Re: Bootstrap failure on trunk: x86_64-linux-gnu

[Eric Botcazou <ebotcazou at adacore dot com>]

> It's an ugly hack in extract_range_from_assert:
>
>   /* Special handling for integral types with super-types.  Some FEs
>      construct integral types derived from other types and restrict
>      the range of values these new types may take.
>
>      It may happen that LIMIT is actually smaller than TYPE's minimum
>      value.  For instance, the Ada FE is generating code like this
>      during bootstrap:
>
>             D.1480_32 = nam_30 - 300000361;
>             if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
>             <L112>:;
>             D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;
>
>     All the names are of type types__name_id___XDLU_300000000__399999999
>      which has min == 300000000 and max == 399999999.  This means that
>      the ASSERT_EXPR would try to create the range [3000000, 1] which
>      is invalid.
>
>      The fact that the type specifies MIN and MAX values does not
>      automatically mean that every variable of that type will always
>      be within that range, so the predicate may well be true at run
>      time.  If we had symbolic -INF and +INF values, we could
>      represent this range, but we currently represent -INF and +INF
>      using the type's min and max values.
>
>      So, the only sensible thing we can do for now is set the
>      resulting range to VR_VARYING.  TODO, would having symbolic -INF
>      and +INF values be worth the trouble?  */

I think we would need to clarify that, because I'm not sure the Ada front-end 
directly generates:

             D.1480_32 = nam_30 - 300000361;
             if (D.1480_32 <= 1) goto <L112>; else goto <L52>;
             <L112>:;
             D.1480_94 = ASSERT_EXPR <D.1480_32, D.1480_32 <= 1>;

-- 
Eric Botcazou