perf: Optimize iterator advance() call #4237
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Skylion007
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rwgk
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Oct 12, 2022
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Description
Inspired by #4232, I found one other place where we ignore the return value of C-API function and blindly call PyErr_Occurred(). Worse, it's in a very hot piece of code, (the advance() function for iterators in C++ bindings). The official C-API documentation example code clearly shows that PyErr_Occurred() check is only necessary when the iteration terminates (ie. the next pointer returned is not null).
PyErrOccurred()involves a good deal of pointer chasing so best to avoid having to so every step: https://github.com/vstinner/pythondev/blob/d7a8d069e5a5d7ad26503f98a2d29c1508a03e73/assembly.rstSuggested changelog entry: