International Business Machines Corporation

Stephen Michael Conor

Paul David Kartschoke

Stephen William Mahin

Stephen J Ciavaglia

Lyman Henry Moulton, Iii

Stephen Emery Rich

A mechanism which manages variable length instructions in cache is comprised of three cooperating elements designed to optimize self modifying code and anticipate next instructions for branch operand management. A content addressable memory (CAM) stores addresses of lines which have been accessed for instruction fetching. In a system having modifiable instruction stream (i.e., store to instruction stream), when the CAM matches, the system must retire certain instructions, flush instructions and then fetch the modified instruction stream. Boundary identification logic examines a field in each cache byte to determine the nature of the byte. This field is initially cleared at the time the cache line is loaded and filled with the line is fetched. An anticipation buffer designed to minimize the circuitry necessary for fetches across cache lines is loaded with sequentially anticipated prefetched instructions from the cache. These anticipated instructions can then be concatenated by a fetch aligner.

Superscaler instruction pipeline having boundary identification logic

Superscaler instruction pipeline having boundary indentification logic

Superscalar instruction pipeline using alignment logic responsive to

Growing community of inventors

Essex Junction, VT, United States of America

Stephen Michael Conor