Abstract: A mapper unit of an out-of-order processor assigns a particular counter currently in a counter free pool to count a number of mappings of logical registers to a particular physical register from among multiple physical registers, responsive to an execution of an instruction by the mapper unit mapping at least one logical register to the particular physical register. The number of counters is less than the number of physical registers. The mapper unit, responsive to the counted number of mappings of logical registers to the particular physical register decremented to less than a minimum value, returns the particular counter to the counter free pool.

Abstract: A computer system assigns a particular counter from among a plurality of counters currently in a counter free pool to count a number of mappings of logical registers from among a plurality of logical registers to a particular physical register from among a plurality of physical registers, responsive to an execution of an instruction by a mapper unit mapping at least one logical register from among the plurality of logical registers to the particular physical register, wherein the number of the plurality of counters is less than a number of the plurality of physical registers. The computer system, responsive to the counted number of mappings of logical registers to the particular physical register decremented to less than a minimum value, returns the particular counter to the counter free pool.

Abstract: A computer processing system method and apparatus having a processor employing an operating system (O/S) multi-task control between multiple user programs and which ensures that the programs do not interfere with each other, said computing processing system having a branch multiple page size prediction mechanism which predicts a page size along with a branch direction and a branch target of a branch for instructions of a processing pipeline, having a branch target buffer (BTB) predicting the branch target, said branch prediction mechanism storing recently used instructions close to the processor in a local cache, and having a translation look-aside buffer TLB mechanism which tracks the translation of the most recent pages and supports multiple page sizes.

Abstract: A computer implemented method of processing instructions of a computer program. The method comprises providing at least two copies of program status data; identifying a first update instruction of the instructions that writes to at least one field of the program status data; and associating the first update instruction with a first copy of the at least two copies of program status data.

Abstract: A novel system and method for working around a processing flaw in a processor is disclosed. At least one instruction is fetched from a memory location. The instruction is decoded. A set of opcode compare logic, associated with an instruction decode unit and/or a set of global completion table, is used for an opcode compare operation. The compare operation compares the instruction and a set of values within at least one opcode compare register in response to the decoding. The instruction is marked with a pattern based on the opcode compare operation. The pattern indicates that the instruction is associated with a processing flaw. The pattern is separate and distinct from opcode information within the instruction that is utilized by the set of opcode compare logic during the opcode compare operation.

Abstract: A method for handling cache coherency includes allocating a tag when a cache line is not exclusive in a data cache for a store operation, and sending the tag and an exclusive fetch for the line to coherency logic. An invalidation request is sent within a minimum amount of time to an I-cache, preferably only if it has fetched to the line and has not been invalidated since, which request includes an address to be invalidated, the tag, and an indicator specifying the line is for a PSC operation. The method further includes comparing the request address against stored addresses of prefetched instructions, and in response to a match, sending a match indicator and the tag to an LSU, within a maximum amount of time. The match indicator is timed, relative to exclusive data return, such that the LSU can discard prefetched instructions following execution of the store operation that stores to a line subject to an exclusive data return, and for which the match is indicated.

Abstract: A method and information processing system manage load and store operations executed out-of-order. At least one of a load instruction and a store instruction is executed. A determination is made that an operand store compare hazard has been encountered. An entry within an operand store compare hazard prediction table is created based on the determination. The entry includes at least an instruction address of the instruction that has been executed and a hazard indicating flag associated with the instruction. The hazard indicating flag indicates that the instruction has encountered the operand store compare hazard. When a load instruction is associated with the hazard indicating flag the load instruction becomes dependent upon all store instructions associated with a substantially similar flag.

Abstract: A method and information processing system manage load and store operations executed out-of-order. At least one of a load instruction and a store instruction is executed. A determination is made that an operand store compare hazard has been encountered. An entry within an operand store compare hazard prediction table is created based on the determination. The entry includes at least an instruction address of the instruction that has been executed and a hazard indicating flag associated with the instruction. The hazard indicating flag indicates that the instruction has encountered the operand store compare hazard. When a load instruction is associated with the hazard indicating flag the load instruction becomes dependent upon all store instructions associated with a substantially similar flag.

Abstract: A system and method for collecting instrumentation data in a processor with a pipelined instruction execution stages arranged in an out-of-order execution architecture. One instruction group in a Global Completion Table is marked as a tagged group. Instrumentation data is stored for processing stages processing instructions associated with the tagged group. Sample signal pulses trigger a determination of whether the tagged group is the next-to-complete instruction group. When the sample pulse occurs at a time when the tagged group is the next-to-complete group, the instrumentation data is written as an output. Instrumentation data present during sample pulses that occur when the tagged group is not the next-to-complete group is optionally discarded. Sample pulses are generated at a rate equal to the desired sample rate times the number of groups in the global completion table to better ensure occurrence of a next-to-complete tagged group.

Abstract: A method, information processing system, and processor work around a processing flaw in a processor. At least one instruction is fetched from a memory location. The at least one instruction is decoded. An opcode compare operation is compared with the at least one instruction and a set of values within at least one opcode compare register in response to the decoding. The instruction is marked with a pattern based on the opcode compare operation. The pattern indicates that the instruction is associated with a processing flaw.

Abstract: A method for link stack misprediction resolution using a rename structure for tracking the link stack processing, in order to quickly resolve link stack corruption from mispredicted function returns. The method comprises establishing a set of physical data structures forming a common pool and an operation control table. Maintaining, within the common pool, a plurality of entries for a plurality of speculative instructions and a plurality of non-speculative instructions. And determining one speculative instruction to be a bad prediction speculative entry, identifying related entries to form a collection, and discarding the collection.

