Industrial Technology Research Institute

Shi-Sheng Shang

Ruey-Liang Ma

Dze-chaung Wang

Kun-Cheng Wu

Ching-Tang Chang

Shih-Yin Lin

Dze-Chaung Wang

George Shiang-Jyh Lai

Bing-Huang Huang

A processor is provided with a decoder, a memory connected to the decoder and an execution stage connected to the decoder. The decoder receives each instruction. Each time the decoder receives an instruction, if the instruction contains a symbolic reference, the decoder determines whether or not the symbolic reference has been resolved into a numeric operand. If the symbolic reference has been resolved into a numeric operand, the memory retrieves, from a numeric reference table, a numeric operand to which the symbolic reference has been resolved. The execution stage then executes the instruction on the retrieved numeric operand in place of the symbolic reference. If the symbolic reference has not been resolved into a numeric operand, then the execution stage searches a data object, which relates each symbolic reference to a memory slot in which a corresponding numeric operand is stored, for a numeric reference relating the symbolic reference to a corresponding numeric operand. The memory then retrieves the numeric operand, that corresponds to the unresolved symbolic reference, from the memory slot indicated by the numeric reference of the data object. The memory stores the retrieved numeric operand in the numeric reference table maintained therein. The execution stage executes the instruction on the retrieved numeric operand in place of the symbolic reference of the instruction and indicates to the decoder that the symbolic reference is resolved. &ldquo;Resolved indications,&rdquo; which each indicates whether or not a specific, respective symbolic reference is resolved, can be stored in a numeric reference buffer and accessed using the instruction fetch address as an index. The numeric reference table can also be stored in the numeric reference buffer and accessed (indexed) the same way.

Intermediate instruction execution processor which resolves symbolic references without modifying intermediate instruction code

A stack management unit for a processing system that manages multiple stacks and corresponding stack pointer data as a frame stack. The stack management unit utilizes a combination of a primary stack and a secondary stack as the frame stack. A background spill/fill detect unit determines when an overflow/underflow of the primary stack occurs. In response to an overflow/underflow condition, the background spill/fill detect unit controls the transfer of a frame portion between the primary stack and the secondary stack without halting the processing system.

Intelligent multiple stack management unit

Methods and systems are disclosed for exploring instruction-level parallelism in superscalar processors by renaming stack entries. In a first embodiment, the stack renaming is implemented in a parallel structure that renames the instructions in parallel. In a second embodiment, the stack renaming is implemented in a serial structure that renames the instructions serially. In a third embodiment, the stack renaming is implemented in a combined parallel-serial structure that renames the instruction partially in parallel and partially in series.

Methods and systems of stack renaming for superscalar stack-based data

A process is provided for determining the beginning and ending of each instruction of a variable length instruction. Data lines are stored in a first memory area which illustratively is an instruction cache. Each data line comprises a sequence of data words that are stored at sequential address in a main memory. The data lines contain multiple encoded variable length instructions that are contiguously stored in the main memory. Multiple indicators are stored in a second memory area, including one indicator associated with each data word of the data lines stored in the first memory area. Each indicator indicates whether or not its associated data word is the initial data word of a variable length instruction. A sequence of data words may be fetched from the cache. The fetched sequence of data words includes a starting data word and at least the number of data words in the longest permissible instruction. Plural indicators (i.e., a vector of indicators) are also fetched from the second memory area including one indicator associated with each of the data words of the fetched sequence. Using the indicators as delimiters of the sequence of to-be-decoded instructions, one or more non-overlapping subsequences of the sequence of data words are identified, wherein each subsequence of data words is comprised in a different, sequential to-be-decoded instruction. Each subsequence of data words is then decoded as a separate instruction.

Apparatus and method for parallel decoding of variable-length

An apparatus for producing in a superscalar pipelined system out-of-order execution and in-order completion of a set of macroinstructions, wherein the set of macroinstructions are translated into a set of microinstructions and the microinstructions are executed by the pipelined system and wherein at least some of said macroinstructions translate into more than one microinstruction, the apparatus including a result completion register having a plurality of entry fields each of which is used to indicate a completion state of a different corresponding microinstruction among the set of microinstructions; an interrupt condition register having a plurality of entry fields each of which is used to specify an occurrence of an interrupt condition during fetching, decoding, and executing a corresponding microinstruction among the set of microinstructions; an instruction size register having a plurality of entry fields which are used to identify locations of boundaries between macroinstructions among the set of microinstructions; a priority encoder which receives input from the result completion register and the instruction size register and which during operation generates an output indicating when all of the microinstructions of a next-in-line macroinstruction have been executed; and a retirement controller which receives the output from the priority encoder and which during operation in response to the output of the priority encoder retires the next-in-line macroinstruction when said output indicates that all of the microinstructions of the next-in-line macroinstruction have been executed.

Growing community of inventors

Kaohsiung, Taiwan

Shi-Sheng Shang