Sun Microsystems, Inc.

Julie M Staraitis

Spencer Montgomery Gold

Jason Eisenberg

Marc E Lamere

Micah C Knapp

Sudarshan Kadambi

Poonacha P Kongetira

Atul Kalambur

Daniel L Liebholz

Masooma Bhiawala

Julian A Prabhu

If a consumer instruction specifies a 64 bit source register comprised of results provided by two 32 bit producer instructions, the number of dependencies that must be tracked per source register can be decreased by transforming one or more of the 32 bit producer instructions so that rather than simply storing its result in a 32 bit destination register, the transformed instruction stores its result into a 64 bit logical register along with another 32 bit value held in another 32 bit register.

Storing results of producer instructions to facilitate consumer instruction dependency tracking

The present invention provides methods and memory structures for efficient tracking and recycling of physical register assignments. The disclosed methods and memory structures each provide an approach to reduce the size of the memory structures needed to track the usage of the physical registers and the recycling of these registers.

Method and system for tracking and recycling physical register assignment

A method and apparatus is provided for restoring a free physical register list to its previous state without having to physically restore any data. The method and semiconductor device utilizes sets of pointers to manage physical register pointers in the physical register list. The physical register list is able to independently track physical registers for multiple threads of a multithreading microprocessor.

Flushable free register list having selected pointers moving in unison

A superscalar processor having a content addressable memory structure that transmits a first and second output signal is presented. The superscalar processor performs out of order processing on an instruction set. From the first output signal, the dependencies between currently fetched instructions of the instruction set and previous in-flight instructions can be determined and used to generate a dependency matrix for all in-flight instructions. From the second output signal, the physical register addresses of the data required to execute an instruction, once the dependencies have been removed, may be determined.

Superscalar processor having content addressable memory structures for determining dependencies

A memory array includes a plurality of memory cells logically arranged in M rows and N columns, wherein N is the number of memory cells per word of digital information and M is the number of words within the array. A plurality of N data output lines are associated with each of the N columns of the array for selectively retrieving output data from a word located at a predetermined word address in the array. Each data output line is selectively shared by each of the M memory cells within its associated column. Each of the cell output lines of the M memory cells in each of the N columns are logically OR-ed together to provide the output data retrieved by each data output line associated with each of the N columns.

System and method for accessing a memory array which tolerates non-exclusive read select enables

A memory cell is provided to store a speculative data value until either a later speculative data value is generated or until the stored speculative data is determined to be the desired data, e.g. no longer speculative. At such time, the invention allows the stored speculative data to quickly and easily be stored as permanent data and further speculative data values to be stored.

Two-stage memory cell

The present invention provides a memory array having an array structure that has at least one memory cell, including a word write bit line and a single transfer line. The memory array is also provided with a two-stage memory cell having a speculative storage node, a non-speculative storage node, and a circuit. The two-stage memory cell is electrically coupled to the array structure. Activation of the circuit causes a speculative data value stored in the speculative storage node to be written to the non-speculative storage node.

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Ayer, MA, United States of America

Julie M Staraitis