[LLVMdev] Overlapping Allocas

John Criswell criswell at illinois.edu
Fri Dec 2 14:23:42 PST 2011

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?

-- John T.

> -Eli

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