Faster side exits via jump patching #140434
Description
Feature or enhancement
Proposal:
So I have another idea: I noticed side exits are extremely slow on our JITted code. I suspect the main reason is that it has 2 jumps to a side exit (one to the jump target, one tail call thru the executor). So much so that having any side exit in the hot path slows things down tremendously. I realised the JIT knows offsets to the side exit jump patches.
So I think I can implement a small little helper in the executor to rewrite the side exits from 2 jumps to 1 jump after _COLD_EXECUTOR gets hot. It would need to mmap the page again from R^X to W then back to R^X but from pypy's experience it should be worth it.
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response