Abstract: Operation of a multi-slice processor that includes a plurality of execution slices and an instruction sequencing unit. Operation of such a multi-slice processor includes: receiving, at the instruction sequencing unit, a load instruction indicating load address data and a load data length; determining a previous store instruction in an issue queue such that store address data for the previous store instruction corresponds to the load address data, wherein the previous store instruction corresponds to a store data length; and generating, in dependence upon the store data length matching the load data length, an indication in the issue queue that indicates a dependency between the load instruction and the previous store instruction.

Abstract: Operation of a multi-slice processor implementing datapath steering, where the multi-slice processor includes a plurality of execution slices. Operation of such a multi-slice processor includes: identifying, from a set of instructions, a second instruction that is dependent upon a first instruction in the set of instructions; and responsive to the second instruction being dependent upon the first instruction in the set of instructions, issuing each of the instructions in the set of instructions to a particular set of execution slices configured with bypass logic between execution slices that reduces execution latencies between dependent instructions.

Abstract: The embodiments relate to a method for managing a garbage collection process. The method includes executing a garbage collection process on a memory block of user address space. A load instruction is run. Running the load instruction includes loading content of a storage location into a processor. The loaded content corresponds to a memory address. It is determined if the garbage collection process is being executed at the memory address. The load instruction is diverted to a process to move an object at the memory address to a location outside of the memory block in response to determining that the garbage collection process is being executed at the first memory address. The load instruction is continued in response to determining that the garbage collection process is not being executed at the memory address.

Abstract: A technique for operating a processor includes allocating an entry in a prefetch filter queue (PFQ) for a cache line address (CLA) in response to the CLA missing in an upper level instruction cache. In response to the CLA subsequently hitting in the upper level instruction cache, an associated prefetch value for the entry in the PFQ is updated. In response to the entry being aged-out of the PFQ, an entry in a backing array for the CLA and the associated prefetch value is allocated. In response to subsequently determining that prefetching is required for the CLA, the backing array is accessed to determine the associated prefetch value for the CLA. A cache line at the CLA and a number of sequential cache lines specified by the associated prefetch value in the backing array are then prefetched into the upper level instruction cache.

Abstract: Hazard avoidance in a multi-slice processor including adding, to a hazard table, an entry for an effective address, wherein the entry comprises an instruction tag (ITAG) offset for the effective address; fetching, by an instruction fetch unit, a processor instruction from a memory location using the effective address; determining that the hazard table includes the entry for the effective address; retrieving, from the hazard table, the ITAG offset for the effective address; identifying a prior internal operation (TOP) using the ITAG offset; and decoding the processor instruction into a load IOP with a dependency on the prior IOP.

Abstract: Hazard avoidance in a multi-slice processor including adding, to a hazard table, an entry for an effective address, wherein the entry comprises an instruction tag (ITAG) offset for the effective address; fetching, by an instruction fetch unit, a processor instruction from a memory location using the effective address; determining that the hazard table includes the entry for the effective address; retrieving, from the hazard table, the ITAG offset for the effective address; identifying a prior internal operation (TOP) using the ITAG offset; and decoding the processor instruction into a load IOP with a dependency on the prior IOP.

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: 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: Fast issuance and execution of a multi-width instruction across multiple slices in a parallel slice processor core is supported in part through the use of an early notification signal passed between issue logic associated with multiple slices handling that multi-width instruction coupled with an issuance of a different instruction by the originating issue logic for the early notification signal.

Abstract: A method for adjusting a frequency of a processor is disclosed herein. In one embodiment, the method includes determining a total current and a temperature of the multi-core processor and estimating a leakage current for the multi-core processor. The method also includes calculating a switching current by subtracting the leakage current from the total current. The method also includes calculating an effective switching capacitance based at least in part on the switching current. The method also includes calculating a workload activity factor by dividing the effective switching capacitance by a predetermined effective switching capacitance stored in vital product data, and enforcing a turbo frequency limit of the multi-core processor based on the workload activity factor.

Abstract: Operation of a multi-slice processor that includes a plurality of execution slices and a plurality of load/store slices, where each load/store slice includes a load miss queue and a load reorder queue, includes: receiving, at a load reorder queue, a load instruction requesting data; responsive to the data not being stored in a data cache, determining whether a previous load instruction is pending a fetch of a cache line comprising the data; if the cache line does not comprise the data, allocating an entry for the load instruction in the load miss queue; and if the cache line does comprise the data: merging, in the load reorder queue, the load instruction with an entry for the previous load instruction.

