prozacchiwawaprozacchiwawa
Apr 4, 2025, 1:29 AMva_list is always black magic. it's often hard to track down an actual concrete definition.
Replies
- prozacchiwawaprozacchiwawaApr 4, 2025, 1:33 AM
going back to the source
- prozacchiwawaprozacchiwawaApr 4, 2025, 1:35 AM
among the most embarrassing thing i've ever done in my life is ask david edelsohn a question i hadn't thoroughly researched first.
- prozacchiwawaprozacchiwawaApr 4, 2025, 3:07 AM
ok stumbled on a raymond chen article:
https://devblogs.microsoft.com/oldnewthing/20180817-00/?p=99515and now i understand... it's not va_list precisely, it's that using va_list causes the function to spill the registers. in reality, we're supposed to provide space for potential arg saves for the callee, _then_ the function subtracts from r1 (which raymond chen also mentions). this mirrors what i see in the prolog of sprintf
Aaron Sawdey, Ph.D.acsawdey@fosstodon.orgApr 4, 2025, 3:28 AM@prozacchiwawa I’m sure he didn’t hold it against you.