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> Also I believe that 486 already had branch prediction I can't find any evidence to support that [1] I suppose it's technically possible to have branch predi
by tomxor 7y ago
> Also I believe that 486 already had branch prediction
I can't find any evidence to support that [1]
I suppose it's technically possible to have branch prediction on a scalar processor, but I imagine it would not be hugely beneficial.
https://books.google.com.sg/books?id=QzsEAAAAMBAJ&pg=PA59&lpg=PA59&dq=486+branch+prediction&source=bl&ots=LCXnhUpS83&sig=g59BBBuiCx-qM6bOjRW5mkq1Nug&hl=en&sa=X&ved=0ahUKEwi7k5aCucXYAhUHQY8KHcgACkUQ6AEIPDAD#v=onepage&q=486%20branch%20prediction&f=false https://books.google.com.sg/books?id=QzsEAAAAMBAJ&pg=PA59&lp...
- gpderetta 7y agoSo it seems that the 486 had a trivial not-taken predictor; but that's still different from stalling on each conditional branch and does require checkpointing and rollback on misprediction (although with a pipeline only 5 deep that's probably also not very complex). Edit: pentium did have a significantly more sophisticated predictor of course, although not without flaws.