Abstract: Method and apparatus for stopping completions using stop codes in an instruction completion table are provided by during a first clock cycle, in response to determining that a given entry in an Instruction Completion Table (ICT) is finalized and is associated with a stop code, completing, according to a program order, instructions included in one or more finalized entries of the ICT located in the ICT before the given entry; during a second clock cycle, after completing the instructions, performing exception processing for a special instruction included in the given entry; and during a third clock cycle, after processing the special instruction, completing, according to the program order, additional instructions in one or more finalized entries located in the ICT after the given entry.

Abstract: A computer-implemented method, computer program product, and computer processing system are provided. The method includes processing, by a superscalar processing pipeline, respective sets of instructions in respective instruction processing cycles using an Instruction Completion Table (ICT) with a Ready-To-Complete (RTC) vector. The ICT includes a plurality of entries, each corresponding to a respective one of the instructions. A Next-To-Complete (NTC) instruction from among the respective sets of instructions is computed using the RTC vector.

Abstract: Method and apparatus for completing atomic instructions in a microprocessor may be provided by identifying from a program-ordered Instruction Completion Table (ICT) a last entry in a completion window of instructions for completion in a current clock cycle of a processor; in response to determining that the last entry includes an atomic instruction that straddles the completion window: excluding the last entry from completion during the current clock cycle; completing instructions in the completion window for the current clock cycle; and shifting the completion window to include the last entry and a next entry adjacent to the last entry in the ICT in a next clock cycle.

Abstract: Method and apparatus for a completion mechanism for a microprocessor are provided by marking entries in a section of an Instruction Completion Table (ICT) as ready to complete using corresponding Ready to Complete (RTC) status bits; determining a tail pointer indicating a start of the entries in the ICT that are ready for completion in a current clock cycle; performing a counting leading ones on an RTC vector that organizes the RTC status bits according to a program order for completing the entries to determine a count leading ones pointer that indicates an end of the entries in the ICT that are ready for completion in the current clock cycle; completing instructions included in the entries between the tail pointer and the count leading ones pointer in one clock cycle; and updating the tail pointer to a value of the count leading ones pointer for a subsequent clock cycle.

Abstract: Method and apparatus for stopping completions using stop codes in an instruction completion table are provided by during a first clock cycle, in response to determining that a given entry in an Instruction Completion Table (ICT) is finalized and is associated with a stop code, completing, according to a program order, instructions included in one or more finalized entries of the ICT located in the ICT before the given entry; during a second clock cycle, after completing the instructions, performing exception processing for a special instruction included in the given entry; and during a third clock cycle, after processing the special instruction, completing, according to the program order, additional instructions in one or more finalized entries located in the ICT after the given entry.

Abstract: A computer system, processor, and method for processing information is disclosed that includes a Dispatch Unit for dispatching instructions; an Issue Queue for receiving instructions dispatched from the Dispatch Unit; and a queue for receiving instructions issued from the Issue Queue, the queue having a plurality of entry locations for storing data. In an embodiment instructions are dispatched with a virtual indicator, and the virtual indicator is set to a first mode for instructions dispatched where an entry location is available, and to a second mode where an entry location is not available, in the queue to receive the dispatched instruction. In addition to virtual tagging dispatched instructions, a system, processor, and method are disclosed for regional partitioning of queues, region based deallocation of queue entries, and circular thread based assignment of queue entries.

Abstract: Within a processor, speculative finishes of load instructions only are tracked in a speculative finish table by maintaining an oldest load instruction of a thread in the speculative finish table after data is loaded for the oldest load instruction, wherein a particular queue index tag assigned to the oldest load instruction by an execution unit points to a particular entry in the speculative finish table, wherein the oldest load instruction is waiting to be finished dependent upon an error check code result. Responsive to a flow unit receiving the particular queue index tag with an indicator that the error check code result for data retrieved for the oldest load instruction is good, finishing the oldest load instruction in the particular entry pointed to by the queue index tag and writing an instruction tag stored in the entry for the oldest load instruction out of the speculative finish table for completion.

Abstract: Systems, methods, and computer-readable media are described for performing speculative execution of both paths/branches of a weakly predicted branch instruction. A branch instruction may be fetched from an instruction queue and determined to be a weakly predicted branch instruction, in which case, both paths of the branch instruction may be dispatched and speculatively executed. When the actual path taken becomes known, instructions corresponding to the path not taken may be flushed. Instructions from both paths of a weakly predicted branch instruction that are speculatively executed may be dispatch and executed in an interleaved manner.

Abstract: Systems, methods, and computer-readable media are described for performing instruction execution using an instruction completion table (ICT) that is configured to accommodate shared ICT entries. A shared ICT entry maps to multiple instructions such as, for example, two instructions. Each shared ICT entry may be referenced by an even instruction tag (ITAG) and an odd ITAG that correspond to respective instructions that have been grouped together in the shared ICT entry. The instructions corresponding to a given shared ICT entry can be executed and finished independently of one another. A shared ICT entry is completed when each execution of each instruction corresponding to the shared ICT entry has finished and when all prior ICT entries have completed. Also described herein are system, methods, and computer-readable media for flushing instructions in shared ICT entries in response to execution of a branch instruction.

