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: 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: 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: 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: Providing exception stack management using stack panic fault exceptions in processor-based devices is disclosed. In this regard, a processor device defines a “stack panic fault exception” that may be raised upon execution of an exception handler store operation attempting to write state data into an exception stack, and provides a dedicated plurality of stack panic fault exception state registers in which stack panic fault exception state data may be saved. Upon detecting a first exception, the processor device transfers program control to an exception handler for the first exception. If a second exception occurs upon execution of a store operation in the exception handler, the processor device determines that the second exception should be handled as a stack panic fault exception, saves the stack panic fault exception state data in the stack panic fault exception state registers, and transfers program control to a stack panic fault exception handler.

Abstract: Providing exception stack management using stack panic fault exceptions in processor-based devices is disclosed. In this regard, a processor device defines a “stack panic fault exception” that may be raised upon execution of an exception handler store operation attempting to write state data into an exception stack, and provides a dedicated plurality of stack panic fault exception state registers in which stack panic fault exception state data may be saved. Upon detecting a first exception, the processor device transfers program control to an exception handler for the first exception. If a second exception occurs upon execution of a store operation in the exception handler, the processor device determines that the second exception should be handled as a stack panic fault exception, saves the stack panic fault exception state data in the stack panic fault exception state registers, and transfers program control to a stack panic fault exception handler.

Abstract: Providing express memory obsolescence in processor-based devices is disclosed. In this regard, an instruction set architecture (ISA) of a processor-based device provides a memory load instruction indicating a final memory load operation from a memory address (i.e., after the memory load operation represented by the memory load instruction is performed, the value at the memory address need not be maintained). Upon receiving the memory load instruction by an execution pipeline of the processor-based device, an entry corresponding to the memory address of the memory load instruction is located in an intermediate memory external to the system memory of the processor-based device, and used to perform the final memory load operation. After the final memory load operation is performed using the entry, a value of an obsolete indicator for the entry is set to indicate that the entry can be reused prior to its contents being written to the system memory.

Abstract: Providing express memory obsolescence in processor-based devices is disclosed. In this regard, an instruction set architecture (ISA) of a processor-based device provides a memory load instruction indicating a final memory load operation from a memory address (i.e., after the memory load operation represented by the memory load instruction is performed, the value at the memory address need not be maintained). Upon receiving the memory load instruction by an execution pipeline of the processor-based device, an entry corresponding to the memory address of the memory load instruction is located in an intermediate memory external to the system memory of the processor-based device, and used to perform the final memory load operation. After the final memory load operation is performed using the entry, a value of an obsolete indicator for the entry is set to indicate that the entry can be reused prior to its contents being written to the system memory.

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: 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: The disclosure relates to accessing memory content with a high temporal locality of reference. An embodiment of the disclosure stores the content in a data buffer, determines that the content of the data buffer has a high temporal locality of reference, and accesses the data buffer for each operation targeting the content instead of a cache storing the content.

Abstract: Systems and methods for dependency-prediction include executing instructions in an instruction pipeline of a processor and detecting a conditionality-imposing control instruction, such as an If-Then (IT) instruction, which imposes dependent behavior on a conditionality block size of one or more dependent instructions. Prior to executing a first instruction, a dependency-prediction is made to determine if the first instruction is a dependent instruction of the conditionality-imposing control instruction, based on the conditionality block size and one or more parameters of the instruction pipeline. The first instruction is executed based on the dependency-prediction. When the first instruction is dependency-mispredicted, an associated dependency-misprediction penalty is mitigated. If the first instruction is a branch instruction, the mitigation involves training a branch prediction tracking mechanism to correctly dependency-predict future occurrences of the first instruction.

Abstract: Systems and methods are directed to prefetch mechanisms involving non-equal magnitude stride values. A non-equal magnitude functional relationship between successive stride values, may be detected, wherein the stride values are based on distances between target addresses of successive load instructions. At least a next stride value for prefetching data, may be determined, wherein the next stride value is based on the non-equal magnitude functional relationship and a previous stride value. Data prefetch may be from at least one prefetch address calculated based on the next stride value and a previous target address. The non-equal magnitude functional relationship may include a logarithmic relationship corresponding to a binary search algorithm.

