Eta Scale Ab

Magnus Själander

Stefanos Kaxiras

Alberto Ros

Alexandra Jimborean

Christos Sakalis

A system and method for efficiently preventing visible side-effects in the memory hierarchy during speculative execution is disclosed. Hiding the side-effects of executed instructions in the whole memory hierarchy is both expensive, in terms of performance and energy, and complicated. A system and method is disclosed to hide the side-effects of speculative loads in the cache(s) until the earliest time these speculative loads become non-speculative. A refinement is disclosed where loads that hit in the L1 cache are allowed to proceed by keeping their side-effects on the L1 cache hidden until these loads become non-speculative, and all other speculative loads that miss in the cache(s) are prevented from executing until they become non-speculative. To limit the performance deterioration caused by these delayed loads, a system and method is disclosed that augments the cache(s) with a value predictor or a re-computation engine that supplies predicted or recomputed values to the loads that missed in the cache(s).

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Ostersund, Sweden

Magnus Själander