From: Raymond Hettinger Date: Sat, 6 Jan 2007 01:14:41 +0000 (+0000) Subject: SF# 1409443: Expand comment to cover the interaction between f->f_lasti and the... X-Git-Tag: v2.6a1~2312 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4bd97d4549cc9e31c2b281095f2770a6ffd50a59;p=python SF# 1409443: Expand comment to cover the interaction between f->f_lasti and the PREDICT macros. --- diff --git a/Python/ceval.c b/Python/ceval.c index 7884051ffb..67eefba07a 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -741,7 +741,16 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag) this wasn't always true before 2.3! PyFrame_New now sets f->f_lasti to -1 (i.e. the index *before* the first instruction) and YIELD_VALUE doesn't fiddle with f_lasti any more. So this - does work. Promise. */ + does work. Promise. + + When the PREDICT() macros are enabled, some opcode pairs follow in + direct succession without updating f->f_lasti. A successful + prediction effectively links the two codes together as if they + were a single new opcode; accordingly,f->f_lasti will point to + the first code in the pair (for instance, GET_ITER followed by + FOR_ITER is effectively a single opcode and f->f_lasti will point + at to the beginning of the combined pair.) + */ next_instr = first_instr + f->f_lasti + 1; stack_pointer = f->f_stacktop; assert(stack_pointer != NULL);