[ python-Bugs-1409443 ] frame->f_lasti not always correct

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Bugs item #1409443, was opened at 2006-01-18 13:57
Message generated for change (Comment added) made by nnorwitz
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Category: Python Interpreter Core
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: John Ehresman (jpe)
>Assigned to: Raymond Hettinger (rhettinger)
Summary: frame->f_lasti not always correct

Initial Comment:
Contrary to the comment in ceval.c, the f_lasti field
is not always correct because it is not updated by the
PREDICT / PREDICTED macros.  This means that when a
GET_ITER is followed by a FOR_ITER, f_lasti will be
left at the index of the GET_ITER the first time
FOR_ITER is executed.  I don't think this is a problem
for YIELD_VALUE because it's not predicted to follow
any other opcode.

I'm running into this when examining bytecode in
calling frames within a debugger callback.

I suggest either documenting that f_lasti may be
incorrect or adjusting it in the PREDICTED macro.

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>Comment By: Neal Norwitz (nnorwitz)
Date: 2006-01-18 21:32

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Raymond?  Given that PREDICTED was added for performance, I
would lean toward updating the doc.  I didn't look at the
code, but I'm pretty sure John's description is accurate.

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