International Business Machines Corporation

Sheldon Bernard Levenstein

Brian William Thompto

David S Levitan

Anthony Saporito

Richard James Eickemeyer

David Allen Hrusecky

Bruce Joseph Ronchetti

Scott Bruce Frommer

Dung Q Nguyen

Phillip G Williams

Christian Zoellin

Mauricio J Serrano

Guy L Guthrie

Derek E Williams

William John Starke

John Michael Borkenhagen

Brian David Barrick

Sundeep Chadha

Harry S Barowski

Rolf Sautter

David John Krolak

Andrew Henry Wottreng

Pradip Patel

Daniel Rodko

Nicholas R Orzol

Richard G Eikill

Gordon B Sapp

Christian Gerhard Zoellin

Hung Qui Le

Bryan J Lloyd

John David Irish

David A Campbell

William Thomas Flynn

Miles Robert Dooley

Michael Thomas Vaden

Niels Fricke

Eric Jason Fluhr

Joaquin Hinojosa

Rachel Flood

Jose Eduardo Moreira

Anthony Gus Aipperspach

Lixin Zhang

Albert James Van Norstrand, Jr

Charles Luther Johnson

Steven R Kunkel

Michael Joseph Corrigan

Michael Ju Hyeok Lee

Nghia Van Phan

Charles Porter Geer

Donald Lee Freerksen

Gary Michael Lippert

Lyle Edwin Grosbach

Jessica Hui-Chun Tseng

Lynn Allen McMahon

Duane Arlyn Averill

Bryan Glen Hickerson

Edelmar Seewann

James Ira Brookhouser

Terrence James Stewart

Joseph P Weigel

Technology for fusing certain load instructions and compare-immediate instructions in a computer processor having a load-store architecture with respect to transferring data between memory and registers of the computer processor. In some embodiments the load and compare-immediate instructions are consecutive. In some embodiments, the instructions are only merged if: (i) the respective RA and RT fields of the two instructions match; (ii) the immediate field of the compare-immediate instruction has a certain value, or falls within a range of certain values; and/or (iii) the instructions are received in a consecutive manner.

Microprocessor that fuses load and compare instructions

Aspects are provided for sharing instruction cache footprint between multiple threads. A set/way pointer to an instruction cache line is derived from a system memory address associated with an instruction fetch from a memory page. It is determined that the instruction cache line is shareable between a first thread and a second thread. An alias table entry is created indicating that other instruction cache lines associated with the memory page are also shareable between threads. Another instruction fetch is received from another thread requesting an instruction from another system memory address associated with the memory page. A further set/way pointer to another instruction cache line is derived from the other system memory address. It is determined that the other instruction cache line is shareable based on the alias table entry.

Sharing instruction cache footprint between multiple threads

Aspects are provided for sharing instruction cache footprint between multiple threads using instruction cache set/way pointers and a tracking table. The tracking table is built up over time for shared pages, even when the instruction cache has no access to real addresses or translation information. A set/way pointer to an instruction cache line is derived from the system memory address associated with a first thread's instruction fetch. The set/way pointer is stored as a surrogate for the system memory address in both an instruction cache directory (IDIR) and a tracking table. Another set/way pointer to an instruction cache line is derived from the system memory address associated with a second thread's instruction fetch. A match is detected between the set/way pointer and the other set/way pointer. The instruction cache directory is updated to indicate that the instruction cache line is shared between multiple threads.

Sharing instruction cache lines between multiple threads

Load store addressing can include a processor, which fuses two consecutive instruction determined to be prefix instructions and treats the two instructions as a single fused instruction. The prefix instruction of the fused instruction is auto-finished at dispatch time in an issue unit of the processor. A suffix instruction of the fused instruction and its fields and the prefix instruction's fields are issued from an issue queue of the issue unit, wherein an opcode of the suffix instruction is issued to a load store unit of the processor, and fields of the fused instruction are issued to the execution unit of the processor. The execution unit forms operands of the suffix instruction, at least one operand formed based on a current instruction address of the single fused instruction. The load store unit executes the suffix instruction using the operands formed by the execution unit.

Program counter (PC)-relative load and store addressing for fused instructions

A system, processor, and/or technique configured to: determine whether two or more load instructions are fusible for execution in a load store unit as a fused load instruction; in response to determining that two or more load instructions are fusible, transmit information to process the two or more fusible load instructions into a single entry of an issue queue; issue the information to process the two or more fusible load instructions from the single entry in the issue queue as a fused load instruction to the load store unit using a single issue port of the issue queue, wherein the fused load instruction contains the information to process the two or more fusible load instructions; execute the fused load instruction in the load store unit; and write back data obtained by executing the fused load instruction simultaneously to multiple entries in the register file.

