System and method for assisting exact Garbage collection by segregating the contents of a stack into sub stacks
US5903899A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 23, 1997 |
| Grant date | May 11, 1999 |
| Priority date | — |
| Expiry date | Apr 23, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99957
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a program data stack in a computer system, every stack is implemented as two substacks, one to contain references and one to contain primitive data. In this manner, whether a piece of information on a stack is a reference or a primitive value is easily determined according to which substack it resides in. Each substack is itself a full-fledged stack data structure with a stack base, a stack pointer, and a stack limit. In the preferred embodiment, there is also a frame pointer for each substack. The normal instruction set is modified so that instructions that operate with references use the reference stack whereas instructions that operate with data use the primitive data stack. Specifically, during compilation, or loading, all instructions which can operate indiscriminately with either references or data are replaced by equivalent, but reference-specific or data-specific instructions. With this arrangement, garbage collection algorithms can locate all references stored within a stack, since the references are all in a more or less contiguous region of memory without interspersed primitive data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.