Abstract: A mechanism is described that predicts the usefulness of a prefetching instruction during the instruction's decode cycle. Prefetching instructions that are predicted as useful (prefetch useful data) are sent to an execution unit of the processor for execution, while instructions that are predicted as not useful are discarded. The prediction regarding the usefulness of a prefetching instructions is performed utilizing a branch prediction mask contained in the branch history mechanism. This mask is compared to information contained in the prefetching instruction that records the branch path between the prefetching instruction and actual use of the data. Both instructions and data can be prefetched using this mechanism.

Abstract: An apparatus and method for partitioning programs between a general purpose core and one or more accelerators are provided. With the apparatus and method, a compiler front end is provided for converting a program source code in a corresponding high level programming language into an intermediate code representation. This intermediate code representation is provided to an interprocedural optimizer which determines which core processor or accelerator each portion of the program should execute on and partitions the program into sub-programs based on this set of decisions. The interprocedural optimizer may further add instructions to the partitions to coordinate and synchronize the sub-programs as required. Each sub-program is compiled on an appropriate compiler backend for the instruction set architecture of the particular core processor or accelerator selected to execute the sub-program. The compiled sub-programs and then linked to thereby generate an executable program.

Abstract: This invention pertains to apparatus, method and a computer program stored on a computer readable medium. The computer program includes instructions for use with an instruction unit having a code page, and has computer program code for partitioning the code page into at least two sections for storing in a first section thereof a plurality of instruction words and, in association with at least one instruction word, for storing in a second section thereof an extension to each instruction word in the first section. The computer program further includes computer program code for setting a state of at least one page table entry bit for indicating, on a code page by code page basis, whether the code page is partitioned into the first and second sections for storing instruction words and their extensions, or whether the code page is comprised instead of a single section storing only instruction words.

Abstract: This invention pertains to apparatus, method and a computer program stored on a computer readable medium. The computer program includes instructions for use with an instruction unit having a code page, and has computer program code for partitioning the code page into at least two sections for storing in a first section thereof a plurality of instruction words and, in association with at least one instruction word, for storing in a second section thereof an extension to each instruction word in the first section. The computer program further includes computer program code for setting a state of at least one page table entry bit for indicating, on a code page by code page basis, whether the code page is partitioned into the first and second sections for storing instruction words and their extensions, or whether the code page is comprised instead of a single section storing only instruction words.

Abstract: An apparatus and method for partitioning programs between a general purpose core and one or more accelerators are provided. With the apparatus and method, a compiler front end is provided for converting a program source code in a corresponding high level programming language into an intermediate code representation. This intermediate code representation is provided to an interprocedural optimizer which determines which core processor or accelerator each portion of the program should execute on and partitions the program into sub-programs based on this set of decisions. The interprocedural optimizer may further add instructions to the partitions to coordinate and synchronize the sub-programs as required. Each sub-program is compiled on an appropriate compiler backend for the instruction set architecture of the particular core processor or accelerator selected to execute the sub-program. The compiled sub-programs and then linked to thereby generate an executable program.

Abstract: A method, system, and computer program product for mixing of conventional and augmented instructions within an instruction stream, wherein control may be directly transferred, without operating system intervention, between one type of instruction to another. Extra instruction word bits are added in a manner that is designed to minimally interfere with the encoding, decoding, and instruction processing environment in a manner compatible with existing conventional fixed instruction width code. A plurality of instruction words are inserted into an instruction word oriented architecture to form an encoding group of instruction words. The instruction words in the encoding group are dispatched and executed either independently or in parallel based on a specific microprocessor implementation. The encoding group does not indicate any form of required parallelism or sequentiality. One or more indicators for the encoding group are created, wherein one indicator is used to indicate presence of the encoding group.

Abstract: This invention pertains to apparatus, method and a computer program stored on a computer readable medium. The computer program includes instructions for use with an instruction unit having a code page, and has computer program code for partitioning the code page into at least two sections for storing in a first section thereof a plurality of instruction words and, in association with at least one instruction word, for storing in a second section thereof an extension to each instruction word in the first section. The computer program further includes computer program code for setting a state of at least one page table entry bit for indicating, on a code page by code page basis, whether the code page is partitioned into the first and second sections for storing instruction words and their extensions, or whether the code page is comprised instead of a single section storing only instruction words.

Abstract: A mechanism is described that prefetches instructions and data into the cache using a branch instruction as a prefetch trigger. The prefetch is initiated if the predicted execution path after the branch instruction matches the previously seen execution path. This match of the execution paths is determined using a branch history queue that records the branch outcomes (taken/not taken) of the branches in the program. For each branch in this queue, a branch history mask records the outcomes of the next N branches and serves as an encoding of the execution path following the branch instruction. The branch instruction along with the mask is associated with a prefetch address (instruction or data address) and is used for triggering prefetches in the future when the branch is executed again. A mechanism is also described to improve the timeliness of a prefetch by suitably adjusting the value of N after observing the usefulness of the prefetched instructions or data.

Abstract: A method and apparatus for storing and utilizing set prediction information regarding which set of a set-associative memory will be accessed for enhancing performance of the set-associative memory and reducing power consumption. The set prediction information is stored in various locations including a branch target buffer, instruction cache and operand history table to decrease latency for accesses to set-associative instruction and data caches.

Abstract: In the system bus controller of a multi-processor system, apparatus is provided for selecting one of the processors to handle an interrupt. A mask is provided for each respective task being executed on each one of the processors. Each mask includes a speculation bit identifying whether the task is speculative. Each mask includes a plurality of class enable bits identifying whether the task can be interrupted by a respective class of interrupts associated with each of the plurality of class enable bits. Control lines in the system bus receive an interrupt having a received interrupt class. A subset of the processors is identified; processors in the subset can be interrupted by the received interrupt based on the received interrupt class and the respective speculation bit and class enable bits assigned to the task being executed on each respective processor. A Boolean AND operation is performed on the mask associated with the respective task executing on each processor.

Abstract: A computer system includes a condition register having multiple fields. Each field may be used as an independent condition register. A compiler which generates executable code for the computer system assigns instructions to different fields, allowing condition values to be saved while other conditions are evaluated and allowing consecutive instructions which generate or test condition values to be overlapped in their execution.