Hi Eric, using your nice patch, I expected both a speed increase and a size decrease. The latter did not happen, because the exception is tested twice. #define StacklessUnwindAndRPyExceptionHandling(unwind_label, resume_label, exception_label) \ if (RPyExceptionOccurred()) { \ if (slp_frame_stack_bottom) \ goto unwind_label; \ resume_label: \ if (RPyExceptionOccurred()) \ FAIL(exception_label); \ } Just out of curiosity: does the code shrink if we do this? : #define StacklessUnwindAndRPyExceptionHandling(unwind_label, resume_label, exception_label) \ resume_label: \ if (RPyExceptionOccurred()) { \ if (slp_frame_stack_bottom) \ goto unwind_label; \ FAIL(exception_label); \ } Maybe this is slightly less machine code and not slower in the common case. Is it correct, btw? :-) ciao - chris -- Christian Tismer :^) <mailto:tismer@stackless.com> tismerysoft GmbH : Have a break! Take a ride on Python's Johannes-Niemeyer-Weg 9A : *Starship* http://starship.python.net/ 14109 Berlin : PGP key -> http://wwwkeys.pgp.net/ work +49 30 802 86 56 mobile +49 173 24 18 776 fax +49 30 80 90 57 05 PGP 0x57F3BF04 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04 whom do you want to sponsor today? http://www.stackless.com/