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GeezerVison is showing github.com — `LOAD_CONST_IMMORTAL` doesn't survive being instrumented and de-instrumented. · Issue #128685 · python/cpython

LOAD_CONST_IMMORTAL doesn't survive being instrumented and de-instrumented. #128685

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LOAD_CONST_IMMORTAL doesn't survive being instrumented and de-instrumented.#128685
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interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

Description

@markshannon
markshannon
opened on Jan 9, 2025
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Bug report

Bug description:

When instrumenting, instructions are first de-optimized to their base instruction.
When instrumentation is removed we assume that specialization will restore the specialized instruction.
However, 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.

The 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.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

  • GH-128685: Specialize (rather than quicken) LOAD_CONST into LOAD_CONST_[IM]MORTAL #128708

Activity

  1. markshannon
    added
    type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error
    on Jan 9, 2025
  2. markshannon
    changed the title [-]`LOAD_CONST_IMMORTAL` doesn't survive being instrumented and de-instruemented.[/-] [+]`LOAD_CONST_IMMORTAL` doesn't survive being instrumented and de-instrumented.[/+] on Jan 9, 2025
  3. picnixz
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)
    on Jan 10, 2025
  4. markshannon
    added a commit that references this issue on Jan 13, 2025

    GH-128685: Specialize (rather than quicken) LOAD_CONST into LOAD_CONS…

    ddd9599
  5. brandtbucher
    closed this as completedon Jan 13, 2025
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    interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

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