Abstract: Embodiments include systems, methods, and computer program products for using a multi-level history buffer (HB) for a speculative transaction. One method includes after dispatching a first instruction indicating start of the speculative transaction, marking one or more register file (RF) entries as pre-transaction memory (PTM), and after dispatching a second instruction targeting one of the marked RF entries, moving data from the marked RF entry to a first level HB entry and marking the first level HB entry as PTM. The method also includes upon detecting a write back to the first level HB entry, moving data from the first level HB entry to a second level HB entry and marking the second level HB entry as PTM. The method further includes upon determining that the second level HB entry has been completed, moving data from the second level HB entry to a third level HB entry.

Abstract: Operation of a multi-slice processor including execution slices and load/store slices, where the load/store slices are coupled to the execution slices via a results bus and the results bus includes segments assigned to carry results of a different instruction type, includes: receiving a producer instruction that includes an identifier of an instruction type and an identifier of the producer instruction, including storing the identifier of the instruction type and the identifier of the producer instruction in an entry of a register; receiving a source instruction dependent upon the result of the producer instruction including storing, in an issue queue, the source instruction, the identifier of the instruction type of the producer instruction, and an identifier of the producer instruction; and snooping the identifier of the producer instruction only from the segment of the results bus assigned to carry results of the instruction type of the producer instruction.

Abstract: A simultaneous multithread (SMT) processor having a shared dispatch pipeline includes a first circuit that detects a cache miss thread. A second circuit determines a first cache hierarchy level at which the detected cache miss occurred. A third circuit determines a Next To Complete (NTC) group in the thread and a plurality of additional groups (X) in the thread. The additional groups (X) are dynamically configured based on the detected cache miss. A fourth circuit determines whether any groups in the thread are younger than the determined NTC group and the plurality of additional groups (X), and flushes all the determined younger groups from the cache miss thread.

Abstract: Operation of a multi-slice processor including execution slices and load/store slices, where the load/store slices are coupled to the execution slices via a results bus and the results bus includes segments assigned to carry results of a different instruction type, includes: receiving a producer instruction that includes an identifier of an instruction type and an identifier of the producer instruction, including storing the identifier of the instruction type and the identifier of the producer instruction in an entry of a register; receiving a source instruction dependent upon the result of the producer instruction including storing, in an issue queue, the source instruction, the identifier of the instruction type of the producer instruction, and an identifier of the producer instruction; and snooping the identifier of the producer instruction only from the segment of the results bus assigned to carry results of the instruction type of the producer instruction.

Abstract: Operation of a multi-slice processor including execution slices and load/store slices, where the load/store slices are coupled to the execution slices via a results bus and the results bus includes segments assigned to carry results of a different instruction type, includes: receiving a producer instruction that includes an identifier of an instruction type and an identifier of the producer instruction, including storing the identifier of the instruction type and the identifier of the producer instruction in an entry of a register; receiving a source instruction dependent upon the result of the producer instruction including storing, in an issue queue, the source instruction, the identifier of the instruction type of the producer instruction, and an identifier of the producer instruction; and snooping the identifier of the producer instruction only from the segment of the results bus assigned to carry results of the instruction type of the producer instruction.

Abstract: Managing a global completion table used to track progress of groups of instructions, in which each group of instructions includes one or more instructions. Entries of the global completion table are allocated to the groups of instructions from a freelist of entries. That is, entries are allocated from a pool of entries, rather than allocating entries in-order in a circular queue.

Abstract: Managing a global completion table used to track progress of groups of instructions, in which each group of instructions includes one or more instructions. Entries of the global completion table are allocated to the groups of instructions from a freelist of entries. That is, entries are allocated from a pool of entries, rather than allocating entries in-order in a circular queue.

Abstract: Dynamic resource allocation is provided in which additional resources, such as additional architected registers, are provided to an instruction, if it is determined that resources in addition to those configured to be provided to the instruction are to be used for the particular instruction. An instruction to be executed is dispatched on a pipe of a pipeline and that pipe is configured to have a set number of architected registers for use by the instruction. However, if one or more other architected registers are needed, those additional architected registers are dynamically allocated to the instruction by assigning one or more source ports of an additional pipe to the instruction.

Abstract: A multi-slice processor that includes execution slices, and a history buffer, where the history buffer includes a plurality of entries, where at least one of the entries includes transactional memory state data that corresponds to a transactional memory instruction updating a transaction memory state, and where operation of such a multi-slice processor includes: propagating a flush signal to the plurality of entries of the history buffer; responsive to the flush signal, generating, from an entry of the history buffer, the transactional memory state data; and restoring to a transactional memory state in dependence upon the transactional memory state data.

Abstract: Operation of a multi-slice processor including execution slices and load/store slices, where the load/store slices are coupled to the execution slices via a results bus and the results bus includes segments assigned to carry results of a different instruction type, includes: receiving a producer instruction that includes an identifier of an instruction type and an identifier of the producer instruction, including storing the identifier of the instruction type and the identifier of the producer instruction in an entry of a register; receiving a source instruction dependent upon the result of the producer instruction including storing, in an issue queue, the source instruction, the identifier of the instruction type of the producer instruction, and an identifier of the producer instruction; and snooping the identifier of the producer instruction only from the segment of the results bus assigned to carry results of the instruction type of the producer instruction.

