We currently remove_CHECK_VALIDITY ops as part of a final linear pass over JIT code, with the heuristic being:

• If any op escaped since the last validity check, leave it in.
• Otherwise, remove it.

However, this is too strict. A looser, still correct heuristic would be:

• If any op escaped since the last validity check,and we have an optimization that relies on that validity before the next validity check, leave it in.
• Otherwise, remove it.

As a simple example:_POP_TOP escapes. If we have twoPOP_TOP instructions in a row, the JIT will check validity between them, which isn't necessary.

Since it's our optimizations that create a reliance on validity checks, the removal of validity checks and the tracking of validity should be done as part of the abstract interpretation. If could be as simple as callingrequire_validity(ctx); whenever we perform a validity-requiring optimization. This helper would just re-insert the last seen_CHECK_VALIDITY instruction.

Linked PRs

• GH-131726: Split up_CHECK_VALIDITY_AND_SET_IP #131810