Abstract: A design structure embodied in a machine readable storage medium for designing, manufacturing, and/or testing a design for minimizing unscheduled D-cache miss pipeline stalls is provided. The design structure includes an integrated circuit device, which includes a cascaded delayed execution pipeline unit having two or more execution pipelines that begin execution of instructions in a common issue group in a delayed manner relative to each other, and circuitry. The circuitry is configured to receive an issue group of instructions, determine whether the issue group is a load instruction, and if so, schedule the load instruction in a first pipeline of the two or more execution pipelines, and schedule each remaining instruction in the issue group to be executed in remaining pipelines of the two or more pipelines, wherein execution of the load instruction in the first pipeline begins prior to beginning execution of the remaining instructions in the remaining pipelines.

Abstract: Improved techniques for executing instructions in a pipelined manner that may reduce stalls that occur when executing dependent instructions are provided. Stalls may be reduced by utilizing a cascaded arrangement of pipelines with execution units that are delayed with respect to each other. This cascaded delayed arrangement allows dependent instructions to be issued within a common issue group by scheduling them for execution in different pipelines to execute at different times.

Abstract: A method of providing history based done logic includes receiving a cache line in a L2 cache; determining if the cache line has a history of access at least three times on a previous call into the L2 cache; providing the cache line directly to a processor if the history of access was less then the at least three times; and loading the cache line into an L1 cache if the history of access was the at least three times.

Abstract: A method of providing history based done logic for instructions includes receiving an instruction in a cache line in a L2 cache; and loading the cache line into an L1 cache with a history count that indicates the number of read references of the previous access.

Abstract: A method and apparatus for executing branch instructions is provided. In one embodiment, the method includes receiving a branch instruction, wherein a first path of the branch instruction branches to a target instruction, and wherein a second path of the branch instruction branches to one or more interceding instructions between the branch instruction and the target instruction. The method further includes issuing the one or more interceding instructions and the target instruction and determining if the branch instruction follows the first path or the second path. Upon determining that the branch instruction follows the first path, the one or more interceding instructions between the branch instruction and the target instruction are invalidated.

Abstract: A method of providing history based done logic includes receiving a cache line in a L2 cache; determining if the cache line has a history of access at least three times on a previous call into the L2 cache; providing the cache line directly to a processor if the history of access was less then the at least three times; and loading the cache line into an L1 cache if the history of access was the at least three times.

Abstract: A method and apparatus for executing branch instructions is provided. In one embodiment, the method includes receiving a branch instruction, wherein a first path of the branch instruction branches to a target instruction, and wherein a second path of the branch instruction branches to one or more interceding instructions between the branch instruction and the target instruction. The method further includes issuing the one or more interceding instructions and the target instruction and determining if the branch instruction follows the first path or the second path. Upon determining that the branch instruction follows the first path, the one or more interceding instructions between the branch instruction and the target instruction are invalidated.

Abstract: A method of providing history based done logic includes receiving a cache line in a L2 cache; determining if the cache line has a history of access at least three times on a previous call into the L2 cache; providing the cache line directly to a processor if the history of access was less then the at least three times; and loading the cache line into an L1 cache if the history of access was the at least three times.

Abstract: A method of providing history based done logic for a D-cache includes receiving a D-cache line in an L2 cache; determining if the D-cache line is unprefetchable; aging the D-cache line without a delay if the D-cache line is prefetchable; and aging the D-cache line with a delay if the D-cache line is unprefetchable.

Abstract: A method of providing history based done logic for a I-cache includes receiving an I-cache line in an L2 cache; determining if the I-cache line is unprefetchable; aging the I-cache line without a delay if the I-cache line is prefetchable; and aging the I-cache line with a delay is the I-cache line is unprefetchable.

Abstract: One embodiment of the invention provides a processor. The processor generally includes a first and second processor core, each having a plurality of pipelined execution units for executing an issue group of multiple instructions and scheduling logic configured to issue a first issue group of instructions to the first processor core for execution and a second issue group of instructions to the second processor core for execution when the processor is in a first mode of operation and configured to issue one or more vector instructions for concurrent execution on the first and second processor cores when the processor is in a second mode of operation.

