[LLVMdev] Implementing customized intrinsic

[Haohui Mai]

Dear all,

Currently I'm working on a project that add various checks into the
LLVM bitcode. For example,  I insert function calls before every
load / store instructions to guarantee that these instructions are
safe. I really want to implement them as LLVM intrinsics or ``special
function calls'' so that I am able to leverage the power of things
like InstVisitor. However, it seems it is difficult to do it without
changing LLVM's source codes, cause

i) all constructors of CallInst are private
ii) There's no interfaces for implementing customized intrinsics
(without changing intrinsics*.td)

It is very helpful to mark these checks as special calls (like
intrinsics), it would ease the implementation of optimizations since
they only work on these special calls, say, I could save some
information in the subclass of CallInst.

I also notice that the access identifier of CallInst are changed after
LLVM 2.0. I would be appreciated if you guys could explain the
rationale behind the changes.

Thank you very much.

Best,

Haohui