[llvm-dev] RFC: Resolving TBAA issues

[Daniel Berlin via llvm-dev]

On Sat, Aug 19, 2017 at 10:48 AM, Ivan A. Kosarev <ikosarev at accesssoftek.com
> wrote:

> Daniel,
>
> > This is an aggregate type that includes a type compatible
> > with the effective type of the object.  In particular,
> > x->i is an lvalue expression of type "int"
> > b->a is an lvalue expression of type "struct A"
> > "struct A" is an aggregate type that includes "int" among
> > its members.
> > Therefore, the b->a object may access x->i by TBAA
>
> My understanding is in x->i there are two accesses by lvalue, of which the
> first one is (*x) and that lvalue is of type that is not compatible with
> [any part of] struct A.
>

Assume we split it as you suggest, into foo = *x, foo.i and bar = *b, b.a

*x contains a struct containing an int.

*b contains a struct containing a struct containing an int

" an aggregate or union type that includes one of the aforementioned types
among its elements or nonstatic
data members (including, recursively, an element or non-static data member
of a subaggregate
or contained union),"

This seems to fall into the "including, recursively" part.

But, let's assume that is true for a second.

GIven
struct A *a
struct X *x

a->i
x->i

Can these accesses alias?


struct B *b
struct X *x

b->a.i
x->i

How about these?
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