Simultaneous prediction of multiple branches for superscalar pro

Details Simultaneous prediction of multiple branches for superscalar pro Simultaneous prediction of multiple branches for superscalar pro

1992-08-11

1995-07-18

Ray, Gopal C.

Boots, shoes, and leggings

395775, 3642613, 3642617, 3642631, 3642624, 3642592, 364DIG1, G06F 938

Patent

active

054349850

ABSTRACT:
System and method for predicting a multiplicity of future branches simultaneously (parallel) from an executing program, to enable the simultaneous fetching of multiple disjoint program segments. Additionally, the present invention detects divergence of incorrect branch predictions and provides correction for such divergence without penalty. By predicting an entire sequence of branches in parallel, the present invention removes restrictions that decoding of multiple instructions in a superscalar environment must be limited to a single branch group. As a result, the speed of today's superscalar processors can be significantly increased. The present invention includes three main embodiments: (1) the first embodiment is directed to a simplex multibranch prediction device, that can predict a plurality of branch groups in one cycle and provide early detection of wrong predictions; (2) the second embodiments is directed to a duplex multibranch prediction device that can detect divergence in a predicted stream, and provide redirection (correction) within the stream; and (3) the third embodiment is directed to an n-plex multibranch prediction device, that can predict n multiplicity of branch predictions simultaneously and provide an early detection of wrong predictions as well as correction of wrong predictions.

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