On Freedag 28 Oktober 2005 09:30, Dave Jones wrote:
> gcc is dumb, it doesn't realise that the variable will be filled by another
> function if its passed thus..
>
> unsigned long foo
> bar(&foo)
> if (foo==1)
> ...
>
> With bar() filling in content of foo.
> I believe there's at least once instance of this in gcc bugzilla.
>
The case is more complicated here. gcc before 4.0 always assumed that
bar(&foo); initializes foo. gcc-4.0 now looks into bar if it is inlining
that and tries to find out if that really initializes foo in every
case.
In the example, bvec_alloc_bs does not initialize &idx when nr is not
between 1 and BIO_MAX_PAGES, so gcc is telling the truth here.
Arnd <><
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