Abstract: Providing memory prefetch instructions with completion notifications in processor-based devices is disclosed. In this regard, an instruction set architecture (ISA) of a processor-based device provides a memory prefetch instruction that, when executed by a processor of a processor-based device, causes the processor to perform a memory prefetch operation by asynchronously retrieving a memory block from the system memory based on the memory address, and storing the memory block in a cache memory of the processor-based device. In response to completing the memory prefetch operation, the processor then notifies an executing software process that the memory prefetch operation is complete. Based on the notification, the executing software process may ensure that any subsequent memory access requests are not attempted until the memory prefetch operation is complete.

Abstract: Process dedicated in-memory translation lookaside buffers (TLBs) (mTLBs) for augmenting a memory management unit (MMU) TLB for translating virtual addresses (VAs) to physical addresses (PA) in a processor-based system is disclosed. In disclosed examples, a dedicated in-memory TLB is supported in system memory for each process so that one process's cached page table entries do not displace another process's cached page table entries. When a process is scheduled to execute in a central processing unit (CPU), the in-memory TLB address stored for such process can be used by page table walker circuit in the CPU MMU to access the dedicated in-memory TLB for executing the process to perform VA to PA translations in the event of a TLB miss to the MMU TLB. If a TLB miss occurs to the in-memory TLB, the page table walker circuit can walk the page table in the MMU.

Abstract: Tracking memory block access frequency in processor-based devices is disclosed herein. In one exemplary embodiment, a processor-based device provides a processing element (PE) that is configured to include an access count table for tracking accesses to memory blocks. The access count table is a packed table that comprises a plurality of access count values, each of which corresponds to a memory block of a plurality of memory blocks. Upon detecting a memory access operation (i.e., data-side operations such as memory load operations, memory store operations, atomic increment operations, set operations, and the like, or instruction-side operations such as code fetch operations) directed to a given memory block, the PE increments an access count value corresponding to the memory block. The access count value then can be accessed (e.g., by a process executing on the PE), and used to determine an access frequency for the memory block.

Abstract: A method, apparatus, and system for storing memory encryption realm key IDs is disclosed. A method comprises accessing a memory ownership table with a physical address to determine a realm ID associated with the physical address, accessing a key ID association structure with the realm ID to determine a realm key IS associated with the realm ID, and initiating a memory transaction based on the realm key ID. Once retrieved, the realm key ID may be stored in a translation lookaside buffer.

Abstract: Obsoleting values stored in registers in a processor based on processing obsolescent register-encoded instructions is disclosed. The processor is configured to support execution of read and/or write instructions that include obsolescence encoding indicating that one or more of its source and/or target register operands are to be obsoleted by the processor. A register encoded as obsolescent means the data value stored in such register will not be used by subsequent instructions in an instruction stream, and thus does not need to be retained. Thus, such register can be set as being in an obsolescent state so that the data value stored in such register can be ignored to improve performance. As one example, data values for registers having an obsolescent state can be ignored and thus not stored in a saved context for a process being switched out, thus conserving memory and improving processing time for a process switch.

Abstract: Process dedicated in-memory translation lookaside buffers (TLBs) (mTLBs) for augmenting a memory management unit (MMU) TLB for translating virtual addresses (VAs) to physical addresses (PA) in a processor-based system is disclosed. In disclosed examples, a dedicated in-memory TLB is supported in system memory for each process so that one process's cached page table entries do not displace another process's cached page table entries. When a process is scheduled to execute in a central processing unit (CPU), the in-memory TLB address stored for such process can be used by page table walker circuit in the CPU MMU to access the dedicated in-memory TLB for executing the process to perform VA to PA translations in the event of a TLB miss to the MMU TLB. If a TLB miss occurs to the in-memory TLB, the page table walker circuit can walk the page table in the MMU.

Abstract: A method, apparatus, and system for storing memory encryption realm key IDs is disclosed. A method comprises accessing a memory ownership table with a physical address to determine a realm ID associated with the physical address, accessing a key ID association structure with the realm ID to determine a realm key IS associated with the realm ID, and initiating a memory transaction based on the realm key ID. Once retrieved, the realm key ID may be stored in a translation lookaside buffer.

