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It's not even about the expense of implementing diverging paths in hardware. This concept, of exploring like a tree vs a path was explored under the name Disjo
by jasonwatkinspdx 5y ago
It's not even about the expense of implementing diverging paths in hardware.
This concept, of exploring like a tree vs a path was explored under the name Disjoint Eager Execution. You know what killed it? Branch predictors. In a world where branch predictors are maybe only 75% effective, DEE could make sense. We live in a world where branch predictors are far better than that. So it just isn't worth speculating off the predicted most likely path.
- monocasa 5y agoWhat killed it was more the effectiveness of Tomasulo style out of order machinery, and the real problem not being control hazards, but data hazards. DEE was thought of in a day where memory was about as fast as the processor. That's why it's always being compared with cores like R3000.