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The ITTAGE indirect branch predictor

(blog.nelhage.com)
49 points Bogdanp | 1 comments | 04 Jul 25 23:57 UTC | HN request time: 0.227s | source
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burnt-resistor ◴[05 Jul 25 02:17 UTC] No.44469619[source]▶
Some architectures have/had branch hint instructions.

https://arcb.csc.ncsu.edu/~mueller/cluster/ps3/SDK3.0/docs/a...

The impact of a branch miss is a particular pipeline stalls to flush the incorrect prediction. If there were resources available for the other branch to be speculatively executed concurrently and in parallel it might take less wall time.

replies(2): >>44469816 #>>44470684 #
1. pbsd ◴[05 Jul 25 03:00 UTC] No.44469816[source]▶
The Pentium 4 had branch hints in the form of taken/not taken prefixes. They were not found to be useful and basically ignored in every subsequent Intel microarchitecture, until Redwood Cove brought back the branch taken prefix in 2023.