How to tell if a pointer is "this"?

IR & Optimizations
1

I’m looking for a way to distinguish “this” from other pointers and wonder how to tell the difference in LLVM. Any pointer is appreciated.

2

What are you trying to do? There are no “this” pointers in IR. There are just regular pointers, so there is no difference. If you compile from C++, it’s usually passed as an implicit first argument (that’s also noundef, nonnull and dereferenceable), but there is nothing special about it in IR. You can try compiling a few simple C++ snippets to IR to get a better understanding: Compiler Explorer (you can notice that there is virtually no difference between A::foo and bar).

3

If its type matches, any pointer can be this I think - would there be a specific optimization for this considering?

4

Thanks very much for your responses @danilaml @aqjune. I was trying to reason about its semantic of being nonmodifiable in C++. Probably this semantic is already captured by attributes. I need to do some exploration.

5

Conceptually, I think “this” would be a const pointer to either const or non-const data, depending on whether the method was marked const or not. I suppose there could be an IR attribute that marks a parameter as unmodifiable? I don’t work with IR enough to know off the top of my head.