On 18 September 2013 08:06, Jan Kiszka <jan.kis...@web.de> wrote: > On 2013-09-17 23:24, Peter Maydell wrote: >> On 17 September 2013 18:03, Stefan Weil <s...@weilnetz.de> wrote: >>> could you please review this patch which removes code added by you earlier? >>> I have run tests with the old code and assertions to see whether the values >>> were really smashed. They never were, and from the documentation of setjmp >>> I'd not expect that they ever might be. >> >> We had a discussion about this back in 2011. Any compiler which needs >> these statements is definitely buggy -- the C standard mandates that >> they're not needed. > > I'm not that sure about this. We have a no-return function involved > between setjmp and the actual longjmp. Why should the compiler have to > preserve local variables when entering cpu_loop_exit?
Because the C standard specification for setjmp and longjmp says it must (if they are not changed between the setjmp and the longjmp call; locals which are changed need not be preserved). I quoted the relevant section from C99 in the discussion I linked. And gcc's documentation of the 'noreturn' attribute specifically says it does not affect the exceptional path where the function returns via longjmp. -- PMM
