Abstract: In an approach for protecting recoding logic in a computing environment, a processor obtains an operand of an instruction in a first data format. A processor converts the operand from the first data format to a second data format. A processor generates a predicted residue of the operand in the second data format, wherein generating the predicted residue of the operand in the second data format comprises: generating a residue of the operand from the first data format.

Abstract: In an approach for protecting recoding logic in a computing environment, a processor obtains an operand of an instruction in a first data format. A processor converts the operand from the first data format to a second data format. A processor generates a predicted residue of the operand in the second data format, wherein generating the predicted residue of the operand in the second data format comprises: generating a residue of the operand from the first data format.

Abstract: Embodiments are directed to a method for optimizing performance of a microprocessor. The method includes monitoring the performance of the microprocessor in each of a plurality of performance modes. The method further includes choosing a performance mode based on the monitoring. Thereafter, using the performance mode for a predetermined amount of time. Each of the plurality of performance modes is a branch prediction mode.

Abstract: Scheduling memory accesses in a memory system having a multiple ranks of memory, at most r ranks of which may be powered up concurrently, in which r is less than the number of ranks. If fewer than r ranks are powered up, a subset of requested powered down ranks is powered up, such that at r ranks are powered up, the subset of requested powered down ranks to be powered up including the most frequently accessed requested powered down ranks. Then, if fewer than r ranks are powered up, a subset of unrequested powered down ranks is powered up, such that a total of at most r ranks is powered up concurrently, the subset of unrequested powered down ranks to be powered up including the most frequently accessed unrequested powered down ranks.

Abstract: Scheduling memory accesses in a memory system having a multiple ranks of memory, at most r ranks of which may be powered up concurrently, in which r is less than the number of ranks. If fewer than r ranks are powered up, a subset of requested powered down ranks is powered up, such that at r ranks are powered up, the subset of requested powered down ranks to be powered up including the most frequently accessed requested powered down ranks. Then, if fewer than r ranks are powered up, a subset of unrequested powered down ranks is powered up, such that a total of at most r ranks is powered up concurrently, the subset of unrequested powered down ranks to be powered up including the most frequently accessed unrequested powered down ranks.

Abstract: A computer-implemented method includes determining, by a stream-based index accelerator predictor of a processor, a predicted stream length between an instruction address and a taken branch ending an instruction stream. A first-level branch predictor of a hierarchical asynchronous lookahead branch predictor of the processor is searched for a branch prediction in one or more entries in a search range bounded by the instruction address and the predicted stream length. A search of a second-level branch predictor of the hierarchical asynchronous lookahead branch predictor is triggered based on failing to locate the branch prediction in the search range.

Abstract: According to an aspect, virtualized weight perceptron branch prediction is provided in a processing system. A selection is performed between two or more history values at different positions of a history vector based on a virtualization map value that maps a first selected history value to a first weight of a plurality of weights, where a number of history values in the history vector is greater than a number of the weights. The first selected history value is applied to the first weight in a perceptron branch predictor to determine a first modified virtualized weight. The first modified virtualized weight is summed with a plurality of modified virtualized weights to produce a prediction direction. The prediction direction is output as a branch predictor result to control instruction fetching in a processor of the processing system.

Abstract: Embodiments relate to multithreaded branch prediction. An aspect includes a system for dynamically evaluating how to share entries of a multithreaded branch prediction structure. The system includes a first-level branch target buffer coupled to a processor circuit. The processor circuit is configured to perform a method. The method includes receiving a search request to locate branch prediction information associated with the search request, and searching for an entry corresponding to the search request in the first-level branch prediction structure. The entry is not allowed based on a thread state of the entry indicating that the entry has caused a problem on a thread associated with the thread state.

Abstract: Embodiments relate to multithreaded branch prediction. An aspect includes a system for dynamically evaluating how to share entries of a multithreaded branch prediction structure. The system includes a first-level branch target buffer coupled to a processor circuit. The processor circuit is configured to perform a method. The method includes receiving a search request to locate branch prediction information associated with the search request, and searching for an entry corresponding to the search request in the first-level branch prediction structure. The entry is not allowed based on a thread state of the entry indicating that the entry has caused a problem on a thread associated with the thread state.

Abstract: A computer-implemented method for predicting a taken branch that ends an instruction stream in a pipelined high frequency microprocessor includes receiving, by a processor, a first instruction within a first instruction stream, the first instruction comprising a first instruction address; searching, by the processor, an index accelerator predictor one time for the stream; determining, by the processor, a prediction for a taken branch ending the branch stream; influencing, by the processor, a metadata prediction engine based on the prediction; observing a plurality of taken branches from the exit accelerator predictor; maintaining frequency information based on the observed taken branches; determining, based on the frequency information, an updated prediction of the observed plurality of taken branches; and updating, by the processor, the index accelerator predictor with the the updated prediction.

