(original) (raw)

The variables ptra and ptrb don't actually alias. A simple way to think of aliasing is to to say two l-values alias if assigning into one changes the other. In your program changing the value of ptra does not change the value of ptrb. What you do have is two pointers that point to the same l-value. The aliasing analysis will show that variable a (which is address taken) is aliased to a shadow of type int. Any indirections through ptra or ptrb will use that same shadow. This is how clang and llvm get the aliasing correct.

This is a common mistake when learning about aliasing. People often think the pointer should alias the object. It's really the shadow (i.e. a pointer indirection) that aliases the object. In fact you can never have two variables ever alasing each other.

Regards
--
Sean Perry
Compiler Development
IBM Canada Lab
(905)-413-6031 (tie 313-6031), fax (905)-413-4839


"��ԣ� ������� via llvm-dev" ---12/12/2018 11:54:24 AM---Dear LLVM Developers, My name is Artem Vopilov, I am a student at TU Darmstadt. I am writing to you

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