llvm dev - May 2013 - [LLVMdev] clone function with constant argument, and constant fold it

Hi,

I'm writing a pass that collects some information from functions, but this
requires constant propagation/constant folding to be done on those functions
beforehand. However some of these functions have an integer argument that can
take certain constant values, and the functions are always called with these
constant values at their various call sites. What I'm trying to do is to
look at the call site, see what the constant argument is, and propagate that
into the function.

I don't want to alter the function (this is purely an analysis pass), so I
want to create a copy of the function beforehand (using cloning), pass the
constant argument to the new copy, and perform constant folding/dead code
elimination on it. Then I can do my analysis on this new, constant folded
version of the original function, collect my information, and then discard it
(Move on to the next call site with possibly a new constant).

Does this seem like a reasonable approach? To me this seems like a combination
of function cloning, interprocedural constant propagation and dead code
elimination that llvm has. Is there an easy way of using these (or certain
functions of them) to perform this task, or do I just have to borrow pieces of
code from them?

Any suggestion/advice would be appreciated.

Ali
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