ZJIT: Profile each instruction at most num_profiles times #13903
+56
−26
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This PR changes ZJIT instructions to only profile at most
--zjit-num-profiles
times.ZJIT currently profiles all instructions for
num_profiles
calls, but when the ISEQ contains a while loop, each instruction can be profiled more thannum_profiles
times, which I didn't expect. So this PR optimizes such cases. We don't really use while loops in reality, but loop methods themselves use a while loop, so this will be helpful for real-world code too.There's a trade-off that we need to consume more memory for the per-insn counters, but the impact seems significant enough to justify it. In addition, we could make it more compact and/or restrict some instructions to profile only once to save memory, but it's out of scope in this PR.