Abstract: A processor includes a queue for storing instructions processed within the context of a current value of a register field, where for some embodiments the instruction is undefined or defined, depending upon the register field at time of processing. After a write instruction (an instruction that writes to the register field) executes, the queue is searched for any entries that contain instructions that depend upon the executed write instruction. Each such entry stores the value of the register field at the time the instruction in the entry was processed. If such an entry is found in the queue and its stored value of the register field does not match the value that the write instruction wrote to the register field, then the processor flushes the pipeline and restarts at a state so as to correctly execute the instruction.

Abstract: Systems and methods for managing access to a cache relate to determining one or more execute permissions associated with a write-address of a write-request to the cache. The cache may be a unified cache for storing data as well as instructions. If there is a write-miss in the cache for the write-request, a cache controller may determine whether to implement a write-allocate policy or a write-no-allocate policy for servicing the write-miss, based on the one or more execute permissions. The one or more execute permissions can relate to a privilege level associated with the write-address. Execute permissions of a producing agent which generated the write-request and an execute permission of a consuming agent which can execute from the write-address may be based on the privilege levels of the producing agent and the consuming agent, respectively.

Abstract: Aspects disclosed herein relate to combining instructions to load data from or store data in memory while processing instructions in processors. An exemplary method includes detecting a pattern of pipelined instructions to access memory using a first portion of available bus width and, in response to detecting the pattern, combining the pipelined instructions into a single instruction to access the memory using a second portion of the available bus width that is wider than the first portion. Devices including processors using disclosed aspects may execute currently available software in a more efficient manner without the software being modified.

Abstract: Delays due to waiting for operands that will not be used by a select operand instruction, are alleviated based on an early recognition that such operand data is not required in order to complete the processing of the select operand instruction. At appropriate points prior to execution, determinations are made regarding a selection criterion or criteria specified by the select operand instruction, conditions that affect the selection criteria, and the availability of operands. A hold circuit uses the determinations to control the activation and release of a hold signal that controls processor pipeline stalls. A stall required to wait for operand data is skipped or a stall is terminated early, if the selected operand is available even though the other operand, that will not be used, is not available. A stall due to waiting for operands is maintained until the selection criteria is met and the selected operand is fetched and made available.

Abstract: Systems and methods pertain to a branch target instruction cache (BTIC) of a processor. The BTIC is configured to store one or more branch target instructions at branch target addresses of branch instructions executable by the processor. At least one of the branch target instructions stored in the BTIC is a conditional branch instruction. Branch prediction techniques for predicting the direction of the conditional branch instruction allow one or more instructions following the conditional branch instruction, as well as a branch target address of the conditional branch instruction to also be stored in the BTIC.

Abstract: Systems and methods for identifying candidate load instructions for prefetch operations based on at least instruction encoding of the load instructions, include an identifier based on a function of at least one or more fields of a load instruction and optionally, a subset of bits of the PC value of the load instruction, wherein the one or more fields exclude a full address or program counter (PC) value of the load instruction. Prefetch mechanisms, including a prefetch table indexed by the identifier, can determine whether the load instruction is a candidate load instruction for prefetching load data, based on the identifier. The function may be a hash, a concatenation, or a combination thereof, of one or more bits of the one or more fields. The fields include one or more of a base register, a destination register, an immediate offset, an offset register, or other bits of instruction encoding of the load instruction.

Abstract: Predicting memory instruction punts in a computer processor using a punt avoidance table (PAT) are disclosed. In one aspect, an instruction processing circuit accesses a PAT containing entries each comprising an address of a memory instruction. Upon detecting a memory instruction in an instruction stream, the instruction processing circuit determines whether the PAT contains an entry having an address of the memory instruction. If so, the instruction processing circuit prevents the detected memory instruction from taking effect before at least one pending memory instruction older than the detected memory instruction, to preempt a memory instruction punt. In some aspects, the instruction processing circuit may determine, upon execution of a pending memory instruction, whether a hazard associated with the detected memory instruction has occurred. If so, an entry for the detected memory instruction is generated in the PAT.