Handling and fusing load instructions in a processor

Technology for fusing an add-immediate instruction with a load-immediate instruction (or store-immediate instruction) in a microprocessor. This can result in quicker address generation while performing a load and store operation.

Fusion to enhance early address generation of load instructions in a microprocessor

A processor reads at least one instruction comprising at least one of a branch instruction and a non-branch instruction. In response to the branch instruction comprising a conditional branch instruction and set in dynamic mode, the processor dynamically predicts a branch path as taken or not taken. The processor, in response to the instruction fetch unit set in static mode for a conditional branch instruction and static branch prediction setting bits received with the conditional branch instruction specifying static branch prediction, statically sets the branch path as taken or not taken according to the static branch prediction setting bits received with the branch instruction. The processor selectively sets the operation of the processor temporarily from the dynamic mode to the static mode only in response to detecting a type of the at least one instruction matches a type of instruction qualifying to trigger static branch prediction.

Selectively supporting static branch prediction settings only in association with processor-designated types of instructions

Processor instruction scheduling by: providing a set of program instructions, selecting instructions for reordering from the set of program instructions, reordering the instructions according to instruction properties, assigning sequential instruction tags to the instructions, tagging the instructions for completion as a group in a completion table; and executing the instructions.

Program instruction scheduling

Instruction prefetching in a computer processor includes, upon a miss in an instruction cache for an instruction cache line: retrieving, for the instruction cache line, a prefetch prediction vector, the prefetch prediction vector representing one or more cache lines of a set of contiguous instruction cache lines following the instruction cache line to prefetch from backing memory; and prefetching, from backing memory into the instruction cache, the instruction cache lines indicated by the prefetch prediction vector.

Instruction prefetching in a computer processor using a prefetch prediction vector

The present invention provides a system and method of testing CAMs and RAMs. In an exemplary embodiment, the system includes a multiple input signature register (MISR) logically coupled to digital outputs of a CAM, to digital inputs of a RAM, and to digital outputs of an ABIST controller circuit, where the MISR includes a plurality of L1 latch circuits logically coupled to a plurality of L2 latch circuits, a plurality of multiplexer circuits logically coupled to the plurality of L1 latch circuits, a plurality of exclusive or circuits (inner XOR circuits) logically coupled to the plurality of MUX circuits and to the plurality of L2 latch circuits, and at least two XOR circuits (outer XOR circuits), each of the outer XOR circuits logically coupled to one of the inner XOR circuits, to at least one of the MUX circuits, and to at least one of the L2 latch circuits.

Testing content addressable memory and random access memory

Blocking instruction fetching in a computer processor, includes: receiving a non-branching instruction to be executed by the computer processor; determining whether executing the non-branching instruction will cause a flush; and responsive to determining that executing the non-branching instruction will cause a flush, disabling instruction fetching for the computer processor for a time, including recoding the instruction such that the recoded instruction will be interpreted by an instruction fetch unit as an unconditional branch instruction.

Blocking instruction fetching in a computer processor

A technique for operating a processor includes allocating an entry in a prefetch filter queue (PFQ) for a cache line address (CLA) in response to the CLA missing in an instruction cache. In response to the CLA subsequently hitting in the instruction cache, an associated prefetch value for the entry in the PFQ is updated. In response to the entry being aged-out of the PFQ, an entry in a backing array for the CLA and the associated prefetch value is allocated. In response to subsequently determining that prefetching is required for the CLA, the backing array is accessed to determine the associated prefetch value for the CLA. A cache line at the CLA and a number of sequential cache lines specified by the associated prefetch value in the backing array are then prefetched into the instruction cache.

Dynamic sequential instruction prefetching

A technique for operating a processor includes allocating an entry in a prefetch filter queue (PFQ) for a cache line address (CLA) in response to the CLA missing in an upper level instruction cache. In response to the CLA subsequently hitting in the upper level instruction cache, an associated prefetch value for the entry in the PFQ is updated. In response to the entry being aged-out of the PFQ, an entry in a backing array for the CLA and the associated prefetch value is allocated. In response to subsequently determining that prefetching is required for the CLA, the backing array is accessed to determine the associated prefetch value for the CLA. A cache line at the CLA and a number of sequential cache lines specified by the associated prefetch value in the backing array are then prefetched into the upper level instruction cache.

Techniques for dynamic sequential instruction prefetching

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Austin, TX, United States of America

Sheldon Bernard Levenstein