Abstract: A dual-issue instruction is decoded to determine a plurality of LSU dependencies needed by an LSU part of the dual-issue instruction and a plurality of non-LSU dependencies needed by a non-LSU part of the dual-issue instruction. During dispatch of the dual-issue instruction by the microprocessor, the dual dependency matrices are employed as follows: a Load-Store Unit (LSU) dependency matrix is written with the plurality of LSU dependencies and a non-LSU dependency matrix is written with the plurality of non-LSU dependencies; an LSU issue valid (LSU IV) indicator is set as valid to issue; an LSU portion of the dual-issue instruction is issued once the plurality of LSU dependencies of the dual issue instruction are satisfied; a non-LSU issue valid (non-LSU IV) indicator is set as valid to issue; and a non-LSU portion of the dual-issue instruction is issued once the plurality of non-LSU dependencies of the dual issue instruction are satisfied.

Abstract: A dual-issue instruction is decoded to determine a plurality of LSU dependencies needed by an LSU part of the dual-issue instruction and a plurality of non-LSU dependencies needed by a non-LSU part of the dual-issue instruction. During dispatch of the dual-issue instruction by the microprocessor, the dual dependency matrices are employed as follows: a Load-Store Unit (LSU) dependency matrix is written with the plurality of LSU dependencies and a non-LSU dependency matrix is written with the plurality of non-LSU dependencies; an LSU issue valid (LSU IV) indicator is set as valid to issue; an LSU portion of the dual-issue instruction is issued once the plurality of LSU dependencies of the dual issue instruction are satisfied; a non-LSU issue valid (non-LSU IV) indicator is set as valid to issue; and a non-LSU portion of the dual-issue instruction is issued once the plurality of non-LSU dependencies of the dual issue instruction are satisfied.

Abstract: Apparatus and method for operating a fuel cell system including a hydrocarbon catalytic reformer and close-coupled fuel cell stack by recycling anode syngas into the reformer in a range between 60% and 95% of the total syngas. At equilibrium conditions, oxygen required for reforming of hydrocarbon fuel is derived from endothermically reformed water and carbon dioxide in the syngas. Reforming temperature is between about 650° C. to 750° C. The stack exit temperature is about 800° C. to 880° C. such that the required endotherm can be provided by the sensible heat of the recycled syngas. The stack has approximately equal anode and cathode gas flows in opposite directions, resulting in cooling from both the anodes and cathodes.

Abstract: A solid-oxide fuel cell system wherein a reformate combustor is disposed in the reformate flow path between a hydrocarbon reformer and a fuel cell stack. At system start-up, reformate is partially burned within the combustor by admitting combustion air, and the partially-burned reformate is passed through the anode chambers of the stack to warm the anodes. In addition, reformate is passed through a cathode-air heat exchanger to warm combustion air entering the cathode chambers of the stack. The combustor may continue to be supplied with a low level of air during steady-state operation of the SOFC, thereby providing a moist environment within the anode chambers to prevent coking of the anodes and providing additional heat to the reformate. The combustor decouples the reformer from the stack thermodynamically, permitting the reformer and the stack each to run in its own optimal temperature range.

Abstract: A method for managing cache memory including receiving an instruction fetch for an instruction stream in a cache memory, wherein the instruction fetch includes an instruction fetch reference tag for the instruction stream and the instruction stream is at least partially included within a cache line, comparing the instruction fetch reference tag to a previous instruction fetch reference tag, maintaining a cache replacement status of the cache line if the instruction fetch reference tag is the same as the previous instruction fetch reference tag, and upgrading the cache replacement status of the cache line if the instruction fetch reference tag is different from the previous instruction fetch reference tag, whereby the cache replacement status of the cache line is upgraded if the instruction stream is independently fetched more than once. A corresponding system and computer program product.

Abstract: Embodiments of the invention include a method of synchronizing translation changes in a processor including a translation lookaside buffer, the method including setting a control bit to enable blocking of all fetch requests that miss the translation lookaside buffer without changing a translation state of the current process; if there is at least one pending translation, then waiting for completion of the at least one pending translation; and resetting the control bit. A processor and a computer program product are provided.

Abstract: A method for handling cache coherency includes allocating a tag when a cache line is not exclusive in a data cache for a store operation, and sending the tag and an exclusive fetch for the line to coherency logic. An invalidation request is sent within a minimum amount of time to an I-cache, preferably only if it has fetched to the line and has not been invalidated since, which request includes an address to be invalidated, the tag, and an indicator specifying the line is for a PSC operation. The method further includes comparing the request address against stored addresses of prefetched instructions, and in response to a match, sending a match indicator and the tag to an LSU, within a maximum amount of time. The match indicator is timed, relative to exclusive data return, such that the LSU can discard prefetched instructions following execution of the store operation that stores to a line subject to an exclusive data return, and for which the match is indicated.

Abstract: A system for using complex branch execution hardware and a hardware based Multiplex (MUX) to multiplex a fetch address of a future branch and a branch fetch address to one index hash value used to index a branch target prediction table for execution by a processor core, to reduce branch mis-prediction by preloading.

Abstract: A microprocessor error detection method, includes providing a primary dependency matrix, providing an issue logic for issuing a micro-op, providing a secondary dependency matrix comprising a copy of the primary dependency matrix, providing a results available vector, the results available vector including an entry for each dependency tracked, receiving an indication from issue logic that it is issuing a micro-op, reading the secondary dependency matrix row corresponding to the issued micro-op, checking if the micro-op being read is dependent on a tracked dependency that is not satisfied by determining if any bit set in the row read from the secondary dependency matrix is not set in the secondary results available vector, and receiving an indication from the issue logic if the micro-op has been rescinded.