Potential fix for rdar://4658012

Richard Guenther richard.guenther@gmail.com
Sat Aug 26 11:36:00 GMT 2006


On 8/26/06, Josh Conner <jconner@apple.com> wrote:
> All -
>
> rdar://4658012 describes a 3.x -> 4.x gcc regression where stack usage
> for a particular C++ function increases by 36x.  I have a relatively
> simple fix that allows the sharing of stack space for temporaries
> generated by the middle-end to hold the result of functions returning
> values in memory.  Unfortunately, this approach is reported to have
> caused an Ada front-end failure at some point in time on Sparc -- see
> thread starting here:
>
>   http://gcc.gnu.org/ml/gcc/2006-08/msg00389.html
>
> So, I went looking for an approach which would fix this in the C++
> front-end instead.  However, I discovered that the C front-end has a
> similar problem.  e.g., this code:
>
>   typedef struct { char x[1000]; } S;
>   S bar (void);
>   void foo (void) {
>     bar();
>     bar();
>   }
>
> eats 2000 bytes of stack, instead of 1000.

Applying the patch doesn't change this.  Is the patch you quoted incomplete?

Thanks,
Richard.



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