[Bug tools/24550] eu-readelf does not know about DW_AT_GNU_{bias,numerator,denumerator}

["tromey at sourceware dot org" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=24550

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
(In reply to Mark Wielaard from comment #1)

> Could you help me with creating gnat examples that compile and show their
> usage?

For bias, the above works.

> If I try to compile your example I get two warnings:
> 
> tt.adb:4:04: warning: size clause forces biased representation for "Small"
> tt.adb:8:03: warning: size clause forces biased representation for
> "Repeat_Count_T"
> 
> Are those expected?

Yes, though I don't know the rationale.

The numerator and denominator attributes are used for fixed-point types.
There is a test for this in git@github.com:pmderodat/dwarf-ada-testsuite.git

murgatroyd. readelf -wi tests/fixedpoint/foo.o |grep DW_AT_GNU_[dn]
    <229>   DW_AT_GNU_numerator: 1
    <22a>   DW_AT_GNU_denominator: 30
    <237>   DW_AT_GNU_numerator: 0
    <238>   DW_AT_GNU_denominator: 0


> Also the subranges come out as:
[...]
> There are three things that surprised me about this.
> First that the byte_size is 1, are these types really using a full byte and
> not 2 or 6 bits?

I'm not totally sure what is going on here.  Maybe the type needs to be
used in a packed record to see it actually shrink?  I will see if I can write
a test for this.

> And second that the bias is on the subrange_type and not the base_type. Is
> that intended?

Yes, the bias only applies to subrange types, not the base type.

> Finally, why is the last type signed?

I think that's the default.  You have to request an unsigned based type
explicitly, like:

   type Byte is mod 256;
   type Repeat_Count_T is new Byte range 1 .. 2 ** 6;

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