Abstract: Performing speculative address translation in processor-based devices is disclosed herein. In one exemplary embodiment, a processor-based device provides a processing element (PE) that defines a speculative translation instruction such as an enqueue instruction for offloading operations to a peripheral device. The speculative translation instruction references a plurality of bytes including one or more virtual memory addresses. After receiving the speculative translation instruction, an instruction decode stage of an execution pipeline circuit of the PE transmits a request for address translation of the virtual memory address to a memory management unit (MMU) of the PE. The MMU then performs speculative address translation of the virtual memory address into a corresponding translated memory address.

Abstract: Cache-based trace logging using tags in an upper cache level. A processor influxes a cache line into a first cache level from an upper second cache level. Influxing the cache line into the first cache level includes, based on the first cache level being a recording cache, the processor reading a tag that is (i) stored in the second cache level and (ii) associated with the cache line. Based on reading the tag, the processor determines whether a first value of the cache line within the second cache level has been previously captured by a trace. The processor performs one of (i) when the first value is determined to have been previously logged, following a logged value logic path when influxing the cache line; or (ii) when the first value is determined to have not been previously logged, following a non-logged value logic path when influxing the cache line.

Abstract: Tracking memory block access frequency in processor-based devices is disclosed herein. In one exemplary embodiment, a processor-based device provides a processing element (PE) that is configured to include an access count table for tracking accesses to memory blocks. The access count table is a packed table that comprises a plurality of access count values, each of which corresponds to a memory block of a plurality of memory blocks. Upon detecting a memory access operation (i.e., data-side operations such as memory load operations, memory store operations, atomic increment operations , set operations, and the like, or instruction-side operations such as code fetch operations) directed to a given memory block, the PE increments an access count value corresponding to the memory block. The access count value then can be accessed (e.g., by a process executing on the PE), and used to determine an access frequency for the memory block.

Abstract: Various aspects disclosed herein relate to combining instructions to load data from or store data in memory while processing instructions in a computer processor. More particularly, at least one pattern of multiple memory access instructions that reference a common base register and do not fully utilize an available bus width may be identified in a processor pipeline. In response to determining that the multiple memory access instructions target adjacent memory or non-contiguous memory that can fit on a single cache line, the multiple memory access instructions may be replaced within the processor pipeline with one equivalent memory access instruction that utilizes more of the available bus width than either of the replaced memory access instructions.

Abstract: Cache-based trace logging using tags in an upper cache level. A processor influxes a cache line into a first cache level from an upper second cache level. Influxing the cache line into the first cache level includes, based on the first cache level being a recording cache, the processor reading a tag that is (i) stored in the second cache level and (ii) associated with the cache line. Based on reading the tag, the processor determines whether a first value of the cache line within the second cache level has been previously captured by a trace. The processor performs one of (i) when the first value is determined to have been previously logged, following a logged value logic path when influxing the cache line; or (ii) when the first value is determined to have not been previously logged, following a non-logged value logic path when influxing the cache line.

Abstract: Cache-based trace logging using tags in an upper cache level. A processor influxes a cache line into a first cache level from an upper second cache level. Influxing the cache line into the first cache level includes, based on the first cache level being a recording cache, the processor reading a tag that is (i) stored in the second cache level and (ii) associated with the cache line. Based on reading the tag, the processor determines whether a first value of the cache line within the second cache level has been previously captured by a trace. The processor performs one of (i) when the first value is determined to have been previously logged, following a logged value logic path when influxing the cache line; or (ii) when the first value is determined to have not been previously logged, following a non-logged value logic path when influxing the cache line.

