Table based data speculation circuit for parallel processing computer
DC CAFCFirst Claim
1. In a processor capable of executing program instructions in an execution order differing from their program order, the processor further having a data speculation circuit for detecting data dependence between instructions and detecting a mis-speculation where a data consuming instruction dependent for its data on a data producing instruction of earlier program order, is in fact executed before the data producing instruction, a data speculation decision circuit comprising:
- a) a predictor receiving a mis-speculation indication from the data speculation circuit to produce a prediction associated with the particular data consuming instruction and based on the mis-speculation indication; and
b) a prediction threshold detector preventing data speculation for instructions having a prediction within a predetermined range.
3 Assignments
Litigations
1 Petition
Accused Products
Abstract
A predictor circuit permits advanced execution of instructions depending for their data on previous instructions by predicting such dependencies based on previous mis-speculations detected at the final stages of processing. Synchronization of dependent instructions is provided by a table creating entries for each instance of potential dependency. Table entries are created and deleted dynamically to limit total memory requirements.
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Citations
9 Claims
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1. In a processor capable of executing program instructions in an execution order differing from their program order, the processor further having a data speculation circuit for detecting data dependence between instructions and detecting a mis-speculation where a data consuming instruction dependent for its data on a data producing instruction of earlier program order, is in fact executed before the data producing instruction, a data speculation decision circuit comprising:
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a) a predictor receiving a mis-speculation indication from the data speculation circuit to produce a prediction associated with the particular data consuming instruction and based on the mis-speculation indication; and b) a prediction threshold detector preventing data speculation for instructions having a prediction within a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a processor capable of executing program instructions in an execution order differing from the program order of the instructions, the processor further having a data speculation circuit for detecting data dependence between instructions and detecting a mis-speculation where a data consuming instruction dependent for its data on a data producing instruction of earlier program order, is in fact executed before the data producing instruction, a data speculation decision circuit comprising:
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a) a prediction table communicating with the data speculation circuit to create an entry listing a particular data consuming instruction and data producing instruction each associated with a prediction when a mis-speculation indication is received; and b) an instruction synchronization circuit only instructing a processor to delay a later execution of the particular data consuming instruction if the prediction table includes an entry.
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Specification