Abstract: In one embodiment, a policy manager may receive operating system scheduling information, performance prediction information for at least one future quantum, and current processor utilization information, and determine a performance prediction for a future quantum and whether to cause a switch between asymmetric cores of a multicore processor based at least in part on this received information. Other embodiments are described and claimed.

Abstract: Embodiments relate to speculative branch handling for transaction abort. An aspect includes detecting a beginning of a current execution of a transaction. Another aspect includes, based on detecting the beginning of the transaction, disabling speculative execution based on branch prediction of an initial branch instruction of the transaction, wherein the initial branch instruction branches to two possible paths, and wherein a first path of the two possible paths comprises an abort handler. Another aspect includes disabling updating of a history table for the initial branch instruction.

Abstract: A system and method for efficiently accessing operands in a datapath. An apparatus includes a data operand register file and an execution pipeline with multiple stages. In addition, the apparatus includes a result bypass cache configured to store data results conveyed by at least the final stage of the execution pipeline stage. Control logic is included which is configured to determine whether source operands for an instruction entering the pipeline are available in the last stage of the pipeline or in the result bypass cache. If the source operands are available in the last stage of the pipeline or the result bypass cache, they may be obtained from one of those locations rather than reading from the register file. If the source operands are not available from the last stage or the result bypass cache, then they may be obtained from the data operand register file.

Abstract: Embodiments relate to vector processor predication in an active memory device. An aspect includes a system for vector processor predication in an active memory device. The system includes memory in the active memory device and a processing element in the active memory device. The processing element is configured to perform a method including decoding an instruction with a plurality of sub-instructions to execute in parallel. One or more mask bits are accessed from a vector mask register in the processing element. The one or more mask bits are applied by the processing element to predicate operation of a unit in the processing element associated with at least one of the sub-instructions.

Abstract: A processor core including a hardware decode unit to decode vector instructions for decompressing a run length encoded (RLE) set of source data elements and an execution unit to execute the decoded instructions. The execution unit generates a first mask by comparing set of source data elements with a set of zeros and then counts the trailing zeros in the mask. A second mask is made based on the count of trailing zeros. The execution unit then copies the set of source data elements to a buffer using the second mask and then reads the number of RLE zeros from the set of source data elements. The buffer is shifted and copied to a result and the set of source data elements is shifted to the right. If more valid data elements are in the set of source data elements this is repeated until all valid data is processed.

Abstract: Embodiments relate to vector processor predication in an active memory device. An aspect includes a method for vector processor predication in an active memory device that includes memory and a processing element. The method includes decoding, in the processing element, an instruction including a plurality of sub-instructions to execute in parallel. One or more mask bits are accessed from a vector mask register in the processing element. The one or more mask bits are applied by the processing element to predicate operation of a unit in the processing element associated with at least one of the sub-instructions.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for selecting native code instructions. One of the methods includes receiving an initial machine language instruction for execution by a processor in a first execution mode; determining that a portion of the initial machine language instruction, when executed by the processor in a second execution mode, satisfies one or more risk criteria; generating one or more alternative machine language instructions to replace the initial machine language instruction for execution by the processor in the first execution mode, wherein the one or more alternative machine language instructions, when executed by the processor in the second execution mode, mitigate the one or more risk criteria; and providing the one or more alternative machine language instructions.

Abstract: Methods, parallel computers, and computer program products for requesting shared variable directory (SVD) information from a plurality of threads in a parallel computer are provided. Embodiments include a runtime optimizer detecting that a first thread requires a plurality of updated SVD information associated with shared resource data stored in a plurality of memory partitions. Embodiments also include a runtime optimizer broadcasting, in response to detecting that the first thread requires the updated SVD information, a gather operation message header to the plurality of threads. The gather operation message header indicates an SVD key corresponding to the required updated SVD information and a local address associated with the first thread to receive a plurality of updated SVD information associated with the SVD key. Embodiments also include the runtime optimizer receiving at the local address, the plurality of updated SVD information from the plurality of threads.

Abstract: Methods, parallel computers, and computer program products for requesting shared variable directory (SVD) information from a plurality of threads in a parallel computer are provided. Embodiments include a runtime optimizer detecting that a first thread requires a plurality of updated SVD information associated with shared resource data stored in a plurality of memory partitions. Embodiments also include a runtime optimizer broadcasting, in response to detecting that the first thread requires the updated SVD information, a gather operation message header to the plurality of threads. The gather operation message header indicates an SVD key corresponding to the required updated SVD information and a local address associated with the first thread to receive a plurality of updated SVD information associated with the SVD key. Embodiments also include the runtime optimizer receiving at the local address, the plurality of updated SVD information from the plurality of threads.

Abstract: Branch prediction is provided by generating a first index from a previous instruction address and from a first branch history vector having a first length. A second index is generated from the previous instruction address and from a second branch history vector that is longer than the first vector. Using the first index, a first branch prediction is retrieved from a first branch prediction table. Using the second index, a second branch prediction is retrieved from a second branch prediction table. Based upon additional branch history data, the first branch history vector and the second branch history vector are updated. A first hash value is generated from a current instruction address and the updated first branch history vector. A second hash value is generated from the current instruction address and the updated second branch history vector. One of the branch predictions are selected based upon the hash values.