Abstract: Operation of a multi-slice processor including execution slices and load/store slices, where the load/store slices are coupled to the execution slices via a results bus and the results bus includes segments assigned to carry results of a different instruction type, includes: receiving a producer instruction that includes an identifier of an instruction type and an identifier of the producer instruction, including storing the identifier of the instruction type and the identifier of the producer instruction in an entry of a register; receiving a source instruction dependent upon the result of the producer instruction including storing, in an issue queue, the source instruction, the identifier of the instruction type of the producer instruction, and an identifier of the producer instruction; and snooping the identifier of the producer instruction only from the segment of the results bus assigned to carry results of the instruction type of the producer instruction.

Abstract: Techniques for error correction in a processor include detecting an error in first data stored in a register. The method also includes generating an instruction to read the first data stored in the register, where the register is both a source register and a destination register of the instruction. The method further includes transmitting the first data to an execution unit, where the first data bypasses an issue queue. The method also includes decoding the instruction and correcting the error to generate corrected data and writing the corrected data to the destination register.

Abstract: A supervisory hardware device in a processor core detects a flush instruction that, when executed, flushes content of one or more general purpose registers (GPRs) within the processor core. The content of the one or more GPRs is moved to a history buffer (HB) and an instruction sequencing queue (ISQ) within the processor core, where the content includes data, an instruction tag (iTag) that identifies an instruction that generated the data, and error correction code (ECC) bits for the data. In response to receiving a restore instruction, the supervisory hardware device error checks the data in the ISQ using the ECC bits stored in the ISQ. In response to detecting an error in the data in the ISQ, the supervisory hardware device sends the data and the ECC bits from the ISQ to an ECC scrubber to generate corrected data, which is restored into the one or more GPRs.

Abstract: An apparatus for processing instructions includes a mapping unit comprising a plurality of mappers wherein each mapper of the plurality of mappers maps a logical sub-register reference to a physical sub-register reference, a decoding unit configured to receive an instruction and determine a plurality of logical sub-register references therefrom, and an execution unit. The mapping unit may be configured to distribute the plurality of logical sub-register references amongst the plurality of mappers according to at least one bit in the instruction and provide a corresponding plurality of physical sub-register references. The execution unit may be configured to execute the instruction using the plurality of physical sub-register references. Corresponding methods are also disclosed herein.

Abstract: Techniques for error correction in a processor include detecting an error in first data stored in a register. The method also includes generating an instruction to read the first data stored in the register, where the register is both a source register and a destination register of the instruction. The method further includes transmitting the first data and error correcting code data to an execution unit, where the first data and error correcting code data bypasses an issue queue. The method also includes decoding the instruction and correcting the error to generate corrected data and writing the corrected data to the destination register.

Abstract: Techniques for error correction in a processor include detecting an error in first data stored in a register. The method also includes generating an instruction to read the first data stored in the register, where the register is both a source register and a destination register of the instruction. The method further includes transmitting the first data and error correcting code data to an execution unit, where the first data and error correcting code data bypasses an issue queue. The method also includes decoding the instruction and correcting the error to generate corrected data and writing the corrected data to the destination register.

Abstract: Techniques are disclosed for restoring register data in a processor. In one embodiment, a method includes receiving an instruction to flush one or more general purpose registers (GPRs) in a processor. The method also includes determining history buffer entries of a history buffer to be restored to the one or more GPRs. The method includes creating a mask vector that indicates which history buffer entries will be restored to the one or more GPRs. The method further includes restoring the indicated history buffer entries to the one or more GPRs. As each indicated history buffer entry is restored, the method includes updating the mask vector to indicate which history buffer entries have been restored.

Abstract: A hardware execution unit within a processor core executes a second instruction, which is part of a software thread, and which is executed out of order within the software thread. A sticky bit flip detection hardware device detects a change to a sticky bit in a floating-point status and control register (FPSCR) within the processor core. An instruction issue hardware unit identifies a first instruction that is in the software thread that is capable of reading or clearing the sticky bit. A flushing execution unit flushes all results of instructions from an instruction completion table (ICT) that include and are after the first instruction in the software thread. A hardware dispatch device dispatches all instructions that include and are after the first instruction in the software thread for execution by one or more hardware execution units within the processor core in a next-to-complete (NTC) sequential order.

Abstract: A supervisory hardware device in a processor core detects a flush instruction that, when executed, flushes content of one or more general purpose registers (GPRs) within the processor core. The content of the one or more GPRs is moved to a history buffer (HB) and an instruction sequencing queue (ISQ) within the processor core, where the content includes data, an instruction tag (iTag) that identifies an instruction that generated the data, and error correction code (ECC) bits for the data. In response to receiving a restore instruction, the supervisory hardware device error checks the data in the ISQ using the ECC bits stored in the ISQ. In response to detecting an error in the data in the ISQ, the supervisory hardware device sends the data and the ECC bits from the ISQ to an ECC scrubber to generate corrected data, which is restored into the one or more GPRs.

Abstract: Operation of a multi-slice processor that includes execution slices and a dispatch network of the multi-slice processor implementing a hardware level transfer of an execution thread between execution slices. Operation of such a multi-slice processor includes responsive to a thread switch signal: halting dispatch of one or more instructions retrieved from an instruction cache; generating a plurality of instructions to transfer an execution thread from a first execution slice to a second execution slice; and dispatching the plurality of instructions instead of the one or more instructions retrieved from the instruction cache; and transferring, in dependence upon execution of the plurality of instructions from the thread switching instruction generator, the execution thread from the first execution slice to the second execution slice.