[LLVMdev] How to handle size_t in front ends?

[Talin]

For the most part, it appears that writing a front end can be almost 
entirely platform-independent. For example, my front end doesn't know 
how big a pointer is, and for the most part doesn't care. All of the 
platform-specific aspects of compilation have, up to this point, been 
hidden behind the IR.

However, where things get tricky is in calling C functions that take a 
size_t as a parameter. Since a size_t is the same size as a pointer, it 
may be either 32 or 64 bits depending on the target platform. All of a 
sudden, I can no longer generate 'target-neutral' IR, but instead must 
introduce into the front end knowledge about the target platform.

So my questions are:

1) Is there a way to declare an integer type in the IR that represents 
"an int the same size as a pointer" without specifying exactly the size 
of a pointer?

2) Assuming the above answer is "no", what's the best way for the front 
end to measure the size of a pointer?

-- Talin