Abstract: A re-encoded instruction set architecture (ISA) provides smaller bit-width instructions or a combination of smaller and larger bit-width instructions to improve instruction execution efficiency and reduce code footprint. The ISA can be re-encoded from a legacy ISA having larger bit-width instructions and can be used to unify one or more ISA extensions such as application specific ASEs. The re-encoded ISA maintains assembly-level compatibility with the ISA from which it is derived. In addition, the re-encoded ISA can have new and different types of additional instructions.

Abstract: A multithreaded processor includes a thread ID for each set of fetched bits in an instruction fetch and issue unit. The thread ID attaches to the instructions and operands of the set of fetched bits. Pipeline stages in the multithreaded processor stores the thread ID associated with each operand or instruction in the pipeline stage. The thread ID are used to maintain data coherency and to generate program traces that include thread information for the instructions executed by the multithreaded processor.

Abstract: A microprocessor system includes an address generator, an address selector, and memory system having multiple memory towers, which can be independently addressed. The address generator simultaneously generates a first memory address and a second memory address that is 1 row greater than the first memory address. The address selector determines whether the row portion of the first memory address or the second memory address is used for each memory tower. Because each tower can be addressed independently, a single memory access can be used to access data spanning multiple rows of the memory system.

Abstract: A multithreaded processor includes a thread ID for each set of fetched bits in an instruction fetch and issue unit. The thread ID attaches to the instructions and operands of the set of fetched bits. Pipeline stages in the multithreaded processor stores the thread ID associated with each operand or instruction in the pipeline stage. The thread ID are used to maintain data coherency and to generate program traces that include thread information for the instructions executed by the multithreaded processor.

Abstract: A variable length instruction pipeline includes optional expansion stages that can be included in the variable length instruction pipeline to avoid pipeline stalls. The expansion stages are removed from the variable length instruction pipeline when not needed to reduce the length of the pipeline, which reduces latency and other problems associated with long pipelines. For example, in one embodiment of the present invention, a variable length instruction pipeline includes a first pipeline stage, a first expansion stage, and a second pipeline stage. The second pipeline stage is configured to selectively receive instructions from the first pipeline stage or the first expansion stage if the first expansion stage holds an instruction.

Abstract: A multi-threaded embedded processor that includes an on-chip deterministic (e.g., scratch or locked cache) memory that persistently stores all instructions associated with one or more pre-selected high-use threads. The processor executes general (non-selected) threads by reading instructions from an inexpensive external memory, e.g., by way of an on-chip standard cache memory, or using other potentially slow, non-deterministic operation such as direct execution from that external memory that can cause the processor to stall while waiting for instructions to arrive. When a cache miss or other blocking event occurs during execution of a general thread, the processor switches to the pre-selected thread, whose execution with zero or minimal delay is guaranteed by the deterministic memory, thereby utilizing otherwise wasted processor cycles until the blocking event is complete.

Abstract: A variable length instruction pipeline includes optional expansion stages that can be included in the variable length instruction pipeline to avoid pipeline stalls. The expansion stages are removed from the variable length instruction pipeline when not needed to reduce the length of the pipeline, which reduces latency and other problems associated with long pipelines. For example, in one embodiment of the present invention, a variable length instruction pipeline includes a first pipeline stage, a first expansion stage, and a second pipeline stage. The second pipeline stage is configured to selectively receive instructions from the first pipeline stage or the first expansion stage if the first expansion stage holds an instruction.

Abstract: A multi-threaded embedded processor that includes an on-chip deterministic (e.g., scratch or locked cache) memory that persistently stores all instructions associated with one or more pre-selected high-use threads. The processor executes general (non-selected) threads by reading instructions from an inexpensive external memory, e.g., by way of an on-chip standard cache memory, or using other potentially slow, non-deterministic operation such as direct execution from that external memory that can cause the processor to stall while waiting for instructions to arrive. When a cache miss or other blocking event occurs during execution of a general thread, the processor switches to the pre-selected thread, whose execution with zero or minimal delay is guaranteed by the deterministic memory, thereby utilizing otherwise wasted processor cycles until the blocking event is complete.

Abstract: A variable length instruction pipeline includes optional expansion stages that can be included in the variable length instruction pipeline to avoid pipeline stalls. The expansion stages are removed from the variable length instruction pipeline when not needed to reduce the length of the pipeline, which reduces latency and other problems associated with long pipelines. For example, in one embodiment of the present invention, a variable length instruction pipeline includes a first pipeline stage, a first expansion stage, and a second pipeline stage. The second pipeline stage is configured to selectively receive instructions from the first pipeline stage or the first expansion stage if the first expansion stage holds an instruction.

Abstract: A load/store pipeline uses a store buffer pipeline to avoid data dependency issues and resource conflicts. Store instructions are stored in the store buffer pipeline. During processing of a later store instruction, the stored instruction stores data into the memory system. Specifically the stored store instruction stores data during the same load/store pipeline stage that a load instruction would read data from the memory system. Thus, memory resource conflicts caused by a store instruction followed by a load instruction are avoided. Some embodiments of the present invention includes N store buffer stages so that a first store instruction is not carried out until the (N+1)th store instruction is processed. The delay provided by the store buffer pipeline can be used to process information regarding the store instruction such as cache hits or misses and store cancellation instructions.