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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`LOAD_CONST_IMMORTAL` doesn't survive being instrumented and de-instrumented.","articleBody":"# Bug report\n\n### Bug description:\n\nWhen instrumenting, instructions are first de-optimized to their base instruction.\nWhen instrumentation is removed we assume that specialization will restore the specialized instruction.\nHowever, that doesn't happen for `LOAD_CONST_IMMORTAL` because `LOAD_CONST_IMMORTAL` isn't a specialization form of `LOAD_CONST`, but a quickened form of it.\n\nThe fix should be simple. Instead of quickening `LOAD_CONST` to `LOAD_CONST_IMMORTAL`, we add a `LOAD_CONST_MORTAL` and have `LOAD_CONST` specialize (rather than quicken) to either `LOAD_CONST_MORTAL` or `LOAD_CONST_IMMORTAL`.\n\n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-128708\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/markshannon","@type":"Person","name":"markshannon"},"datePublished":"2025-01-09T18:23:39.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/128685/cpython/issues/128685"}