10.10.21 23:38, Guido van Rossum пише:
> What's exasperating to me about this whole discussion is that nobody has
> shown any reason why this kind of code would be occurring in user code.
> STORE_FAST x LOAD_FAST x seems that it must come from a user writing
>
> x = x
No, it comes from pretty common code:
for x in a:
y = x**2
with open() as f:
for x in f:
...
x = get():
if x:
...
But there is nothing to optimize here. This sequence is already fast. It
can be replaced with "DUP_TOP; STORE_FAST x", but it would not be
faster. Even if we introduce a new combined opcode, it would not be
significantly faster, and it can slow down the eval loop.
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