From 4bd97d4549cc9e31c2b281095f2770a6ffd50a59 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Sat, 6 Jan 2007 01:14:41 +0000 Subject: [PATCH] SF# 1409443: Expand comment to cover the interaction between f->f_lasti and the PREDICT macros. --- Python/ceval.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/Python/ceval.c b/Python/ceval.c index 7884051ffb6f..67eefba07ad8 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); -- 2.47.3