[issue42115] Caching infrastructure for the evaluation loop: specialised opcodes

[Guido van Rossum]

Guido van Rossum <guido at python.org> added the comment:

I had a simpler idea for an inline cache for LOAD_METHOD than GH-23503. The essential part goes like this (sorry for the hybrid C/Python):

if <optimized etc.>:
    if type == lm->type and type->tp_version_tag == lm->tp_version_tag:
        meth = lm->meth
        SET_TOP(meth)
        PUSH(obj)
        DISPATCH()

name = GETITEM(names, oparg)
meth_found = _PyObject_GetMethod(obj, name, &meth)
<error check>

if meth_found:
    SET_TOP(meth)
    PUSH(obj)
    if <optimizing etc.>:
        lm = ...
        lm->type = type
        lm->meth = meth

<etc.>

What am I missing? Why is the hash of the name needed?


Oh, it's probably because there could still be an overriding value in obj.__dict__. But certainly we could check for type == lm->type before the other checks (HasFeature and tp_version_tag).

But what if we only did this for classes without an instance dict? That could work for things like list.append and str.find.

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<https://bugs.python.org/issue42115>
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