Abstract: Embodiments described herein include a computing system that permits partial writes into a memory element—e.g., a register on a processor. For example, the data to be written into the memory element may be spread across multiple sources. The register may receive data from two different sources at different times and perform two separate partial write commands to store the data. Embodiments herein generate an ECC value for each of the partial writes. That is, when storing the data of the first partial write, the computing system generates a first ECC value for the data in the first partial write and stores this value in the memory element. Later, when performing the second partial write, the computing system generates a second ECC value for this data which is also stored in the memory element.

Abstract: The embodiments relate to a computer system, computer program product and method for managing a garbage collection process. Processing control is obtained based on execution of a load instruction and a determination that an object pointer to be loaded indicates a location within a selected portion of memory undergoing a garbage collection process. The determination includes identifying a base address and size of a first memory block subject to the garbage collection, subdividing the first memory block into sections, assigning a binary value to each section, and determining if the first memory block corresponds to the enabled section. An image of the load instruction is obtained and a pointer address is calculated from the image. The object pointer is read and it is determined whether the object pointer is to be modified. The object pointer is modified and stored in a selected location.

Abstract: The embodiments relate to a method for managing a garbage collection process. The method includes executing a garbage collection process on a memory block of user address space. A load instruction is run. Running the load instruction includes loading content of a storage location into a processor. The loaded content corresponds to a memory address. It is determined if the garbage collection process is being executed at the memory address. The load instruction is diverted to a process to move an object at the memory address to a location outside of the memory block in response to determining that the garbage collection process is being executed at the first memory address. The load instruction is continued in response to determining that the garbage collection process is not being executed at the memory address.

Abstract: Embodiments of the present invention provide systems and methods for mapping the architected state of one or more threads to a set of distributed physical register files to enable independent execution of one or more threads in a multiple slice processor. In one embodiment, a system is disclosed including a plurality of dispatch queues which receive instructions from one or more threads and an even number of parallel execution slices, each parallel execution slice containing a register file. A routing network directs an output from the dispatch queues to the parallel execution slices and the parallel execution slices independently execute the one or more threads.

Abstract: The embodiments relate to a method for managing a garbage collection process. The method includes executing a garbage collection process on a memory block of user address space. A load instruction is run. Running the load instruction includes loading content of a storage location into a processor. The loaded content corresponds to a memory address. It is determined if the garbage collection process is being executed at the memory address. The load instruction is diverted to a process to move an object at the memory address to a location outside of the memory block in response to determining that the garbage collection process is being executed at the first memory address. The load instruction is continued in response to determining that the garbage collection process is not being executed at the memory address.

Abstract: Handling unaligned load operations, including: receiving a request to load data stored within a range of addresses; determining that the range of addresses includes addresses associated with a plurality of caches, wherein each of the plurality of caches are associated with a distinct processor slice; issuing, to each distinct processor slice, a request to load data stored within a cache associated with the distinct processor slice, wherein the request to load data stored within the cache associated with the distinct processor slice includes a portion of the range of addresses; executing, by each distinct processor slice, the request to load data stored within the cache associated with the distinct processor slice; and receiving, over a plurality of data communications busses, execution results from each distinct processor slice, wherein each data communications busses is associated with one of the distinct processor slices.

Abstract: Handling unaligned load operations, including: receiving a request to load data stored within a range of addresses; determining that the range of addresses includes addresses associated with a plurality of caches, wherein each of the plurality of caches are associated with a distinct processor slice; issuing, to each distinct processor slice, a request to load data stored within a cache associated with the distinct processor slice, wherein the request to load data stored within the cache associated with the distinct processor slice includes a portion of the range of addresses; executing, by each distinct processor slice, the request to load data stored within the cache associated with the distinct processor slice; and receiving, over a plurality of data communications busses, execution results from each distinct processor slice, wherein each data communications busses is associated with one of the distinct processor slices.

Abstract: Method and system for writing data into a register entry of a processing unit is provided. A logic unit issues an instruction for writing result data into a register entry. At least one functional unit coupled to the logic unit receives the instruction and provides partial result data to be written into the register entry and information regarding the partial result data. A logic circuit coupled to the register entry receives the information regarding the partial result data and writes the partial result data into at least one portion of the register entry based on the received information, the at least one portion of the register entry being determined based on the received information.

Abstract: Embodiments described herein include a computing system that permits partial writes into a memory element—e.g., a register on a processor. For example, the data to be written into the memory element may be spread across multiple sources. The register may receive data from two different sources at different times and perform two separate partial write commands to store the data. Embodiments herein generate an ECC value for each of the partial writes. That is, when storing the data of the first partial write, the computing system generates a first ECC value for the data in the first partial write and stores this value in the memory element. Later, when performing the second partial write, the computing system generates a second ECC value for this data which is also stored in the memory element.