Abstract: An apparatus, method, and system for memory bandwidth aware data prefetching is presented. The method may comprise monitoring a number of request responses received in an interval at a current prefetch request generation rate, comparing the number of request responses received in the interval to at least a first threshold, and adjusting the current prefetch request generation rate to an updated prefetch request generation rate by selecting the updated prefetch request generation rate from a plurality of prefetch request generation rates, based on the comparison. The request responses may be NACK or RETRY responses. The method may further comprise either retaining a current prefetch request generation rate or selecting a maximum prefetch request generation rate as the updated prefetch request generation rate in response to an indication that prefetching is accurate.

Abstract: A processor supporting a translation lookaside buffer (TLB) modification instruction for updating a hardware-managed TLB is disclosed. A page table (PT) entry (PTE) corresponding to a virtual memory address is identified by a PT walking circuit walking the PT and a corresponding TLB entry is created. An execution circuit in the processor executes a TLB modification instruction to cause the TLB entry corresponding to the virtual memory address to be updated based on an update to the PT mapping information in the PTE corresponding to the virtual memory address. In one example, a portion of the PT mapping information in a PTE corresponding to a virtual memory address is stored in a TLB mapping information in a TLB entry corresponding to the virtual memory address in response to the TLB modification instruction being executed by the execution circuit without invalidating the TLB entry.

Abstract: Cache-based trace logging using tags in system memory. A processor influxes a cache line into a first cache level. Influxing the cache line into the first cache level includes, based on the first cache level being a recording cache, the processor reading a tag that is (i) stored in system memory and (ii) associated with the cache line. Based on reading the tag, the processor determines whether a first value of the cache line has been previously captured by a trace has been previously captured by a trace. The processor performs one of (i) when the first value is determined to have been previously logged, following a logged value logic path when influxing the cache line; or (ii) when the first value is determined to have not been previously logged, following a non-logged value logic path when influxing the cache line.

Abstract: Treating main memory as a collection of tagged cache lines for trace logging. A computer system allocates a plurality of memory blocks, and a corresponding plurality of tags, within a main memory. Each tag indicates whether data stored in a corresponding memory block has been captured by an execution trace. The computer system synchronizes these tags with tags in a memory cache and manages a traced status of the memory blocks. This can include one or more of (i) setting a tag to indicate a memory block has not been captured based on identifying a direct memory access operation, (ii) setting a tag based on whether a paged-in value of a memory block has been captured, (iii) setting a tag or memory categorization based whether a memory block has been initialized, or (iv) setting a tag or memory categorization based whether a memory block is mapped to a file.

Abstract: Cache-based trace logging using tags in an upper cache level. A processor influxes a cache line into a first cache level from an upper second cache level. Influxing the cache line into the first cache level includes, based on the first cache level being a recording cache, the processor reading a tag that is (i) stored in the second cache level and (ii) associated with the cache line. Based on reading the tag, the processor determines whether a first value of the cache line within the second cache level has been previously captured by a trace. The processor performs one of (i) when the first value is determined to have been previously logged, following a logged value logic path when influxing the cache line; or (ii) when the first value is determined to have not been previously logged, following a non-logged value logic path when influxing the cache line.

Abstract: Performing speculative address translation in processor-based devices is disclosed herein. In one exemplary embodiment, a processor-based device provides a processing element (PE) that defines a speculative translation instruction such as an enqueue instruction for offloading operations to a peripheral device. The speculative translation instruction references a plurality of bytes including one or more virtual memory addresses. After receiving the speculative translation instruction, an instruction decode stage of an execution pipeline circuit of the PE transmits a request for address translation of the virtual memory address to a memory management unit (MMU) of the PE. The MMU then performs speculative address translation of the virtual memory address into a corresponding translated memory address.

Abstract: Exemplary reach-based explicit dataflow processors and related computer-readable media and methods. The reach-based explicit dataflow processors are configured to support execution of producer instructions encoded with explicit naming of consumer instructions intended to consume the values produced by the producer instructions. The reach-based explicit dataflow processors are configured to make available produced values as inputs to explicitly named consumer instructions as a result of processing producer instructions. The reach-based explicit dataflow processors support execution of a producer instruction that explicitly names a consumer instruction based on using the producer instruction as a relative reference point from the producer instruction.