RE: Undefined behavior in genautomata.c?

["Dave Korn" <dave dot korn at artimi dot com>]

----Original Message----
>From: Richard Henderson
>Sent: 19 September 2005 11:26

> On Mon, Sep 19, 2005 at 12:07:45PM +0200, Sebastian Pop wrote:
>> By the way, how is this different than detecting a bound on: ...
>>   int foo[1335];
> ...
>>   some_struct{ int foo[1335];} s;
> 
> Because here the variables are *known* to have a specific size.
> 
> Similarly with static and global variables, though you must be
> careful for
> 
>   struct S { struct B b; int x[]; };
>   struct T { struct S s; int x2[10]; } t;
> 
> where (&t.s) is used as an S in places that expect it, with 10
> data elements allocated for the flexible array member.
> 
> In the case of the (fake) flexible array member, you do not know
> how large the object allocated from malloc was unless you can
> track down the actual malloc call.

  Do you suppose the idiom is common enough that VRP could special-case
"arrays of size 1 at the end of a struct" ?  And still obtain the benefits
of the optimisation in 99.99% of all non-variable-length-tail-array cases?


    cheers,
      DaveK
-- 
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