Abstract: A computer-implemented method for predicting a taken branch that ends an instruction stream in a pipelined high frequency microprocessor includes receiving, by a processor, a first instruction within a first instruction stream, the first instruction including a first instruction address. The computer-implemented method further includes searching, by the processor, a stream-based index accelerator predictor one time for the stream; determining, by the processor, a prediction for a branch ending the branch stream; influencing, by the processor, a metadata prediction engine based on the prediction; and updating, by the processor, a stream-based index accelerator predictor with information indicative of the prediction.

Abstract: A computer-implemented method for predicting a taken branch that ends an instruction stream in a pipelined high frequency microprocessor includes receiving, by a processor, a first instruction within a first instruction stream, the first instruction comprising a first instruction address; searching, by the processor, an index accelerator predictor one time for the stream; determining, by the processor, a prediction for a taken branch ending the branch stream; influencing, by the processor, a metadata prediction engine based on the prediction; observing a plurality of taken branches from the exit accelerator predictor; maintaining frequency information based on the observed taken branches; determining, based on the frequency information, an updated prediction of the observed plurality of taken branches; and updating, by the processor, the index accelerator predictor with the the updated prediction.

Abstract: Examples of techniques for distance-based branch prediction are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes: determining, by a processing system, a potential return instruction address (IA) by determining whether a relationship is satisfied between a first target IA and a first branch IA; storing a second branch IA as a return when a target IA of a second branch matches a potential return IA for the second branch; and applying the potential return IA for the second branch as a predicted target IA of a predicted branch IA stored as a return.

Abstract: Examples of techniques for distance-based branch prediction are disclosed.

Abstract: A method, system, and computer program product of utilizing branch prediction logic in a system that processes instructions that include a branch are described. The method includes identifying the branch as conventionally predictable or not conventionally predictable, and based on the branch being identified as not conventionally predictable according to the identifying, either foregoing branch prediction and reallocating, using a processor, the branch prediction logic to another thread of the instructions or performing, using the processor, the branch prediction and speculative execution of one or more of the instructions following the branch to obtain prediction information. Based on the performing the branch prediction and the speculative execution, the method also includes verifying a match between a branch end according to the instructions and a branch end according to the branch prediction prior to providing the prediction information to a second processor processing the instructions.

Abstract: According to an aspect, virtualized weight perceptron branch prediction is provided in a processing system. A selection is performed between two or more history values at different positions of a history vector based on a virtualization map value that maps a first selected history value to a first weight of a plurality of weights, where a number of history values in the history vector is greater than a number of the weights. The first selected history value is applied to the first weight in a perceptron branch predictor to determine a first modified virtualized weight. The first modified virtualized weight is summed with a plurality of modified virtualized weights to produce a prediction direction. The prediction direction is output as a branch predictor result to control instruction fetching in a processor of the processing system.

Abstract: A method, system, and computer program product of utilizing branch prediction logic in a system that processes instructions that include a branch are described. The method includes identifying the branch as conventionally predictable or not conventionally predictable, and based on the branch being identified as not conventionally predictable according to the identifying, either foregoing branch prediction and reallocating, using a processor, the branch prediction logic to another thread of the instructions or performing, using the processor, the branch prediction and speculative execution of one or more of the instructions following the branch to obtain prediction information. Based on the performing the branch prediction and the speculative execution, the method also includes verifying a match between a branch end according to the instructions and a branch end according to the branch prediction prior to providing the prediction information to a second processor processing the instructions.

Abstract: A method, system, and computer program product of utilizing branch prediction logic in a system that processes instructions that include a branch are described. The method includes identifying the branch as conventionally predictable or not conventionally predictable, and based on the branch being identified as not conventionally predictable according to the identifying, either foregoing branch prediction and reallocating, using a processor, the branch prediction logic to another thread of the instructions or performing, using the processor, the branch prediction and speculative execution of one or more of the instructions following the branch to obtain prediction information. Based on the performing the branch prediction and the speculative execution, the method also includes verifying a match between a branch end according to the instructions and a branch end according to the branch prediction prior to providing the prediction information to a second processor processing the instructions.

Abstract: Embodiments relate to multithreaded branch prediction. An aspect includes a system for dynamically evaluating how to share entries of a multithreaded branch prediction structure. The system includes a first-level branch target buffer coupled to a processor circuit. The processor circuit is configured to perform a method. The method includes receiving a search request to locate branch prediction information associated with the search request, and searching for an entry corresponding to the search request in the first-level branch prediction structure. The entry is not allowed based on a thread state of the entry indicating that the entry has caused a problem on a thread associated with the thread state.

Abstract: According to an aspect, branch prediction in a processing system that includes a primary branch predictor and an auxiliary perceptron branch predictor is provided. The primary branch predictor and the auxiliary perceptron branch predictor are searched to make a branch prediction. A perceptron magnitude of a perceptron branch predictor from the auxiliary perceptron branch predictor is compared to a magnitude usage limit. An auxiliary predictor result from the auxiliary perceptron branch predictor is selected as the branch prediction based on the perceptron magnitude exceeding the magnitude usage limit. A primary predictor result from the primary branch predictor is selected as the branch prediction based on the perceptron magnitude not exceeding the magnitude usage limit.