Abstract: The present invention provides system and method for a group priority issue schema for a cascaded pipeline. The system includes a cascaded delayed execution pipeline unit having a plurality of execution pipelines that execute instructions in a common issue group in a delayed manner relative to each other. The system further includes circuitry configured to receiving an issue group of instructions, reordering the issue group of instructions using instruction type priority, and executing the reordered issue group of instructions in the cascaded delayed execution pipeline unit. The method, among others, can be broadly summarized by the following steps: receiving an issue group of instructions, reordering the issue group of instructions using instruction type priority, and executing the reordered issue group of instructions in the cascaded delayed execution pipeline unit.

Abstract: The present invention provides system and method for a group priority issue schema for a cascaded pipeline. The system includes a cascaded delayed execution pipeline unit having a plurality of execution pipelines that execute instructions in a common issue group in a delayed manner relative to each other. The system further includes circuitry configured to: (1) receive an issue group of instructions; (2) determine if a plurality of load instructions are in the issue group, if so, schedule the plurality of load instructions in descending order of longest dependency chain depth to shortest dependency chain depth in a shortest to longest available execution pipelines; and (3) execute the issue group of instructions in the cascaded delayed execution pipeline unit.

Abstract: Embodiments of the invention provide a look-aside-look-aside buffer (LLB) configured to retain a portion of the real addresses in a translation look-aside (TLB) buffer to allow prefetching of data from a cache. A subset of real address bits associated with an effective address may be retrieved relatively quickly from the LLB, thereby allowing access to the cache before the complete address translation is available and reducing cache access latency.

Abstract: Embodiments of the invention provide a look-aside-look-aside buffer (LLB) configured to retain a portion of the real addresses in a translation look-aside (TLB) buffer to allow prefetching of data from a cache. A subset of real address bits associated with an effective address may be retrieved relatively quickly from the LLB, thereby allowing access to the cache before the complete address translation is available and reducing cache access latency.

Abstract: The present invention provides system and method for a group priority issue schema for a cascaded pipeline. The system includes a cascaded delayed execution pipeline unit having a plurality of execution pipelines that execute instructions in a common issue group in a delayed manner relative to each other. The system further includes circuitry configured to: (1) receive an issue group of instructions, (2) determine the dependency chain depth of all the instructions in the issue group, (3) schedule the instructions in an order of the longest dependency chain depth to shortest dependency chain depth, and (4) execute the issue group of instructions in the cascaded delayed execution pipeline unit.

Abstract: One embodiment provides a method of forwarding data in a processor. The method generally includes providing at least one cascaded delayed execution pipeline unit having at least a first pipeline and a second pipeline for executing first and second instructions in a common issue group, wherein the second pipeline executes the second instruction in a delayed manner relative to the execution of the first instruction in the first pipeline, storing results generated by an execution unit of the first pipeline in a first-in first-out (FIFO) storage target delay queue, determining if the target delay queue contains source data for executing the second instruction, and if the target delay queue contains source data for the second instruction, forwarding the source data for the second instruction from the target delay queue to an execution unit of the second pipeline.

Abstract: The present invention provides a system and method for prioritizing arithmetic instructions in a cascaded pipeline. The system includes a cascaded delayed execution pipeline unit having a plurality of execution pipelines that execute instructions in a common issue group in a delayed manner relative to each other. The system further includes circuitry configured to: (1) receive an issue group of instructions; (2) determine if at least one arithmetic instruction is in the issue group, if so scheduling the least one arithmetic instruction in a one of the plurality of execution pipelines based upon a first prioritization scheme; (3) determine if there is an issue conflict for one of the plurality of execution pipelines and resolving the issue conflict by scheduling the at least one arithmetic instruction in a different execution pipeline; (4) schedule execution of the issue group of instructions in the cascaded delayed execution pipeline unit.

Abstract: Improved techniques for executing instructions in a pipelined manner that may reduce stalls that occur when executing dependent instructions are provided. Stalls may be reduced by utilizing a cascaded arrangement of pipelines with execution units that are delayed with respect to each other. This cascaded delayed arrangement allows dependent instructions to be issued within a common issue group by scheduling them for execution in different pipelines to execute at different times.

Abstract: Embodiments of the invention provide an apparatus of storing branch prediction information. In one embodiment, an integrated circuit device includes a first table for storing local branch prediction information, a second table for storing global branch prediction information, and circuitry. The circuitry is configured to receive a branch instruction and store local branch prediction information for the branch instruction in the first table. The local branch prediction information includes a local predictability value for the local branch prediction information. The circuitry is further configured to store global branch prediction information for the branch instruction in the second table only if the local predictability value is below a threshold value of predictability.