Abstract: Systems, methods, and computer program products are disclosed that control issuing branch instructions in a simultaneous multi-threading (SMT) system. An embodiment system includes an SMT processor circuit that receives, from one of a plurality of threads, a branch instruction having a favor bit. The SMT processor circuit schedules the branch instruction to issue, relative to branch instructions received from other threads in the plurality of threads, based on the favor bit. When the favor bit has a first value, the branch instruction is scheduled to have a higher priority to issue before the branch instructions received from other threads in the plurality of threads. When the favor bit has a second value, the branch instruction is scheduled to issue based an age of the branch instruction relative to respective ages of the branch instructions received from other threads in the plurality of threads.

Abstract: Within a processor, speculative finishes of load instructions only are tracked in a speculative finish table by maintaining an oldest load instruction of a thread in the speculative finish table after data is loaded for the oldest load instruction, wherein a particular queue index tag assigned to the oldest load instruction by an execution unit points to a particular entry in the speculative finish table, wherein the oldest load instruction is waiting to be finished dependent upon an error check code result. Responsive to a flow unit receiving the particular queue index tag with an indicator that the error check code result for data retrieved for the oldest load instruction is good, finishing the oldest load instruction in the particular entry pointed to by the queue index tag and writing an instruction tag stored in the entry for the oldest load instruction out of the speculative finish table for completion.

Abstract: A simultaneous multithreading processor and related method of operating are disclosed. The method comprises dispatching portions of a first instruction to be executed by a respective plurality of execution units of the processor; receiving, at an instruction completion table of the processor, respective finish reports responsive to execution of the portions of the first instruction; determining, using the received finish reports, that all of the portions of the first instruction have been executed; and updating the instruction completion table to indicate that the first instruction is ready for completion.

Abstract: Implementations are disclosed for a simultaneous multithreading processor configured to execute a plurality of threads. In one implementation, the simultaneous multithreading processor is configured to select a first thread of the plurality of threads according to a predefined scheme, and access an instruction completion table to determine whether the first thread is eligible to have a first instruction prioritized. Responsive to determining that the first thread is eligible to have the first instruction prioritized, the simultaneous multithreading processor is further configured to execute the first instruction of the first thread using a dedicated prioritization resource.

Abstract: Embodiments include systems, methods, and computer program products for using a multi-tier hang buster for detecting and breaking out of hang conditions in a processor. One method includes determining a plurality of actions available at each of a plurality of tiers used for breaking out of the hang condition in the processor. The method also includes, after detecting the hang condition on a first thread of the processor, performing one or more actions available at a first tier of the plurality of tiers to break out of the hang condition. The method further includes, after performing the one or more actions at the first tier and determining that the hang condition is still present, performing one or more actions available at one or more second tiers of the plurality of tiers to break out of the hang condition.

Abstract: An instruction sequencing unit in an out-of-order (OOO) processor includes a Most Favored Instruction (MFI) mechanism that designates an instruction as an MFI. The processing queues in the processor identify when they contain the MFI, and assures processing the MFI. The MFI remains the MFI until it is completed or is flushed, and which time the MFI mechanism selects the next MFI.

Abstract: An approach is provided in which a mapper control unit matches a result instruction tag corresponding to an executed instruction to a history buffer entry's instruction tag. The matched history buffer entry includes multiple history buffer field sets that each include a field set state indicator. The mapper control unit identifies a subset of the history buffer field sets having a valid field set state indicator and stores result data corresponding to the result instruction tag in the identified subset of history buffer field sets. In turn, the mapper control unit restores a subset of a register's fields utilizing content from the subset of history buffer field sets.

Abstract: An approach is provided in which a mapper control unit receives first dispatch information corresponding to a first instruction that identifies a first register and a first register type. The mapper control unit dynamically configures a first history buffer entry to support the first register type and, in turn, stores content from the first register into the first history buffer entry. The mapper control unit then receives second dispatch information corresponding to a second instruction that identifies a second register and a second register type, which is different than the first register type. The mapper control unit dynamically configures a second history buffer entry to support the second register type and, in turn, stores content from the second register into the second history buffer entry.

Abstract: An approach is provided in which a mapper control unit receives dispatch information corresponding to a dispatching instruction that targets some of the register fields in a register. The mapper control unit selects, in a history buffer, an available history buffer entry that includes multiple field sets, each including an itag field. In turn, the mapper control unit modifies some of the history buffer field sets, including the itag fields, based on the existing content stored in the targeted register fields.

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: An instruction sequencing unit in an out-of-order (OOO) processor includes a Most Favored Instruction (MFI) mechanism that designates an instruction as an MFI. The processing queues in the processor identify when they contain the MFI, and assures processing the MFI. The MFI remains the MFI until it is completed or is flushed, and which time the MFI mechanism selects the next MFI.