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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: 0.298s | source
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nynx ◴[05 Jul 25 00:40 UTC] No.44469206[source]▶
I must be missing something here. How would this help predict interpreter dispatch? Those won’t be a function of previous branch history or pc, which may very well be independent of the next opcode. They’d be a function of state in memory or registers.
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1. brigade ◴[05 Jul 25 01:16 UTC] No.44469360[source]▶
In a hot loop, the next opcode can be predicted quite well from the history of previous opcodes executed, especially once have a couple iterations available in your history. And the opcodes executed in an interpreter are generally equivalent to the dispatch branch target.