------- Comment #11 from sebpop at gmail dot com  2010-01-08 17:55 -------
Subject: Re:  [4.5 Regression] integer wrong code bug 
        with loop

> Ok, I have that fixed locally at the place of the patch but I wonder if
> initial_condition () shouldn't return for example
>
>  1ul for (unsigned long) { 1, +, 1 }_1
>

This is correct.

> and
>
>  (int) i_2 for (int) { i_2, +, 1 }_1
>
> and further (for short i_2)
>
>  i_2 for (short) { (int) { i_2, +, 1 }_2, +, 1 }_1
>
> ?  Can the latter two happen all?

Yes, these could happen, and you are right, we should see
the initial value of a chrec through the type conversion lenses.

> Is it even correct to talk about a
> general initial condition in this case?  Consider
>
>  { { 1, +, 1 }_2, +, 1 }_1
>
> initial_condition will return 1 for the chrec even though that is not
> correct because the initial condition is not constant in loop 1.

If you want, there is an initial condition for the loop_1 and that would be
{1, +, 1}_2, and there is an initial condition 1 for loop nest loop_2:

loop_2
  i = loop_2_phi (0, i+1) = {1, +, 1}_2
  loop_1
    j = loop_1_phi (i, j+1) = {{1, +, 1}_2, +, 1}_1

> I suppose I'd only see that if instantiating the chrec at the point
> where I placed the fix?  So I really only see at most a single outer
> conversion around the chrec?

Yes, I think that at most you can have only one conversion around a chrec.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42512