Abstract: An apparatus has tag checking circuitry responsive to a target address to: identify a guard tag stored in a memory system in association with a block of one or more memory locations, the block containing a target memory location identified by the target address, perform a tag check based on the guard tag and an address tag associated with the target address, and in response to detecting a mismatch in the tag check, perform an error response action. The apparatus also has tag mapping storage circuitry to store mapping information indicative of a mapping between guard tag values and corresponding address tag values. The tag checking circuitry remaps at least one of the guard tag and the address tag based on the mapping information stored by the tag mapping storage circuitry to generate a remapped tag for use in the tag check.

Abstract: A data storage device comprises an array of data storage elements arranged as multiple partitions each comprising two or more data storage elements, each data storage element being associated with a respective identifier which identifies a data item currently stored by that data storage element; a predictor configured to compare, for each partition, information derived from the identifiers associated with the data storage elements of that partition with information derived from an identifier associated with the required data item, to identify a subset of partitions that do not store the required data item; and a comparator configured to compare identifiers associated with data storage elements of one or more partitions with the identifier associated with the required data item, wherein any partitions in the subset of partitions are excluded from the test group of partitions.

Abstract: A method of compiling a sequence of program instructions, a method of parallel execution of a sequence of program instructions and apparatuses and software supporting such methods are disclosed. The sequence of program instructions is analyzed in terms of basic blocks forming a control flow graph and execution paths through that control flow graph are identified. When more than one execution path leads to a given basic block, or when a loop path is found leading from a given basic block back to the same basic block, a potential convergence point may be identified. A convergence marker is added to the computer program associated with the basic blocks identified in this way and then when the program is executed, the convergence markers found are used to trigger a determination of a subset of the multiple execution threads which are executed following that convergence marker.

Abstract: A data storage device comprises an array of data storage elements arranged as multiple partitions each comprising two or more data storage elements, each data storage element being associated with a respective identifier which identifies a data item currently stored by that data storage element; a predictor configured to compare, for each partition, information derived from the identifiers associated with the data storage elements of that partition with information derived from an identifier associated with the required data item, to identify a subset of partitions that do not store the required data item; and a comparator configured to compare identifiers associated with data storage elements of one or more partitions with the identifier associated with the required data item, wherein any partitions in the subset of partitions are excluded from the test group of partitions.

Abstract: A method of compiling a sequence of program instructions, a method of parallel execution of a sequence of program instructions and apparatuses and software supporting such methods are disclosed. The sequence of program instructions is analysed in terms of basic blocks forming a control flow graph and execution paths through that control flow graph are identified. When more than one execution path leads to a given basic block, or when a loop path is found leading from a given basic block back to the same basic block, a potential convergence point may be identified. A convergence marker is added to the computer program associated with the basic blocks identified in this way and then when the program is executed, the convergence markers found are used to trigger a determination of a subset of the multiple execution threads which are executed following that convergence marker.