International Business Machines Corporation

Albert Thomas Williams

Hung Qui Le

Francis Patrick O'Connell

John Barry Griswell, Jr

Dung Q Nguyen

William Elton Burky

William John Starke

Rajiv V Joshi

Jeffrey A Stuecheli

Wei Hwang

Bradly George Frey

Cathy May

Edward John Silha

Eric Jason Fluhr

Balaram Sinharoy

Christopher Michael Abernathy

Kurt Alan Feiste

David Andrew Schroter

Sean Michael Carey

Adil Bhanji

Walter H Henkels

Richard E Fry

Jack DiLullo

Vern Anthony Victoria

Bjorn P Christensen

Walter Harvey Henkels, Deceased

James Albert Van Norstrand, Jr

Prashant D Joshi

Don Richard Rozales

A modeling system includes a processor with software that performs static timing analysis (STA) on a design model. STA software executes a static timing analysis (STA) run with shortened clock cycles to model full cycle clock variability. Designers or other entities interpret the results of the shortened STA run data by performing modeling on the output data to generate slack data for design model data paths. STA software executes an STA run with an extended clock cycle to automatically separate half cycle data path (HCDP) slack data from full cycle data path (FCDP) slack data. The full and half cycle clock variability method may automatically adjust slack data for all half cycle data paths (HCDP)s to account for the additional half cycle variation (AHCV) and half cycle clock edge variability that may penalize the design model results in a real hardware implementation.

Modeling full and half cycle clock variability

An information handling system includes a processor that may perform issue queue virtual load/store instruction operations. The issue queue maintains load and store instructions with a real/virtual dependency flag. The issue queue provides storage resources for real and virtual load/store instructions. Real load/store instructions execute in a load store unit LSU. Virtual load/store instructions are pending execution in the LSU. The LSU may keep track of each virtual load/store instruction within the issue queue by thread, type, and pointer data. Provided that all dependencies are clear for a pending virtual load/store instruction, the LSU marks the pending virtual load/store instruction as real. The pending virtual load/store instruction may then issue to the LSU as a real load/store instruction.

Information handling system with real and virtual load/store instruction issue queue

A method of prefetching data in a microprocessor includes identifying a data stream associated with a process and determining a depth associated with the data stream based upon prefetch factors including the number of currently concurrent data streams and data consumption rates associated with the concurrent data streams. Data prefetch requests are allocated with the data stream to reflect the determined depth of the data stream. Allocating data prefetch requests may include allocating prefetch requests for a number of cache lines away from the cache line currently being referenced, wherein the number of cache lines is equal to the determined depth. The method may include, responsive to determining the depth associated with a data stream, configuring prefetch hardware to reflect the determined depth for the identified data stream. Prefetch control bits in an instruction executed by the processor control the prefetch hardware configuration.

Data stream prefetching in a microprocessor

In a microprocessor having a load/store unit and prefetch hardware, the prefetch hardware includes a prefetch queue containing entries indicative of allocated data streams. A prefetch engine receives an address associated with a store instruction executed by the load/store unit. The prefetch engine determines whether to allocate an entry in the prefetch queue corresponding to the store instruction by comparing entries in the queue to a window of addresses encompassing multiple cache blocks, where the window of addresses is derived from the received address. The prefetch engine compares entries in the prefetch queue to a window ofcontiguous cache blocks. The prefetch engine suppresses allocation of a new entry when any entry in the prefetch queue is within the address window. The prefetch engine further suppresses allocation of a new entry when the data address of the store instruction is equal to an address in a border area of the address window.

Store stream prefetching in a microprocessor

In a microprocessor having a load/store unit and prefetch hardware, the prefetch hardware includes a prefetch queue containing entries indicative of allocated data streams. A prefetch engine receives an address associated with a store instruction executed by the load/store unit. The prefetch engine determines whether to allocate an entry in the prefetch queue corresponding to the store instruction by comparing entries in the queue to a window of addresses encompassing multiple cache blocks, where the window of addresses is derived from the received address. The prefetch engine compares entries in the prefetch queue to a window of 2contiguous cache blocks. The prefetch engine suppresses allocation of a new entry when any entry in the prefetch queue is within the address window. The prefetch engine further suppresses allocation of a new entry when the data address of the store instruction is equal to an address in a border area of the address window.

