[LLVMdev] global question

[Mike Stump]

On Mar 7, 2009, at 8:56 AM, John Regehr wrote:
> it seems clear that a constant propagation pass could have inferred  
> that x is 0.

The only problem is that you could have another translation unit, and  
it could be in C++, and it could have a global object with a  
constructor that runs, and that constructor might set the value of x  
to 1.  So, inferring the value is 0 isn't possible in that case.  Now,  
if you do -fwhole-program and/or tell the optimizer the only export is  
main, it might have a chance at doing that you want.