Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Multiple Execution Unit Store Bypass

IP.com Disclosure Number: IPCOM000105048D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Ray, DS: AUTHOR [+2]

Abstract

Multiple Execution unit Store bypass is disclosed. Cycles are saved by bypassing the result from one execution unit to a store in another execution unit during the same cycle.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 94% of the total text.

Multiple Execution Unit Store Bypass

      Multiple Execution unit Store bypass is disclosed.  Cycles are
saved by bypassing the result from one execution unit to a store in
another execution unit during the same cycle.

      High performance multiple execution unit computers require
careful partitioning to have fast cycle times.  An organization of a
machine which will allow an operation which feeds a store to execute
in parallel is highly desirable to obtain the highest cpi (cycles per
instruction) without degrading cycle time.

      In this implementation, there are two execution units with
separate decodes and dataflows.  This particular implementation also
has a dual ported cache directory and cache.  The organization is
arranged such that two operations can proceed in parallel at the
shortest cycle time possible.  One feature allowed by this
organization is the ability of an operation in the left unit feeding
a store in the right unit.  In the drawing attached the machine
organization is shown which supports the following operation in
parallel in the same cycle.

   add  RT, RA, RB             ;RT  <== RA + RB
 store  RT, RA', RB'           ;memory(RA' + RB') <== RT

      In this example, the add would go in the left execution unit.
The store would go in the right execution unit.  The control logic
would detect a dependency of the store on the add and would select
the path from the left execution unit instead of the...