Abstract: Embodiments relate to management of shared transactional resources. A system includes a transactional facility configured to support transactions that effectively delay committing stores to memory or results to an architectural state until transaction completion. The system includes a processor configured to perform an allocation or arbitration of processing resources to instructions of a transaction within a thread. The processor detects that the transaction has exceeded a manageable capacity of a resource or a potential collision of a transactional instruction storage access has occurred, resulting in a transaction abort. A transaction abort reason and a current configuration are examined to determine whether the transaction abort was based on an initiating program exceeding a restricted limit on the manageable capacity of the resource or an allocation. A processor state is updated to increase a likelihood of success upon retrying the transaction.

Abstract: Technical solutions are described for avoiding a transaction abort in a multiprocessor that supports transactional memory during out-of-order execution of an instruction stream. An example method described includes detecting an instruction that represents an end of a transaction in the instruction stream. The method also includes identifying a conflict in execution of an outside instruction in conjunction with execution of the transaction, the outside instruction being after instruction that represents the end of the transaction, and where the conflict causes the transaction to abort. The method also includes flushing the outside instruction; and resuming the execution of the transaction, without aborting the transaction.

Abstract: Embodiments of systems, apparatuses, and methods for performing in a computer processor vector packed butterfly horizontal cross add or subtract of packed data elements in response to a single vector packed butterfly horizontal cross add or subtract instruction that includes a destination vector register operand, a source vector register operand, an immediate, and an opcode are described.

Abstract: Embodiments relate to speculative branch handling for transaction abort. An aspect includes detecting a beginning of a current execution of a transaction. Another aspect includes, based on detecting the beginning of the transaction, disabling speculative execution based on branch prediction of an initial branch instruction of the transaction, wherein the initial branch instruction branches to two possible paths, and wherein a first path of the two possible paths comprises an abort handler. Another aspect includes disabling updating of a history table for the initial branch instruction.

Abstract: Restricted instructions are prohibited from execution within a transaction. There are classes of instructions that are restricted regardless of type of transaction: constrained or nonconstrained. There are instructions only restricted in constrained transactions, and there are instructions that are selectively restricted for given transactions based on controls specified on instructions used to initiate the transactions.

Abstract: Restricted instructions are prohibited from execution within a transaction. There are classes of instructions that are restricted regardless of type of transaction: constrained or nonconstrained. There are instructions only restricted in constrained transactions, and there are instructions that are selectively restricted for given transactions based on controls specified on instructions used to initiate the transactions.

Abstract: Processing of transactions within a computing environment is facilitated by taking actions to increase the chances of successfully executing a transaction. A counter is maintained that provides a count of how often a transaction has aborted. The counter increments the count each time the transaction is aborted, and it is reset to zero upon successful completion of the transaction or an interruption leading to no more re-executions of the transaction. If the count reaches a threshold value, then an interrupt is presented and transaction execution is unsuccessful. However, before the count reaches the threshold, a number of actions may be taken to increase the chances of successfully executing the transaction. These actions include actions to be performed within the processor executing the transaction, and/or actions to be performed against conflicting processors.

Abstract: Embodiments relate to a semi-exclusive second-level branch target buffer. An aspect includes a system for a semi-exclusive second-level branch target buffer. The system includes a first-level branch target buffer (BTB1), a branch target buffer preload table (BTBP), and a second-level branch target buffer (BTB2) coupled to a processing circuit. The processing circuit is configured to perform a method. The method includes performing a search to locate entries in the BTB2 having a memory region corresponding to a search request. Based on locating entries in the BTB2, a bulk transfer of located entries is performed from the BTB2 to the BTBP. A state associated with the located entries is updated to encourage exclusivity between the BTB1 and the BTB2. Based on transferring a BTBP entry from the BTBP to the BTB1, a BTB1 entry is evicted from the BTB1. The evicted BTB1 entry is transferred from the BTB1 to the BTB2.

Abstract: A system and method for efficiently reducing the latency of initializing registers. A register rename unit within a processor determines whether prior to an execution pipeline stage it is known a decoded given instruction writes a particular numerical value in a destination operand. An example is a move immediate instruction that writes a value of 0 in its destination operand. Other examples may also qualify. If the determination is made, a given physical register identifier is assigned to the destination operand, wherein the given physical register identifier is associated with the particular numerical value, but it is not associated with an actual physical register in a physical register file. The given instruction is marked to prevent it from proceeding to an execution pipeline stage. When the given physical register identifier is used to read the physical register file, no actual physical register is accessed.

Abstract: Embodiments relate to a semi-exclusive second-level branch target buffer. An aspect includes a computer-implemented method for a semi-exclusive second-level branch target buffer. The method includes performing a search to locate entries in a BTB2 having a memory region corresponding to a search request. Based on locating the entries in the BTB2, a bulk transfer of located entries is performed from the BTB2 to a BTBP. A state associated with the located entries is updated to encourage exclusivity between the BTB1 and the BTB2. Based on transferring a BTBP entry from the BTBP to a BTB1, a BTB1 entry is evicted from the BTB1. The evicted BTB1 entry is transferred from the BTB1 to the BTB2.