Intel Corporation

Michael M Hancock

Darrell D Boggs

Donald D Parker

Gary L Brown

Andrew F Glew

David B Papworth

Michael A Fetterman

Lawrence O Smith

Gail M Rupnick

Beth Schultz

A state recovery and restart method that simplifies assist handling. The recovery and restart method also handles micro-branch mispredictions. An assist sequence is executed in microcode to assist an error-causing macroinstruction. If data is required from an error-causing macroinstruction, it is fetched, decoded, and macro-alias registers are restored with macro-alias data. To recover the state of the micro-alias registers, micro-alias data from a micro-operation of the flow may be loaded into the micro-alias register. Subsequently, control returns to the Micro-operation Sequence (MS) unit to issue further error correction Control micro-operations (Cuops). In order to simplify restart, the Cuops originating from the error-causing macroinstruction supplied by the translate programmable logic arrays (XLAT PLAs) are loaded into the Cuop registers, with their valid bits unasserted. If microcode requests a restart beginning at one of the Cuops stored in the Cuop register, then the bits for that Cuop and subsequent Cuops are marked valid. Thus, the instruction can be restarted anywhere within the microcode sequence.

Method for state recovery during assist and restart in a decoder having

A decoder that includes a micro-alias register to store information from a micro-operation for use by later micro-operations in the micro-operation flow. The decoder includes one or more XLAT PLAs that produces PLA control micro-operations ('Cuops'), a microcode sequencing unit that produces microcode Cuops, and an aliasing mechanism that extracts fields and stores them in macro-alias registers. A multiplexer is provided to select the appropriate Cuop to be stored in a Cuop register. Multiple Cuops may issue each cycle. A multiplexer is coupled to select one of the Cuops and to store predetermined fields in the micro-alias register for use by subsequent Cuops. Micro-alias data and macro-alias data can be utilized simultaneously with a Cuop to form an Auop.

Decoder having independently loaded micro-alias and macro-alias

In a pipelined processor, an apparatus for handling string operations. When a string operation is received by the processor, the length of the string as specified by the programmer is stored in a register. Next, an instruction sequencer issues an instruction that computes the register value minus a pre-determined number of iterations to be issued into the pipeline. Following the instruction, the pre-determined number of iterations are issued to the pipeline. When the instruction returns with the calculated number, the instruction sequencer then knows exactly how many iterations should be executed. Any extra iterations that had initially been issued are canceled by the execution unit, and additional iterations are issued as necessary. A loop counter in the instruction sequencer is used to track the number of iterations.

Apparatus and method for handling string operations in a pipelined

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Portland, OR, United States of America

Michael M Hancock