[GSoC] generation of GCC expression trees from isl ast expressions

[Roman Gareev]

> I assume so. However, we always want signed types, so the second
> argument should be zero, no?

Yes, you are right.

> How did you verify that the semantics of the GCC and isl expressions are
> identical?

I haven't tested it on examples yet. I've only matched their semantics
from the isl manual and the documentation of gcc internals
(https://gcc.gnu.org/onlinedocs/gccint/Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions).

> The kind of code you write looks very good. Now, the only question is
> how can we commit it as quickly as possible. This means we need to add
> just enough functionality such that we create a working subset that is
> testable. Testing in gcc is a little difficult, as we commonly work
> from C output to a testable executable. Maybe we should have a look at
> the existing graphite test cases for -fgraphite-identify and identify
> the simplest ones. Or we can even create simpler ones.
>
> I assume the easiest one is a single loop:
>
> for (i = 0; i < 100; i++)
>   A[i] = i;
>
> Alternatively, we could try create unit tests for the expressions.
> However, I am not sure if there exists a unit-test infrastructure in
> gcc.

Yes, I've started to working on simple DejaGnu test cases for these
expressions, which will possibly use the previous ones.

--
                                   Cheers, Roman Gareev