address space, each structure stores information describing the set of data of the respective object, the information including the particular address range to which the set of data applies, and a second address range over which the set of data is stored;

for a particular structure, determining whether the particular address range stored in the particular structure includes the particular address; and

using the second address range stored in the particular structure to locate the particular set of data.

7. The method of claim 1 wherein the step of locating a particular set of data includes

locating a particular tag section that defines the particular set of data, the particular tag section includes one or more tags, each of the tags applies to a respective address range that is within the particular address range to which the particular set of data applies;

and

the step of searching the particular set of data includes

locating a particular tag in the particular tag section, and

determining whether the address range to which the particular tag applies includes the particular address, the particular tag indicating that one or more of the values are stored in a stack frame for a function of the program when the program is executing within the particular address range to which the particular tag applies.

8. The method of claim 7, wherein all of the tags in each tag section are independent of the address at which the object including the tag section is loaded.

9. A computer program product for locating information that applies to a particular address in a program comprising:

code for locating a particular set of data that applies to a particular object, the particular object being either a primary object or a shared object that is loaded into an address space during execution of the program, each object includes a set of compiled instructions and occupies a respective address range;

code for determining a particular address range to which the particular set of data applies;

code for determining whether the particular address range includes the particular address;

code for searching, if the particular address range includes the particular address, the particular set of data for the information that applies to the particular address; and

a computer-readable storage medium that stores the codes.

10. The product of claim 9, wherein each set of data is independent of the address space of the object to which the set of data applies.

11. The product of claim 9 wherein the code for locating a particular set of data includes:

code for searching a linked list of structures, wherein each structure in the linked list is associated with a respective primary or shared object and is inserted into the linked list when the respective objects is loaded into the address space, each structure stores information describing the set of data of the respective object, the information including the particular address range to which the set of data applies, and a second address range over which the set of data is stored;

code for determining, for a particular structure, whether the particular address range stored in the particular structure includes the particular address; and

code for using the second address range stored in the particular structure to locate the particular set of data.

12. The product of claim 9 wherein the code for locating a particular set of data includes

code for locating a particular tag section that defines the particular set of data, the particular tag section includes one or more tags, each of the tags applies to a respective address range that is within the particular address range to which the particular set of data applies;

and

the code for searching the particular set of data includes

code for locating a particular tag in the particular tag section, and

code for determining whether the address range to which the particular tag applies includes the particular address, the particular tag indicating that one or more of the values are stored in a stack frame for a function of the program when the program is executing within the particular address range to which the particular tag applies.

13. The product of claim 12, wherein all of the tags in each tag section are independent of the address at which the object including the tag section is loaded.

14. A method for retrieving, when execution of a program reaches a particular address, values of one or more non-volatile registers stored, upon entry into a function, in a stack frame, the method comprising:

locating a particular tag, the particular tag indicates that values of a non-contiguous subset of the registers, upon entry to the function, are stored in the stack frame for the function, the particular tag further indicates a particular address range to which the particular tag applies;

determining whether the particular address range includes the particular address of program execution; and

retrieving the values of the non-contiguous subset of the registers in the stack frame for the function.

15. The method of claim 14, wherein:

the particular tag contains a respective bit for each of the registers; and

for each register, the bit for the register indicates if the value of the register is stored, upon entry to the function, in the stack frame for the function.

16. A computer program product for retrieving, when execution of a program reaches a particular address, values of one or more non-volatile registers stored, upon entry into a function, in a stack frame, the product comprising:

code for locating a particular tag, the particular tag indicates that values of a non-contiguous subset of the registers upon entry to the function are stored in the stack frame for the function, the particular tag further indicates a particular address range to which the particular tag applies;

code for determining whether the particular address range includes the particular address of program execution;

code for retrieving the values of the non-contiguous subset of the registers in the stack frame for the function; and

a computer-readable storage medium that stores the codes.

17. The product of claim 16, wherein:

the particular tag contains a respective bit for each of the registers; and

for each register, the bit for the register indicates if the value of the register is stored, upon entry to the function, in the stack frame for the function.

18. A method for retrieving a value of a particular register when execution of a program reaches a particular address within a function, the method comprising:

locating a tag that indicates that values of registers are stored when the program is executing within an address range, the tag further indicates a particular address range to which the tag applies;

determining whether the particular address range includes the particular address within the function; and

retrieving the value of the particular register.

19. A computer program product for retrieving a value of a particular register when execution of a program reaches a particular address within a function, the product comprising:

code for locating a tag that indicates that values of registers are stored when the program is executing within an address range, the tag further indicates a particular address range to which the tag applies;

code for determining whether the particular address range includes the particular address within the function;

code for retrieving the value of the particular register; and

a computer-readable storage medium that stores the codes.

20. A computer-implemented method for reconstructing one or more sets of values, each set of values corresponding to a function in a function call chain, the method comprises:

locating a set of data;

determining a particular address range to which the set of data applies;

determining whether a particular program address of a particular function in the function call chain is within the particular address range;

retrieving the set of values within the set of data; and

repeating the locating, both determining, and the retrieving for all functions in the function call chain.

21. The method of claim 20, wherein:

each set of data is a tag, and each tag is implemented using a linked list structure.

22. The method of claim 21, wherein:

the linked list structures are sorted based on their associated program addresses.

23. The method of claim 20, wherein:

the set of values is representative of content of registers that have been saved.