[LLVMdev] intended use/structure of AllocA/local variables

edA-qa mort-ora-y eda-qa at disemia.com
Mon Jul 1 20:14:54 PDT 2013

I'm trying to determine what is the best approach to using AllocA.
Currently I just allocate all my variables at the beginning of the
function but wondering if they should rather be done closer to the scope
they are used. This would also require a way to do a free on the
allocated structure, but there doesn't appear to be such a function.

Is it the intent that all stack variables are alloc'd at the beginning
of the function? I guess this has the advantage that LLVM then knows the
full size of the function's stack at entry and can just use fixed
offsets for all variables. It has the disadvantage that all potentially
used stack variables are always allocated, which uses more stack memory
than is actually required.

What's the intended practice with AllocA?

Can the optimizer determine when the use of two AllocA spaces is
exclusive and share the stack space?

edA-qa mort-ora-y
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