[LLVMdev] Overlapping Allocas

[John Criswell]

On 12/2/11 4:27 PM, Eli Friedman wrote:
> On Fri, Dec 2, 2011 at 2:23 PM, John Criswell<criswell at illinois.edu>  wrote:
>> On 12/2/11 3:24 PM, Eli Friedman wrote:
>>> On Fri, Dec 2, 2011 at 1:04 PM, John Criswell<criswell at illinois.edu>
>>>   wrote:
>>>> Dear All,
>>>>
>>>> Is there an optimization in the x86 back-end that could cause two
>>>> alloca's to use overlapping memory?
>>> It's theoretically possible, but IIRC there isn't any such
>>> optimization implemented at the moment.
>>
>> Could the tail call optimization cause something like this?  If there's an
>> alloca in a function and the function is called recursively, could tail call
>> optimization cause all dynamic instances of the alloca to be allocated in
>> the same place on the stack?
> Yes, that's possible (although I would expect it to be rare).

Thanks.

Is there any way to turn tail call optimization off from the clang 
command line?

-- John T.

>
> -Eli