A method and processor for performing on-demand scratch register reallocation by dynamically adjusting the number of scratch registers from within the pool of rename registers includes initially allocating from a set of physical registers one or more architected registers and a pool of one or more rename registers and allocating from the pool of rename registers an initial number of scratch registers for storing microcode operands. In response to detecting that a fetched instruction requires an additional scratch register beyond the initial number, a selected physical register is reallocated from among the pool of rename registers as the additional scratch register, and a flag is set to indicate the rename register is allocated as the additional scratch register. In response to determining that the additional scratch register is no longer needed, the additional scratch register is deallocated and the flag is reset, such that the selected physical register returns to the pool of rename registers.

Method and system for on-demand scratch register renaming

A circuit and method provide rename register reallocation for simultaneous multi-threaded (SMT) processors that redistributes rename (mapped) resources between one thread during single-threaded (ST) execution and multiple threads during multi-threaded execution. The processor receives an instruction specifying a transition from a single-threaded to a multi-threaded mode or vice-versa and halts execution of all threads executing on the processor. The internal control logic then signals the resources to reallocate the resources. Rename resources are reallocated by directing an action at the rename mapper. When switching from SMT to ST mode, the mapper is directed to drop entries for the dying thread, but on a switch from ST to SMT mode, 'dummy' instruction group dispatch indications are sent to the mapper that indicate use of all architected registers for each thread.

Method and logical apparatus for rename register reallocation in a simultaneous multi-threaded (SMT) processor

A hardware design technique allows checking of design system language (DSL) specification of an element and schematics of large macros with embedded arrays and registers. The hardware organization reduces CPU time for logical verification by exponential order of magnitude without blowing up a verification process or logic simulation. The hardware organization consists of horizontal word level rather than bit level. A memory array cell comprises a pair of cross-coupled inverters forming a first latch for storing data. The first latch has an output connected to a read bit line. True and complement write word and bit line input to the first latch. A first set of pass gates connects between the true and complement write word and bit line inputs via gates and the input of said first latch. The first set of pass gates is responsive to a first clock via a second pass gate. A pair of cross-coupled inverters forms a second latch of a Level Sensitive Scan Design (LSSD). The second latch has output connected to an LSSD output for design verification. A second pass gate connects between the output of the first set of pass gates and the input of said first latch. The second pass gate is responsive to said first clock. A third pass gate connects between the output of said first latch and the input of said second latch. The third pass gate is responsive to a second clock. The first and second clocks are responsive to a black boxing process for incremental verification.

Provably correct storage arrays

An apparatus for integer exception register (XER) renaming and methods of using the same are implemented. In a central processing unit (CPU) having a pipelined architecture, integer instructions that use or update the XER may be executed out-of-order using the XER renaming mechanism. Any instruction that updates the XER has an associated instruction identifier (IID) stored in a register. Subsequent instructions that use data in the XER use the stored IID to determine when the XER data has been updated by the execution of the instruction corresponding to the stored IID. As each instruction that updates XER data is executed, the data is stored in an XER rename buffer. Instructions using XER data then obtain the updated, valid, XER data from the rename buffer. In this way, these instructions can obtain valid XER data prior to completion of the preceding instructions. The XER data is retrieved from the XER rename buffer by indexing into the buffer by using an index derived from the stored IID. Because the updated XER data is available in the rename buffer before the updating instruction completes, out-of-order execution of instructions using or updating XER data is thereby realized.

Data processing system having an apparatus for exception tracking during

A hardware design technique allows checking of design system language (DSL) specification of an element and schematics of large macros with embedded arrays and registers. The hardware organization reduces CPU time for logical verification by exponential order of magnitude without blowing up a verification process or logic simulation. The hardware organization consists of horizontal word level rather than bit level. Using the elimination process for elements which are difficult to be extracted in Boolean form the logic around and inside a memory structure can be verified. The resultant register array hardware organization can be verified to all pins and nets up to the storage element.

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Austin, TX, United States of America

Albert Thomas Williams